The effect of high-dose fentanyl anaesthesia on P50 in man

The effect of high dosage fentanyl anaesthesia on P50 was studied in patients undergoing coronary bypass surgery. After induction of fentanyl anaesthesia 100 micrograms X kg-1 with pancuronium muscle relaxation P50 changed significantly (P less than 0.005) from 3.40 +/- 0.12 to 3.33 +/- 0.13 kPa. This anaesthesia technique decreases P50 in vivo, but this has more theoretical than practical importance.