Ventilation During Cardiac Arrest and After Return of Spontaneous Circulation: Like Father, Like Son?

To the Editor:

We read with great interest the paper “Mechanical Ventilation Management During Mechanical Chest Compressions” by Orso et al,¹ in which they identified available knowledge on mechanical ventilation strategies during cardiopulmonary resuscitation (CPR).

We share their conclusion that there is urgent need to find ventilatory strategies and goals for ventilation during CPR. In a study of blood gas analyses during CPR, our working group has reported an association between blood gas exchange metrics and hospital admission.² Whether this finding is an area for future attempts to improve ventilation in resuscitation care or is simply a sign of cardiopulmonary integrity remains uncertain.

Nevertheless, chest compressions and ventilation interact with each other and can affect each other. That is why we applaud the great effort of Orso et al¹ to look specifically into ventilation during ongoing chest compressions in contrast to the much broader topic of ventilation during cardiac arrest, including post-resuscitation care.

Notably, Orso and colleagues¹ specifically excluded studies of mechanical ventilation after the return of spontaneous circulation (ROSC). Therefore, we would like to point out that, to our knowledge, the cited paper by Moskowitz et al³ only reports tidal volumes administered immediately after ROSC. A similar problem appears to exist with the cited paper by Ebner et al,⁴ which was a substudy of the Target Temperature Management trial that included subjects after out-of-hospital cardiac arrest. More specifically, the authors stated that median time from ROSC to inclusion was 133 (IQR 83–188) min.⁴

In addition, Oh et al⁵ gathered data from arterial blood gas analyses within 10 min after ROSC. While this is not precisely intra-arrest data, ventilation during CPR might be reflected in these measurements. However, we previously found the partial pressure of oxygen to increase rapidly after ROSC.²

While the mentioned sources should have been excluded by the defined exclusion criteria, as they primarily analyzed ventilation data after ROSC, the fact that they have been included further illustrates how scarce our available knowledge regarding ventilation during cardiac arrest is.

It appears to be crucial for further research to point out that the distinction between intra-arrest ventilation and post-arrest ventilation has to be maintained as they are fundamentally different interventions in different patient populations with different pathophysiological needs.

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