Looking for indicators of imminent cardiovascular collapse

Abstract

Various indicators are used as predictors of lifesaving intervention requirements and mortality risk following severe hemorrhage. We examined hemorrhage and resuscitation data for sensitive and specific indications of imminent cardiovascular collapse. Methods: 8 anesthetized, ventilated dogs were hemorrhaged (H, 90min mean arterial pressure [MAP]=35-40mmHg or MAP<30mmHg>10min or MAP<25mmHg>1min), hypotensively stabilized (S, 120min enalaprilat 0.01mg/kg/hr + hemoglobin based oxygen carrier [HBOC] or 7.8% hypertonic saline dextran 70 [HSD] for MAP=40-45mmHg), resuscitated (60min lactated Ringer’s for MAP=75-80mmHg), monitored (60min no fluids), and euthanized. Results: 2 of 8 died of cardiovascular collapse: 1 of 5 HBOC 117min into S and 1 of 3 HSD 9min into S. No threshold values were found for predicting cardiovascular collapse. Within the 30 minute interval preceding death, trend differences (sharply declining values for heart rate, blood pressure, and end-tidal PCO2) were visible only in the final 10 minutes. Conclusions: Perhaps these visible trends could be useful for guiding the application of high risk interventions to patients who would die if they only received conventional care. The shortness of the pre-death window may limit the usefulness of the observed patterns.