Introduction. Gastric tonometry is used to assess splanchnic perfusion. There are no guidelines for optimal catheter position and frequency of arterial bicarbonate (HCO3) sampling for accurate pHt calculation from gastric pCO2. Hypothesis: pHt would vary dependent on gastric location and require frequent HCO3 sampling. Methods. Yorkshire swine (38-50 kg) pretreated with 1 mg/kg IV rantidine had invasive monitors and 2 gastric tonometers placed by laparotomy (1 proximal, 1 distal) under isofluorane. Forty % hemorrhage (15") was followed by shock (60"), resuscitation (60") and reperfusion (120"; n=6) or shock without resuscitation (120", n=4). Arterial HCO3 and proximal/distal gastric pCO2. were sampled q15"; pHt was determined by Henderson-Hassdbach. Data are analyzed by student's t-test and linear regression; p<0 05 defined significance (*). Results. Proximal pHt was significantly different from distal at baseline and reperfusion. exceeding "normal" values of 7.30 to 7.40. The correlation (r2) between pCO2 and pHt was 0.72. indicating an important contribution of fluctuating HCO3 to pHt determination. Conclusions. In porcine hemorrhage and resuscitaton: 1) pHt varies greatly between the proximal and distal stomach despite H2 blockade and 2) Arterial HCO3 must be sampled frequently for accurate pHt calculation from gastric pCO2 by Henderson-Hasselbach methodology. This may have important clinical ramifications.
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine