CO2 For Insufflation Research Articles

Image quality of abdominal ultrasonography after esophagogastroduodenoscopy is preserved by using carbon dioxide insufflation: A non-inferiority test in the same subject.

Because bowel gas deteriorates the image quality of abdominal ultrasonography (AUS), it is common to perform AUS prior to esophagogastroduodenoscopy (EGD). This one-way order limits the availability of examination appointments. To evaluate whether EGD using insufflation of carbon dioxide (CO2), which is rapidly absorbed by the gastrointestinal mucosa, preserves the image quality of AUS performed subsequently, we designed a non-inferiority test in which each subject underwent AUS, EGD with CO2 insufflation, and a second AUS, in that order. All saved AUS moving images were randomized and imaging quality was evaluated at 16 organs using a four-point Likert-like scale that divides the depiction rate by 25%. Sample size was calculated to be 26 using the following: non-inferiority margin of -0.40 corresponding to depiction rate of -10%, difference of means of 0.40, common standard deviation of 1.25, power of 90%, and 1-sided α-level of 0.025. We enrolled 30 subjects. The mean and 95% confidence interval (CI) of the image quality score of all 16 organs at pre- and post-EGD AUS in the 30 subjects were 3.54 [3.48-3.60] and 3.46 [3.39-3.52], respectively. The difference in the means was 0.08 of the scores, corresponding to a 2% depiction rate. The effect size was 0.172. The image quality of post-EGD AUS was not inferior, as demonstrated by the 97.5% CI of the difference, which did not cross the non-inferiority margin of -0.40. In conclusion, the use of CO2 for insufflation in EGD does not cause much deterioration in the image quality of AUS performed subsequently. Therefore, it is permissible to perform EGD prior to AUS, which is expected to improve the efficiency of examination setup.

Warmed and humidified insufflation to prevent perioperative hypothermia and improve the quality of recovery in elective laparoscopic colorectal resection patients: a feasibility study for a triple-blind randomized controlled trial.

The use of standard CO2 for insufflation during laparoscopic colorectal surgery may be associated with cooling and drying of the peritoneal cavity, contributing to perioperative hypothermia. The aim of this work was the assess the feasibility of a study to compare insufflation of warmed, humidified CO2 (WHCO2) (using HumiGard, Fisher and Paykel Healthcare) with standard measures and its impact on the quality of recovery of surgical patients. A single-centre, triple-blind, feasibility, randomized controlled trial (RCT) of adults scheduled for planned laparoscopic colorectal surgery. The primary outcome was recruitment. Secondary outcomes included feasibility of blinding, acceptability to patients and suitability of objective measures: patient-reported quality of recovery using a validated questionnaire (QoR-40), patient pain scores and semi-continuous core temperature measurements. Thirty-nine participants were randomized to either the WHCO2 group (n=19) or standard care alone (n=20). Recruitment to the study was successful and acceptable to patients. Blinding of the surgeons, patients and assessors was effective. Response rates to QoR-40 were high but ceiling effects were observed, indicating that the tool was unsuitable in this population. Fewer patients in the WHCO2 group reported postoperative nausea and vomiting (PONV) at days 1 (53% vs. 65%) and 3 (37% vs. 60%). The median hospital length of stay was 5.5days in the standard care group and 4days in the WHCO2 group. A study of WHCO2 for insufflation in laparoscopic colorectal surgery would be highly acceptable to both patients and researchers. Potential reductions in PONV and hospital length of stay in patients treated with WHCO2 merit further investigation. The design of the full-scale RCT will benefit from this feasibility study.

Influence of insufflated carbon dioxide on abdominal temperature compared to oesophageal temperature during laparoscopic surgery

