Do hourly averaged pH readings correlate with those from point readings of aspiration? Comparison of two different electrode positions with simultaneous aspiration.

Hourly averaged data from continuous intraluminal pH recording were compared with the point aspiration in five 24-hour studies performed on healthy volunteers. Two different electrode positions were compared simultaneously with aspiration. The correlation was performed using the median from the whole hour's recording of the electrode against the aspiration point. There was a significant correlation between both electrodes and aspiration (p less than 0.001), although both electrodes read consistently lower than aspiration: electrode A (gastric antrum), median pH = 1.4; electrode B (gastric body), pH = 1.9; aspiration, pH = 2.3. These findings show that data reported in clinical trials using different recording techniques are not directly comparable and must be interpreted appropriately. The position of the electrode may also be important.