Changes in acid-base balance in arterial blood and cerebrospinal fluid (CSF) during hypothermia anesthesia
Hiraga, K.
Masui. Japanese Journal of Anesthesiology 34(6): 776-784
1985
ISSN/ISBN: 0021-4892 PMID: 4032703 Document Number: 253123
This study was undertaken to make clear the changes of acid-base balance in arterial blood and CSF during moderate hypothermia anesthesia with spontaneous breathing; 14 patients with intracranial aneurysm scheduled for surgery were selected. As the temperature drops, standard HCO3-, base excess and arterial blood pH decreased gradually and lactate increased. The blood pH returned to normal after rewarming of the patient. Acid-base balance also returned to the normal value within several h after anesthesia. Evidently, these changes were due to the induced hypotension to prevent the premature rupture of the aneurysm during operation. In 5 cases, arterial blood pH increased during cooling because of the influence of the metabolic factors. Acid-base balance of arterial blood showed relative constant alkalinity (RCA) when there was no influence of the metabolic factors. According to the cooling temperature, pH of the CSF increased and PCO2 CO2 pressure decreased. Equation of pH of CSF to esophageal temperature (T) and PCO2 to T were as follows; pH = 7.926-0.016T (R = -0.482, P < 0.01). PCO2 = 1.23T-6.91 (R = 0.443, P < 0.01). During cooling, acid base balance of CSF showed the same pattern as RCA. Metabolic acidosis during hypothermia anesthesia with spontaneous breathing should not be corrected with alkalinizing drugs. There is no need to correct the pH and PCO2 to the values at 37.degree. C.