Animals with restored spontaneous circulation exhibited maintained neuronal functionality in RVLM beyond this critical time-window, alongside resumption of baseline tissue oxygen and enhancement of local blood flow.
Still, even if spontaneous circulation is maintained at moderate (30 to 34°C) or severe (below 30°C) body temperature [ 3] during accidental hypothermia, victims may present with impaired cardiovascular function.
TTM (core temperature, 32 - 34 °C) was maintained for 8 hours post-return of spontaneous circulation, and the animals were rewarmed for 12 hours.
The therapy involved cooling the core body temperature to 32 34°C through surface cooling with misted water immediately (within 15 min) after return of spontaneous circulation and therapeutic hypothermia was maintained for 6 hours.
We showed that whereas maintained functional integrity of the RVLM interfaces the vital window between resumption of spontaneous circulation and cardiac arrest, necrotic cell death as a result of bioenergetic failure triggered by anoxia in the RVLM underlies brain stem death and negates cardiac resuscitation.
Based on this experimental index, we were able to reveal the novel finding that a crucial determinant for successful revival of cardiac arrest is that spontaneous circulation must resume before brain stem death commences, and that maintained functional integrity of the RVLM, leading to sustained sympathetic vasomotor tone, holds the key to this vital time-window.
We conclude that whereas necrotic cell death because of bioenergetic failure triggered by anoxia in RVLM, which precipitates brain stem death, negates resuscitation of an arrested heart, maintained functional integrity of this neural substrate holds the key to resumption of spontaneous circulation after cardiac arrest in rats.
aDefined as systolic blood pressure < 100 mmHg or vasopressor support required to maintain systolic blood pressure > 100 mmHg during the first 24 hours after return of spontaneous circulation; bDefined as a base deficit ≤ - 6 mmol/L during the first 24 hours after return of spontaneous circulation; ‡FiO2, fraction of inspired oxygen; PEEP, peak end expiratory pressure.
Therapeutic hypothermia (TH) is the process whereby BT is reduced to a target temperature of 32 34°C and maintained at this temperature for 24 48 hours following cardiac arrest (CA) and return of spontaneous circulation (ROSC) [ 8- 11].
