GENDER DIFFERENCES IN 24-HOUR OUTCOME FOLLOWING RESUSCITATION AFTER 9MINUTES OF CARDIAC-ARREST IN DOGS

Objective: To examine possible gender-specific differences in 24-hr ou tcome following resuscitation from 9 mins of controlled cardiac arrest . Design: Preclinical, prospective study comparing two similarly prepa red, independent control groups (one female group, one male group) inc luded in a larger series of studies. Setting: Physiology research labo ratory at a major medical center. Subjects: Male and female mongrel do gs (Canis familiaris), weighing 16 to 22 kg. Interventions: Cardiopulm onary-cerebral resuscitation following 9 mins of normothermic cardiac arrest in male vs. female dogs. Measurements and Main Results: Mean ar terial blood pressure, heart rate, urine output, arterial blood oxygen , and Pco(2) values, arterial pH, temperature, plasma glucose concentr ations, and hematocrit were measured and recorded at the precardiac ar rest and postcardiac arrest period, and at 30 mins, and 1, 4, 6, 12, a nd 24 hrs following resuscitation. Neurologic dysfunction was assessed using a well-standardized neurologic deficit score assigned at 6, 12, and 24 hrs after arrest. Plasma concentrations of malonaldehyde, 4-hy droxynonenal, and erythrocyte-reduced glutathione were measured at the precardiac arrest period, and 6, 12, and 24 hrs following resuscitati on. Additionally, serum concentrations of alanine aminotransferase, as partate aminotransferase, total bilirubin, alkaline phosphatase, gamma -glutamyl transferase, creatinine kinase, creatinine, albumin, and tot al protein were measured before arrest, and at 6, 12, and 24 hrs after resuscitation. Plasma concentrations of inorganic phosphorus, blood u rea nitrogen, and electrolytes (sodium, chloride, calcium, and potassi um) were measured. The estrous cycle phase in the female dogs enrolled in the study was determined by physical examination and vaginal cytol ogy. No prearrest differences were detectable between males and female s in basic physiologic variables. No differences in neurologic deficit were detectable between males and females across the 24-hr recovery p eriod following resuscitation. No detectable differences in malonaldeh yde, 4-hydroxynonenal, and erythrocyte-reduced glutathione occurred be tween groups. Serum concentrations of aspartate aminotransferase (p =. 02), alanine aminotransferase (p =.009), creatinine kinase (p=.01), to tal bilirubin (p =.05), and plasma concentrations of inorganic phospho rus (p =.03), blood urea nitrogen (p=.0003), and creatinine (p =.02) a ll were significantly and dramatically higher in female than male dogs at the 24-hr time point. The trend of increase in these Values began at the 6- and 12-hr time points and was consistent with a steadily dec reasing trend in mean arterial pressure and an increasing trend in hea rt rate in the female group. Conclusions: An extensive history with th is preclinical canine model(restricted to male dogs) had indicated lit tle or no change in standard clinical chemistry markers of systemic dy sfunction following 9 mins of cardiac arrest. However, when compared w ith male dogs, the female dogs tested here appear to have sustained a more significant hepatic and renal ischemic injury with no differences in the neurologic deficit.