Mechanical Ventilation - Philadelphia University Jordan · 2013. 11. 6. · Mechanical Ventilation...

Critical Care Nursing Theory Mechanical ventilation

Dr. Abdul-Monim Batiha- Assistant Professor Of Critical Care Nursing 1

Mechanical Ventilation

Mechanical Ventilation is ventilation of the lungs by artificial means usually

by a ventilator. Once a patient’s PaO2 cannot be maintained by the basic

methods of oxygen delivery systems, i.e. masks, cannula; endotracheal

intubation and mechanical ventilation are instituted. A ventilator

delivers gas to the lungs with either negative or positive pressure.

It must be understood that no mode of mechanical ventilation can or will

cure a disease process but merely supports the patient until resolution of his/

her symptoms is accomplished.

Purposes:

Mechanical ventilation is instituted to:

1- Maintain or improve ventilation, i.e. for adequate tissue oxygenation.

2- Decrease the work of breathing and improve patient’s comfort.

Indications:

Acute respiratory failure due to:

Mechanical failure, includes neuromuscular diseases as Myasthenia

Gravis, Guillain-Barré Syndrome, and Poliomyelitis (failure of the

normal respiratory neuromuscular system)

Musculoskeletal abnormalities, such as chest wall trauma (flail chest)

Infectious diseases of the lung such as pneumonia, tuberculosis.

Abnormalities of pulmonary gas exchange as in:

Obstructive lung disease in the form of asthma, chronic bronchitis or

emphysema.

Conditions such as pulmonary edema, atelectasis, pulmonary fibrosis.



**Patients who has received general anesthesia as well as post cardiac

arrest patients often require ventilatory support until they have

recovered from the effects of the anesthesia or the insult of an arrest.

Criteria for institution of ventilatory support:

Parameters

Ventilation

indicated

Normal range

Pulmonary function studies:

Respiratory rate (breaths/min).

Tidal volume (ml/kg body wt)

Vital capacity (ml/kg body wt)

Maximum Inspiratory Force (cm

HO2)

> 35

< 5

< 15

<-20

10-20

5-7

65-75

75-100

Arterial blood Gases

PH

Pa2 (mmHg)

PaCO2 (mmHg)

< 7.25

< 60

> 50

7.35-7.45

75-100

35-45

NB. These parameters are used in making judgments about the adequacy of

respiratory function.

Types of Mechanical ventilators:

1- Negative-pressure ventilators

2- Positive-pressure ventilators.



Negative-Pressure Ventilators

- Early negative-pressure ventilators were known as ―iron lungs.‖ The

patient’s body was encased in an iron cylinder and negative pressure was

generated by a large piston to enlarge the thoracic cage. This caused

alveolar pressures to fall, and a pressure gradient was formed so that air

flowed into the lungs. The iron lung are still occasionally used today.

- Intermittent short-term negative-pressure ventilation is sometimes used in

patients with chronic diseases. Rarely, this method of support is chosen for

patients who are not candidates for aggressive mechanical ventilation as

provided through an artificial airway. These patients suffer from a wide

variety of conditions such as

- COPD,

- Diseases of the chest wall (kyphoscoliosis),

- Neuromuscular diseases (Duchenne’s muscular

dystrophy, amyotrophic lateral sclerosis [ALS]).

- The iron lung is cumbersome to use and very large. Most negative-pressure

ventilators in use today are more portable. To improve mobility and

comfort, there is a device that fits like a tortoise shell, forming a seal over

the chest. A hose connects the shell to a negative-pressure generator. The

thoracic cage is literally pulled outward to initiate inspiration.



- The use of negative-pressure ventilators is restricted in clinical practice,

however, because they limit positioning and movement and they lack

adaptability to large or small body torsos.

- Our focus will be on the positive-pressure ventilators.

Positive-pressure ventilators

- Positive-pressure ventilators deliver gas to the patient under positive-

pressure, during the inspiratory phase.

Positive-Pressure Ventilators

Volume Ventilators.

- The volume ventilator is commonly used in critical care settings. The basic

principle of this ventilator is that a designated volume of air is delivered

with each breath.

- The amount of pressure required to deliver the set volume depends on :-

- Patient’s lung compliance

- Patient–ventilator resistance factors.

- Therefore, PIP must be monitored in volume modes because it varies from

breath to breath.



- With this mode of ventilation, a respiratory rate, inspiratory time, and tidal

volume are selected for the mechanical breaths.

Pressure Ventilators.

- The use of pressure ventilators is increasing in critical care units. A typical

pressure mode delivers a selected gas pressure to the patient early in

inspiration, and sustains the pressure throughout the inspiratory phase. By

meeting the patient’s inspiratory flow demand throughout inspiration,

patient effort is reduced and comfort increased.

- Although pressure is consistent with these modes, volume is not. With

changes in resistance or compliance, volume will change.

- Therefore, exhaled tidal volume is the variable to monitor closely.

- With pressure modes, the pressure level to be delivered is selected, and

with some mode options (i.e., pressure controlled [PC], described later),

rate and inspiratory time are preset as well.

High-Frequency Ventilators.

- The high-frequency ventilator accomplishes oxygenation by the diffusion

of oxygen and carbon dioxide from high to low gradients of concentration.

This diffusion movement is increased if the kinetic energy of the gas

molecules is increased.

- High-frequency ventilators use small tidal volumes (1 to 3 mL/kg) at

frequencies greater than 100 breaths/minute. The breathing pattern of a

person on a high-frequency ventilator is somewhat analogous to the

breathing pattern of a panting dog; panting entails moving small volumes

of air at a very fast rate.

- A high-frequency ventilator would be used to achieve lower peak

ventilatory pressures, thereby



- Lowering the risk of barotrauma

- Improving ventilation– perfusion matching because .

- Potential adverse effects associated with high-frequency ventilators

include:

- Gas trapping

- Necrotizing tracheobronchitis, when used in the absence of adequate

humidification.

Classification of positive-pressure ventilators:

- Ventilators are classified by their method of cycling from the inspiratory

phase to the expiratory phase (changeover from inspiratory to expiratory

phase), that is to say according to how the inspiratory phase ends. The

factor which terminates the inspiratory cycle reflects the machine type.

- They are classified as: pressure, volume or time cycled machines.

Volume-cycled ventilator,

- In which inspiration is terminated after a preset volume has been delivered

by the ventilator. i.e. the ventilator delivers a preset tidal volume (VT), and

inspiration stops when the preset tidal volume is achieved.

Pressure-cycled ventilator,

- In which inspiration is terminated when a specific airway pressure has been

reached. i.e. the ventilator delivers a preset pressure; once this pressure is

achieved, end inspiration occurs.



Time-cycled ventilator,

- In which inspiration is terminated when a preset inspiratory time, has

elapsed. Time cycled machines are not used in adult critical care settings.

They are used in pediatric intensive care areas.

Ventilator Modes

- Several different modes of ventilatory control are available on ventilators.

- There is no one best mode for managing patients in respiratory failure,

although each mode has its advantages and disadvantages.

Modes of mechanical ventilation

- The term ―ventilator mode‖ refers to the way the machine ventilates the

patient .i.e. how much the patient will participate in his own ventilatory



pattern. Each mode is different in determining how much work of

breathing the patient has to do.

A- Volume Modes

1- Assist-control (A/C) mode

2- Synchronized intermittent mandatory ventilation (SIMV) mode.

1- Assist Control Mode A/C

- The ventilator provides the patient with a pre-set tidal volume at a pre-set

rate and the patient may initiate a breath on his own, but the ventilator

assists by delivering a specified tidal volume to the patient.

- Client can initiate breaths that are delivered at the preset tidal volume.

- Client can breathe at a higher rate than the minimum number of

breaths/minute that has been set.

- The total respiratory rate is determined by the number of spontaneous

inspiration initiated by the patient plus the number of breaths set on the

ventilator.

- In A/C mode, a mandatory (or ―control‖) rate is selected.

- If the patient wishes to breathe faster, he or she can trigger the ventilator

and receive a full-volume breath.

- Often used as initial mode of ventilation

-This mode of ventilation is often used fully to support a patient, such as

- When the patient is first intubated

- When the patient is too weak to perform the work of breathing

(e.g., when emerging from anesthesia).

Advantages:

- Ensures ventilator support during every breath

- Each breath has the same tidal volume

Disadvantages:

- Hyperventilation,

- Air trapping

- Work of breathing may be increased if sensitivity or flow rate is too low.



