Preterminal Gasping During Hypoxic Cardiac Arrest Increases Cardiac Function in Immature Rats

Abstract

Newborn animals are more resistant to anoxia than older animals, partly due to an increased tolerance of the immature heart to anoxia. Newborn animals also have a more robust preterminal gasp. We investigated the relationship between gasping and cardiac function in immature and maturing rats exposed to anoxia. Immature postnatal day 7 (PND7) rats (n ϭ 13) and maturing PND17 rats (n ϭ 13) were exposed to 100% nitrogen (anoxia) for 10 min. Echocardiography was used to calculate cardiac contractility (CC) by left ventricular shortening fraction and cardiac output (CO) from Doppler velocity recordings of pulmonary artery blood flow. In a separate group of PND7 rats, CC and CO were recorded after the paralytic agent pancuronium was used to prevent gasping. Anoxia decreased CC and CO in PND7 and PND17 rats, followed by a partial and transient recovery. Gasping preceded recovery of CO and was required to sustain CO. Gasping in PND7 rats lasted longer (541 s versus 351 s, p Ͻ 0.01) and resulted in a greater recovery of CC and CO. Anoxia-induced gasping and the associated recovery of cardiac function were abolished by paralysis. Thus, anoxia-induced gasping transiently improves cardiac function, and more robust gasping in immature rats is associated with increased cardiac anoxic tolerance. (Pediatr Res 60: 174-179, 2006)

Gasping during cardiac arrest

“…These pressure gradients augment effective forward blood flow [17]. Improved cardiac output and cardiac contractility by gasping have been confirmed in a rat model [16]. Consequently, increased aortic pressure and coronary perfusion pressure [17,21], increased carotid blood flow [21], and decreased intracranial pressure with associated gasping during ventricular fibrillation [20] have been demonstrated.…”

“…The occurrence of gasping has been described in cardiac arrest models in both rats [15,16] and swine [17][18][19][20][21].…”

“…The start of gasping has been reported to occur typically within 1 min after arrest [15,20,21], and afterwards follows a crescendo-decrescendo pattern [15,16,20,21]. A single study, by Menegazzi and Check [18], documents active breathing or gasping during an untreated ventricular fibrillation cardiac arrest period of more than 5 min.…”

The presence of gasping predicts long-term survival in out-of-hospital cardiac arrest patients

“…In combination with unconsciousness it is considered a pathognomonic sign of cardiac arrest 8,9 . It is a common mammalian pattern of breathing based on the simple brain stem reflex expressed in the setting of cerebral hypoxia 10 . The beneficial effect of gasping on circulation and gas exchange during cardiac arrest has been described [11][12][13][14] .…”

“…The beneficial effect of gasping on circulation and gas exchange during cardiac arrest has been described [11][12][13][14] . It has been formerly hypothesized that gasping is a protective mechanism for anoxia during delivery of immature animals 10 . The reported incidence of gasping fluctuates between 33 and 60% in all OHCA patients 1,15,16 .…”