Warming and humidification of insufflation carbon dioxide in laparoscopic colonic surgery: a double-blinded randomized controlled trial. Heated and humidified insufflation during laparoscopic gastric bypass surgery: effect on temperature, postoperative pain, and recovery outcomes. Prospective randomized trial of heated humidified versus cold dry carbon dioxide insufflation during laparoscopic gastric bypass. A randomized controlled trial assessing the benefit of humidified insufflation gas during laparoscopic surgery. The clinical impact of warmed insufflation carbon dioxide gas for laparoscopic cholecystectomy. Double-blind, prospective, randomized study of warmed, humidified carbon dioxide insufflation vs standard carbon dioxide for patients undergoing laparoscopic cholecystectomy. Effect of heated and humidified carbon dioxide gas on core temperature and postoperative pain: a randomized trial. Beneficial effects of humidified, warmed carbon dioxide insufflation during laparoscopic bariatric surgery: a randomized clinical trial. The effect of heated humidified carbon dioxide on postoperative pain, core temperature, and recovery times in patients having laparoscopic surgery: a randomized controlled trial. Effect of humidified and heated CO2 during gynecologic laparoscopic surgery on analgesic requirements and postoperative pain. Reduction of laparoscopic-induced hypothermia, postoperative pain and recovery room length of stay by pre-conditioning gas with the Insuflow device: a prospective randomized controlled multi-center study. Metabolic and immunologic consequences of laparoscopy with helium or carbon dioxide insufflation: a randomized clinical study. Warming of insufflation gas during laparoscopic hysterectomy: effect on body temperature and the autonomic nervous system. A randomized controlled trial assessing the effect of heated carbon dioxide for insufflation on pain and recovery after laparoscopic fundoplication. Randomized comparison of conventional carbon dioxide insufflation and abdominal wall lifting for laparoscopic cholecystectomy. Effect of CO(2) gas warming on pain after laparoscopic surgery: a randomized double-blind controlled trial.
We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced postoperative pain and improved recovery by reducing peritoneal inflammation in laparoscopic colonic surgery.
                Warming and humidification of insufflation gas is thought be beneficial in laparoscopic surgery, but evidence in prolonged laparoscopic procedures is lacking.
                We used a multicenter, double-blinded, randomized controlled design. The Study Group received warmed (37 degrees C), humidified (98% RH) insufflation carbon dioxide, and the Control Group received standard gas (19 degrees C, 0% RH). Anesthesia and analgesia were standardized. Intraoperative oesophageal temperature was measured at 15 minutes intervals. At the conclusion of surgery, the primary surgeon was asked to rate camera fogging on a Likert scale. Postoperative opiate usage was determined using Morphine Equivalent Daily Dose (MEDD), and pain was measured using visual analogue scores. Peritoneal and plasma cytokine concentrations were measured at 20 hours postoperatively. Postoperative recovery was measured using defined discharge and complication criteria, and the Surgical Recovery Score.
                Eighty-two patients were randomized, with 41 in each arm. Groups were well matched at baseline. Intraoperative core temperature was similar in both groups. Median camera fogging score was significantly worse in the Study group (4 vs. 2, P = 0.040). There were marginal differences in pain scores, but no significant differences were detected in MEDD usage, cytokine concentrations, or any recovery parameters measured.
                Warming and humidification of insufflation CO2 does not attenuate the early inflammatory cytokine response, and confers no clinically significant benefit in laparoscopic colonic surgery. Controversy exists regarding the efficacy of heated and humidified intraperitoneal gases in maintaining core body temperature. We performed a sham-controlled study to test the hypothesis that active warming and humidification of the insufflation gas reduces intraoperative heat loss and improves recovery outcomes.
                Fifty morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass procedures using a standardized anesthetic technique were randomly assigned to either a control (sham) group receiving room temperature insufflation gases with an inactive Insuflow (Lexion Medical, St. Paul, MN) device, or an active (Insuflow) group receiving warmed and humidified intraperitoneal gases. Esophageal and/or tympanic membrane temperature was measured perioperatively. Postoperative pain was assessed at 15 minute intervals using an 11-point verbal rating scale, with 0 = none to 10 = maximal. In addition, postoperative opioid requirements, incidence of nausea and vomiting, as well as the quality of recovery, were recorded.