2- Synchronized Intermittent Mandatory Ventilation SIMV

- The ventilator provides the patient with a pre-set number of breaths/minute

at a specified tidal volume and fio2. In between the ventilator-delivered

breaths, the patient is able to breathe spontaneously. The ventilator does

not assist the spontaneous breaths i.e. the patient determines the respiratory

rate and tidal volume.

- Between machine breaths, the client can breathe spontaneously at his own

tidal volume and rate with no assistance from the ventilator.

- In SIMV mode, the rate and tidal volume are preset.

- If the patient wants to breathe above this rate, he or she may.

- However, unlike the A/C mode, any breaths taken above the set rate are

spontaneous breaths taken through the ventilator circuit.

- The tidal volume of these breaths can vary drastically from the tidal

volume set on the ventilator, because the tidal volume is determined solely

by the patient’s spontaneous effort.

- Adding pressure support during spontaneous breaths can minimize the risk

of increased work of breathing. In the past, SIMV has been used as a

popular weaning mode.

- Same as intermittent mandatory ventilation except stacking is avoided i.e.

ventilators breaths are synchronized with the patient spontaneous breathe.

- Used to wean the patient from the mechanical ventilator.

- To wean the patient, the mandatory breaths were gradually decreased,

thereby allowing the patient to assume more and more of the work of

breathing.

- Often used as initial mode of ventilation and for weaning

Advantages:

- Allows spontaneous breaths (tidal volume determined by patient) between

ventilator breaths;

- Weaning is accomplished by gradually lowering the set rate and allowing

the patient to assume more work

Disadvantages:

Patient–ventilator asynchrony possible



B- Pressure Modes

- Pressure modes include :-

1- Pressure-controlled ventilation (PCV) mode,

2- Pressure-support ventilation (PSV) mode,

3- Continuous positive airway pressure (CPAP)/PEEP mode,

5- Noninvasive bilevel positive airway pressure ventilation (BiPAP) mode.

1- Control Mode CM

Continuous Mandatory Ventilation( CMV)

- Ventilation is completely provided by the mechanical ventilator with a

preset tidal volume, respiratory rate and oxygen concentration prescribed

by the physician.

-Ventilator totally controls the patient’s ventilation i.e. the ventilator initiates

and controls both the volume delivered and the frequency of breath.

- Client does not breathe spontaneously.

- Client can not initiate breathe

1- Pressure-Controlled Ventilation Mode( PCV)

The PCV mode is used

- to control plateau pressures in conditions such as ARDS where

compliance is decreased and the risk of barotrauma is high.

- It is used when the patient has persistent oxygenation problems

despite a high FIO2 and high levels of PEEP.

- The inspiratory pressure level, respiratory rate, and inspiratory–expiratory

(I:E) ratio must be selected.

- Tidal volume varies with compliance and airway resistance and must be

closely monitored.



- Sedation and the use of neuromuscular blocking agents are frequently

indicated, because any patient–ventilator asynchrony usually results in

profound drops in the SaO2.

- This is especially true when inverse ratios are used. The ―unnatural‖

feeling of this mode often requires muscle relaxants to ensure patient–

ventilator synchrony.

- Most ventilators operate with a short inspiratory time and a long expiratory

time (1:2 or 1:3 ratio). This promotes venous return and allows time for air

to exit the lungs passively.

- Inverse ratio ventilation (IRV) mode reverses this ratio so that inspiratory

time is equal to, or longer than, expiratory time (1:1 to 4:1).

- Inverse I:E ratios are used in conjunction with pressure control

to improve oxygenation in patients with ARDS by expanding stiff

alveoli by using longer distending times,

thereby providing more opportunity for gas exchange and

preventing alveolar collapse.

- As expiratory time is decreased, one must monitor for the development of

hyperinflation or auto-PEEP. Regional alveolar overdistension and

barotrauma may occur owing to excessive total PEEP.

- When the PCV mode is used, the mean airway and intrathoracic pressures

rise, potentially resulting in a decrease in cardiac output and oxygen

delivery. Therefore, the patient’s hemodynamic status must be monitored

closely.

- Used to limit plateau pressures that can cause barotrauma

Severe ARDS

Disadvantages:

Patient–ventilator asynchrony possible, necessitating sedation/paralysis

Monitor

a- Tidal volume at least hourly.

b- Barotraumas

c- Hemodynamic instability

Inverse ratio ventilation (IRV)

Usually used in conjunction with PCV



Increases ratio I:E to

a- Allow for recruitment of alveoli

b- Improve oxygenation

Disadvantages:

- Almost always requires paralysis

Monitor for

a- Auto-PEEP,

b- Barotrauma,

c- Hemodynamic instability.

2- Pressure Support Ventilation ( PSV)

- The patient breathes spontaneously while the ventialtor applies a pre-

determined amount of positive pressure to the airways upon inspiration.

- Pressure support ventilation augments patient’s spontaneous breaths with

positive pressure boost during inspiration i.e. assisting each spontaneous

inspiration.

- Helps to overcome airway resistance and reducing the work of breathing.

- Patient must initiate all pressure support breaths.

- Pressure support ventilation may be combined with other modes such as

SIMV or used alone for a spontaneously breathing patient.

- Indicated for patients with small spontaneous tidal volume and difficult to

wean patients.

- It is a mode used primarily for weaning from mechanical ventilation.

- PSV mode augments or assists spontaneous breathing efforts by delivering

a high flow of air to a selected pressure level early in inspiration, and

maintaining that level throughout the inspiratory phase.

- The patient’s effort determines the rate, inspiratory flow, and tidal volume.

- When PSV mode is used as a stand-alone mode of ventilation, the pressure

support level is adjusted to achieve the approximate targeted tidal volume

and respiratory rate.

- At high pressure levels, PSV mode provides nearly total ventilatory

support.

- Specific uses of PSV are

- To promote patient comfort



- To promote synchrony with the ventilator,

- To decrease the work of breathing necessary to

overcome the resistance of the endotracheal tube,

- For weaning. As a weaning tool,

- PSV is thought to increase the endurance of the respiratory muscles by

- Decreasing the physical work

- Decreasing oxygen demands during spontaneous breathing.

- Because the level of pressure support can be gradually decreased,

endurance conditioning is enhanced.

- In PSV mode, the inspired tidal volume and respiratory rate must be

monitored closely to detect changes in lung compliance.

- In general, if compliance decreases or resistance increases, tidal volume

decreases and respiratory rate increases.

- PSV mode should be used with caution in patients with

- Bronchospasm

- other reactive airway conditions.

Intact respiratory drive in patient necessary

Used as a weaning mode, and in some cases of dyssynchrony

2- Continuous Positive Airway Pressure CPAP (a variation of PEEP)

- Positive pressure applied at the end of expiration during spontaneous

breaths i.e. for patients breathing spontaneously.

- No mandatory breaths (ventilator-initiated are delivered in this mode)

- All ventilation is spontaneously initiated by the patient.

- PEEP & CPAP are used in patients with hypoxemia refractory to oxygen

therapy. They improve oxygenation by opening collapsed alveoli &

preventing them from collapsing at the end of expiration.

- CPAP allows the nurse to observe the ability of the patient to breathe



spontaneously while still on the ventilator.

- CPAP is supplied during spontaneous breathing. PEEP is the term used to

describe positive end-expiratory pressure with positive-pressure (machine)

breaths. CPAP assists spontaneously breathing patients to improve their

oxygenation by elevating the end-expiratory pressure in the lungs

throughout the respiratory cycle.

- CPAP can be used for intubated and nonintubated patients.

- It may be used as a weaning mode and for nocturnal ventilation (nasal or

mask CPAP) to splint open the upper airway, preventing upper airway

obstruction in patients with obstructive sleep apnea.

- Constant positive airway pressure for patients who breathe spontaneously

Advantages:

- Used in intubated or nonintubated patients

Disadvantages:

- On some systems, no alarm if respiratory rate falls

- Monitor for increased work of breathing.

4- Noninvasive Bilateral Positive Airway Pressure Ventilation (BiPAP)

- BiPAP is a noninvasive form of mechanical ventilation provided by means

of a nasal mask or nasal prongs, or a full-face mask.

- It is used in the treatment of :-

a- Patients with chronic respiratory insufficiency to manage acute or

chronic respiratory failure without intubations and conventional

mechanical ventilation.

b- Used as a bridge to weaning patients from mechanical ventilation,

c- As an alternative to conventional mechanical ventilation in patients

who are ventilated in their homes.



- The system allows the clinician to select two levels of positive-pressure

support:

a- An inspiratory pressure support level (referred to as IPAP)

b- An expiratory pressure called EPAP (PEEP/CPAP level).

