Acid-base status of pregnant guinea pigs during neuroleptanalgesia with diazepam and fentanyl-fluanisone.

Neuroleptanalgesia was induced in late pregnancy in guinea pigs with diazepam and fentanyl-fluanisone. Hypotension occurred, but the arterial acid-base status after 45-60 min was near normal. When repeated injections of fentanyl-fluanisone were given to maintain neuroleptanalgesia, the blood pressure fell further and severe metabolic acidosis developed. Placental blood flow determined with radioactive microspheres was much lower during maintained neuroleptanalgesia than in guinea pigs anaesthetized with diazepam and pentobarbitone.