                Use of the active Insuflow device was associated with significantly higher mean +/- standard deviation (SD) intraoperative core body temperatures (35.5 +/- 0.5 vs. 35.0 +/- 0.4 degrees C). Postoperative shivering (0 vs. 19%) and the requirement for morphine in the postanesthesia care unit (5 +/- 4 vs. 10 +/- 5 mg) were both significantly lower in the Insuflow vs. control groups. Patients in the Insuflow group also reported a higher quality of recovery 48 hours after surgery (15 vs. 13, P < 0.05).
                The Insuflow device modestly reduced shivering and heat loss, as well as the need for opioid analgesics in the early postoperative period. However, it failed to improve laparoscopic visualization due to fogging, and provided improvement in the quality of recovery only on postoperative day 2. The replacement of cold dry carbon dioxide with heated humidified gas for insufflation during complex laparoscopic procedures has been reported to decrease hypothermia and peritoneal cell desiccation, with a resultant decrease in postoperative pain and narcotic use and a shortened recovery, but may prevent the paralysis of the peritoneal polymorphonuclear cell cytokine cascade and add to the cost of the procedure. We report our outcomes comparing carbon dioxide insufflation with different characteristics during laparoscopic gastric bypass.
                Fifty consecutive patients were randomized to undergo laparoscopic gastric bypass with either cold-dry or heated-humidified carbon dioxide insufflation. Statistical analysis of variance between groups was determined by Levine's t test with the Greenhouse-Geisser correction, at a significance level of P <.05.
                The two groups were similar for preoperative gender, age, weight, body mass index, and baseline C-reactive protein. The intraoperative room and patient core temperature, liters of insufflation used, lens cleanings, operating time, recovery room time, and narcotics used were not significantly different. The postoperative subjective analog shoulder pain score was significantly less (P = .025) for the heated-humidified group at 18 hours, but not at 6, 12, 24, or 48 hours. The abdominal pain scores and overall narcotic use, postoperative C-reactive protein, and length of stay were not significantly different between the two groups.
                Heated-humidified insufflation resulted in a transient reduction in subjective shoulder pain at 18 hours postoperatively, but no reduction in abdominal pain or narcotics used. We were unable to verify any clinically significant difference between the two groups comparing heated-humidified and cold-dry insufflation after laparoscopic gastric bypass. We conducted a randomized controlled trial during laparoscopic cholecystectomy to determine the extent of heat preservation and postoperative pain reduction using humidified carbon dioxide (CO2) gas insufflation instead of standard dry insufflation gas.
                Forty consecutive patients were randomized. Twenty patients received humidified CO2, and 20 control patients received standard CO2 insufflation. A sample of 16 patients from each group was evaluated for postoperative pain levels.
                No adverse effects from the humidification of insufflated gas were observed. There was no significant difference in core body temperature between the two groups for this brief operation. Pain, as assessed by the Analogue Pain Score (APS) was significantly less for the group with humidified gas insufflation than for the control group at 6 h postoperatively as well as on the 1st, 2nd, and 3rd postoperative day and at follow-up 10 days after the operation. In the humidified group, the mean time to return to normal activities was significantly less-5.9 days, as compared to 10.9 days in the control group.
                The use of humidified insufflation gas reduces postoperative pain following laparoscopic cholecystectomy, but except for these relatively brief procedures, the heat-preserving effect of humidified gas insufflation is not significant. Reports suggest that the insufflation of cold gas to produce a pneumoperitoneum for laparoscopic surgery can lead to an intraoperative decrease in core body temperature and increased postoperative pain.
