Relationship between Gastric pH Measurement and Intra-abdominal Pressure in Patients Undergoing Laparoscopic Surgery

Laparoscopic surgery (LS) is a safe and widely used technique. During LS, carbon dioxide insufflation may produce significant hemodynamic and ventilatory consequences, such as elevated intra-abdominal pressure (IAP) and hypercarbia. Splanchnic and cardiovascular blood flow can be affected by the elevated IAP, which can result in ischemia in the splanchnic region prior to hemodynamic changes. Changes in gastric pH may be an early precursor of changes in splanchnic blood circulation. This study investigated the relationship between gastric pH measurement and IAP in patients undergoing LS.

This study included 49 patients aged 18-65 years with American Society of Anesthesiologists (ASA) physical status I - III who were undergoing elective laparoscopic cholecystectomy. A gastric pH tonometer probe was applied using an orogastric catheter. Simultaneously, insufflation pressure, cardiac apex beat (CAB), and mean arterial blood pressure (MAP) values were recorded. Indirect IAP was then measured through the bladder. Measurements were performed at baseline; at 15, 30, and 60 minutes after onset of insufflation (AI 15, AI 30, and AI 60, respectively); and at the end of insufflation (EI). Two pH measurements were obtained with a gastric tonometer pH probe, using an automated function of the gastric tonometer to improve measurement reliability.

IAP was significantly higher than baseline at AI 15, AI 30, AI 60, and EI (p<0.001). The pH₁ and pH₂ levels were significantly lower at AI 15 and AI 30, compared with baseline (p<0.001). There were no significant differences between pH₁ and pH₂ measurements at AI 60 and EI. Compared with baseline, CAB was significantly lower at AI 15, AI 30, AI 60, and EI (p=0.001, p<0.001, p=0.006). There were no statistically significant differences in MAP changes at any time point.

Elevated IAP caused by CO₂ insufflation during LS led to reductions of pH₁ and pH₂. There was a correlation between gastric pH measurement and IAP. Measurement of gastric pH may be useful to assess blood circulation in the splenic area during LS.