- BiPAP is beneficial in worsening nocturnal hypoventilation in patients

with

- Neuromuscular disease,

- Chest wall deformity,

- Obstructive sleep apnea,

- COPD;

- To avoid intubation in patients with respiratory failure & hypercarbia

- To avoid reintubation after extubation in borderline cases.

- Ventilation with a full-face mask should be used cautiously because it may

increase the risk of aspiration and of rebreathing carbon dioxide;

- Thick or copious secretions and poor cough may be relative

contraindications to BiPAP.

Advantages:

a- Decreased cost when patients can be cared for at home;

b- No need for artificial airway

Disadvantages:

- Patient discomfort or claustrophobia

- The patient should be monitored for :-

a- Gastric distension,

b- Air leaks from mouth



Common Ventilator Settings

● Fraction of inspired oxygen (FIO2)

- The percent of oxygen concentration that the patient is receiving from the

ventilator. (Between 21% & 100%) (room air has 21% oxygen content).

- Most ventilators allow for easy adjustment of oxygen percentage (FIO2) by

means of a dial. Oxygen analyzers, either in-circuit or external, allow the

nurse to ascertain the FIO2 that is being delivered.

- Initially a patient is placed on a high level of FIO2 (60% or higher).

Subsequent changes in FIO2 are based on ABGs and the SaO2.

- In adult patients who can tolerate higher levels of oxygen for a period of

time, the initial FiO2 may be set at 100% until arterial blood gases can

document adequate oxygenation.

- An FiO2 of 100% for an extended period of time can be dangerous

( oxygen toxicity) but it can protect against hypoxemia from

unexpected intubation problems.

- For infants, and especially in premature infants, high levels of FiO2

(>60%) should be avoided.

- Usually the FIO2 is adjusted to maintain an SaO2 of greater than 90%

(roughly equivalent to a PaO2 >60 mm Hg). Oxygen toxicity is a concern

when an FIO2 of greater than 60% is required for more than 25 hours;

therefore, most clinicians attempt to use strategies to allow for

maintenance of an FIO2 of 60% or less.

Signs and symptoms of oxygen toxicity :-

1- Flushed face

2- Dry cough

3- Dyspnea

4- Chest pain

5- Tightness of chest



6- Sore throat

Tidal Volume (VT)

- The volume of air delivered to a patient during a ventilator breath.

- The amount of air inspired and expired with each breath.

(Usual volume selected is between 5 to 15 ml/ kg body weight)

- In the volume ventilator, Tidal volumes of 10 to 15 mL/kg of body weight

were traditionally used.

- Research has identified a phenomenon of iatrogenic lung injury

(volutrauma) in which forces produced in the lungs by the large tidal

volumes may aggravate the damage inflicted on the lungs by the

pathological process that necessitated mechanical ventilation.

- For this reason, lower tidal volume targets (6 to 8 mL/kg) are now

recommended.

Peak Flow/ Flow Rate

- Peak flow is the velocity/ spead of air flow (delivering air) per unit of time,

and is expressed in liters per minute. On many volume ventilators, this is a

separate dial.

- If auto-PEEP (due to inadequate expiratory time) is present, peak flow is

increased to shorten inspiratory time so that the patient may exhale

completely.

- However, increasing peak flow increases turbulence, which is reflected in

increasing airway pressures.

- In the pressure ventilator, the inspiratory time determines the duration of

inspiration by regulating the air flow rate.

- The higher the flow rate, the faster peak airway pressure is

reached and the shorter the inspiration;

- The lower the flow rate, the longer the inspiration.

- A very high flow rate may produce turbulence, shallow inspirations, and



uneven distribution of volume.

Respiratory Rate/ Breath Rate / Frequency ( F)

- The number of breaths the ventilator will deliver/minute (10-16 b/m).

- Total respiratory rate equals patient rate plus ventilator rate.

- The nurse double-checks the functioning of the ventilator by observing the

patient’s respiratory rate.

For adult patients and older children:-

- Without existing lung disease --- a tidal volume of 12 mL per kg

body weight is set to be delivered at a rate of 12 times a minute

- With COPD ---A reduced tidal volume of 10 ml/kg is to delivered

10 times a minute to prevent overinflation and hyperventilation.

- With chronic pulmonary disease, however, should be ventilated to

stay relatively close to their normal ABG values. This usually means

accepting relatively high carbon dioxide levels, lower-than average

oxygenation, or both.

- With ARDS --- a more reduced tidal volume of 6-8 mL/kg is used with a

rate of 10-12/minute. This reduced tidal volume allows for minimal

volutrauma but may result in an elevated PCO2 (due to the relative

decreased oxygen delivered) but this elevation does not need to be

corrected (termed permissive hypercapnia)

For infants and younger children:-

- Without existing lung disease -- a tidal volume of 4-10 ml/kg to be

delivered at a rate of 30-35 breaths per minute.

- With ARDS -- decrease tidal volume and increase respiratory rate

sufficient to maintain PCO2 between 45-55. Allowing higher PCO2 ,

may help prevent ventilator induced lung injury

Minute Volume (VE)

- The volume of expired air in one minute .

http://en.wikipedia.org/wiki/RDS



- Respiratory rate times tidal volume equals minute ventilation

- VE = (VT x F)

- Minute volume determines alveolar ventilation.

- Increasing the minute volume decreases the PaCO2. Conversely, decreasing

the minute volume increases the PaCO2.

- In special cases, hypoventilation or hyperventilation is desired.

In a patient with head injury,

Respiratory alkalosis may be required to promote cerebral

vasoconstriction, with a resultant decrease in ICP.

In this case, the tidal volume and respiratory rate are increased to

achieve the desired alkalotic pH by manipulating the PaCO2.

In a patient with COPD

Baseline ABGs reflect an elevated PaCO2 should not hyperventilated.

Instead, the goal should be restoration of the baseline PaCO2.

These patients usually have a large carbonic acid load, and lowering

their carbon dioxide levels rapidly may result in seizures.

Rate adjustments may also be necessary to enhance patient comfort or

when rapid rates cause air trapping that result in auto-PEEP.

I:E Ratio (Inspiration to Expiration Ratio):-

- The ratio of inspiratory time to expiratory time during a breath

(Usually = 1:2)

Sigh:-

- A deep breath.

- A breath that has a greater volume than the tidal volume.

- It provides hyperinflation and prevents atelectasis.



Sigh volume :------------------Usual volume is 1.5 –2 times tidal volume.

Sigh rate/ frequency :---------Usual rate is 4 to 8 times an hour.

Peak Airway Pressure:-

- In adults if the peak airway pressure is persistently above 45 cmH2O, the

risk of barotrauma is increased and efforts should be made to try to reduce

the peak airway pressure.

- In infants and children it is unclear what level of peak pressure may cause

damage. In general, keeping peak pressures below 30 is desirable.

Pressure Limit

- On volume-cycled ventilators, the pressure limit dial limits the highest

pressure allowed in the ventilator circuit.

- Once the high pressure limit is reached, inspiration is terminated.

- Therefore, if the pressure limit is being constantly reached, the designated

tidal volume is not being delivered to the patient.

- The cause of this can be :-

- Coughing,

- Accumulation of secretions,

- kinked ventilator tubing,

- Pneumothorax,

- Decreasing compliance

- A pressure limit set too low.

Positive End-Expiratory Pressure (PEEP)

- Positive pressure applied at the end of expiration during ventilator breaths.

- The PEEP control adjusts the pressure that is maintained in the lungs at the

end of expiration.

- PEEP can be visualized on the respiratory pressure gauge or display.

Instead of returning to zero (atmospheric pressure) at the end of



expiration, the pressure value drops to the PEEP level.

- Reduction of PEEP is considered if

- PaO2 is 80 to 100 mm Hg on an FIO2 of 50% or less,

- Hemodynamic stablility,

- Stabilization or improvement of the underlying illness.

- Monitor the effects of PEEP before and after changes in PEEP by

evaluating :-

- ABGs,

- SaO2,

- Compliance,

- Hemodynamic pressures (cardiac output & blood pressure)

- PEEP is usually USED IN low levels increased in increments of 2 to 5 cm

H2O in the intubated patient.

- Monitor the patient for adverse effects, such as :-

- Hypotension

- Dysrhythmias.

- If these occur, the PEEP is reduced. If higher PEEP is tolerated, the patient

is stabilized on the new PEEP settings for approximately 15 minutes. The

monitored parameters are then repeated.