BackgroundBody core temperature is an important vital parameter during surgery and anaesthesia. It is influenced by several patient-related and surgery-related factors. Laparoscopy is considered beneficial in terms of a variety of parameters, for example, postoperative pain and length of hospital stay. Non-humidified, non-warmed insufflated CO2 applied during laparoscopy is standard of care. This prospective observational trial therefore evaluates the impact of non-humidified CO2 at room temperature on abdominal temperature and its correlation to body core temperature.MethodsSeventy patients undergoing laparoscopic surgery were included in this prospective observational study. Temperature was measured oesophageal and abdominal before induction of anaesthesia (T1), right before skin incision (T2), 15 min, 30 min and 60 min after skin incision. All patients were treated according to actual guidelines for perioperative temperature measurement.ResultsBody core temperature and abdominal temperature correlated moderately (r = 0.6123; p < 0.0001). Bland–Altman plot for comparison of methods showed an average difference of 0.4 °C (bias − 0.3955; 95% agreement of bias from − 2.365 to 1.574). Abdominal temperature further decreased after establishing pneumoperitoneum (T2: 36.2 °C (35.9/36.4) to T5: 36.1 °C (35.6/36.4); p < 0.0001), whereas oesophageal temperature increased (T2: 36.2 °C (35.9/36.4) to 36.4 °C (36.0/36.7); p = 0.0296). Values of oesophageal and abdominal measurement points differed at T4 (36.3 °C (36.0/36.6) vs. 36.1 °C (35.4/36.6); p < 0.0001) and T5 (36.4 °C (36.0/36.7) vs. 36.1 °C (35.6/36.4) p = 0.0003).ConclusionThis prospective observational trial shows the influence of insufflated, non-humidified carbon dioxide at room temperature on abdominal temperature during laparoscopic surgery. We show that carbon dioxide applied at these conditions decreases abdominal temperature and therefore might be a risk factor for perioperative hypothermia.

Is Carbon Dioxide Insufflation During Endoscopy in Children as Safe and as Effective as We Think?

Distension of the gastrointestinal lumen is crucial for visualization and advancement during endoscopic procedures. An increasing number of pediatric centers now use carbon dioxide (CO2) preferentially over air as many adult studies and a few pediatric studies have concluded that CO2 is better tolerated than air, especially for colonoscopy. The aim of the study was to determine if CO2 is as safe and as effective as air and if it reduces abdominal discomfort and distension in children undergoing upper endoscopy and colonoscopy. Double blinded, prospective, randomized clinical study. Patient- and nursing-reported outcomes of pain and distension were recorded. End tidal CO2 (EtCO2) was monitored continuously with a CO2-sampling nasal cannula for patients undergoing procedural sedation and via the endotracheal tube for those who were intubated. One hundred seventy-eight patients with 180 procedures were enrolled, 91 procedures were randomized to receive CO2, and 89 to air. Groups did not differ significantly with respect to nursing-assessed abdominal discomfort, change in girth from baseline, or endoscopist-perceived ease of inflation. Use of CO2 was associated with transient spikes in the EtCO2 (≥60 mmHg) in a significant number of patients during sedated upper endoscopy without endotracheal intubation. There was a reduction of bloating and flatulence for all procedures in the CO2 group. The benefits of using CO2 for insufflation were minimal in our patients. The observed transient elevations of EtCO2 during sedated upper endoscopy raise concerns of possible systemic hypercarbia. The wisdom of its routine use for all pediatric endoscopic procedures is questioned.

Normothermic Insufflation to Prevent Perioperative Hypothermia and Improve Quality of Recovery in Elective Colectomy Patients: Protocol for a Randomized Controlled Trial.

BackgroundPerioperative hypothermia during laparoscopy for bowel resection is a risk factor for postoperative medical complications and surgical wound infections. Despite various warming methods used during surgery, a significant number of patients experience perioperative hypothermia. Use of dry, unwarmed insufflation carbon dioxide (CO2) during laparoscopic procedures may contribute to this problem. Evidence exists that the HumiGard device, which humidifies and heats CO2 for insufflation, can reduce the risk of perioperative hypothermia.ObjectiveThe aim is to determine if insufflation with warmed, humidified CO2 using the HumiGard device, alongside standard perioperative warming techniques, can improve patient recovery, including pain, surgical site infections, complications, and the use of analgesia compared with standard care alone.MethodsThe study is a multicenter, randomized, blinded (patient, surgeon, and assessor), sham device-controlled, parallel group-controlled trial of 232 patients. The study aims to recruit patients undergoing elective laparoscopic, segmental, or total colectomy. Patients will be randomized to receive HumiGard plus standard care or standard care alone (1:1 ratio). The primary outcome is patient-reported quality of recovery, measured by the validated QoR-40 (quality of recovery) questionnaire, from baseline to postoperative day 1. Secondary outcomes include postoperative pain, the incidence of hypothermia, and the rate of postoperative complications.ResultsThe information gathered during a small-scale service evaluation at a single hospital was used to inform this study protocol. Before applying for a grant for this full randomized controlled trial, the authors will conduct a feasibility study of 40 patients to ensure that the protocol is feasible and to inform our sample size calculation.ConclusionsThe randomized controlled trial is designed to provide high-quality evidence on the effectiveness of the HumiGard device in potentially reducing the risk of perioperative hypothermia in patients scheduled for laparoscopic colectomy. The results will be used to improve the maintenance of adequate patient body temperature during surgery.International Registered Report Identifier (IRRID)PRR1-10.2196/14533

