Carbon dioxide, temperature and laparoscopic cholecystectomy

Prevention of laparoscopic surgery induced hypothermia with warmed humidified insufflation: Is the experimental combination of a warming blanket synergistic?

INTRODUCTION

Maintaining normothermia during anesthesia is imperative to provide quality patient care and to prevent adverse outcomes. Prolonged laparoscopic procedures have been identified as a potential risk factor for hypothermia, due to continuous insufflation of cold and dry carbon dioxide. Perioperative hypothermia is associated with increased hospital cost and many complications including; impaired drug metabolism, impaired immune function, cardiac morbidity, shivering, coagulopathy.

METHODS

In this experimental study, four pigs underwent four interventions each, resulting in 16 total trials. Using standardized general anesthesia in a randomized Latin-square sequence the four interventions include: 1. Control group without an administered pneumoperitoneum, 2. Administered standard pneumoperitoneum using 21°C insufflated gas and under-body forced-air warming, 3. Administered pneumoperitoneum with insufflation of warmed/humidified carbon dioxide, 4. Administered pneumoperitoneum with insufflation of warmed/humidified carbon dioxide and under-body forced-air warming. The primary outcome was distal esophageal temperature change 4 hours after trocar insertion.

RESULTS

Four hours after trocar insertion, pigs in the control group lost 2.1 ± 0.4°C; pigs with warmed and humidified insufflation lost 1.8 ± 0.4°C; pigs with forced-air warming group lost 1.3 ± 0.9°C; and pigs exposed to a combination of warmed and humidified insufflation with forced-air warming increased by 0.3 ± 0.2°C.

CONCLUSION

This experimental animal study provides evidence that a combination of warmed and humidified insufflation of carbon dioxide (CO2) in conjunction with forced-air warming is an effective strategy in the prevention of perioperative hypothermia. Further clinical trials investigating humans are therefore indicated.

Heated insufflation with or without humidification for laparoscopic abdominal surgery

BACKGROUND

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies on heated insufflation have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times.

OBJECTIVES

To determine the effect of heated gas insufflation compared to cold gas insufflation on maintaining intraoperative normothermia as well as patient outcomes following laparoscopic abdominal surgery.

SEARCH METHODS

We searched Cochrane Colorectal Cancer Specialised Register (September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2016, Issue 8), Ovid MEDLINE (1950 to September 2016), Ovid Embase (1974 to September 2016), International Pharmaceutical Abstracts (IPA) (September 2016), Web of Science (1985 to September 2016), Scopus, www.clinicaltrials.gov and the National Research Register (1956 to September 2016). We also searched grey literature and cross references. Searches were limited to human studies without language restriction.

SELECTION CRITERIA

Only randomised controlled trials comparing heated (with or without humidification) with cold gas insufflation in adult and paediatric populations undergoing laparoscopic abdominal procedures were included. We assessed study quality in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. Two review authors independently selected studies for the review, with any disagreement resolved in consensus with a third co-author.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed screening of eligible studies, data extraction and methodological quality assessment of the trials. We classified a study as low-risk of bias if all of the first six main criteria indicated in the 'Risk of Bias Assessment' table were assessed as low risk. We used data sheets to collect data from eligible studies. We presented results using mean differences for continuous outcomes and relative risks for dichotomous outcomes, with 95% confidence intervals. We used Review Manager (RevMan) 5.3 software to calculate the estimated effects. We took publication bias into consideration and compiled funnel plots.

