What are the recommended ventilator settings for a previously healthy patient receiving cardiopulmonary resuscitation (CPR)?

Ventilator Settings During CPR in Previously Healthy Patients

For a previously healthy patient receiving CPR with an advanced airway, set the ventilator to: tidal volume 8 mL/kg predicted body weight, respiratory rate 10 breaths/minute, FiO₂ 100%, PEEP 0 cm H₂O, I:E ratio 1:5, and volume control mode with peak pressure alarm set at 60 cm H₂O. 1, 2

Core Ventilator Parameters

Tidal Volume and Oxygenation

• Use a tidal volume of 8 mL/kg predicted body weight with FiO₂ 100% to ensure adequate oxygenation during the low-flow state of cardiac arrest 1
• This is slightly higher than the 6-7 mL/kg used for manual ventilation, accounting for potential volume loss during chest compressions 1
• The 100% oxygen concentration is essential during cardiac arrest to optimize arterial oxyhemoglobin content and oxygen delivery in the setting of severely compromised circulation 1

Respiratory Rate

• Set respiratory rate at exactly 10 breaths per minute (1 breath every 6 seconds) without pausing chest compressions 1, 3
• Hyperventilation rates exceeding 12 breaths/minute decrease venous return, diminish cardiac output, and worsen survival outcomes 1, 3
• This lower rate minimizes the negative impact of positive-pressure ventilation on blood flow during the critical low-flow state of CPR 1

PEEP Settings

• Use zero PEEP (0 cm H₂O) to allow maximal venous return to the heart during chest compressions 1, 2
• Positive-pressure ventilation significantly lowers cardiac output during CPR, making minimization of intrathoracic pressure essential 1
• Any PEEP level increases mean intrathoracic pressure and impedes venous return, which is already critically compromised during cardiac arrest 1

Inspiratory-Expiratory Ratio

• Set I:E ratio at 1:5 to provide adequate inspiratory time (approximately 1 second) while maximizing expiratory time 1, 2
• This ratio minimizes mean airway pressure and allows adequate time for venous return between breaths 1
• The prolonged expiratory phase is crucial for reducing intrathoracic pressure and optimizing hemodynamics during CPR 1

Additional Ventilator Settings

Ventilation Mode and Alarms

• Use volume control ventilation mode to ensure consistent tidal volume delivery despite the mechanical interference from chest compressions 2
• Set maximum peak inspiratory pressure (P max) alarm at 60 cm H₂O to allow tidal volume delivery during chest compressions without triggering nuisance alarms 2
• Switch OFF the trigger function to prevent inadvertent triggering by chest recoil during compressions 2

Monitoring During CPR

• Continuously monitor delivered tidal volume and respiratory rate to ensure adherence to targets 1
• Consider capnography monitoring, though optimal ETCO₂ targets during active CPR remain undefined 1
• Real-time monitoring of CPR quality parameters should be incorporated into every resuscitation to prevent hyperventilation 1

Critical Pitfalls to Avoid

Hyperventilation Dangers

• Never exceed 12 breaths/minute, as hyperventilation increases intrathoracic pressure, decreases venous return, and significantly worsens survival 1, 3
• Hyperventilation may also cause auto-PEEP (gas trapping), which further depresses venous return and cardiac output 4
• The temptation to "help more" by increasing ventilation rate must be actively resisted, as it is counterproductive during CPR 1

Post-ROSC Considerations

• After return of spontaneous circulation (ROSC), immediately adjust ventilator settings to avoid hyperventilation with hypocapnia 4
• Target normocapnia with PaCO₂ 40-45 mm Hg or ETCO₂ 35-40 mm Hg after ROSC 4
• Routine hyperventilation with hypocapnia after ROSC worsens global brain ischemia through excessive cerebral vasoconstriction (Class III recommendation) 4
• Transition to lung-protective ventilation with tidal volumes of 6-8 mL/kg predicted body weight and appropriate PEEP (typically 5-10 cm H₂O) once circulation is restored 4

Body Weight Calculations

• Always use predicted body weight (based on height), not actual body weight, for tidal volume calculations 5, 3
• Using actual body weight in obese patients leads to excessive volumes and potential barotrauma 5, 3