                In a randomized controlled trial with 20 patients undergoing laparoscopic cholecystectomy, the effect of insufflation using carbon dioxide gas warmed to 37 degrees C (group W) was compared with insufflation using room-temperature cold (21 degrees C) gas (group C). Intraoperative body core and intra-abdominal temperatures were determined at the beginning and end of surgery. Postoperative pain intensity was evaluated using a visual analog scale and recording the consumption of analgesics.
                There were no significant group-specific differences during the operation, neither in body temperature (group W: 36.1 +/- 0.4 degrees C vs group C: 35.7 +/- 0.6 degrees C) nor in intra-abdominal temperature (group W: 35.9 +/- 0.3 degrees C vs group C: 35.6 +/- 0. 6 degrees C). Postoperatively, the two groups did not differ in pain susceptibility and need of analgesics.
                The use of carbon dioxide gas warmed to body temperature to produce a pneumoperitoneum during short-term laparoscopic surgery has no clinically important effect. Patients undergoing warmed, humidified carbon dioxide (CO2) insufflation for laparoscopic cholecystectomy will (1) maintain a warmer intraoperative core temperature, (2) have their surgeon experience less fogging of the camera lens, and (3) have less postoperative pain than patients undergoing laparoscopic cholecystectomy with standard CO2 insufflation.
                A double-blind, prospective, randomized study comparing patients undergoing laparoscopic cholecystectomy with standard CO2 insufflation vs those receiving warmed, humidified CO2 (Insuflow Filter Heater Hydrator; Lexion Medical, St Paul, Minn) was performed. Main variables included patient core temperature, postoperative pain, analgesic requirements, and camera lens fogging.
                One hundred one blinded patients (69 women, 32 men) undergoing laparoscopic cholecystectomy were randomized into 2 groups-52 receiving standard CO2 insufflation (group A) and 49 receiving warmed, humidified CO2 (group B). Mean patient intraoperative core temperature change (group A decreased by 0.03 degrees C, group B increased by 0.29 degrees C, P =.01) and mean abdominal pain (Likert scale, 0-10) at 14 days postoperatively (group A, 1.0; group B, 0.3; P =.02) were different. Other variables (camera lens fogging, early postoperative pain, narcotic requirements, recovery room stay, and return to normal activities) between groups were similar.
                While patients undergoing laparoscopic cholecystectomy with warmed, humidified CO2 had several advantages that were statistically significant, no major clinically relevant differences between groups A and B were evident. Intraoperative hypothermia is a common event during laparoscopic operations. An external warming blanket has been shown to be effective in preventing hypothermia. It has now been proposed that using heated and humidified insufflation gas can prevent hypothermia and decrease postoperative pain. Therefore, we examined the extent of intraoperative hypothermia in patients undergoing laparoscopic Nissen fundoplication using an upper body warming blanket. We also attempted to determine whether using heated and humidified insufflation gas in addition to an external warming blanket would help to maintain intraoperative core temperature or decrease postoperative pain.
                Twenty patients were randomized to receive either standard carbon dioxide (CO2) gas (control, n = 10) or heated and humidified gas (heated and humidified, n = 10). After the induction of anesthesia, an external warming blanket was placed on all patients in both groups. Intraoperative core temperature and intraabdominal temperature were measured at 15-min intervals. Postoperative pain intensity was assessed using a visual analogue pain scale, and the amount of analgesic consumption was recorded. Volume of gas delivered, number of lens-fogging episodes, intraoperative urine output, and hemodynamic data were also recorded.
                There was no significant difference between the two groups in age, length of operation, or volume of CO2 gas delivered. Compared with baseline value, mean core temperature increased by 0.4 degrees C in the heated and humidified group and by 0.3 degrees C in the control group at 1.5 h after surgical incision. Intraabdominal temperature increased by 0.2 degrees C in the heated and humidified group but decreased by 0.5 degrees C in the control group at 1.5 h after abdominal insufflation. There was no significant difference between the two groups in visual analog pain scale (5.4 +/- 1.6 control vs 4.5 +/- 2.8 heated and humidified), morphine consumed (27 +/- 26 mg control vs 32 +/- 19 mg heated and humidified), urine output, lens-fogging episodes, or hemodynamic parameters.