MAIN RESULTS

We included 22 studies in this updated analysis, including six new trials with 584 additional participants, resulting in a total of 1428 participants. The risk of bias was low in 11 studies, high in one study and unclear in the remaining studies, due primarily to failure to report methodology for randomisation, and allocation concealment or blinding, or both. Fourteen studies examined intraoperative core temperatures among heated and humidified insufflation cohorts and core temperatures were higher compared to cold gas insufflation (MD 0.31 °C, 95% CI, 0.09 to 0.53, I² = 88%, P = 0.005) (low-quality evidence). If the analysis was limited to the eight studies at low risk of bias, this result became non-significant but remained heterogeneous (MD 0.18 °C, 95% CI, -0.04 to 0.39, I²= 81%, P = 0.10) (moderate-quality evidence).In comparison to the cold CO₂ group, the meta-analysis of the heated, non-humidified group also showed no statistically significant difference between groups. Core temperature was statistically, significantly higher in the heated, humidified CO₂ with external warming groups (MD 0.29 °C, 95% CI, 0.05 to 0.52, I² = 84%, P = 0.02) (moderate-quality evidence). Despite the small difference in temperature of 0.31 °C with heated CO₂, this is unlikely to be of clinical significance.For postoperative pain scores, there were no statistically significant differences between heated and cold CO₂, either overall, or for any of the subgroups assessed. Interestingly, morphine-equivalent use was homogeneous and higher in heated, non-humidified insufflation compared to cold insufflation for postoperative day one (MD 11.93 mg, 95% CI 0.92 to 22.94, I² = 0%, P = 0.03) (low-quality evidence) and day two (MD 9.79 mg, 95% CI 1.58 to 18.00, I² = 0%, P = 0.02) (low-quality evidence). However, morphine use was not significantly different six hours postoperatively or in any humidified insufflation groups.There was no apparent effect on length of hospitalisation, lens fogging or length of operation with heated compared to cold gas insufflation, with or without humidification. Recovery room time was shorter in the heated cohort (MD -26.79 minutes, 95% CI -51.34 to -2.25, I² = 95%, P = 0.03) (low-quality evidence). When the one and only unclear-risk study was removed from the analysis, the difference in recovery-room time became non-significant and the studies were statistically homogeneous (MD -1.22 minutes, 95% CI, -6.62 to 4.17, I² = 12%, P = 0.66) (moderate-quality evidence).There were also no differences in the frequency of major adverse events that occurred in the cold or heated cohorts.These results should be interpreted with caution due to some limitations. Heterogeneity of core temperature remained significant despite subgroup analysis, likely due to variations in the study design of the individual trials, as the trials had variations in insufflation gas temperatures (35 ºC to 37 ºC), humidity ranges (88% to 100%), gas volumes and location of the temperature probes. Additionally, some of the trials lacked specific study design information making evaluation difficult.

AUTHORS' CONCLUSIONS

While heated, humidified gas leads to mildly smaller decreases in core body temperatures, clinically this does not account for improved patient outcomes, therefore, there is no clear evidence for the use of heated gas insufflation, with or without humidification, compared to cold gas insufflation in laparoscopic abdominal surgery.

Body temperature evaluation during induced pneumoperitoneum with CO₂: an experimental study in pigs

BACKGROUND

In prolonged laparoscopic procedures, hypothermia is frequently observed. The possible influence of the vasodilating action of CO(2), due to its increased levels in the blood during the laparoscopic procedures, has yet to be studied. The objective of this study was, therefore, to evaluate body temperature patterns in pigs subjected to pneumoperitoneum with CO(2).

METHODS

Thirty male pigs were allocated into three groups of ten animals each: group I, anesthetic procedure and abdominal puncture only; group II, the same as for group I and insufflation with CO(2); and group III, the same as for group I and insufflation with medical grade compressed air. After anesthetic induction and surgical preparation, rectal and esophageal temperatures were measured every 10 min. Blood was collected during the experiment for the gasometric measurement of pCO(2). Animals were insufflated with no gas loss and were kept anesthetized for 180 min. For statistical analysis, Friedman and Kruskal-Wallis tests were used at a level of significance of 95% (P < 0.05).

RESULTS

Animals in groups I and II (P = 0.000) had a statistically significant drop in both esophageal and rectal temperatures during the experiment, but not animals in group III. However, when the groups were compared among themselves, no statistically significant differences were found at any of the times measured. A statistically significant drop in pCO(2) levels was observed for groups I and III, but not for animals in groups II.

