Ventilatory pattern variability predicts long‐term survival following cardiac arrest and resuscitation in rats

Abstract

Ventilatory pattern variability (VPV) reflects brainstem function with respect to cardio‐respiratory regulation. We applied linear and nonlinear tools to assess VPV following cardiac arrest and resuscitation with the goal of predicting long‐term survival. Spontaneous breathing (plethysmography) was recorded for 1h for VPV analysis at baseline and after cardiac arrest (12 min) and resuscitation in male Wistar rats. VPV was similar before cardiac arrest but differed between survivors (survived for 4d, n = 15) and non‐survivors (died before 4d, n = 12) after resuscitation. The nonlinear complexity index (NLCI), a measure of deterministic structure in ventilatory patterns, was similar between survivors and non‐survivors (0.08 ± 0.03 vs.0.07 ± 0.03 bits) before cardiac arrest. On day 0 and day 1 post‐resuscitation NLCI was significantly increased (~3 folds) in the non‐survivors while remained unchanged from baseline in the survivors. Traditional measures such as respiratory rate and coefficient of variation of respiratory cycle length cannot distinguish the difference in ventilatory pattern between the survivors and non‐survivors. The characteristic changes in VPV early in recovery distinguished the survivors from non‐survivors, suggesting that VPV could be a predictor of long‐term survival following cardiac arrest and resuscitation. Supported by NS 38632, HL 087377, VA Research Service (I01BX000873).