- Hemodynamic measurements are taken at end-expiration with the patient

on PEEP.

- Cardiac output [ CO ],

- Pulmonary artery pressure [PAP],

- Central venous pressure [CVP],

- Pulmonary artery wedge pressure [PAWP]

- Accuracy in selecting the point of end-expiration on the waveform tracing



is facilitated by using continuous airway monitoring ( PEEP does not need

to be discontinued before obtaining hemodynamic measurements.

- Hemodynamic measurements can be inaccurate (as an indicator of volume

status) if a patient is on high PEEP or the position of the transducer is not

leveled at the phlebostatic axis.

- Attempts are made to minimize removing the patient from the ventilator

when using high levels of PEEP. Oxygenation can deteriorate and be slow

to rebound because it takes a significant amount of time for the effects of

PEEP to be reestablished. Therefore, if the patient is being oxygenated

using an MRB, it must be equipped with a valve that allows levels of

PEEP to be dialed in. An inline suction apparatus may be helpful to

prevent breaking the PEEP circuit to suction the patient.

- PEEP is increased in 2- to 5-cm H2O increments when FIO2 levels are

greater than 50% to attain an acceptable SaO2 (<90%) or PaO2 (>60 to 70

mm Hg).

- PEEP is most often necessary in patients with refractory hypoxemia (e.g.,

those with ARDS), where the PaO2 deteriorates rapidly despite greater

concentrations of oxygen administration.

- PEEP is used to keep alveoli stented open and it may recruit alveolar units

that are totally or partially collapsed.

- This end-expiratory pressure increases the functional residual capacity

(FRC) by reinflating collapsed alveoli, maintains the alveoli in an open

position, and improves lung compliance. This decreases shunt and

improves oxygenation enhances surfactant regeneration by keeping the

alveoli open.

- High levels of PEEP should rarely be interrupted because it may take

several hours to recruit alveoli again and restore the FRC; until this occurs,

oxygenation may suffer.

- The patient who does not have adequate circulating blood volume,

institution of PEEP decreases venous return to the heart, decreases cardiac

output, and decreases oxygen delivery to the tissues.

- If hypotension or decreased cardiac output results from PEEP application,



restoring circulating intravascular volume with administration of

intravenous fluids may correct the hypotension.

- Another serious complication of PEEP is barotrauma. It can occur in any

mechanically ventilated patient but is most common when high levels of

PEEP are used (≥10 to 20 cm H2O) in lungs with high ventilating pressures

and low compliance, and in patients with obstructive airway disease.

- The development of barotrauma is an emergency and usually requires

placement of a chest tube.

Sensitivity

- The sensitivity function controls the amount of patient effort needed to

initiate an inspiration, as measured by negative inspiratory effort.

- Increasing the sensitivity (requiring less negative force) decreases the

amount of work the patient must do to initiate a ventilator breath.

- Decreasing the sensitivity increases the amount of negative pressure that

the patient needs to initiate inspiration and increases the work of breathing.

Ensuring humidification and thermoregulation

- All air delivered by the ventilator passes through the water in the

humidifier, where it is warmed and saturated. Because of this, insensible

water loss is decreased.

- Humidifier temperatures should be kept close to body temperature 35 ºC-

37ºC.

- In some rare instances (severe hypothermia), the air temperatures can be

increased. Caution is advised because prolonged inhalation of air at high

temperatures can cause tracheal burns.

- The humidifier should be checked for adequate water levels

- An empty humidifier contributes to drying the airway, often with resultant

dried secretions, mucus plugging and less ability to suction out secretions.



- Humidifier should not be overfilled as this may increase circuit resistance

and interfere with spontaneous breathing.

- As air passes through the ventilator to the patient, water condenses in the

corrugated tubing. This moisture is considered contaminated and must be

drained into a receptacle and not back into the sterile humidifier.

- If the water is allowed to build up, resistance is developed in the circuit and

- PEEP is generated. In addition, if moisture accumulates near the

endotracheal tube, the patient can aspirate the water.

- The nurse and respiratory therapist jointly are responsible for preventing

this condensation buildup. The humidifier is an ideal medium for bacterial

growth. Institutional policies should describe the frequency of ventilator

circuit changes.

Ventilator alarms:-

- Mechanical ventilators comprise audible and visual alarm systems, which

act as immediate warning signals to altered ventilation.

- Mechanical ventilators are used to support life. Alarm systems are

necessary to warn the nurse of developing problems. Alarm systems can be

categorized according to volume and pressure (high and low).

- High-pressure alarms warn of rising pressures. Electrical failure alarms are

necessary for all ventilators.

- Low-pressure alarms warn of disconnection of the patient from the

ventilator or circuit leaks.

- Complications of Mechanical Ventilation:-

I- Airway Complications,

I- Mechanical complications,

III- Physiological Complications,



IV- Artificial Airway Complications.

I- Airway Complications

1- Aspiration

2- Decreased clearance of secretions

3- Nosocomial or ventilator-acquired pneumonia

II- Mechanical complications

1- Hypoventilation with atelectasis with respiratory acidosis or hypoxemia.

2- Hyperventilation with hypocapnia and respiratory alkalosis

3- Barotrauma

a- Closed pneumothorax,

b- Tension pneumothorax,

c- Pneumomediastinum,

d- Subcutaneous emphysema.

4- Alarm ―turned off‖

5- Failure of alarms or ventilator

6- Inadequate nebulization or humidification

7- Overheated inspired air, resulting in hyperthermia

III- Physiological Complications

1- Fluid overload with humidified air and sodium chloride (NaCl) retention

2- Depressed cardiac function and hypotension

3- Stress ulcers

4- Paralytic ileus

5- Gastric distension

6- Starvation

7- Dyssynchronous breathing pattern



IV- Artificial Airway Complications

A- Complications related to Endotracheal Tube:-

1- Tube kinked or plugged

2- Rupture of piriform sinus

3- Tracheal stenosis or tracheomalacia

4- Mainstem intubation with contralateral lung atelectasis

5- Cuff failure

6- Sinusitis

7- Otitis media

8- Laryngeal edema

B- Complications related to Tracheostomy tube:-

1- Acute hemorrhage at the site

2- Air embolism

3- Aspiration

4- Tracheal stenosis

5- Erosion into the innominate artery with exsanguination

6- Failure of the tracheostomy cuff

7- Laryngeal nerve damage

8- Obstruction of tracheostomy tube

9- Pneumothorax

10- Subcutaneous and mediastinal emphysema

11- Swallowing dysfunction

12- Tracheoesophageal fistula

13- Infection

14- Accidental decannulation with loss of airway



Nursing care of patients on mechanical ventilation

Assessment:

- Assess the patient

- Assess the artificial airway (tracheostomy or endotracheal tube)

- Assess the ventilator

Assessment of the mechanically ventilated patient

1- Assess the patient at least hourly for the following:

● Vital signs.

- Regularly monitor the vital signs (according to policy)

● Respiratory status

- Respiratory rate for a full minute & compared with the set ventilatory rate.

(To identify whether they are machine-controlled breaths or combined

machine-controlled and spontaneous breaths.)

- Symmetry of chest movement during machine breath

- Synchronization of chest movement with the ventilator during machine

breath

- Breath sounds q2–4h and PRN. (lack of breaths sounds may indicate that

the ETT is displaced)

- Pulse oximetry and end-tidal CO2.

- ABGs as indicated by changes in noninvasive parameters, patient status, or

weaning protocol. ( to evaluate oxygenation status & acid-base status)

- Need for suctioning. (As secretions heard during respiration, a

rise in ventilator peak inspiratory pressures, assess color, amount,

consistency & odor of sputum.)

- Perform systematic assessment of the oral mucosa daily, and with

each cleaning.

● Cardiovascular status

- Heart rate

- Blood pressure,



- Cardiac output

- Continuous cardiac monitoring should be initiated. (dysrhythmia may

occur due to:-

- Hypoxia,

- Acidosis,

- Alkalosis,

- Electrolyte imbalance.

- Central venous pressure measurement (reflect right heart function)

- Pulmonary artery pressure

- Hemodynamic effects of initiating positive-pressure ventilation (e.g.,

potential for decreased venous return and cardiac output).

- Electrocardiogram (ECG) for dysrhythmias related to hypoxemia.

- Assess effects of ventilator setting changes (inspiratory pressures, tidal

volume, positive end-expiratory pressure[PEEP], and fraction of inspired

oxygen [FIO2]) on hemodynamic and oxygenation parameters.