CONCLUSIONS

The use of CO(2) did not significantly affect body temperature variation in pigs subjected to pneumoperitoneum. However, CO(2) produced a temperature drop pattern different than that of compressed air, indicating that CO(2) may lead to thermoregulatory changes and influence the peripheral temperature drop.

Heated CO(2) with or without humidification for minimally invasive abdominal surgery

BACKGROUND

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times.

OBJECTIVES

To determine the effect of heated gas insufflation on patient outcomes following minimally invasive abdominal surgery.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (PubMed), EMBASE, International Pharmaceutical Abstracts (IPA), Web of Science, Scopus, www.clinicaltrials.gov and the National Research Register were searched (1956 to 14 June 2010). Grey literature and cross-references were also searched. Searches were limited to human studies without language restriction.

SELECTION CRITERIA

All included studies were randomized trials comparing heated (with or without humidification) gas insufflation with cold gas insufflation in adult and pediatric populations undergoing minimally invasive abdominal procedures. Study quality was assessed in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. The selection of studies for the review was done independently by two authors, with any disagreement resolved in consensus with a third co-author.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, data extraction and methodological quality assessment of the trials were performed by the authors. Data from eligible studies were collected using data sheets. Results were presented using mean differences for continuous outcomes and relative risks with 95% confidence intervals for dichotomous outcomes. The estimated effects were calculated using the latest version of RevMan software. Publication bias was taken into consideration and funnel plots were compiled.

MAIN RESULTS

Sixteen studies were included in the analysis. During laparoscopic abdominal surgery, no effect on postoperative pain nor changes in core temperature, morphine consumption, length of hospitalisation, lens fogging, length of operation or recovery room stay were associated with heated compared to cold gas insufflation with or without humidification.

AUTHORS' CONCLUSIONS

The study offers evidence that during laparoscopic abdominal surgery, heated gas insufflation, with or without humidification, has minimal benefit on patient outcomes.

Maintaining perioperative normothermia during laparoscopic and open urologic surgery

PURPOSE

The ability to maintain normothermia during surgical procedures is crucial for improvement of the quality of patient care and the outcome of the procedure. We tested the hypothesis of whether one warming protocol is able to maintain normothermic core temperatures equally well in major open and laparoscopic urologic procedures.

PATIENTS AND METHODS

In this prospective study, 300 patients who were scheduled for open (n=53) or laparoscopic (n=247) urologic procedures were included and received intraoperative warming using a combination of an upper and lower body forced-air warmer and a single warming blanket. Core temperature was measured at baseline, at induction of anesthesia, at the start of the operation, and at the end of the operation.

RESULTS

A significant improvement in core temperature during the operation was achieved in all patients (P<0.001). There was no difference in the end-of-operation core temperature between laparoscopic and open procedures: (36.29 degrees C+/-0.03 degrees C v 36.23 degrees C+/-0.06 degrees C; P=0.224). Further, 23.3% of all patients had a core temperature of lower than 36.0 degrees C at the end of the operation (laparoscopy 23.8% v open 26.6%). Linear regression analysis revealed a correlation between duration of the operation and intraoperative core temperature (P<0.001).

CONCLUSION

The present warming protocol is effective in maintaining perioperative normothermia during major open and laparoscopic urologic procedures.

The effects of isothermic and hypothermic carbon dioxide pneumoperitoneum on respiratory function test results

BACKGROUND/PURPOSE

This study investigated the effects of isothermic and hypothermic carbon dioxide, used for pneumoperitoneum during laparoscopic cholecystectomy, on respiratory function test results.

METHODS

Thirty patients who underwent elective laparoscopic cholecystectomy were enrolled in this prospective randomized study. The patients were divided into two groups. Carbon dioxide at 37 degrees C (isothermic) was used in the isothermic group, and carbon dioxide at 21 degrees C (hypothermic) was used in the hypothermic group. Respiratory function tests were performed in the preoperative period and at 12 h after the operation.

