Acute Respiratory Failure Mechanical Ventilation
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Transcript of Acute Respiratory Failure Mechanical Ventilation
Acute Respiratory FailureMechanical Ventilation
Acute Respiratory Failure
• Characterized by– PaO2 < 60– O2 Sat < 90– PaCO2 > 50– pH < 7.30
Types of Failure
• Ventilatory Failure
• Oxygenation Failure
• Combined Ventilatory/Oxygenation Failure
Ventilatory Failure
• V/Q • Adequate Perfusion• Inadequate ventilation
– Insufficient air movement
O2 to alveoli– CO2 retention
• Caused by– Mechanical
abnormality of lungs or chest wall
– Defect in respiratory control center
– Impaired function of respiratory muscles
Oxygenation Failure
• Adequate ventilation
• Decreased perfusion
• Inadequate oxygenation of pulmonary blood
• Caused by– Pulmonary Embolism– Inadequate hemoglobin
Combined Ventilatory/Oxygenation Failure
• Hypoventilation
• Inadequate gas exchange
• Occurs in clients with abnormal lungs
• Cardiac failure– Cannot compensate for O2
Assessment• Signs of Hypoxemia• Decreased PO2
– Dyspnea, tachypnea– Cyanosis– Restlessness– Apprehension– Confusion– Tachycardia– Dysrhythmias– Metabolic acidosis
• Signs of Hypercapnia• Increased PCO2
– Dyspnea resp. depression
– Headache– Tachycardia– Coma– Systemic vasodialation– Heart failure– Respiratory acidosis
Interventions• Correct underlying cause
• Support ventilation PO2 and PCO2
– O2 therapy– Positioning anxiety– Energy conservation– Bronchodialators
Mechanical Ventilation
• Unresponsive to interventions
• Hypoxemia
• Progressive alveolar hypoventilation with respiratory acidosis
• Respiratory support after surgery
Endotracheal Intubation
• Short term (10-14 days)
• Maintain patent airway work of breathing
• Remove secretions• Provide ventilation & O2
Types of Ventilators• Negative Pressure (Mimic spontaneous breaths)
– Iron Lung
• Positive Pressure (Push air into lungs)– Pressure cycled
• Air delivered until preset pressure reached– Time cycled (Pediatrics/Neonates)
• Push air in with preset time• Tidal volume & pressure variable
– Volume cycled• Push air in until preset volume reached• Constant tidal volume• Variable pressure
Modes of ventilation
• Controlled ventilation
• Assist-control (A/C)
• Synchronized Intermittent Mandatory Ventilation (SIMV)
Controlled ventilation
• Least used
• All breaths delivered at preset tidal volume, pressure & rate
• Client with no spontaneous effort– Severe ICP– Brain death– Voluntary paralysis of muscles
Assist-Control Ventilation
• Most commonly used
• Tidal volume & rate preset
• Client does not trigger breath, ventilator will deliver breath
• Advantage- client controls rate of breathing
• Disadvantage - respiratory rate hyperventilation respiratory alkalosis
SIMV
• Similar to A/C ventilation
• Spontaneous breathing between ventilator breaths at clients own rate & tidal volume
• Used as primary ventilator mode or weaning mode
Ventilator Settings• Tidal Volume (VT)
– Volume of air delivered each breath– 7-10 cc/kg body wt.
• 75 kg = 750 cc
• Rate– # of breath/minute– 10-14 BPM
• Fraction of inspired O2 (FIO2)– Oxygen concentration– 21% (room air) to 100%
Ventilator Settings• Peak Airway (Inspiratory) Pressure (PIP)
– Pressure needed to deliver set tidal volume– Highest pressure indicated during
inspiration airway resistance
• Bronchospasms secretions• Pulmonary edema pulmonary compliance
– Prevents barotrauma • Lung damage from excessive pressure
Ventilatory Settings
• Continuous Positive Airway Pressure (CPAP)– Spontaneous respirations– Intubation or tight fitting mask– Positive pressure during the entire respiratory
cycle (5-15 cm H2O)– Keeps alveoli open during inspiration– Prevents alveoli collapse during expiration– Improves gas exchange & oxygenation– Used during weaning– Nasal CPAP, BIPAP
Ventilatory Settings
• Positive End-Expiratory Pressure (PEEP)– Must be intubated– Positive pressure exerted during expiration
(+5 to +15 cm H2O)– Keeps alveoli open between breaths– Improves oxygenation– Enhances gas exchange– Treatment for persistent hypoxemia
Ventilatory Settings• Pressure Support Ventilation (PSV)
– Client’s inspiratory effort is assisted to a certain level of pressure
work of breathing & comfort through control by client
– PSV 5-20
Management
• Anxiety– Education– Communication– Alarms
• Treat client first, then ventilator
Management• Assessment
– Client response to treatment– Continuous O2 saturation– Vital signs– Lung Sounds– Ventilator settings & alarms– Management of secretions
• Closed suction system
Prevent Complications• Cardiac
– Hypotension• Application of positive pressure intrathoracic
pressure venous return to heart cardiac output
• Dehydration• Requires high PIP
– Fluid retention cardiac output stimulation of renin-
angiotensin-aldosterone response fluid retention
Prevent Complications• Lungs
– Barotrauma• COPD
• Pneumothorax, subq emphysema– Volutrauma– Acid-base abnormalities
• Infection– Within 48 hrs of intubation, bacteria
colonization
Prevent Complications
• Electrolyte Imbalances– Monitor K+, Ca++, Mg++, phosphate levels– Efficiency of respiratory muscle function
• Muscular– Immobility muscle tone & strength– Facilitates gas exchange
Prevent Complications• Ventilator Dependence
– Respiratory muscle fatigue– Client unable to resume independent
breathing
• Extubation– Monitor respiratory effort– Supplemental O2
– Monitor O2 saturation
Weaning from Ventilator
• Parameters set for PaO2, O2 Sat, PaCO2 &
pH FIO2 spontaneous effort by client• Remain on T-piece after ventilator before
extubation aerosol mask• Minimal sedation while weaning• Monitor respiratory effort & rate, vital signs