Acid-Base Regulation during Hypothermia in Dogs / 대한마취과학회지

ABSTRACT

BACKGROUND: Controversy exists regarding acid-base management during hypothermia. Two different concepts of arterial blood gas (ABG) management during hypothermia have been proposed to date; pH-stat and alpha-stat. There has been no consistency about physiological benefit provided by one protocol over the other. Most of previous studies have investigated the effects of two different strategies during cardiopulmonary bypass or controlled ventilation. We studied the actual acid-base regulation during acute hypothermia in anesthetized dogs with spontaneous ventilation. METHODS: With institutional review board approval, 10 mongrel dogs were anesthetized with intravenous pentobarbital 25 mg/kg. The dogs were kept to have spontaneous ventilation with trachea intubated. After monitoring devices were placed, the rectal temperature was lowered to 32oC with wet towel, cold solution, and ice cubes. ABG analyses were performed at each degree drop of body temperature from 37oC to 32oC. The pH and arterial carbon dioxide tension (PaCO2) were measured at 37oC and were corrected to the actual body temperature. [OH- ]/[H- ] was also calculated. RESULTS: Non-corrected pH values tended to decrease and PaCO2 values tended to increase as the temperature dropped. The temperature corrected pH and PaCO2 values were almost constant through 37oC to 32oC. [OH- ]/[H-] was declined with a drop of temperature. CONCLUSIONS: The acid-base regulation during acute hypothermia in anesthetized dogs with spontaneous ventilation is considered to be the pattern close to "pH-stat" regulation.