                Heated and humidified gas, when used in addition to an external warming blanket, minimized the reduction of intraabdominal temperature but did not alter core temperature or reduce postoperative pain. Recent data has shown that the use of warmed, humidified carbon dioxide (CO2) insufflation during laparoscopic surgery may be associated with better outcomes.
                We performed a randomized, doubleblind, prospective controlled clinical trial of 30 patients undergoing laparoscopic Roux-en-Y gastric bypass (LRYGBP). Patients were randomized into 2 groups. The first group (group 1, n=15) received standard (dry, room temperature) CO2 for insufflation during the surgery, while the second group (group 2, n=15) received warmed (35 degrees C) and humidified (95%) CO2. Patients received postoperative analgesia from morphine delivered via a patient-controlled analgesia (PCA) pump. Pain scores (on a scale of 0 to 10, 0 being no pain and 10 being the worst pain) were measured postoperatively at 3 h, 6 h, 1 day and 2 days. The amount of morphine that was delivered through the PCA was also measured at the same time intervals. Operating-room (OR) time, core temperature, and total hospital length of stay were documented.
                Postoperative pain as documented by pain scores and narcotic usage were not statistically different in the 2 groups. We demonstrated a statistically significant difference (mean+/-SD) in OR time (76+/-16 min vs 101+/-34 min, P=0.02), total hospital length of stay (3.2+/-.4 days vs 4.0+/-.9 days, P=0.01) and end-of-case core temperature (36.2+/-.5 degrees C vs 35.7+/-.6 degrees C, P=0.02) in group 2 compared with group 1.
                The use of warmed, humidified CO2 insufflation in bariatric patients undergoing LRYGBP was not associated with any significant benefit with regards to postoperative pain. To determine whether use of heated humidified carbon dioxide as insufflation gas during gynecologic laparoscopy reduced postoperative pain and hypothermia.
                A randomized controlled trial (Canadian Task Force classification 1).
                A tertiary referral hospital.
                Sixty women scheduled for gynecologic laparoscopy between 30 and 90 minutes' duration.
                Operative laparoscopic management of endometriosis, adhesions, or adnexal pathology.
                Sixty patients were randomized into either receiving heated humidified carbon dioxide (study group) or standard cold dry gas (control group). Intraoperative and postoperative core temperature, total analgesic use, postoperative nausea, and recovery room time were recorded. Postoperative pain intensity was assessed using visual analog scale. Statistical analysis was performed using software. No significant difference was revealed between groups with regard to postoperative pain, analgesic requirements, recovery room time, or postoperative nausea. The control group had less postoperative hypothermia, suggesting that external warming blankets may be more effective than heated humidified gas at maintaining intraoperative normothermia.
                The use of heated humidified carbon dioxide insufflation for short-duration gynecologic laparoscopy up to 90 minutes' duration was not associated with any significant benefit with regard to postoperative pain, hypothermia, or time of recovery room stay. To determine the effect of humidified and heated CO(2) for pneumoperitoneum during laparoscopic surgery on analgesic requirements, postoperative pain, and patient satisfaction.
                Prospective, randomized, double-blind, controlled study (Canadian Task Force classification I).
                University hospital.
                Ninety consecutive women scheduled for gynecologic laparoscopic surgery.
                Operative laparoscopic management of adnexa surgery or adhesiolysis.
                Thirty consecutive patients were randomized into each study group. Group I received humidified, heated gas; group II dry, heated gas; and group III (control group) standard dry, cold gas. No significant difference in intraoperative and postoperative analgesic requirements or postoperative pain score between group I and group II was found. There was even a tendency (not significant) toward less pain and higher postoperative satisfaction in patients in the control group. Therefore, the evaluation was stopped after 53 patients.
                The use of humidified, heated gas did not reduce postoperative pain or intraoperative analgesic requirements and is thus not preferable to standard dry, cold gas in gynecologic laparoscopic surgery. To assess the efficacy and safety of Insuflow (Georgia BioMedical, Inc.) filter heater hydrator device in reducing the incidence, severity and extent of hypothermia, length of recovery room stay and postoperative pain at the time of laparoscopy.
