Mechanical Vent Training - Oplinger 11-2010

8/8/2019 Mechanical Vent Training - Oplinger 11-2010

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Mechanical Vent training

Adam Oplinger

November 10, 2010 FLA

(Creb cycle)

C6H12O6+6O26CO2+6H2O+~34 ATP

In the end the cycle accepts 1 electron and continues.

(carbonic anhydrase cycle.. the byproducts)

CO2+H2O H2CO3H++HCO

-3

Surface tension: surface tension results from Hydrogen bonds

Attracting., surfactants break the Hydrogen bonds allowing lower

Surface tension.

Surfactant is produced in Type I and Type II cells in the respiratory system.

Hydrogen ions are the acid part of an acid

Respiratory drive is the change in pH of CSF

Oxygen can develop isotopes and become O3, O2-, and bind with DNA causing replication problems.

Remember that negative pressure vent. Promotes blood flow return to Right side of heart, in positive

pressure ventilation this is not found.

Compliance- amount of pressure change to move a volume of gas

Normal compliance 200mL/cm H2O

Poorer compliance= harder to push ventilation in

Remember about compliance of the thoracic cage and abdomen

Resistance= resistance of flow through a tube (Poiseuille Law)

i.e.: use the largest tube possible, it will make weaning from the ETT easier

High PIP?.. do they have reactive airway disease and need bronchodilators.

Elastince is the opposite of compliance (elastic recoil)


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Gas exchange is dependent on 3 things:

Pressure gradient

Thickness of basement membrane

Gas permeability

Interpulmonary shunt- (ARDS), or lung tissue which is being perused but no gas exchange

Dead space ventilation- (Pulmon. Emb.) ventilation without perfusion.

Daltons Law: The total press. Of gases is equil to the sum of the individual of pressure ofeach

of the gases.

Atm. At sea level- 760 mm/Hg

(Atm pressure ./. 21% = 160 torr)

Gas is exchanged on the basis of pressure gradients in the lungs and tissues

ABGs Oxygen is actually Oxygen in the plasma and a monogram is used to give a useable range

Oxygen dissociation curve:

P50 is (usually 26mm O2 pressure)

the point that 50% of your Hgb is bound

if P50 shifts to Right Hgb has less affinity or Oxygen

if to the left it has greater affinity.

Left shift:

Dec. temp, Dec 2-3 DPG, Dec. H+

(Alcolosis)

Right shift:

Inc temp, Inc H+

(acidosis),

CO2 gas exchange is more complicated:

The change is gradients is much less (partly because its 20x more soluliable in water)

CO2: most of it is carried bound to hemoglobin as Hydrogen ions

Hemoglobin- the biggest buffer system in the body


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(i.e.: increasing minute volume improves ventilation)

Vt= VD(dead space) + VA(alveolar space)

VE (minute volume) (6-8L/Min- norm)

FiO2- 0.21 to 1.0 or as a percent

Physiologic PEEP is 3-5

I:E is normally 1:2-1:3 (on the low end)

On the Eagle vent setting the I:E setting (i.e.: flow rate)

** remember to ask for the I time to set the ratio**

(the default I:E ratio is uncomfortably long for most patients)

Mean airway pressure (the pressure applied to the lung over the complete cycle) (PMA)

(PIP is only the highest pressure seen in the cycle)

As PEEP increases PAP increases

As PAP increases Cardiac output goes down

Norm PAP is 10 cm/H2O

Peak inspiratory pressure (PIP):

Equation of motion: PIP= Vt/C+ (R*Q)

** this is good for trouble shooting PIP problems.

PIP= VT / C + (R.Q)

** if you have a high PIP increase the I:E

PIP: OK is 30.. 40- start change


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Alveolar pressure (the pressure at the alveoli) (Palv) which is best measured by end-insp plateau pressure

(PLAT)

Resistance and flow do not effect Pplat pressures

(Pplat pressure is not measureable on Eagle Vent)

PIP represents the pressure in the vent circuit, Pplat is the pressure in the entire circuit including the

lungs.

Plateau pressure setting: the plateau button when pressed, sets a ~pressure support~ 10cm below the

PIP. This may be useful in patients with consistently high PIP.

Auto PEEP: a new volume has been delivered but the last exhalation has not finished (air trapping,

breath stacking) usually seen in high rate ventilations.

*to fix, stop and give 10-12 exhalation phase and restart with better vent settings. (maybe change to

SIMV or more sedation?)

CSV modes:

patient usually doesnt need

Much or any sedation but there is no

Apnea back-up and there may be a

Minute volume change requiring machine

Assist to be set in addition.

**PIP should not exceed 30 cm H2O unless

The is a chest wall compliance is decreased.

A good starting point:

VT 10-12 mL/kg

Rate 8-12

(in restrictive lung disease:/ protective lung/

Pneumonia/ H1-N1/ COPD)

** but not in head injuries due to increasing

CO2)

4-8 mL/kg

Rate- 15-25


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See ARDS.net for ideal body weight charts for diagram and tools

If you have a patient is severe cardiac compromise consider decreased PEEP or no PEEP

Volume pressure loop to optimize PEEP when setting a patient up initially

Consider changing the trigger sensitivity during transport if many inadvertent triggered ventilations are

being delivered due to bumps and patient organ movement/ thoracic pressure changes.

Beware low ETCO2 (PETCO2) in patients with low cardiac output.

When adjusting vent settings you may want to start with VT in small changes and reevaluate VT changes

are more forgiving and you dont effect I:E times.

Ventilator-induced lung injury (VILI) (aka: ARDS)

We give peep to maintain recruitment of lung units and prevent atalec-trauma

Remember sitting the patient up can decrease PIP and make the patient more comfortable.

Mechanical Vent Training - Oplinger 11-2010

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