Comparison of immunologic and physiologic effects of CO2 pneumoperitoneum at room and body temperatures

The impact of warmed and humidified CO2 insufflation during robotic radical prostatectomy: Results of a randomized controlled trial

Background:

Cool and dry gas insufflation during laparoscopy induces hypothermia and cytokine increase, with significant perioperative morbidity. Our aim was to assess if warmed and humidified CO2 insufflation with HumiGard™ device can achieve significant benefits over standard insufflation in terms of risk of hypothermia, cytokine response, blood gases, and intra- and postoperative parameters, in the setting of robot-assisted radical prostatectomy (RARP).

Methods:

This was a prospective, randomized controlled clinical trial. Sixty-four patients with prostate cancer undergoing RARP were randomized to receive warmed and humidified CO2 insufflation with HumiGard device, plus hot air warming blanket (treatment group, H + WB), or standard CO2 insufflation, plus hot air warming blanket (control group, WB). Body core temperature (BCT), plasma levels of IL-6 and TNF-α, pain scores, and intraoperative parameters were recorded. The data were analyzed according to the Bayesian paradigm.

Results:

Intraoperative BCT increased in both groups during surgery, with a statistically significant difference favoring group H + WB, ending at 0.2°C higher on average than group WB. No difference across groups was shown for cytokine levels. Blood gas parameters were not affected by warmed CO2 insufflation. No statistical differences were noted for pain scores and the other intra- and postoperative parameters.

Conclusions:

During RARP, warm and humidified CO2 insufflation with the HumiGard device was more effective than the standard CO2 insufflation in maintaining the patient’s heat homeostasis, even if the difference was minimal. No imbalances were detected on blood gas analyses. No benefit could be shown in terms of cytokine levels and pain scores.

Control of body temperature and immune function in patients undergoing open surgery for gastric cancer

The influence of mild perioperative hypothermia on the immune function and incidence of postoperative wound infections has been suggested, but the specific mechanism is unclear. This study aimed to analyze the body temperature, immune function, and wound infection rates in patients receiving open surgery for gastric cancer. Body temperature was controlled in each patient using one of four different methods: wrapping limbs, head and neck; insulated blankets; warming infusion fluids and insulated blankets; and warming fluids without insulated blankets. One hundred patients were randomly divided into four groups of 25 patients each, and every group received a different intraoperative treatment for maintaining normal body temperature. Nasopharyngeal and rectal temperatures, transforming growth factor beta (TGF-β), interleukin 10 (IL-10) levels, and cluster of differentiation (CD)3+T and CD4+/CD25+ regulatory T cell (Treg) counts were measured before surgery and at 2 and 4 hours postoperatively. Patients were evaluated at one week after surgery for signs of infection. Intraoperative body temperature and measures of immune function varied significantly between the four groups, with the largest temperature changes observed in the group in which only the limbs were wrapped in cotton pads to control the body temperature. The lowest temperature change (i.e., close to normal temperature) and cytokine response after surgery were observed in the group in which infusion fluids and transfused blood (if needed) were heated to 37℃, peritoneal irrigation fluid was heated to 37℃, and an insulation blanket was heated to 39℃ and placed under the patient. No intergroup differences were found in the infection rates at one week after surgery. In conclusion, body temperature variation during surgery affects the immune function of patients, and maintaining body temperature close to normal results in the least variation of immune function.

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.

Humidification during laparoscopic surgery: overview of the clinical benefits of using humidified gas during laparoscopic surgery

PURPOSE

The peritoneum is the serous membrane that covers the abdominal cavity and most of the intra-abdominal organs. It is a very delicate layer highly susceptible to damage and it is not designed to cope with variable conditions such as the dry and cold carbon dioxide (CO2) during laparoscopic surgery. The aim of this review was to evaluate the effects caused by insufflating dry and cold gas into the abdominal cavity after laparoscopic surgery.

