Laparoscopic pain, hypothermia cut with warmed, wet [Co.sub.2]

OB/GYN News,  Feb 15, 2002  by Erik L. Goldman

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NEW YORK -- Warm and moist is a whole lot nicer than cold and dry when it comes to laparoscopic peritoneal insufflation.

A simple $125 device that heats and humidifies the [CO.sub.2] before insufflating a patient's abdomen can markedly reduce intraoperative hypothermia as well as shoulder tip pain, the major adverse effect associated with laparoscopy, Dr. Larry Demco said at an international congress sponsored by the Society of Laparoendoscopic Surgeons.

The average insufflator pumps [CO.sub.2] at 21 [degrees] C, with a water vapor content of 0.0002%, into a peritoneal cavity that is normally 37 [degrees] C and extremely moist, said Dr. Demco of the department of obstetrics and gynecology, University of Calgary (Alta.).

These extreme differences result in marked desiccation of peritoneal and mesothelial tissues, cellular destruction, release of cytokines, and exposure of basal lamina to chemical irritation. Dr. Demco and several other speakers at the conference believe these are the major contributors to shoulder tip pain, a referred-pain phenomenon that affects up to 80% of women undergoing [CO.sub.2] insufflation. "If you heat and humidify the [CO.sub.2], you can really reduce pain, need for analgesia, and postoperative recovery time. Many patients will be able to tolerate an awake procedure (local anesthesia only), and you won't need warming blankets."

The Insuflow device, manufactured by Lexion Medical, Sr. Paul, Minn., can be connected to any insufflator. A small electric heater regulated by a controller box warms the gas; by the time it reaches the cannula valve, it is roughly 36 [degrees] C. The gas also passes through a reservoir containing 8 cc of warm sterile water that moistens the gas to 95% relative humidity

Dr. Demco studied the effects of warm, heated gas versus untreated gas in 50 patients undergoing a variety of common laparoscopic procedures. The outcomes weighed clearly in favor of Insuflow. Dr. Demco has received product support from Lexion but has no financial interest in the device.

All patients began their procedures under local anesthesia. With the insufflation of 700 mL of [CO.sub.2] 30% of the controls but only 10% of the Insuflow patients experienced shoulder tip pain. In the latter group, the pain tended to be transient; only 10% of the Insuflow group required general anesthesia to complete their procedures. In contrast, 50% of the control group had pain severe enough to warrant general anesthesia (J. Am. Assoc. Gynecol. Laparosc. 8[2]:247-5 1, 2001).

Thirty percent of the Insuflow patients got through their procedures without any analgesics beyond the local injections of lidocaine at the incision sites. Fifty percent of the Insuflow group required small amounts of intravenous fentanyl. In contrast, only 5% of the plain gas patients needed no analgesics, while 75% required fentanyl.

Use of warm, wet gas also resulted in shorter postoperative recovery times. Forty percent of the Insuflow patients but only 20% of the plain gas patients were discharged within 60 minutes of procedure completion. At the other end of the spectrum, 50% of the plain gas patients but only 20% of the Insuflow patients required 120-150 minutes in the recovery room prior to discharge.

According to Dr. Douglas Ott, a physician and engineer who worked on the development of Insuflow, the device is also a good way to brighten faces at the Joint Commission on Accreditation of Healthcare Organizations. "JCAHO is pushing hard for pain reduction in hospitals. This is a very simple, inexpensive, and nonpharmacologic way to achieve significant pain reduction for a lot of procedures." He estimated that about 250 hospitals and surgery centers in the United States are now using Insuflow

Dr. Ott of the Mercer University School of Engineering, Macon, Ca., led a study of 72 patients treated at seven centers around the country The patients, undergoing laparoscopic work-up for uterine leiomyomas, infertility adhesions, or endometriosis, were randomly assigned to insufflation with untreated or Insuflow-treated [CO.sub.2.]

Those receiving untreated gas had an average intraoperative core temperature reduction of 1.64[degrees] C per procedure, an average loss of more than 0.6 [degrees] C per hour. In contrast, those in the Insuflow group had an average total loss of 0.3 [degrees] C per procedure. Ninety-four percent of the untreated-gas patients experienced intraoperative and postoperative hypothermia, as compared with only 8.3% of the Insuflow group.

Patient questionnaires using visual analog scales showed consistently lower pain scores for the Insuflow group. All of the Insuflow patients were out of the recovery room within 2 hours, and 89% were out within an hour. In contrast, only 33% of the untreated gas patients went home within an hour, and 67% required 2 or more hours in the recovery room.

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