Physiological and Pathological Evaluation of Mechanically Ventilated Anesthetized Pigs

Abstract

Prolonged assisted ventilation during anesthesia and critical care is associated with increased morbidity and mortality in both humans and animals. However, no study of mechanically ventilated patients has examined the mortality-related physiology and pathology. Our study investigated physiological, hematological and pathological changes in pigs that died during anesthesia. Six pigs were placed under ventilation-assisted anesthesia for up to 48h. The heart rate (HR), respiratory rate (RR), mean arterial blood (MAP), end-tidal carbon dioxide (ETCO2), and oxygen saturation (SpO2) were monitored every 15min until the pigs dies. Blood glucose, serum lactate, pH, and serum bicarbonate (HCO3-) were measured every 12h until death. Tissues were harvested from lung, liver, heart, and kidney of pigs immediately after death during anesthesia. All pigs died during anesthesia. Times of death varied. One pig died at approximately 18h (Group I), two pigs at 24h (Group II), one pig at 36h (Group III), and two pigs at 48h (Group IV). Decreased MAP was reported in all groups throughout anesthesia. Each group showed different changes before death; Group I and III showed decreased blood glucose (45mg/dL) and (17mg/dL), respectively; Group III showed elevated serum lactate (9.76 mmol/l) and reduced pH (7.13) that suggested metabolic acidosis; Group IV showed increased ETCO2 (64.35±5.79 mmHg). Pigs that survived longer showed a higher level of cellular injury to the liver and respiratory system. Blood glucose, MAP, and ETCO2 should be carefully monitored during anesthesia for better patient outcomes and reduced mortality.