METHODS

A literature search using the Pubmed was carried out. Articles identified focused on the key issues of laparoscopy, peritoneum, morphology, pneumoperitoneum, humidity, body temperature, pain, recovery time, post-operative adhesions and lens fogging.

RESULTS

Insufflating dry and cold CO2 into the abdomen causes peritoneal damage, post-operative pain, hypothermia and post-operative adhesions. Using humidified and warm gas prevents pain after surgery. With regard to hypothermia due to desiccation, it can be fully prevented using humidified and warm gas. Results relating to the patient recovery are still controversial.

CONCLUSIONS

The use of humidified and warm insufflation gas offers a significant clinical benefit to the patient, creating a more physiologic peritoneal environment and reducing the post-operative pain and hypothermia. In animal models, although humidified and warm gas reduces post-operative adhesions, humidified gas at 32 °C reduced them even more. It is clear that humidified gas should be used during laparoscopic surgery; however, a question remains unanswered: to achieve even greater clinical benefit to the patient, at what temperature should the humidified gas be when insufflated into the abdomen? More clinical trials should be performed to resolve this query.

Perioperative hypothermia in patients undergoing major colorectal surgery

BACKGROUND

Perioperative hypothermia occurs frequently and can have serious health-related and financial consequences. Despite multiple warming methods available, perioperative hypothermia remains prevalent. To be effective, preventative measures must be timely and target patients most at risk. The aim of this retrospective review was to document the incidence and patterns of hypothermia in patients undergoing major colorectal surgery.

METHODS

Hospital records were used to obtain demographic and clinical information on 255 patients undergoing major colorectal surgery over one year. Temperatures were recorded from five perioperative time-points and correlated with potential contributing factors.

RESULTS

Most patients (74%) experienced mild hypothermia, which was most common intraoperatively. Elective patients experienced the greatest drop in temperature between admission and commencement of surgery while emergency patients experienced a similar drop intraoperatively. The most significant determinant of intraoperative hypothermia was core temperature at the start of surgery (P < 0.01). Factors increasing hypothermia at the start of surgery were an elective presentation, an arrival temperature below 36.5°C (P < 0.01) and an age greater than 70 years (P < 0.05).

CONCLUSIONS

Mild hypothermia in patients undergoing major colorectal surgery is common, despite preventative measures. Core temperatures prior to commencement of the operation should be optimized with both active and passive warming measures, particularly for older patients and those arriving with lower core temperatures. Elective patients should also have their temperatures monitored as closely, if not more closely, than emergency patients. Preventing early declining trends in core temperature may positively influence later perioperative temperatures and improve outcomes.

The effects of insufflation conditions on rat mesothelium

Aim. The aim of this investigation was to examine the alterations in the peritoneum after cold dry CO₂, heated dry CO₂, and humidified heated CO₂ at pressures equivalent to intraperitoneal pressures used in human laparoscopy. Methods. Eighteen rats were divided into 4 treatment groups—group 1: untreated control; group 2: insufflation with cold dry CO₂; group 3: insufflation with heated, dry CO₂; group 4: insufflation with heated and humidified CO₂. The abdomen was insufflated to 5 mm/Hg (flow rate 50 mL/min) for 2 h. Twelve hours later, tissue samples were collected for analysis by light microscopy (LM) and scanning electron microscopy (SEM). Results. Group 1: no abnormalities were detected. Group 2: specimens revealed an inflammatory response with loss of mesothelium and mesothelial cell nuclei showing lytic change. Cells were rounded with some areas of cell flattening and separation. Group 3: some animals showed little or no alteration, while others had a mild inflammatory response. Mesothelial cells were rounded and showed crenation on the exposed surface. Group 4: specimens showed little change from the control group. Conclusions. The LM results indicate that insufflations with heated, humidified CO₂ are the least likely to induce mesothelial damage.

Warm, humidified carbon dioxide gas insufflation for laparoscopic appendicectomy in children: a double-blinded randomized controlled trial

OBJECTIVE

To investigate clinical benefits of warm, humidified carbon dioxide (CO(2)) insufflation for acute laparoscopic appendicectomy on postoperative pain and recovery in children (age 8-14 years).