3089 Orifice to Orifice Evaluation, in a Single Exam

INTRODUCTION: We present a case of a middle age Caucasian male with Peutz-Jeghers syndrome who underwent an antegrade double balloon enteroscopy (DBE) for surveillance of a known small bowel polyps. He has a history of right hemicolectomy for a large polyp and subsequent partial small bowel resection for intussusception of a jejunal polyp. He had a DBE a year ago which revealed several small bowel polyps, the larger ones requiring therapeutic intervention. We show a video demonstrating feasibility of complete entero-colonoscopy dictated by necessity. CASE DESCRIPTION/METHODS: A 55-year-old Caucasian male with Peutz-Jeghers syndrome presented for his surveillance antegrade DBE. He has history of right hemicolectomy &amp; partial jejunal resection due to intussusception deemed secondary to a large hamartomatous polyp. He has been getting EGD, Colonoscopy and antegrade DBE every 2 years given his history of multiple large hamartomatous polyps. His vital signs, physical examination and lab work were unremarkable. DISCUSSION: This patient underwent antegrade DBE with a therapeutic double-balloon enteroscope (Fujinon EN-450 T5) using push and pull maneuver, under general anesthesia and utilizing CO2 for insufflation. A stiffening device (Zutron medical) was used during portions of the procedure to help prevent loop formation. Around the distal jejunum, the stiffening device snapped within the biopsy channel at the boot of the insertion tube of the enteroscope. Given that a significant amount of time has been already invested in the procedure an attempt at reaching the anus was pursued with success. The stiffening device was pushed out of the channel using a biopsy forceps and the procedure was resumed. Multiple polyps (atleast 30) were observed in the small bowel ranging in size from 4-25 mm, some of which were oozing. The oozing polyps and those larger than 10 mm (total 6) were resected. The procedure was completed with no adverse events. The patient's oral cavity was cleaned using hydrogen peroxide swab before he was extubated and sent to recovery. The patient experienced no infection related complication, bleeding, perforation or pancreatitis. CONCLUSION: 1. It is feasible and safe to perform through and through entero-colonoscopy in specific scenarios. 2. Panendoscopy in one encounter may not always be achievable in patients without a history of bowel resection. 3. Advancing the enteroscopy outside the anus may be considered to clear an obstructed biopsy channel as an option to salvage a long procedure. Watch the video: http://bit.ly/2XTDKhY

Efficacy and safety of carbon dioxide insufflation versus air insufflation during endoscopic retrograde cholangiopancreatography in randomized controlled trials: a systematic review and meta-analysis.

Background and study aims Ambient air is the most commonly used gas for insufflation in endoscopic procedures worldwide. However, prolonged absorption of air during endoscopic examinations may cause pain and abdominal distension. Carbon dioxide insufflation (CO 2 i) has been increasingly used as an alternative to ambient air insufflation (AAi) in many endoscopic procedures due to its fast diffusion properties and less abdominal distention and pain. For endoscopic retrograde cholangiopancreatography (ERCP), use of CO 2 for insufflation is adequate because this procedure is complex and prolonged. Some randomized controlled trials (RCTs) have evaluated the efficacy and safety of CO 2 as an insufflation method during ERCP but presented conflicting results. This systematic review and meta-analysis with only RCTs evaluated the efficacy and safety of CO 2 i versus AAi during ERCP. Methods A literature search was performed using online databases with no restriction regarding idiom or year of publication. Data were extracted by two authors according to a predefined data extraction form. Outcomes evaluated were abdominal pain and distension, complications, procedure duration, and CO 2 levels. Results Eight studies (919 patients) were included. Significant results favoring CO 2 i were less abdominal distension after 1 h (MD: −1.41 [−1.81; −1.0], 95 % CI, I² = 15 %, P < 0.00001) and less abdominal pain after 1 h (MD: −23.80 [−27.50; −20.10], 95 %CI, I² = 9 %, P < 0.00001) and after 6 h (MD: −7.00 [−8.66; −5.33]; 95 % CI, I² = 0 %, P < 0.00001). Conclusion Use of CO 2 i instead of AAi during ERCP is safe and associated with less abdominal distension and pain after the procedure.

