Breathing patterns during cardiac arrest

Abstract

The absence of respiratory movements is a major criterion recommended for use by bystanders for recognizing an out-of-hospital cardiac arrest (CA), as the persistence of eupneic breathing is considered to be incompatible with CA. The basis for CA-related apnea is, however, uncertain, since brain stem Po(2) is not expected to drop immediately to the critical level where anoxic apnea occurs. It is therefore essential on both clinical and physiological grounds to determine whether and when breathing stops after the onset of CA. In eight patients, we measured the ventilatory response at the onset of ventricular fibrillation (VF) for 12-15 s during the placement of an implantable cardioverter-defibrillator device. We found that regular eupneic breathing was maintained unchanged despite the cessation of systemic and pulmonary blood flow generated by the heart. We extended these findings in adult sheep and found that, as in humans, the normal ventilatory pattern persists unchanged for the first 15 s despite the drop in blood pressure, followed by a progressive increase in minute ventilation, which was sustained for up to 164 s. The ensuing apnea was disrupted by typical gasps occurring at a very slow frequency. These observations suggest a complete "decoupling" between the return of CO(2) to the pulmonary circulation and continued effective respiratory activity, contrary to what we predicted. This delayed cessation of eupneic breathing during the absence of cardiac pump function is likely related to the time needed for brain stem anoxia to develop. These findings challenge the notions that 1) ventilation stops as pulmonary blood flow/cardiac output ceases and 2) the presence of eupneic breathing is a reliable sign of effective cardiac pumping activity.

Sudden Cardiac Arrest and Death Following Application of Shocks From a TASER Electronic Control Device

“…Normal breathing has been documented in pigs and sheep for a minute after the onset of ventricular fibrillation and in humans for at least the first 12-15 seconds. 33,34 From these observations, it is clear that continuous monitoring of vital signs and ECG, if available, in an individual unconscious following ECD deployment, should be mandatory.…”

Sudden unexpected death in epilepsy: basic mechanisms and clinical implications for prevention

“…Prolonged respiratory difficulty is often not an early symptom of sudden cardiac death, but is instead typically followed by an increase in ventilation and then gasping (figure 4). 96 Therefore, it is unlikely for SUDEP to be caused principally by a primary cardiac mechanism in which seizure-induced autonomic dysfunction of the heart leads to a lethal arrhythmia. Additionally, the fact that many patients are found prone in bed suggests that this position plays a role in the pathophysiology.…”

TASER Electronic Control Devices and Cardiac Arrests: Coincidental or Causal?

“…In 9 cases, there was no consideration of the time to breathing cessation, which is critical because the mean time was 6.1±3.1 minutes compared with the maximum of 60 seconds (P<0.0001 by t test) for normal breathing after a cardiac arrest. 31,32 There was typically no mention (9 cases) of the failure of prompt defibrillation as indicating a nonelectric source for the cardiac arrest. 16,17 Almost all cases (11 of 12) ignored the critical dart-to-heart distance, which is well established in the literature for the induction of VF.…”

“…31,32 After a cardiac arrest, normal breathing ceases in 12 to 60 seconds. 31,32 However, some subjects will also have agonal breathing for a maximum total of 6 minutes. 33 Successful prompt defibrillation (with ≤3 shocks) was scored as +1.…”