                Prospective, randomized, blinded, controlled multi-center study. Patients underwent gynecologic procedures via laparoscopy; surgeons, anesthesiologists and recovery room personnel assessed the results.
                Seven North American institutions.
                Seventy-two women for safety evaluation and efficacy studies.
                Intraoperative pre-conditioning of laparoscopic gas with the Insuflow device (treatment) or standard raw gas (control) during laparoscopic surgery and postoperatively.
                Incidence, severity and extent of hypothermia, postoperative pain perception and length of recovery room stay.
                The Insuflow group had significantly less intraoperative hypothermia, reduced length of recovery room stay and reduced postoperative pain. Pre-conditioning of laparoscopic gas by filtering heating and hydrating was well tolerated with no adverse effects. The safety profile of the Insuflow pre-conditioned gas showed significant benefits compared to currently used raw gas.
                Pre-conditioning laparoscopic gas by filtering heating and hydrating with the Insuflow device was significantly more effective than the currently used standard raw gas and was safe in reducing or eliminating laparoscopic-induced hypothermia, shortening recovery room length of stay and reducing postoperative pain. Previous studies using animal models have demonstrated that carbon dioxide (CO2) pneumoperitoneum during laparoscopy is associated with adverse physiological, metabolic, immunological and oncological effects, and many of these problems can be avoided by the use of helium insufflation. The present study was performed in patients to compare the effect of helium and CO2 insufflation on intraperitoneal markers of immunological and metabolic function.
                Eighteen patients undergoing elective upper gastrointestinal laparoscopic surgery were randomized to have insufflation achieved by using either helium (n = 8) or CO2 (n = 10) gas. Intraperitoneal pH was monitored continuously during surgery, and peritoneal macrophage function was determined by harvesting peritoneal macrophages at 5 min and 30 min after commencing laparoscopy, and then assessing their ability to produce tumour necrosis factor-alpha (TNF-alpha), and their phagocytic function.
                Carbon dioxide laparoscopy was associated with a lower intraperitoneal pH at the commencement of laparoscopy, although this difference disappeared as surgery progressed. The production of TNF-alpha was better preserved by CO2 laparoscopy, but the insufflation gas used did not affect macrophage phagocytosis. Patients undergoing helium laparoscopy required less postoperative analgesia.
                The choice of insufflation gas can affect intraperitoneal macrophage function in the clinical setting, and possibly acid-base balance. The present study suggested no immunological advantages for the clinical use of helium as an insufflation gas. The outcomes of the present study, however, are different to those obtained from previous laboratory studies and further research is needed to confirm this outcome. Hypothermia is a known side effect of laparoscopic operations. It may increase the sympathetic activity of the autonomic nervous system (ANS), which can be evaluated noninvasively by heart rate variability (HRV). We tested the hypothesis that warming of the delivered CO2 insufflation gas helps to maintain the normal body temperature.
                Thirty-seven healthy women undergoing laparoscopic hysterectomy were randomized into heated (37 degrees C, n=18) or unheated (24 degrees C, n = 19) gas insufflation groups. Anesthesia was induced with propofol and maintained with sevoflurane in O2-air. Tympanic (ttymp) temperature was recorded before, during and after the operation. Nasopharyngeal (tnaso) temperature was recorded only during operation. Electrocardiograms were recorded and stored to evaluate changes in HRV. The individual changes in HRV were compared after decibel (dB) transformation.
                A median decrease in tympanic temperatures during the operation was 0.7 degrees C in the heated and 0.3 degrees C in the unheated group (P = 0.01 between groups), and in nasopharyngeal 0.3 degrees C and 0.1 degrees C (P = 0.03), respectively. Preanesthetic tympanic values were reached within 90 min after anesthesia. After dB transformation, HRV high frequency power differed between the groups. It was better preserved in the patients receiving unheated gas.
