Studies of gastric content: comparison of two methods.

In 20 patients studied under general anaesthesia, we found good agreement between gastric fluid volumes aspirated blindly and total volumes determined by fibreoptic gastroscopy (mean under-estimation 6 ml (22%); range 0-50 ml). Gastric fluid acidity measurements using an electronic pH meter and pH indicator paper also provided results with good agreement (mean difference in pH 0.1; range -0.3 to 0.5). As the use of a standardized blind gastric aspiration technique and pH indicator paper is simpler and provided sufficiently accurate measurements for clinical study purposes, we think this method is preferable.