Neurologic outcome and heart resuscitability with closed-chest cardiopulmonary bypass after prolonged cardiac arrest times in rabbits.
OBJECTIVE
To observe the influence of prolonged cardiac arrest times on neurologic outcome and heart resuscitability, using a resuscitation model with cardiopulmonary bypass in the rabbit, and to determine whether the changes in the plasma concentrations of lactate and lipoperoxide correlate with the severity of global brain ischemia.


METHODS
Randomized, prospective, controlled animal trial.


METHODS
University research laboratory.


METHODS
Forty-three New Zealand white rabbits.


METHODS
Rabbits were randomly assigned to one of five groups: control, and four groups with cardiac arrest times of 8, 10, 12, and 15 mins. A bolus of 4 to 6 mL of 0.5-M potassium chloride was injected into the right atrium to induce cardiac arrest within 5 secs. Resuscitation was performed using closed-chest cardiopulmonary bypass, and mechanical ventilation with pure oxygen. When necessary, a DC shock of 10 joules/kg was used to terminate ventricular fibrillation.


RESULTS
Hemodynamics, electroencephalogram, electrocardiogram, and return times of various cranial reflexes were observed throughout the experiment. Plasma concentrations of lactate and lipoperoxide were determined before cardiac arrest and 5, 30, 90, and 150 mins after resuscitation. The neurologic outcome, measured by Neurologic Deficit Score, was determined at 150 mins postresuscitation. Values for the Neurologic Deficit Score were: 8 +/- 8 in the control group; 31 +/- 13; 37 +/- 19; 69 +/- 22; and 62 +/- 26 in the cardiac arrest groups of 8, 10, 12, and 15 mins, respectively. No significant differences in cardiac resuscitability were found among the four cardiac arrest groups. The plasma concentrations of lactate and lipoperoxide were significantly higher than the prearrest levels; however, there were no significant differences among the four cardiac arrest groups.


CONCLUSIONS
Cardiopulmonary bypass can be used to establish a resuscitation model in rabbits. Neurologic outcome worsens progressively in proportion to the prolonged cardiac times, especially when it exceeds 10 mins. Cardiac resuscitability is still possible, even when arrest time exceeds 15 mins. Changes in plasma concentrations of lactate and lipoperoxide do not correlate with the neurologic outcome and heart resuscitability following cardiac arrest.
Xu
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First Department of Anesthesiology School of Medicine, Dokkyo University, Tochigi, Japan.
Ogata
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D000704:Analysis of Variance; D000818:Animals; D002545:Brain Ischemia / Q000097:blood / Q000503:physiopathology / Q000628:therapy; D002315:Cardiopulmonary Bypass / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D004195:Disease Models, Animal; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006323:Heart Arrest / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008054:Lipid Peroxides / Q000097:blood; D008297:Male; D009420:Nervous System / Q000503:physiopathology*; D011446:Prospective Studies; D011817:Rabbits; D011897:Random Allocation; D012151:Resuscitation / Q000706:statistics & numerical data; D013997:Time Factors
D007773:Lactates; D008054:Lipid Peroxides; D019344:Lactic Acid