                The heating of insufflation gas does not prevent a decrease in body temperature and is thus unnecessary during laparoscopic hysterectomy. Insufflation with heated gas for laparoscopy may reduce postoperative pain. This study assessed the effect of heated gas on outcome after fundoplication.
                A blinded, randomized trial compared the effect of heated or standard carbon dioxide (CO2) on core temperature, postoperative pain, analgesic requirement, and postoperative recovery. Pain scores were assessed with a 100 mm visual analog scale (VAS). Recovery was assessed with a patient diary and clinical follow-up assessment at 8 days and 1 month postoperatively.
                For this study, 40 patients were randomized to heated CO2 (n = 19) and standard CO2 (control) (n = 21) groups. The heated CO2 group increased core body temperature from 35.9 degrees to 36.1 degrees C, (p = 0.008), whereas the control group maintained core temperature at 35.8 degrees C. The control group had lower analgesic requirements and pain scores, significant at 12 h (VAS: 20 vs 36 mm; p = 0.04). There was no difference between the groups in terms of late recovery. The heated CO2 group showed a significant correlation between operative duration and requirement for postoperative morphine (p = 0.01).
                Heated gas provides no benefit for patients and may be associated with increased early pain. The elevation of core body temperature observed with heated CO2 is of little clinical significance. Gasless laparoscopy using abdominal wall lifting (AWL) has been developed in an attempt to avoid the adverse effects of carbon dioxide pneumoperitoneum that may occur in conventional laparoscopy. However, lifting has been criticized for its poor operative space and surgical invasiveness. This study compared the AWL method with conventional CO2 pneumoperitoneum for laparoscopic cholecystectomy with respect to operation performance, postoperative course, and stress response.
                During a 6-month period, 95 patients with symptomatic gallstones were randomly assigned to receive laparoscopic cholecystectomy with conventional CO2 pneumoperitoneum (CO2 group; N = 47) or the AWL method (AWL group; N = 48). Operative results and operative time were recorded. Cardiopulmonary functions were assessed, and arterial blood gases were analyzed during surgery. Urinary cortisol, vanillylmandelic acid, metanephrines, and nitrogen loss; serum complement 3, C-reactive protein, and interleukin-6; postoperative pain; and the presence of nausea and vomiting were assessed for 48 hours after surgery. Postoperative time to recovery of flatus, tolerance of a full oral diet, and full activity were also determined.
                Only three significant differences were found. First, intraoperative ventilatory function deteriorated significantly less in the AWL group. Second, arterial blood gas determinations and capnography showed a greater decrease in intraoperative arterial pH and compliance with CO2 retention and an increase in peak airway pressure in the CO2 group (P < 0.05), reflecting poorer ventilatory performance. Third, preparation time and total operating time were significantly greater with the AWL method (P < 0.05).
                Although AWL required a longer operation time, our results suggest that the technique may still have value in high-risk patients with cardiorespiratory diseases. Previous studies have suggested that gas temperature has an influence on postlaparoscopy pain. This trial therefore was conducted to study the effect of gas warming on pain after upper abdominal laparoscopic surgery.
                Patients who underwent laparoscopic cholecystectomy, fundoplication, or Heller's myotomy were included and randomly allocated to receive either warm or cold gas. Primary end point was shoulder tip pain, and secondary end points were subcostal, trocar wound, and visceral pains, as well as other postoperative events. Criteria of pain assessment were the visual analog scale, verbal rating scale, and amount of analgesics.
                A total of 100 patients were suitable for postoperative evaluation. The groups were well matched. Shoulder tip and subcostal pains were significantly more intense after gas warming (p < 0.05). The three assessment criteria showed the same differences. No difference was observed concerning trocar wound and visceral pains and the other secondary end points. Subdiaphragmatic temperature was not significantly different (34.4 degrees with warming vs. 34 degrees without warming).
                Gas warming does not reduce, and probably increases, postoperative shoulder tip and subcostal pains.
The study offers evidence that during laparoscopic abdominal surgery, heated gas insufflation, with or without humidification, has minimal benefit on patient outcomes.