BACKGROUND

Conventional CO(2) insufflation leads to desiccation-related peritoneal inflammation and injury, which is preventable with warm, humidified CO2 gas. We hypothesized that reduced peritoneal desiccation would improve patient-centered outcomes in children after laparoscopic appendicectomy.

METHOD

A double-blinded, randomized controlled trial was conducted. Intervention group participants received warm (37°C), humidified (98% relative humidity) CO(2) gas insufflation, whereas control participants received standard room temperature (20°C) gas with 0% relative humidity. Perioperative analgesia and anesthesia were standardized. Postoperative opiate usage was converted to morphine equivalent daily dosages (MEDD) for comparison, and pain intensity at rest and on moving was rated by participants using visual analog scales. Postoperative recovery and return to normal activities was assessed using a questionnaire on day 10.

RESULTS

Between February 2010 and March 2011, a total of 190 participants were randomized. Both intervention and control groups were matched at baseline. Postoperative MEDD and pain scores were also similar. There were no differences in postoperative recovery parameters.

CONCLUSIONS

Warm, humidified CO(2) insufflation for acute laparoscopic appendicectomy has no short-term clinical benefits on postoperative outcomes in pediatric patients (ClinicalTrials.gov trial identifying code: NCT01027455).

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.

Laparoscopic lens fogging: a review of etiology and methods to maintain a clear visual field

Laparoscopic surgical procedures are becoming common across surgical specialties, including urology. Maintaining a clear field of vision is paramount in such procedures not only for safety by preventing inadvertent injury, but also to improve precision and reduce operative time. Laparoscopic lens fogging (LLF) is a major impediment to a clear visual field during laparoscopy and is caused by condensation as well as particulate debris, blood, and smoke accumulation on the scope lens. Despite many available techniques to improve vision during laparoscopy, available data on etiology and methods to improve vision have only sporadically been considered in the literature. The objective of this review was to summarize current literature on the etiology of LLF and other causes of poor vision during laparoscopy and also review the current approaches for minimizing or reducing such events. In summary, although the etiology of LLF is well understood, that is, temperature and humidity differences, the methods to reduce its occurrence lack significant data. Of those methods that are often espoused, most are not supported in the literature, such as warmed and humidified insufflation gas, or simply lack data, such as antifogging solutions.

The humoral response after laparoscopic versus open colorectal surgery: a meta-analysis

BACKGROUND

The local and systemic humoral response after colorectal surgery is thought to affect postoperative recovery. It is commonly claimed that laparoscopic surgery elicits a diminished inflammatory response than equivalent open surgery. Despite these claims, the evidence is conflicting. Therefore, we aimed to systematically review the results from randomized controlled clinical trials comparing the humoral response associated with laparoscopic versus open colorectal surgery.

MATERIALS AND METHODS

A high-sensitivity search was conducted independently by two of the authors with no language restriction. Studies were identified from the Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), Cochrane Library, Medline (January 1966 to January 2009), PubMed (1950 to January 2009), and Embase (1947 to January 2009). Relevant meeting abstracts and reference lists were manually searched. Data analysis was performed using Review Manager ver. 5.0.

RESULTS

Thirteen randomized controlled trials were included. Meta-analysis demonstrated a significantly higher serum IL-6 on d 1 after open colorectal resection for neoplasia (n = 97) compared with laparoscopic resection (n = 76, P = 0.0008) without significant heterogeneity. Data for plasma IL-6 were heterogeneous, with no apparent difference between groups. No other significant differences were identified, and there were not enough data on local peritoneal humoral factors to allow meta-analysis.

CONCLUSION

Open colorectal resection for neoplasia is associated with higher postoperative serum levels of IL-6 on d 1 than equivalent laparoscopic surgery. The aetiology and clinical significance of this finding is uncertain, and further studies are required to elucidate any differences in the local humoral response which may be more clinically relevant in surgery for this indication.