RESULTS

Mean forced vital capacity (FVC), forced expiratory volume (FEV1), maximum peak expiratory flow (PEF), and the FEV1/FVC ratio were significantly higher in the isothermic group than in the hypothermic group (P < 0.05).

CONCLUSIONS

Using isothermic carbon dioxide for pneumoperitoneum has fewer negative effects than hypothermic carbon dioxide on respiratory function tests results. Isothermic carbon dioxide may be preferable for patients with respiratory problems.

Impact of temperature and humidity of carbon dioxide pneumoperitoneum on body temperature and peritoneal morphology

BACKGROUND

The insufflation of cold gas during laparoscopic surgery exposes patients to the risk for hypothermia. The objectives of this study were to investigate whether heating or humidification of insufflation gas could prevent peroperative hypothermia in a rat model, and to assess whether the peritoneum was affected by heating or humidification of the insufflation gas.

METHODS

Rats were exposed to insufflation with either cold, dry carbon dioxide CO2 (group I); cold, humidified CO2 (group II); warm, dry CO2 (group III); or warm, humidified CO2 (group IV); another group underwent gasless laparoscopy (group V). Core temperature and intraperitoneal temperature were registered in all animals during 120 minutes. Specimens of the parietal peritoneum were taken directly after desufflation and 2 and 24 hours after the procedure. All specimens were analyzed with scanning electron microscopy (SEM).

RESULTS

During the 120-minute study period, core temperature and intraperitoneal temperature were significantly reduced in groups I, II, and III. In the animals that underwent warm, humidified insufflation (group IV) and the gasless controls (group V), intraoperative hypothermia did not develop. At SEM, retraction and bulging of mesothelial cells and exposure of the basal lamina were seen in the four insufflation groups (groups I-IV) and also in the gasless controls (group V).

CONCLUSION

Insufflation with cold, dry CO2 may lower the body temperature during laparoscopic surgery. Hypothermia can be prevented by both heating and humidifying the insufflation gas. Changes of the peritoneal surface occur after CO2 insufflation, despite heating or humidifying, and also after gasless surgery.

Intraperitoneal hypothermia during surgery enhances postoperative tumor growth

BACKGROUND

Recent work has shown that intraoperative hypothermia is a significant source of surgical trauma, with wide-ranging physiological and immunological sequelae. The aim of this study was to examine the effects of intraperitoneal hypothermia during laparoscopy on tumor growth in an animal model.

METHODS

Thirty WAG rats were randomized to undergo anesthesia alone (n = 10), insufflation with cold carbon dioxide (CO2) (n = 10), or insufflation with warm CO2 (n = 10). During insufflation, 1 x 105/ml CC531s colon cancer cells in suspension were injected into the peritoneal cavity. The control group was anesthetized and tumor cells were injected without insufflation. After 3 weeks, total tumor weight and the extent of tumor spread, as assessed by the modified Peritoneal Cancer Index (PCI), were compared at autopsy.

RESULTS

Laparoscopy with cold CO2 resulted in a significant reduction in local and core body temperatures (p <0.05). Tumor growth in both groups that underwent CO2 pneumoperitoneum was significantly increased compared with the group that did not (p <0.0001, control vs warm CO2 and cold CO2). There was significantly more tumor growth in the rats insufflated with unwarmed CO2 than in the normothermic group (mean total tumor 0.01 g +/- 0.03 vs. 0.043 g +/- 0.07; p = 0.025 Mann-Whitney U test). Tumor spread as shown by the PCI scores was less in the warm gas group than it was in the animals insufflated with cold gas (151 vs 266).

CONCLUSIONS

These data demonstrate that the peritoneal insufflation of CO2 enhances tumor growth and that the prevention of perioperative hypothermia during laparoscopy attenuates tumor growth. This effect may be partially mediated by the increased peritoneal trauma that results from insufflation with cold gas.

Intraoperative thermal regulation in patients undergoing laparoscopic vs open surgical procedures

BACKGROUND

Although perioperative hypothermia is a well-known consequence of general anesthesia, it has been hypothesized that laparoscopic surgery exacerbates hypothermia to a greater extent than open surgery. The aim of this study was to demonstrate that laparoscopic surgery does not represent an increased risk for hypothermia.

