Plasma catecholamines, pH, and blood pressure during cardiac arrest in pigs

This study examined plasma epinephrine (E) and norepinephrine (NE) concentrations, pH, and mean arterial blood pressure (MAP) in a cardiac arrest model. Twenty-three domestic swine (15-26 kg) were anesthetized with ketamine 20 mg/kg, i.m. and alpha-chloralose 25 mg/kg, i.v. and ventilated with a respirator. Catheters were placed in the right ventricle, left ventricle and femoral arteries for MAP recordings and blood pH sampling every 2 min. Catecholamine samples were taken from the femoral artery every 2 min. Cardiac arrest was induced by endocardial stimulation with a Grass S88 stimulator. Five minute post arrest resuscitation was initiated with a mechanical resuscitator. Ten minute post arrest NaHCO3 1 mEq/kg was administered by the peripheral i.v. (P; n = 6), central (CE; n = 5), or intraosseous, via the tibia, (I; n = 6), route. Controls (C; n = 6) did not receive NaHCO3. MAP (mean +/- S.D.) prior to arrest was: C 144 +/- 16, P 139 +/- 11, CE 137 +/- 13 and I 133 +/- 11 mmHg. Five and 25 min post arrest it was: C 21 +/- 5 and 17 +/- 6, P 34 +/- 8 and 23 +/- 7, CE 17 +/- 7 and 14 +/- 10 and I 26 +/- 6 and 11 +/- 3 mmHg, respectively. A 2-way analysis of variance did not reveal any difference in MAP values in the four groups. In all groups the blood pH from the femoral artery demonstrated a respiratory alkalosis that peaked at approximately 7.48 5 min after initiation of mechanical resuscitation. In the groups receiving NaHCO3, it peaked at 7.77 +/- 0.09 CE and 7.65 +/- 0.06 P 2 min post infusion and at 7.71 +/- 0.06 I 8 min post infusion. An analysis of variance revealed that the CE and I routes were significantly different (P less than 0.05) from the P group and that all three groups were different (P less than 0.05) from the C. Plasma E and NE concentrations at 0, 6, 10, 12, 20 and 30 min post arrest in the C group were, respectively: 3 and 10, 94 and 327, 119 and 329, 92 and 234, 33 and 135, and 127 and 62 ng/ml, respectively. All 3 groups receiving NaHCO3 demonstrated similar patterns and were not significantly different from C when compared with a 2-way analysis of variance.(ABSTRACT TRUNCATED AT 400 WORDS)