Peritoneal changes due to laparoscopic surgery

Background

Laparoscopic surgery has been incorporated into common surgical practice. The peritoneum is an organ with various biologic functions that may be affected in different ways by laparoscopic and open techniques. Clinically, these alterations may be important in issues such as peritoneal metastasis and adhesion formation.

Methods

A literature search using the Pubmed and Cochrane databases identified articles focusing on the key issues of laparoscopy, peritoneum, inflammation, morphology, immunology, and fibrinolysis.

Results

Laparoscopic surgery induces alterations in the peritoneal integrity and causes local acidosis, probably due to peritoneal hypoxia. The local immune system and inflammation are modulated by a pneumoperitoneum. Additionally, the peritoneal plasmin system is inhibited, leading to peritoneal hypofibrinolysis.

Conclusion

Similar to open surgery, laparoscopic surgery affects both the integrity and biology of the peritoneum. These observations may have implications for various clinical conditions.

Systematic review of oxidative stress associated with pneumoperitoneum

Background

There have been several reports of ischaemic complications after routine laparoscopy. The aim of this review was to investigate the relationship between this oxidative stress and pneumoperitoneum.

Methods

Medline, Medline in-process, The Cochrane Library, PubMed and EMBASE were searched for papers on oxidative stress and pneumoperitoneum, from 1947 to March 2008 with no language restriction or restriction on trial design. Papers that did not investigate pneumoperitoneum as a causative factor, or did not report outcome measures related to oxidative stress, were excluded.

Results

A total of 73 relevant papers were identified: 36 animal studies, 21 human clinical trials, nine case reports, five review articles and two comments. Pneumoperitoneum causes a reduction in splanchnic blood flow, resulting in biochemical evidence of oxidative stress in a pressure- and time-dependent manner. There is evidence that the use of carbon dioxide for insufflation is contributory. Several measures proposed to minimize the oxidative stress have shown promise in animal studies, but few have been evaluated in the clinical setting.

Conclusion

There is an increasing body of evidence, mainly from animal studies, that pneumoperitoneum decreases splanchnic perfusion with resulting oxidative stress. It is now appropriate to investigate the clinical significance of pneumoperitoneum-associated oxidative stress.

Laparoscopic splenectomy in goats

OBJECTIVE

To report laparoscopic splenectomy in goats.

STUDY DESIGN

Experimental study.

ANIMALS

Healthy female goats (n=9); aged, 10-18 months; weighing, 22-30 kg.

METHODS

Food was withheld for 24 hours and water for 10 hours. Anesthetized right laterally recumbent goats had a laparoscopic portal and 3 instrumental portals created in the left flank. Splenic attachments were dissected with monopolar electrocautery and blunt dissection through 2 instrument portals. Exposure and isolation of splenic vessels was performed with laparoscopic "right-angle" preparation forceps. Vessels were ligated with a medium-titanium clip and 2 silk sutures and then transected between the silk sutures. The detached spleen was manipulated into a specimen retrieval bag, morcellated, and the bag retrieved through an enlarged portal. Repeat laparoscopic examination was performed at 1 month.

RESULTS

Laparoscopic splenectomy required 70 minutes (range, 52-88 minutes) and was successful without major intraoperative and postoperative complications. Postoperatively, all goats had signs of mild abdominal discomfort. On repeat laparoscopy, with the exception of 1 goat that had a focal omental adhesion to the enlarged portal site, no other abnormalities were identified.

CONCLUSIONS

Laparoscopic splenectomy can be accomplished in goats using 4 portals in the left flank and a combination of monopolar cautery dissection of splenic attachments, ligation of vessels using metal clips and intracorporeal ligatures, and intra-abdominal morcellation of the detached spleen in a specimen retrieval bag.

CLINICAL RELEVANCE

Laparoscopic splenectomy is an effective and safe technique in goats.