Physiological effects of partial amniotic carbon dioxide insufflation with cold, dry vs heated, humidified gas in a sheep model.

ABSTRACTObjectivePartial amniotic carbon dioxide (CO2) insufflation (PACI) is used to improve visualization and facilitate complex fetoscopic surgery. However, there are concerns about fetal hypercapnic acidosis and postoperative fetal membrane inflammation. We assessed whether using heated and humidified, rather than cold and dry, CO2 might reduce the impact of PACI on the fetus and fetal membranes in sheep.MethodsTwelve fetal lambs of 105 days' gestational age (term = 145 days) were exteriorized partially, via a midline laparotomy and hysterotomy, and arterial catheters and flow probes were inserted surgically. The 10 surviving fetuses were returned to the uterus, which was then closed and insufflated with cold, dry (22 °C at 0–5% humidity, n = 5) or heated, humidified (40 °C at 100% humidity, n = 5) CO2 at 15 mmHg for 180 min. Fetal membranes were collected immediately after insufflation for histological analysis. Physiological data and membrane leukocyte counts, suggestive of membrane inflammation, were compared between the two groups.ResultsAfter 180 min of insufflation, fetal survival was 0% in the group which underwent PACI with cold, dry CO2, and 60% (n = 3) in the group which received heated, humidified gas. While all insufflated fetuses became progressively hypercapnic (PaCO2 > 68 mmHg), this was considerably less pronounced in those in which heated, humidified gas was used: after 120 min of insufflation, compared with those receiving cold, dry gas (n = 3), fetuses undergoing heated, humidified PACI (n = 5) had lower arterial partial pressure of CO2 (mean ± standard error of the mean, 82.7 ± 9.1 mmHg for heated, humidified CO2 vs 170.5 ± 28.5 for cold, dry CO2 during PACI, P < 0.01), lower lactate levels (1.4 ± 0.4 vs 8.5 ± 0.9 mmol/L, P < 0.01) and higher pH (pH, 7.10 ± 0.04 vs 6.75 ± 0.04, P < 0.01). There was also a non‐significant trend for fetal carotid artery pressure to be higher following PACI with heated, humidified compared with cold, dry CO2 (30.5 ± 1.3 vs 8.7 ± 5.5 mmHg, P = 0.22). Additionally, the median (interquartile range) number of leukocytes in the chorion was significantly lower in the group undergoing PACI with heated, humidified CO2 compared with the group receiving cold, dry CO2 (0.7 × 10–5 (0.5 × 10–5) vs 3.2 × 10–5 (1.8 × 10–5) cells per square micron, P = 0.02).ConclusionsPACI with cold, dry CO2 causes hypercapnia, acidosis, hypotension and fetal membrane inflammation in fetal sheep, raising potential concerns for its use in humans. It seems that using heated, humidified CO2 for insufflation partially mitigates these effects and this may be a suitable alternative for reducing the risk of fetal acid–base disturbances during, and fetal membrane inflammation following, complex fetoscopic surgery. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Reversal From Propofol Anesthesia to Midazolam/Fentanyl Sedation Using Water Exchange Insertion Colonoscopy