● Neurological status

- Level of consciousness;

- Changes in arousability

- Changes in behavior,

- Ability to follow commands,

● Renal status

- Fluid balance

- Intake and output

- Fluid balance

- Hydration status in relation to clinical examination,

- Daily weight

- Urine specific gravity, or serum osmolality

- Electrolyte values

● Gastro-intestinal status

- Gastric secretions for bleeding.

- Bowel sound



- Nutritional assessment

- PH of gastric secretion

- urea, creatinine, albumin and total protein

blood glucose levels

● Integumentary system/ skin

- Assess skin integrity at least every shift.

- Assess bony prominences for evidence of pressure injury.

● Signs & symptoms of complications

- Signs of decreased cardiac output

- Decrease in pulse &B.P

- Signs of pneumothorax (barotrauma):

- Asymmetrical chest movements;

- Diminished / absent breath sounds on

affected side;

- Cyanosis;

- Tachycardia with weak pulse;

- Hypotension.

- Signs of infection:-

- Increase temperature above 38ºC,

- Heart rate above 100 b/m

- Erythema of tracheostomy

- Change in secretions characteristics

- Blood work

- Chest X-ray

2- Assess the tracheostomy or endotracheal tube:

- Soiled or loosened tape

- Presence of ulcer in tissue around the endotracheal tube



- Endotracheal tube position through marking the point at which

the tube exits the mouth or nose. (to know whether it is moved in or out.)

- Cuff inflation pressure. (Inadequate cuff pressure can lead to loss of

delivered tidal volume.)

3- Assess the ventilator parameters/ settings at least hourly :-

- Mode of ventilation

- Ventilator setting

- Fio2

- Tidal volume VT

- Minute ventilation VE

- Respiratory rate (number of breaths / minute delivered

by the ventilator)

- PEEP level if in use or CPAP

- I:E ratio

- Sigh (frequency / rate & volume)

- Airway pressures q1–2h.

- Airway pressures after suctioning

- Alarm settings, that alarms are turned on.

- Alarm checks q4h (minimum) or per hospital protocol

- Level of water in the humidifying unit

- Temperature of the humidifier

- Tubing and connections to ensure circuit leaks do not occur

- Tubing to ensure that it is well drained and free from water build-up

NB:-

- Ventilator settings must be frequently evaluated against patient

response.

Nursing Diagnosis:

- Ineffective, airway clearance

- Ineffective Breathing Pattern

- Comfort, Altered pain



- Fluid volume excess

- Impaired Tissue Perfusion

- Impaired Acid–Base Status

- Nutrition, Altered: less than body requirements

- Altered oral mucous membrane

- Bowel Elimination, Altered: constipation

- Anxiety / Fear

- Communication, Impaired verbal

- Ineffective Coping

- Alteration in Body Image (related to intubation or tracheostomy)

- Impaired Thought Processes—Agitation or Anxiety

- High Risk for Impaired Gas Exchange

- High risk for infection

- High risk for impaired skin integrity

- High Risk for Complications Associated with Mechanical Ventilation

- High Risk for Complications Associated with Tracheostomy

Nursing Interventions:

1-Maintain airway patency& oxygenation

2- Promote comfort

3- Maintain fluid & electrolytes balance

4- Maintain nutritional state

5- Maintain urinary & bowel elimination

6- Maintain eye , mouth and cleanliness and integrity:-

7- Maintain mobility/ musculoskeletal function:-

8- Maintain safety:-

9- Provide psychological support

10- Facilitate communication

11- Provide psychological support & information to family

12- Responding to ventilator alarms /Troublshooting ventilator alarms

13- Prevent nosocomial infection

14- Documentation

Nursing Interventions

1- Maintain patent airway & Oxygenation

- Provide adequate humidification and warming

- Perform measures to mobilize secretions through chest physiotherapy



and proper suctioning technique to clear the airway (guideline for

proper suctioning technique to be revised.)

- Suction as needed for rhonchi, coughing, or oxygen desaturation.

- Hyperoxygenate and hyperventilate before and after each suction pass.

- Provide tube care through:

- Anchoring ETT securely to prevent tube movement

- Placing an oral bite block to prevent the patient from biting on tube

- Anchoring a large loop of the tube to the bed to facilitate patient

movement without tube movement.

- Checking the tube cuff pressures.

- Administer bronchodilators and mucolytics as ordered.

- Perform chest physiotherapy if indicated by clinical examination

or chest x-ray.

- Turn side to side q2h.

- Consider kinetic therapy or prone positioning as indicated by clinical

scenario.

- Get patient out of bed to chair or standing position when stable.

2- Promote comfort:-

- Perform arterial punctures by skilled personnel

- Suction tracheal secretions skillfully and gently

- Provide meticulous oral care q1–4h.

- Change position frequently

- Perform range of motion exercises

- Assist the patient to a chair as often as possible when he is stable.

- Prevent pulling and jarring of the ventilator tubing and endotracheal or

tracheostomy tube.

- Document pain assessment, using numerical pain rating or similar scale

when possible.

- Provide analgesia as appropriate, document efficacy after each dose.

- Administer sedation as indicated.

3- Maintain fluid and electrolytes balance:-

- Administer intravascular volume as ordered to maintain preload

- Administer electrolyte replacements (IV or enteral) per physician’s order.



4- Maintain nutritional state

- Administer the prescribed medication (cimetidine, ranitidine, and

antacid prophylactically)

- Provide the correct proportions of fats, CHO, and proteins as well as

water through enteral or parenteral routes.

- Establish regular bowel elimination pattern.

- Consult dietitian for metabolic needs &recommendations.

- Provide early nutritional support by enteral or parenteral feeding, start

within 48 hours of intubation.

- Administer bowel regimen medications as ordered, along with adequate

hydration.

- Respiratory muscles, like all other body muscles, need energy to work. If

energy needs are not met, muscle fatigue occurs, leading to discoordination

of respiratory muscles and a decrease in tidal volume.

- Hypomagnesemia and hypophosphatemia have been implicated in muscle

fatigue caused by depleted levels of adenosine triphosphate (ATP). In

prolonged starvation, the body cannibalizes the intercostals and

diaphragmatic muscles for energy.

- Metabolic needs in critically ill patients are much higher than in normal

subjects. Basic caloric requirements are usually increased by 25% for

hospital activity and stress associated with treatment.

. If the gastrointestinal tract is intact, enteral nutrition is preferred and can be

provided through a feeding tube.

- Many chronically ill patients, such as those with COPD, have long-

standing protein and calorie malnutrition. Initial tube feeding is started

slowly,

. The nurse observes the patient for signs of intolerance, such as diarrhea

and hyperosmolar dehydration. If the patient tolerates feedings, the rate is

gradually increased until the desired rate is achieved.

- If tube feedings cannot be tolerated, parenteral hyperalimentation should be

considered.



- Patients who require long-term mechanical ventilation typically need 2,000

to 2,500 calories per day.

- Overly large caloric loads increase carbon dioxide production and can

precipitate respiratory failure in a compromised patient.

5- Maintain urinary and bowel elimination:-

- Nursing care for urinary catheter

- Maintain urinary output at 30-60 ml/hour

- Nursing measures to prevent constipation and diarrhea

- Avoid constipation by use of :-

Mild cathartic

Suppositories

Enemas

6-Maintain eye , mouth and cleanliness and integrity:-

Eye care

- Use of artificial tears

- Instill lubricating drops or ointment,

- Apply antibiotic drops or ointments as ordered

- Close the eyelids with tape to prevent corneal ulceration

- Apply eye shields, or applying a moisture chamber

- Raise the head of the bed may reduce scleral edema. (Scleral edema is

common in the ventilated patient).

Oral care

- Perform regular oral hygiene (every 2 hours) to prevent infection

- Establishe a scheduled, regular oral care regimen, using products that

remove plaque and cleanse the mouth without causing pain or irritation.

- Use a non–alcohol-based mouthwash , and brush the teeth a minimum of



every 8 hours.

- Use toothbrushes which have soft bristles with toothpaste

- Use foam brush instead of toothbrush in patients with bleeding disorders or

a low platelet count

- Perform oral suctioning and care to remove subglottic secretions every 1

to 2 hours. Alternatively, Each oral care should include suctioning of

the subglottic secretions to prevent aspiration.

- Use of a chlorhexidine-based mouthwash, hydrogen peroxide or other

antibacterial or antifungal mouthwashes that is compatible with the

patient’s condition, and should not cause pain due to additives for flavor,

alcohol, or strength.)

- Use half-strength solutions diluted with water may help the patient tolerate

more frequent oral care.