Thermoregulatory responses of sevoflurane, desflurane, and isoflurane during gynecologic laparoscopic surgery

BACKGROUND

Core temperature decreases rapidly after the induction of general anesthesia, because the heat is redistributed to peripheral tissues. Thermoregulatory responses of volatile anesthetics have been tested, but their effects have not been directly compared. Therefore, we evaluated the thermoregulatory responses to sevoflurane, desflurane, and isoflurane.

METHODS

Sixty healthy patients scheduled for laparoscopic myomectomy or radical hysterectomy were allocated into three groups; Group S (sevoflurane, n = 20), Group D (desflurane, n = 20), and Group I (isoflurane, n = 20). Anesthesia was maintained with 1 minimum alveolar concentration (MAC) of sevoflurane, desflurane, and isoflurane in a 50/50 mixture of N2O/O2. Patients were maintained in a normovolemic and normocapnic state. The core temperature and forearm minus fingertip skin-temperature gradient (an index of peripheral vasoconstriction) were monitored after the induction of general anesthesia.

RESULTS

Each of the seven patients given sevoflurane, desflurane, and isoflurane vasoconstricted at a core temperature of 35.3 +/- 0.5degrees C, 33.6 +/- 0.4degrees C, and 35.2 +/- 0.4degrees C, respectively. The vasoconstriction threshold was the lowest in patients anesthetized with desflurane. The core temperature gradient (Ti-Tf) was significantly higher in patients that were anesthetized with desflurane than in those that were anesthetized with sevoflurane or isoflurane. The core temperature of desflurane was significantly lower than that of sevoflurane or isoflurane 15 minutes after the induction of anesthesia until 180 minutes of anesthesia.

CONCLUSIONS

These results indicate that the core temperature is maintained at a higher level in patients that have been anesthetized with sevoflurane or isoflurane than in those that have been anesthetized with desflurane.

Use of a warming bath to prevent lens fogging during laparoscopy

PURPOSE

To describe a techique of using a warming bath to prevent lens fogging during laparoscopy.

MATERIALS AND METHODS

A warming machine (OR Solutions Inc., Chantilly, Virginia, model ORS-2038) containing a sterile water bath maintained at 120 degrees F is used to warm laparoscope lenses during laparoscopic surgery in order to prevent lens fogging.

RESULTS

We have used this technique in place of a hot water thermos or defogging solution the past 5 years during hundreds of laparoscopic cases and have noted a significant decrease in lens fogging and the need to clean the lens of water vapor condensate.

CONCLUSIONS

A water bath capable of maintianing hot water at a stable 120 degrees F is an effective alternative technique for maintaining warm laparoscope lenses and preventing lens fogging during laparoscopy.

Heated and humidified CO2 prevents hypothermia, peritoneal injury, and intra-abdominal adhesions during prolonged laparoscopic insufflations

BACKGROUND

Insufflation with standard cold-dry CO(2) during laparoscopic surgery has been shown to predispose patients to hypothermia and peritoneal injury. This study aimed to compare the effect of prolonged cold-dry CO(2) insufflation with heated-humidified CO(2) insufflation (3-5 h) on hypothermia, peritoneal damage, and intra-abdominal adhesion formation in a rat model.

MATERIALS AND METHODS

A total of 160 Wistar rats were randomized to undergo no insufflation or insufflation with cold-dry CO(2) (21 degrees C, <1% relative humidity) or heated-humidified CO(2) (37 degrees C, 95% relative humidity) for 3, 4, or 5 h. Core body temperature was measured via rectum before and during insufflations. Peritoneal samples were taken at 6, 24, 48, and 96 h after treatments and analyzed with light microscopy and scanning electron microscopy. Intra-abdominal adhesions were evaluated 2 weeks later.

RESULTS

Core body temperature significantly decreased in the cold-dry group, whereas it was maintained and increased in the heated-humidified group. Scanning electron microscopy and light microscopy studies showed intense peritoneal injury in the cold-dry CO(2) group but significantly less damages in the heated-humidified group. Increased intra-abdominal adhesion formation was observed in the cold-dry CO(2) group, while no adhesions were found in the rats insufflated with heated-humidified CO(2).