Introduction: Propofol-based anesthesia (P) is rapidly replacing midazolam/fentanyl-based conscious sedation (MF) during colonoscopy. At the same time several technical developments, including more flexible instruments, use of CO2 for insufflation and water exchange during the insertion phase have greatly decreased the discomfort associated with colonoscopy. Goal: To determine whether two half-day observations in water exchange insertion colonoscopy allows successful reversal from P to MF given current patient, nurse and organizational expectations. Setting: Two rural Wisconsin practices (A and B), where up to half of colonoscopies are performed under P (practice A) by a single experienced endoscopist. In practice B reversal from P to MF was encouraged by leadership given P-related expenses. Methods: Prior to preferential use of MF the endoscopist performing screening colonoscopy in practices A and B requested observation of water exchange colonoscopies performed at the University of Minnesota Medical Center. The focus of the observation sessions was on water exchange insertion technique, early rotation of the patient to facilitate endoscope advancement and prophylactic abdominal pressure to prevent loop formation (AJG 2017;112:578). After two observation sessions, the endoscopist started performing water exchange colonoscopy at practice B and at the same time reduced use of P in favor of MF. As before, patients were given the amount of MF to achieve the usual patient level of comfort. Sedation/ anesthesia type and MF doses were obtained by retrospective review of medical records. To prevent bias, 100 successive colonoscopies from practice A from before the conversion from P to MF were compared with 100 successive colonoscopies from practice B after institution of preferential use of MF. Results: In practice A 52/100 (52%) of colonoscopies were done under P anesthesia whereas after preferential use of MF in practice B this was 4/100 (4%; p<0.01). In the 48 patients in practice A the dose of MF when used was significantly higher than the MF dose used in the 96 patients in practice B: Fentanyl 165±31 mcg vs 87±38; Midazolam 3.7±0.8 mg vs 3.0±0.9 (M±SD; p<0.01). Conclusion: (1) Using water exchange insertion technique allowed successful reversal from P to MF colonoscopy in a practice where reduction in the use of P-related expenses was pursued. (2) Water exchange insertion technique significantly reduced the administered doses of midazolam and fentanyl.

Single-Incision Laparoscopic Sterilization of the Cheetah (Acinonyx jubatus).

To describe laparoscopic ovariectomy and salpingectomy in the cheetah (Acinonyx jubatus) using single-incision laparoscopic surgery (SILS). Prospective cohort. Female cheetahs (Acinonyx jubatus) (n = 21). Cheetahs were randomly divided to receive either ovariectomy (n = 11) or salpingectomy (n = 10). The use and complications of a SILS port was evaluated in all of cheetahs. Surgery duration and insufflation volumes of carbon dioxide (CO2 ) were recorded and compared across procedures. Laparoscopic ovariectomy and salpingectomy were performed without complications using a SILS port. The poorly-developed mesosalpinx and ovarian bursa facilitated access to the uterine tube for salpingectomy in the cheetah. The median surgery duration for ovariectomy was 24 minutes (interquartile range 3) and for salpingectomy was 19.5 minutes (interquartile range 3) (P = .005). The median volume of CO2 used for ovariectomy was 11.25 L (interquartile range 3.08) and for salpingectomy was 4.90 L (interquartile range 2.52), (P = .001) CONCLUSIONS: Laparoscopic ovariectomy and salpingectomy can be performed in the cheetah using SILS without perioperative complications. Salpingectomy is faster than ovariectomy and requires less total CO2 for insufflation.

An Assessment by Calorimetric Calculations of the Potential Thermal Benefit of Warming and Humidification of Insufflated Carbon Dioxide

Heat transfer from a patient to warm and humidify insufflated carbon dioxide (CO2) during laparoscopic surgery may contribute to perioperative hypothermia. The magnitude of this effect was calculated using calorimetric calculations. Warming to 37°C and humidifying to 100%, each 100 L of insufflated CO2 would prevent a heat transfer of 3220 calories, which would result in a decrease of temperature by 0.06°C in a 70 kg patient after total body distribution of heat. We conclude that the thermal benefit of warming and humidifying insufflated CO2 is minor, particularly in comparison with other effective and inexpensive perioperative technologies, some of which are not always used out could easily be used. The decision to use heating and humidification of insufflated CO2 should be based on its other risks, benefits, and costs.

