Background: Cyclic GMP (cGMP) has been implicated in modulating the effects of general anaesthesia. Changes in cGMP in humans undergoing anaesthesia have not been reported previously.
Methods: In this pilot study we measured cGMP in the saliva of six healthy volunteers and eight patients undergoing general anaesthesia for minor gynaecological procedures. Samples were obtained using a commercially available sampling device and cGMP was determined with an enzyme immunoassay and results expressed as a cGMP per mg protein.
Results: There was no statistically significant variation in salivary cGMP either day-to-day or between time points in healthy volunteers. Analysis of variance of salivary cGMP of patients undergoing general anaesthesia showed that cGMP increased significantly intraoperatively and returned to preoperative levels after surgery (P=0.03).
Conclusions: This is the first time that real time in vivo changes in salivary cGMP levels during general anaesthesia in humans have been demonstrated and may allow an alternative technique for measuring depth of anaesthesia in the future.