CONCLUSIONS

Heated-humidified CO(2) insufflation results in significantly less hypothermia, less peritoneal damage, and decreased adhesion formation as compared with cold-dry CO(2) insufflation. Heated-humidified CO(2) may be more suitable for insufflation application in prolonged laparoscopic surgery.

Hyperglycemia and lipopolysaccharide decrease depression effect of interleukin 8 production by hypothermia: an experimental study with endothelial cells

OBJECTIVE

This study assessed whether hyperglycemia and lipopolysaccharide (LPS) decrease the depression effect of interleukin (IL) 8 production by hypothermia in endothelial cells.

DESIGN AND SETTING

Laboratory study in a university laboratory.

SUBJECTS

Human umbilical vein endothelial cells (HUVECs).

INTERVENTIONS

HUVECs were cultivated in various concentrations of glucose (5.5 or 16.5mM = 100 or 300mg/dl) with or without LPS stimulation for 5, 12, or 24h at either 30 degrees or 37 degrees C.

RESULTS

After culturing, IL-8 mRNA expressions and IL-8 levels were measured. At 37 degrees C, hyperglycemia significantly increased basal IL-8 mRNA at 12h and basal IL-8 at 24h. At 37 degrees C hyperglycemia significantly increased LPS-stimulated IL-8 mRNA at 12h and LPS-stimulated IL-8 at 12 and 24h. At 30 degrees C basal IL-8mRNA, basal IL-8, and LPS-stimulated IL-8 were significantly decreased by hypothermia, but these hypothermic effects were not observed in LPS-stimulated IL-8 mRNA. Furthermore even at 30 degrees C hyperglycemia significantly increased LPS-stimulated IL-8 mRNA at all time points and LPS stimulated IL-8 at 24h.

CONCLUSIONS

Hypothermia (30 degrees C) decreases the production of IL-8 in HUVECs but does not decrease the expression of IL-8 mRNA. When hypothermia is followed by hyperglycemia and LPS stimulation, such a combination may expose the patients to a high risk of secondary tissue damage during therapeutic hypothermia.

A randomized controlled study evaluating the effects of the temperature of insufflated CO2 on core body temperature and blood gases (an experimental study)

BACKGROUND

Heated carbon dioxide (CO2) was used for pneumoperitoneum (Pp) to prevent hypothermia. This study aimed to investigate the relationship between the temperature of the insufflated CO2 and blood gases together with the core body temperature (CBT).

METHODS

A prospective controlled study was performed with 24 pigs weighing approximately 20 kg randomized into four groups of 6 pigs each. A pneumoperitoneum at 12 mmHg of pressure was applied for 60 min with the pig under general anesthesia. The CO2)temperature was 22 degrees C in group 1, 37 degrees C in group 2, and 7 degrees C in group 3. In the "sham" group, pneumoperitoneum was not applied. Arterial blood pH and partial pressure of CO2 (PaCO2) were analyzed before insufflation, every 15 min during the pneumoperitoneum, and 15 min after the desufflation. The CBT was recorded before the insufflation, every 20 min during pneumoperitoneum, and 20 min after the desufflation. Blood gas analyses and CBT records for the "sham" group were performed at the same intervals.

RESULTS

Arterial blood pH gradually decreased during pneumoperitoneum. At the 60th minute of pneumoperitoneum, a minimum decrease in arterial blood pH (0.04; p = 0.027) and a minimum increase in PaCO2 (3.67; p = 0.027) were recorded in group 3, whereas a maximum decrease in arterial blood pH (0.18; p = 0.027) and a maximum increase in PaCO2 (17.17; p = 0.027) were recorded in group 2. There was a significant negative correlation between PaCO2 and arterial blood pH in all the groups (r = -0.993; p < 0.01). The mean values of CBT decreases were statistically significant in all the groups: group 1 (p = 0.023), group 2 (p = 0.026), group 3 (p = 0.026), and "sham" group (p = 0.024).