METHODS

A case-controlled retrospective study was conducted on 45 patients, 25 undergoing laparoscopic cholecystectomy and 20 undergoing parathyroid surgery under endotracheal general anesthesia. Data were collected regarding age, sex, weight, height, American Society of Anesthesiologists (ASA) status, length of surgery, and anesthesia. In addition, we analyzed the type of intraoperative intravenous fluids, anesthetics and perioperative drugs, and temperature, blood pressure, and heart rate recordings during anesthesia.

RESULTS

There was no significant difference between the two groups with respect to age, sex, body mass index (BMI), ASA status, type or amount of intravenous fluids infused, length of anesthesia or surgery, changes in mean blood pressure, or heart rate. Core body temperatures in both groups decreased significantly over time (p 0.05). There was no difference between the groups in terms of maximum drop in temperature (lowest temperature recorded vs baseline temperature) (1.1 +/- 0.7 vs 1.0 +/- 0.7 degrees C, p > 0.05).

CONCLUSION

This study demonstrates that patients who undergo laparoscopic and open procedures of similar duration under endotracheal general anesthesia have similar profiles in terms of perioperative hypothermia.

Measurement of CO(2) hypothermia during laparoscopy and pelviscopy: how cold it gets and how to prevent it

STUDY OBJECTIVE

To evaluate intraabdominal CO(2) temperature during a variety of standard operative laparoscopy procedures with different insufflators (BEI Medical, Snowden & Pencer, Storz Laparoflator, Storz Endoflator, Wolf) and devices to maintain body temperature (Bair Hugger, fluid warmer, Blanketrol blankets).

DESIGN

Prospective, nonrandomized study (Canadian Task Force classification II-1).

SETTING

Community hospital in rural Alabama.

PATIENTS

Sixty-two consecutive patients (53 women, 9 men; average age 56.8 yrs, range 21-94 yrs).

INTERVENTIONS

Patients underwent standard laparoscopic and pelviscopic procedures during which intraoperative temperature changes in the insufflation system, abdomen, and rectum were measured.

MEASUREMENTS AND MAIN RESULTS

Carbon dioxide was at room temperature in the insufflation hose ( approximately 23 degrees C). During insufflation, intraabdominal gas temperature decreased to as much as 27.7 degrees C (average 32.7 degrees C) depending on length of operation (23 min-5 hrs 8 min), amount of gas used (12.8-801 L), gas flow (up to 20 L/min), and leakage rate. Preoperative and postoperative temperature comparisons showed no decline in rectal temperature (average +0.18 degrees C) because warming equipment was sufficient.

CONCLUSION

The decrease in intraoperative intraabdominal gas temperature is remarkable and can potentially harm the patient. It can be limited by restricting gas flow and leakage. In operations longer than 1 hour, substantial core body temperature drop should be prevented with appropriate heating and hydration devices. An insufflator with internal gas heating (Snowden & Pencer) had no significant clinical effect. (J Am Assoc Gynecol Laparosc 6(3):289-295, 1999)

Hypothermia induced by laparoscopic insufflation. A randomized study in a pig model

Hypothermia is a common postsurgical problem, yet information documenting the impact of laparoscopy on perioperative heat balance is scarce. This paper quantifies the changes in core temperature over a 3-h period of high-flow CO2 insufflation in a randomized, controlled trial of six pigs. Each animal was anesthetized and studied on three occasions under standardized conditions, acting as its own control via insufflation with no gas compared with insufflation by cold gas and warmed gas. Insufflation of CO2 gas at high-flow rates over a prolonged period of time results in a significant fall in core temperature. The provision of warmed rather than cold insufflated gas confers no protection against changes in core temperature during laparoscopic surgery due to the small amount of heat required to warm the gas to body temperature. A much greater effect is the latent heat required to saturate the insufflated gas. Most of the hypothermic effect is due to this, and could be minimized by humidifying the flow.