CORONARY PERFUSION-PRESSURE DURING CARDIOPULMONARY-RESUSCITATION AFTER SPINAL-ANESTHESIA IN DOGS

Cardiac arrest during spinal anesthesia is a rare event, but when it d oes happen cardiopulmonary resuscitation (CPR) is often ineffectual. T his study examines the effect of spinal anesthesia on coronary perfusi on pressure (CPP) during CPR and the subsequent response of CPP to epi nephrine administration. Twenty mongrel dogs were anesthetized, and ra ndomly assigned to a spinal injection with either 0.5 mg/kg bupivacain e or with an equivalent volume of normal saline. Twenty minutes later, ventricular fibrillation was electrically induced and af ter 1 min CP R was started. CPP was measured every minute. After 4 min of CPR, epin ephrine 0.01 mg/kg was given followed by 0.1, 0.2, and 0.4 mg/kg epine phrine intravenously (TV) at 6, 8, 10 min of CPR, respectively. The bu pivacaine (n = 11) group had significantly less CPP than the sham spin al (n = 8) group, 12-13 mm Hg as compared to 27-34 mm Hg. Only 4/11 do gs (36%) in the bupivacaine group had CPP greater than or equal to 15 mm Hg during the first 4 min after arrest as compared to 8/8 (100%) in the sham spinal group. This increased to 7/11 dogs (64%) after 0.01 m g/kg epinephrine and to 9/11 af ter 0.1 mg/kg epinephrine. Total spina l anesthesia decreases CPP and thus the efficacy of CPR in dogs below the threshold previously established for predicting successful resusci tation. Epinephrine is effective in increasing CPP during CPR above th e critical threshold. These data suggest that if cardiac arrest occurs during spinal anesthesia, epinephrine should be given in doses of 0.0 1-0.02 mg/kg IV initially and then increasing to 0.1 mg/kg IV. When th is does not work, and ineffective CPR is suspected, alternative resusc itative measures should be considered.