Physiologic effects of simultaneous carbon dioxide insufflation by laparoscopy and colonoscopy: prospective evaluation.

BACKGROUND: The use of intraoperative carbon dioxide (CO(2)) colonoscopy during a laparoscopic colon operation is becoming more common. Simultaneous intracolonic and intraabdominal CO(2) insufflation may result in significant physiologic changes, but in-depth physiologic effects have not been studied to date. This study aimed to evaluate the physiologic changes and the overall safety of simultaneous CO(2) laparoscopy and colonoscopy. METHODS: A prospective pilot study was performed with 26 subjects (17 men and 9 women) undergoing laparoscopic surgical treatment for colorectal conditions adjunctively managed with CO(2) intraoperative colonoscopy. Surgery proceeded with CO(2) insufflation to a maximum pressure of 12 mmHg by laparoscopy and with a maximum CO(2) flow of 5 l/min via colonoscopy. Serial intra- and postoperative arterial blood gases, end-tidal CO(2), and minute ventilation were recorded during predetermined periods: during initial laparoscopy, during simultaneous colonoscopy and laparoscopy, during laparoscopy after colonoscopy, and after desufflation. RESULTS: No significant morbidity resulted from simultaneous CO(2) insufflation. Three patients had a CO(2) partial pressure (PaCO(2)) greater than 50, and one patient with a body mass index (BMI) higher than 42 kg/m(2) had a PaCO(2) greater than 50 for more than 30 min and was compensated by increasing minute ventilation. The mean pH was 7.36 in the recovery room. Postoperatively, no patient had a pH lower than 7.3, prolonged intubation, or reintubation. CONCLUSION: Simultaneous CO(2) colonoscopy and laparoscopy lead only to transient alterations in respiratory parameters that can be compensated. Based on these findings, simultaneous insufflation of CO(2) into the peritoneal cavity and the large bowel lumen during complex endoscopic procedures may be considered safe for most patients.

Clinical pharmacology of GW280430A in humans.

BACKGROUND: An ultrashort-acting nondepolarizing neuromuscular blocking agent that could be an alternative to succinylcholine has been the focus of a concerted effort in the field of muscle relaxants. GW280430A showed a promising pharmacodynamic profile in preclinical work and a wide margin of safety and so was selected for study in humans. METHODS: Thirty-one volunteers participated in this study, which determined the dose producing 95% block (ED95) and the safety and pharmacodynamics of increasing ED95 multiples. Anesthesia was induced and maintained with propofol, midazolam, and fentanyl. Neuromuscular transmission was measured at the adductor pollicis using ulnar nerve stimulation, and responses were recorded continuously by standard mechanomyographic monitoring. RESULTS: The ED95 for GW280430A is 0.19 mg/kg. The time to onset of 90% block ranged from 1.3 to 2.1 min, depending on the dose. Clinical durations ranged from 4.7 to 10.1 min and increased with increasing dose. Five to 95% and 25-75% recovery rates were approximately 7 and 3 min, respectively, and were independent of the dose administered. Transient cardiovascular side effects were observed at doses beginning at 3 x ED95 and above and were suggestive of histamine release. Most volunteers receiving 4 x ED95 exhibited plasma histamine concentrations indicative of significant histamine release. CONCLUSIONS: GW280430A has a rapid onset and ultrashort duration of action. The recovery rate is rapid, predictable, and independent of dose. Doses at least up to 2.5 x ED95 seem to be free of side effects and seem to be able to provide relaxation within 60-90 s.