- Place the tube in a central position to avoid contact with the corners of the

mouth and the lips. or it can be rotated from side to side.)

Skin care:

- Turn the patient every 2 hours

- Provide pressure relief to sitting surfaces at least q1h when patient is out of

bed to chair,.

- Use special mattresses

- Perform complete bed bath for the patient daily and whenever necessary

- Keep the patient’s clothes clean and dry

- Keep the linen clean, dry and unwrinkled

- Massage & lubricate the back and over the bony prominences

7- Maintain mobility/ musculoskeletal function:-

- Collaborate with physical/occupational therapy staff to encourage patient

effort/participation to increase mobility.

- Progress activity to sitting up in chair, standing at bedside, ambulating with

assistance as soon as possible.

- Assist patient with active or passive range-of-motion exercises to all

extremities at least every shift.

- Keep extremities in physiologically neutral position using pillows or

appropriate splint/support devices as indicated.

8- Maintain Safety:-



- Keep endotracheal tube in proper position.

- Stabilize endotracheal tube in positio securely

- Note and record the ―cm‖ line on endotracheal tube position at lip or teeth.

- Use patient self-protective devices or sedation per hospital protocol.

- Evaluate endotracheal tube position on chest x-ray (by viewing film or by

report).

- Keep emergency airway equipment and manual resuscitation bag readily

available, and check each shift.

- Inflate cuff using minimal leak technique, or pressure less than 25 mm Hg

by manometer.

- Monitor cuff inflation/leak every shift and PRN.

- Maintain proper inflated endotracheal tube cuff.

- Protect pilot balloon from damage.

- Keep ventilator alarm system activated.

9- Provide Psychological support

- Provide adequate information and explanation of all procedures before

they are initiated.

- Answer alarms promptly.

- Describe the alarm system and explain that it will alert staff in the event

of an accidental disconnection.

- Oxygenate the patient before and after suctioning and remain with the

patient until his respiratory pattern and vital signs return to normal.

- Keep noise levels to a minimum especially during rest periods

- Diminish lights during the night to stimulate night and day cycles

- Place clocks & calendars within the patient’s view & verbally confirm

time & date with the patient.

- Provide a T.V or radio for the patient.

- Communicate a caring and unhurried attitude to the patient.

- Patient participates in self-care and decision making related to own

activities of daily living (ADLs) (e.g., turning, bathing).

- Patient communicates with health care providers and visitors.

- Encourage patient to move in bed and attempt to meet own basic

comfort/hygiene needs independently.

- Establish a daily schedule for bathing, out of bed, treatments, and so forth

with patient input.

- Provide a means for patient to write notes and use visual tools to facilitate

communication.

- Encourage visitor conversations with patient in normal tone of voice and



subject matter.

- Teach visitors to assist with range-of-motion and other simple care delivery

tasks, to facilitate normal patterns of interaction.

10- Facilitate Communication:-

- Use alternative methods of communication such as:

- Touch or hand gesturing

- Provide paper and pencil

- Use word or letter boards / picture boards

- Use erasable marker board.

- A number of interventions can facilitate communication with the patient

who has an endotracheal or tracheostomy tube.

-, provide the patient with his or her eyeglasses or hearing aid (if applicable)

Before assessing the patient’s ability to communicate.

- Complete explanations from staff members regarding any procedures to

help decrease the patient’s stress.

- The caregiver can use verbal and nonverbal communication skills.

- Nonverbal communication may include sign language, gestures, or lip

reading.

- If the patient is unable to use these forms of nonverbal communication,

helpful devices include pencil and paper, ―grease‖ boards, and picture or

alphabet boards.

- Once he or she is off the ventilator and tolerating the tracheostomy collar,

the tracheostomy patient can communicate by using ―buttons‖ that occlude

the tracheostomy tube.

- The buttons allow for the passage of air around the tracheostomy to the

vocal chords. The Kirshner button mentioned later in this chapter in

weaning section is one type of button.

- Two other buttons are the Passy-Muir valve and the Shiley speaking valve.

- The Passy-Muir valve is a oneway valve that allows air to enter during



inspiration, then closes to allow the air to flow over the vocal chords with

exhalation.

- The Shiley speaking valve works in the same way as the Passy-Muir valve,

but has a side port for oxygen tubing to be attached, providing oxygen

support without using a tracheostomy collar.

- Patients with copious secretions are at risk for obstruction of these valves.

- They must be monitored very closely. In addition, patients at high risk for

aspiration, and especially patients with laryngeal or pharyngeal

dysfunction, should be carefully assessed before one of these devices is

used.

- The nurse should store these valves in a container clearly identified with

the patient’s name for safekeeping because each type of valve is relatively

costly.

- The patient should be taught to remove the valve with excessive sputum

during cough and call for assistance to clean the valve before reuse.

- The tracheostomy patient with a speaking valve is at increased risk for

aspiration because the cuff must be deflated for the patient to communicate.

11- Provide psychological support & information to family:-

- Consider the needs of the patient’s family,

- Establishes open communication with the patient and family,

- Familiarize the family with the physical surroundings of ICU,

- Informing the family of the visiting hours & visitation policies,

- Provide frequent progress reports about their patient’s condition.

- Encourag family participation & involvement in patient care whenever the

patient’s condition allows through guiding and observing the family while

participating in hygienic care, feeding

- Arranges for visits proactively & encourage open visitation policies,,

12- Responding To Alarms

- If an alarm sounds, respond immediately because the problem could be

serious.

- Assess the patient first, while you silence the alarm. If you can not

quickly identify the problem, take the patient off the ventilator and



ventilate him with a resuscitation bag connected to oxygen source until the

physician arrives.

- A nurse or respiratory therapist must respond to every ventilator alarm.

- Alarms must never be ignored or disarmed.

- Ventilator malfunction is a potentially serious problem. Nursing or

respiratory therapists perform ventilator checks every 2 to 4 hours, and

recurrent alarms may alert the clinician to the possibility of an equipment-

related issue.

- When device malfunction is suspected, a second person manually

ventilates the patient while the nurse or therapist looks for the cause. If a

problem cannot be promptly corrected by ventilator adjustment, a different

machine is procured so the ventilator in question can be taken out of

service for analysis and repair by technical staff.

Troubleshooting Ventilator Alarms

Alarm type Possible Causes Nursing Interventions

High pressure - Increased secretions - Suction the patient

- Kinked ventilator tubing or

endotracheal tube (ETT)

- Unkink tubing

- Check for adequate lung sounds

bilaterally

- Patient biting the ETT - Place an oral airway in patient’s mouth

-Water in the ventilator tubing. - Empty water from tubing

-ETT advanced into right

mainstem bronchus.

- Notify the doctor, who will order a chest

X-ray to evaluate ETT position

Low pressure - Disconnected tubing - Secure all connections

- A cuff leak - Deflate, then reinflate the cuff

- Recheck cuff pressure (normal pressure

is about 18 mm Hg)

- A hole in the tubing (ETT or

ventilator tubing)

- Change the tube.

- A leak in the humidifier - Tighten the humidifier

Oxygen - The oxygen supply is

Insufficient or is not properly

connected.

- Notify staff to correct the malfunction

and manually ventilate the Patient with

O2 source - Monitor oxygen saturation

High respiratory

rate

- Episodes of tachypnea, anxiety,

pain, hypoxia, fever.

Apnea - During weaning, indicates that

the patient has a slow

- Assess respirations, V.S ABGs, Sao2 &

report



- Respiratory rate and a period

of apnea.

- A rapid or slow respiratory rate denotes

patient’s intolerance to weaning and a

need for ventilator setting changes.

Temperature

Alarm

- Overheating due to too low or

no gas flow.

- Improper water levels

- Check gas flow

- Check water levels

13- Preventing nosocomial infections:-

- Wash hands frequently.

- Use meticulous sterile technique when:

- Suctioning and suction on ―as needed basis"

- Suction the tracheobronchial tree before suctioning the oropharynx to

avoid introducing oral pathogens into tracheobronchial tree.

- Changing tracheostomy dressings; skin around tracheostomy stoma should

be kept free of secretions, dry and clear at all times.

- Perform stoma care at least every 8 hours using aseptic technique until

stoma is completely healed.

- Perform mouth care every 2 to 4 hours, to reduce the potential of the

oropharynx as a focus of infection.

- Change ventilator equipment and tubing regularly and sterilize it before

using it again.

- Maintain asepsis of ventilator connector when disconnected by placing

them on opened sterile gauze pads and avoid unnecessary disconnection.

- Change the ventilator circuit every 24 to 72 hours.

