UMEM Educational Pearls

In cardiac arrest, avoidance of excessive ventilation is key to achieving HQ-CPR and minimizing decreases in venous return to the heart. The controversy regarding BVM vs definitive airway and OHCA outcomes continues, but data indicates that mechanical ventilation during CPR carries no more variability in airway peak pressures and tidal volume delivery than BVM ventilation [1], with the AHA suggestion to keep in-hospital cardiac arrest patients with COVID-19 on the ventilator during the pandemic [2]. 

So, can we automate this part of CPR?

Two recent studies looked at mechanical ventilation (MV) compared to bagged ventilation (BV) in intubated patients with out-of-hospital-cardiac arrest (OHCA).  

Shin et al.'s pilot RCT evaluated 60 intubated patients, randomizing half to MV and half to BV, finding no difference in the primary outcome of ROSC or sustained ROSC, or ABG values, despite significantly lower tidal volumes and minute ventilation in the MV group [3]. 

Malinverni et al. retrospectively compared MV and BV OHCA patients from the Belgian Cardiac Arrest Registry, finding that MV was associated with increased ROSC although not with improved neurologic outcomes. Of note, patients across the airway spectrum were included (mask, supraglottic, intubated), and the mechanical ventilation was a bilevel pressure mode called Cardiopulmonary Ventilation (CPV) specific to their ventilators, specifically for use during cardiac arrest [4]. 

Bottom Line: Larger randomized trials will be necessary to get a definitive answer as to how mechanical ventilation affects outcomes in OHCA, but in instances where the cause of arrest is not primarily pulmonary (severe asthma, pneumothorax) and the ED is short-staffed or prolonged resuscitations are likely (such as in accidental hypothermic arrests), it is probably reasonable to keep patients on the ventilator:

• in a control mode
• with a target tidal volume of 6ml/kg,
• a PEEP of 5-8cmH2O (depending on habitus)
• and an FiO2 of 100% while still in arrest.
• Set the trigger to “off” to avoid additional breaths triggered by chest compressions
• Pressure alarms may need adjustment to allow asynchronous breath delivery during chest compressions

References

1. Neumamm LBA, Jardim-Neto AC, Motta-Ribeiro GC. Empirical evidence for safety of mechanical ventilation during simulated cardiopulmonary resuscitation on a physical model. Am J Emerg Med. 2021;48:312-5. doi: 10.1016/j.ajem.2021.06.062.
2. Edelson DP, Sasson C, Chan PS, et al; American Heart Association ECC Interim COVID Guidance Authors. Interim Guidance for Basic and Advanced Life Support in Adults, Children, and Neonates With Suspected or Confirmed COVID-19: From the Emergency Cardiovascular Care Committee and Get With The Guidelines-Resuscitation Adult and Pediatric Task Forces of the American Heart Association. Circulation. 2020;141(25):e933-43. doi: 10.1161/CIRCULATIONAHA.120.047463. 
3. Shin J, Lee HJ, Jin KN, et al. Automatic Mechanical Ventilation vs Manual Bag Ventilation During CPR: A Pilot Randomized Controlled Trial. Chest. 2024:S0012-3692(24)00248-4. doi: 10.1016/j.chest.2024.02.020. Epub ahead of print. 
4. Malinverni S, Wilmin S, de Longueville D, et al A retrospective comparison of mechanical cardio-pulmonary ventilation and manual bag valve ventilation in non-traumatic out-of-hospital cardiac arrests: a study from the Belgian Cardiac Arrest Registry. Resuscitation. 2024:110203. doi: 10.1016/j.resuscitation.2024.110203. Epub ahead of print. PMID: 38582442.