Carbon dioxide insufflation safety in double‐balloon enteroscopy: An experimental animal study

The aim of the present study was to assess the safety and efficacy of CO(2) during double-balloon enteroscopy (DBE) in an experimental animal model study. In this study, insufflation with room air and with CO(2) was compared. Twenty healthy swines were used. The animals were randomly allocated to two groups. The room air-DBE group was insufflated with room air, whereas the CO(2)-DBE group was insufflated with CO(2). Endoscopy duration was 90 min. The following parameters were measured during the study (basal, 30 min, 60 min, 90 min): invasive hemodynamic parameters, ventilatory parameters, arterial blood gases, exploration depth, as well as biochemical tests. Residual gas was evaluated at the end of DBE, at 180 min and 24 h after DBE. During the endoscopic exploration none of the animals showed hemodynamic, ventilatory or arterial blood gas alterations in the normal reference range for the swine species. The CO(2) group showed statistically significant differences over the room air group with lower post-procedure residual gas and greater depth of the small bowel explored. The use of CO(2) for insufflation during DBE was safe and no complications associated with CO(2) were observed. In addition, the use of CO(2) offers benefits over the use of room air for insufflation during DBE.

Independent testing of the Fisher & Paykel Healthcare MR860 Laparoscopic Humidification System

In laparoscopic surgery CO2 is commonly insufflated at room temperature, with a relative humidity approaching 0%. There has been an increase in utilization of devices to warm and humidify the insufflated gas to avoid potential detrimental effects caused by desiccation. Available data on the performance of these devices are limited. We aimed to conduct independent testing of the Fisher & Paykel MR860 Laparoscopic Humidification System at variable flow rates. A 2.5l insulated chamber was constructed and a digital thermo-hygrometer placed inside it. The humidifier water vessel was weighed and exactly 30.0g of water poured in. 50.0L of CO2 was insufflated into the chamber via the humidifier at 2.0L/min, 4.0l/min, 6.0l/min, 8.0l/min, and 10l/min using a laparoscopic insufflator. Measurements of temperature and humidity in the chamber were taken at 30 second intervals. After 50.0l of gas was insufflated the water left in the humidifier was weighed, and this was used to calculate the mean absolute humidity of the insufflated gas by the gravimetric method. At every flow rate, > 98.0% relative humidity was achieved in the chamber after less than 30 seconds of insufflation. Using the gravimetric estimate, the humidifier was able to saturate 50.0l of CO2 to close to saturation humidity at every flow rate tested. The Fisher & Paykel MR860 Laparoscopic Humidification System effectively humidifies insufflated CO2 at a range of flow rates commonly used in the surgical setting.

Use of CO2 for Insufflation during Colonoscopy in Children

Use of CO2 for Insufflation during Colonoscopy in Children

Beneficial Effects of Humidified, Warmed Carbon Dioxide Insufflation during Laparoscopic Bariatric Surgery: a Randomized Clinical Trial

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.

Tumour cell movement during heating and humidification of insufflating CO2: an in vitro model.

Intra-operative hypothermia and port-site recurrence have been associated with laparoscopic surgery. Heating and humidification of insufflating CO2 may protect against laparoscopy-associated hypothermia. However, the effect of heated, humidified CO2 upon tumour cell movement is unknown. Twenty-four in vitro studies that used 4-L plastic bottles were performed. Thirteen million human colorectal cancer cells were placed in each bottle. Twelve studies used dry room temperature CO2 for insufflation: the remaining 12 used heated, humidified CO2 as the insufflating gas. Both groups were subdivided into bottles with leaks around the trocars and with airtight sealing around the trocars. Two trocars and a laparoscopic grasper were used. The exiting insufflating gas was filtered and examined for the presence of cells. Laparoscopic instruments agitated the contents of the bottles. The instruments and trocars were washed. These washings were examined for the presence of cells. Heated, humidified CO2 insufflation was able to maintain a warmer and more humid environment within the bottles when compared with dry room-temperature CO2. No cells were detected on the gas filters. Tumour cells were found on 12 out of 12 instruments and 11 out of 12 trocars with dry CO2 insufflation. Tumour cells were found on 8 out of 12 instruments and 7 out of 12 trocars with heated humidified CO2 insufflation. The only statistically significant difference in tumour cell spread to trocars was found between heating and humidification when no leak was present, and heating and humidification with leak present, and dry insufflation with no leak present (P = 0.015, Fisher's two-tailed exact test). Heating and humidifying CO2 during in vitro laparoscopy does not increase the aerosolization of tumour cells when compared with dry CO2. However, the use of heated and humidified gas with airtight seals around the trocars in vitro may lessen cell deposition on trocars.