- Use only sterile water in the humidifier and nebulizer

- Drain & discard condensation in the ventilator tubing regularly

- Keep the connectors on manual resuscitator bags clean and free of

secretions between uses.

- Avoid using resuscitator bag between patients without sterilization.

- Remove and clean oral airway if present every 8 to 12 hours

14- Documentation:-

The nurse should record all:

- Patient’s measurements

- Ventilator settings

- Nursing care provided



Weaning from mechanical ventilator

- Weaning is the gradual process whereby a patient is transferred from

mechanical ventilation support to spontaneous breathing.

Weaning From Mechanical Ventilation

- As soon as the patient is placed on mechanical ventilation, plans begin for

weaning the patient from mechanical support.

- The process to achieve this goal includes:-

1- Correcting the cause of respiratory failure,

2- Preventing complications,

3- Restoring or maintaining physiological and

psychological functional status.

- Each patient should be evaluated daily for readiness to wean before

initiating weaning trials.

- Comprehensive assessment of the patient’s needs and progress toward

weaning, monitoring of the weaning parameters, and following established

goals promote successful weaning.

- Multidisciplinary and comprehensive approaches to weaning based on a

health care professional (nurse) monitoring and promoting a weaning plan

with continuity have demonstrated positive outcomes.

Methods of Weaning:-

1- T-piece trial,

2- Continuous Positive Airway Pressure (CPAP) weaning,

3- Synchronized Intermittent Mandatory Ventilation (SIMV) weaning,

4- Pressure Support Ventilation (PSV) weaning.



1- T-Piece trial

- It consists of removing the patient from the ventilator and having him / her

breathe spontaneously on a T-tube connected to oxygen source.

- The T-piece is connected to the patient at the desired FIO2 (usually slightly

higher than the previous ventilator setting). The patient’s response to and

tolerance of the trial are continuously observed.

- During T-piece weaning, periods of ventilator support are alternated with

spontaneous breathing.

- The goal is to progressively increase the time spent off the ventilator.

- The duration of T-piece trials is not standardized,

- Some clinicians extubate if an initial trial of 30 minutes ends with

acceptable ABGs and patient response.

- Some clinician use trials of increasing frequency and duration to

evaluate and build the patient’s endurance with periods of rest on

the ventilator between trials. When the latter method is used, the

patient is usually deemed ready to be extubated after 25 successive

hours on a T-piece.

2-Synchronized Intermittent Mandatory Ventilation ( SIMV) Weaning

- SIMV is the most common method of weaning. allowing for some

spontaneous breathing (to prevent respiratory muscle atrophy) while

providing a backup rate.

- It consists of gradually decreasing the number of breaths delivered by the

ventilator to allow the patient to increase number of spontaneous breaths

- Weaning with the SIMV method entails a gradual reduction in the number

of delivered breaths until a low rate is reached (usually 4 breaths/minute).

The patient is then extubated if all other weaning criteria are met.

- However, low levels of SIMV (fewer than 4 breaths/ minute) may result in

a high level of work and fatigue.



3-Continuous Positive Airway Pressure ( CPAP)Weaning

- CPAP is very similar to T-piece trial, except the patient is placed on the

CPAP mode instead of a T-tube.

- When placed on CPAP, the patient does all the work of breathing without

the aid of a back up rate or tidal volume.

- No mandatory (ventilator-initiated) breaths are delivered in this mode i.e.

all ventilation is spontaneously initiated by the patient.

- CPAP entails breathing through the ventilator circuit with a small amount

(or zero amount) of positive pressure.

4- Pressure Support Ventilation (PSV) Weaning

- The patient must initiate all pressure support breaths.

- During weaning using the PSV mode the level of pressure support is

gradually decreased based on the patient maintaining an adequate tidal

volume (8 to 12 mL/kg) and a respiratory rate of less than 25

breaths/minute.

- PSV is associated with less work of breathing than with volume modes, so

longer weaning trials may be tolerated

- Low levels of PSV decrease the work of breathing associated with

endotracheal tubes and ventilator circuits

- PSV weaning is indicated for :-

- Patients who are difficult to wean from the mechanical

ventilator using conventional means (T-piece, SIMV, CPAP),

- Patients with small spontaneous tidal volume.

CPAP & PSV are modes of mechanical ventilation that are completely

dependent on the spontaneous effort of the patient for initiation of

inspiration. These modes are often used for weaning purposes.

Weaning readiness Criteria

- Awake and alert



- Hemodynamically stable, adequately resuscitated, and not requiring

vasoactive support

- Arterial blood gases (ABGs) normalized or at patient’s baseline

- PaCO2 acceptable

- PH of 7.35 – 7.45

- PaO2 > 60 mm Hg ,

- SaO2 >92%

- FIO2 ≤40%

- Positive end-expiratory pressure (PEEP) ≤5 cm H2O

- F < 25 / minute

- Vt 5 ml / kg

- VE 5- 10 L/m (f x Vt)

- VC > 10- 15 ml / kg

- NIF > - 20 cm H2O ( indicates patient’s ability to take a deep

breath & cough),

- Chest x-ray reviewed for correctable factors; treated as indicated,

- Major electrolytes within normal range,

- Hematocrit >25%,

- Core temperature >36°C and <39°C,

- Adequate management of pain/anxiety/agitation,

- Adequate analgesia/ sedation (record scores on flow sheet),



- No residual neuromuscular blockade.

Types of Weaning Interventions:-

1-Short term weaning for patient requiring short-term ventilation (≤3 days)

2-Long term weaning for patient requiring long-term ventilation (>3 days).

1- Short-Term Ventilation Weaning

- The weaning process in this setting may proceed rapidly, based on

individual patient response to reducing ventilatory support.

- Weaning within a short time is desirable because physiological changes

caused by the mechanical ventilation begin within 72 hours.

- This type of weaning intervention is indicated for patients typically

intubated for a short time for :-

1- Surgical or other procedures,

2- Acute exacerbation of an underlying lung disease that can easily

reversed,

3 - Respiratory distress related to underlying pulmonary disease or

traumatic injury.

4- The need for airway protection because of :-

a- Airway swelling (e.g.,as a result of acute inhalation injury)

b- An acute neurological event (e.g., drug overdose).

c- Significant change in mental status (e.g., as with

cerebrovascular accident [CVA] or head injury).

- The goal of short term weaning should be extubation as soon as :-

- The procedure is completed,

- The patient is stabilized,

- The patient is able to protect the airway.



2- Long-Term Ventilation Weaning

- The process of long term weaning often takes weeks. Usually this process

is complicated, and involves multiple delays and setbacks.

- The longer a patient requires mechanical ventilation, the greater the

potential for development of volume–pressure trauma, which consists of:-

- Multiple alveolar fractures

- Leaky alveolar–capillary membranes.

- During long-term weaning, the patient may fail a weaning trial and should

then be rested on the ventilator before another trial is attempted. The rest

period is to allow the recovery of the respiratory muscles.

- Patients who fail a weaning trial often exhibit rapid, shallow breathing

patterns consistent with their respiratory muscle weakness.

- Regular reevaluation of the weaning plan by the multidisciplinary team,

coupled with continuous communication with the patient and family, is

necessary .

- Patients on mechanical ventilation for longer than 72 hours or those having

failed short-term weaning often display significant deconditioning as a

result of acute or chronic complex illness, or both.

- These patients usually require a period of ―exercising‖ respiratory muscles

to regain the strength and endurance needed for successful return to

spontaneous breathing.

- The use of fenestrated tracheostomy tube improve weaning tolerance and

patient comfort in long term weaning intervention.

- The goals of long term weaning are:

- To have the patient tolerate two to three daily weaning trials of



reduction in ventilatory support without exercising to the point of

exhaustion.

- To rest the patient between weaning trials and overnight on

ventilator settings that provide diaphragmatic rest, with minimal or

no work of breathing for the patient.

Nursing Role in Weaning from mechanical ventilator

Role of nurse before weaning:-

1- Ensure that indications for the implementation of Mechanical ventilation

have improved

2- Ensure that all factors that may interfere with successful weaning are

corrected:-

- Acid-base abnormalities

- Fluid imbalance

- Electrolyte abnormalities

- Infection

- Fever

- Anemia

- Hyperglycemia

- Protein loss

- Sleep deprivation

3- Assess readiness for weaning

4- Ensure that the weaning criteria / parameters are met.

5- Explain the process of weaning to the patient and offer reassurance

to the patient.

6- Initiate weaning in the morning when the patient is rested.

7- Elevate the head of the bed.

8- Place the patient upright to facilitate breathing.

9- Ensure a patent airway and suction if necessary before a weaning trial,

10- Suction the tracheobronchial secretions before weaning.

11- Provide for rest period on ventilator for 15 – 20 minutes after suctioning.

12- Ensure patient’s comfort.,

13- Administer pharmacological agents for comfort, such as bronchodilators

or sedatives as indicated.

14- Help the patient through some of the discomfort and apprehension.

15- Support and reassurance help the patient through the discomfort and



apprehension as remains with the patient after initiation of the weaning

process.

16- Evaluate and document the patient’s response to weaning.

Role of nurse during weaning:-

1- Wean only during the day.

2- Remain with the patient during initiation of weaning.

3- Instruct the patient to relax and breathe normally.

4- Monitor the respiratory rate, vital signs, ABGs, diaphoresis and use of

accessory muscles frequently.

5- Monitor the patient continuously for signs of weaning intolerance:-

Signs of Weaning Intolerance Criteria

- Diaphoresis

- Dyspnea

- Labored respiratory pattern

- Increased anxiety

- Restlessness

- Decrease in level of consciousness

- Dysrhythmias

- Increase or decrease in heart rate of > 20 beats /min.

or heart rate > 110b/m

- Sustained heart rate >20% higher or lower than baseline

- Increase or decrease in blood pressure of > 20 mm Hg

- Systolic blood pressure >180 mm Hg or <90 mm Hg

- Increase in respiratory rate of > 10 above baseline or > 30

- Sustained respiratory rate greater than 35 breaths/minute

- Tidal volume ≤5 mL/kg

- Sustained minute ventilation <200 mL/kg/minute

- SaO2 < 90%

- PaO2 < 60 mmHg

- A decrease in PH of < 7.35.

- Increase in PaCO2

6- Stop the weaning trial and return the patient to ―rest‖ settings if the

patient displays any of the signs of weaning intolerance.



Short Term Weaning Intervention

1- Reduce ventilator rate,

2- Convert to pressure-support ventilation (PSV) only.

3- Wean PSV as tolerated to ≤10 cm H2O.

If patient meets tolerance criteria for at least 2 hours on this level

of support and meets extubation criteria:-

- Extubate the patient.

If patient fails tolerance criteria:-

- Increase PSV or add ventilator rate as needed to achieve ―rest‖ settings

(consistent respiratory rate <20 breaths/minute) and review weaning

criteria for correctable factors.

- Repeat wean attempt on PSV 10 cm after rest period (minimum 2 hours).

If patient fails second wean trial:-

- Return to rest settings and use ―long-term‖ ventilation weaning approach.

Long Term Weaning Intervention

- Transfer to pressure-support ventilation (PSV) mode,

- Adjust support level to maintain patient’s respiratory rate at less than

35 breaths /minute.

- Observe for 30 minutes for signs of early failure (intolerance criteria)

If tolerated,

- Continue trial for 2 hours,

- Return patient to ―rest‖ settings by adding ventilator breaths or increasing

PSV to achieve a total respiratory rate of less than 20 breaths/minute.



- Repeat trial for 2 to 4 hours at same PSV level as previous trial after at

least 2 hours of rest,.

If the patient exceeds the tolerance criteria

- Stop the trial

- Return to ―rest‖ settings.

- Perform the next weaning trial at a higher support level than the ―failed‖

trial.

- Record the results of each weaning episode, including specific parameters

and the time frame if ―failure‖ observed, on the ICU flow sheet.

- The goal is to increase the length of the trials and reduce the PSV level

needed on an incremental basis.

- With each successive trial, the PSV level may be decreased by 2 to 4 cm

H2O, the time interval may be increased by 1 to 2 hours, or both, while

keeping the patient within tolerance parameters.

- The pace of weaning is patient-specific and tolerance may vary from day to

day.

- Review readiness criteria for correctable factors daily and each time

the patient ―fails‖ a weaning trial.

- Ensure nocturnal ventilation at ―rest‖ settings (with a respiratory rate of

<20 breaths/minute) for at least 6 hours each night until the patient’s

weaning trials demonstrate readiness to discontinue ventilatory support.

Discontinuing Mechanical Ventilation

- Wean the patient until ventilator settings are

- FIO2 ≤40%,

- PSV ≤10 cm H2O,

- Positive end-expiratory pressure (PEEP) ≤8 cm H2O.

- Ensure that these settings are well tolerated,

- Place the patient on continuous positive airway pressure (CPAP) 5 cm

H2O or (if tracheostomy in place) on tracheostomy collar.



If the patient meets tolerance criteria over the first 5 minutes,

- Continue the trial for 1 to 2 hours.

If clinical observation and arterial blood gases (ABGs) indicate that

the patient is maintaining adequate ventilation and oxygenation on

this ―minimal‖ support,

- Consider the following options

- Attempt extubation if the patient meets extubation criteria

If the patient is on tracheostomy collar,

- Continue the trials two to three times per day with daily

increases in time on tracheostomy collar by 1 to 2 hours per

trial until total time off the ventilator reaches 18 hours

per day.

- At this point, the patient may be ready to remain on tracheostomy

collar for longer than 25 hours unless the tolerance criteria are

exceeded.

- Both of these factors are affected by physiological changes that change the

resting position of the diaphragm. With COPD, the resting length is shorter

(weakening force of contraction), and with diaphragmatic distension

ascites, or morbid obesity, the diaphragm must push down

abdominal contents as it contracts.

- Reactive airway disease increases the resistance to air flow, with increased

workload for muscles of respiration. Any of these abnormalities can lead to

significant fatigue of these muscles and respiratory distress.

- Respiratory muscle fatigue impedes weaning. It may take as long as 25

hours of complete rest (the mechanical ventilator assumes all of the work

of breathing for the patient) for recovery of fatigued respiratory muscles.



Therefore, it is common practice to increase ventilatory support at night to

ensure rest. This can be accomplished with any of the ―resting‖ modes, so

long as the patient’s respiratory rate is less than 20 breaths/minute. The

intent here is to promote and simulate the normal decrease in rate and work

of breathing that occurs during each person’s sleep/rest cycle.

If signs of fatigue or respiratory distress develop.

- Discontinue weaning trials.

- Limit the use of sedatives and narcotics during weaning to only the level of

medication clearly needed to control pain or anxiety.

Role of nurse in extubation:-

1- Ensure that extubation criteria are met .

Extubation Criteria

a- Mental status: an appropriate level of consciousness

(Alert and able to respond to commands)

b- Presence of good cough and gag reflexes,

c- Able to protect airway and clear secretions

d- Able to move air around endotracheal tube with cuff deflated

and end of tube occluded

2- Perform the ―cuff leak test‖ before extubation in all patients,

especially in those with a history of :-

- Difficult intubation,

- Reactive airway disease.

3- Perform the cuff leak test by:-

- Suctioning of the oropharynx

- Deflating the tube cuff

- Occluding the endotracheal tube for a brief

period to demonstrate an air leak with

patient inspiration.



NB

(Absence of a leak can indicate edema, and may predict laryngeal stridor

post-extubation. )

If the cuff leak test fails,

- Give the patient corticosteroids as prescribed to reduce edema for

25 to 48 hours,

- Re-assess for cuff leak.

- Prepare the patient for direct visualization of the trachea with a

bronchoscope as prescribed before extubation to determine if the

edema has resolved.

- Ensure that a qualified person is available to re-intubate emergently if the

patient does not tolerate extubation.

- Explain the procedure and prepare the patient

- Suctions the patient’s tube and posterior oropharynx.

- Ensure that equipment includes an manual resuscitation bag (MRB) and

mask at bedside.

- Loosen the endotracheal tube securing device or tape,

- Deflate the tracheal cuff.

- Remove the endotracheal tube quickly while having the patient cough.

- Suction the patient’s mouth

- Apply humidified oxygen immediately.

- Evaluate the patient for immediate signs of distress: stridor, dyspnea,

and decrease in SaO2.

- Administer medications for treatment of stridor as prescribed

- Administer epinephrine by inhalation

- Administer intravenous steroids (because steroids

do not work immediately, they are given before

extubation in those at risk).

- Prepare for immediate re-intubation if these interventions fail

Documentation:-

- Date & time of starting weaning

- Method of weaning used

- ABGs & oxygen saturation



- Spontaneous respiratory rate

- Use of accessory muscle

- Time spent in the weaning process

- Patient’s response

Mechanical Ventilation - Philadelphia University Jordan · 2013. 11. 6. · Mechanical Ventilation...

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