CONCLUSIONS

The changes in PaCO2 were directly proportional and the changes in pH contrarily proportional to the temperature of the insufflated CO2. Significant differences in CBT decreases were found between the groups receiving heated gas and room temperature gas and the groups receiving heated gas and gas below room temperature.

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.

Prospective randomized trial of heated humidified versus cold dry carbon dioxide insufflation during laparoscopic gastric bypass

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Effect of desiccation and temperature during laparoscopy on adhesion formation in mice

OBJECTIVE

To investigate the effects of desiccation (without cooling) and of oversaturation of the pneumoperitoneum on adhesion formation.

DESIGN

Prospective randomized trial.

SETTING

Academic research center.

ANIMAL(S)

BALB/c and NMRI female mice.

INTERVENTION(S)

The effect of desiccation using nonhumidified CO(2) on adhesion formation was evaluated in a laparoscopic mouse model. Body temperature (BT) was maintained at 37 degrees C using a homeothermic blanket. In addition to controls without desiccation, the effect of both hypothermia and desiccation on adhesion formation was evaluated. Subsequently the effect of oversaturating the pneumoperitoneum using a high energy gas to avoid any desiccation was studied.

MAIN OUTCOME MEASURE(S)

During surgery BT, pneumoperitoneum temperature, and relative humidity were monitored. Adhesions were scored after 7 days.

RESULT(S)

Adhesions increased with increasing levels of desiccation when BT was kept at 37 degrees C. This was prevented with humidified gas. If BT decreased, adhesions were fewer. Oversaturating the pneumoperitoneum increased adhesions due to high energy gas causing an increase in both BT and pneumoperitoneum temperature.

CONCLUSION(S)

Adhesions increase with desiccation and decrease when BT is reduced. Adhesions are minimized when humidified gas is used. Since desiccation is associated with cooling, its effect is generally underestimated because of the counterbalance with cooling. The concept of combining controlled intraperitoneal cooling with a rigorous prevention of desiccation might be important for clinical adhesion prevention.

A Systematic Review of Intraoperative Warming to Prevent Postoperative Complications

This systematic review examines whether preventing hypothermia during surgery prevents postoperative complications and thereby improves outcomes for patients. Twenty-six randomized controlled trials were identified, and data extraction and assessment of study quality were carried out by two researchers independently. The results of studies with similar patients, surgical procedures, and outcomes were pooled. Outcomes measured included postoperative pain levels, thermal comfort, and treatment costs. Postoperative complications identified were shivering, cardiac events, need for blood transfusion, wound infections, and pressure ulcers. The majority of studies favored treatment.

Cœlioscopie et cancer en gynécologie : le point en 2005

All the surgical procedures, which may be required to treat a gynecologic cancer, can be performed endoscopically. However prospective randomized studies required to confirm the oncologic efficacy of the technique are still lacking in gynecology, whereas such studies are available in digestive surgery. Animal studies suggested that the risk of tumor dissemination in non traumatized peritoneum is higher after a pneumoperitoneum than after a laparotomy. Experimental studies also emphasized two points: the surgeon and the surgical technique are essential, all the parameters of the pneumoperitoneum may influence the postoperative dissemination. Changing these parameters we may, in the future, be able to create a peritoneal environment adapted to oncologic patients in order to prevent or to decrease the risks of peritoneal dissemination and/or of postoperative tumor growth. Until the results of prospective randomized studies become available, the preoperative selection of the patients and the surgical technique should be very strict. In patients with endometrial cancer, the laparoscopic approach should be reserved to clinical stage I disease, if the vaginal extraction is anticipated to be easy accounting for the volume of the uterus and the local conditions. In cervical cancer, the laparoscopic approach should be reserved to patients with favorable prognostic factors: stage IB of less than 2 cm in diameter. Laparoscopy is the gold standard for the surgical diagnosis of adnexal masses. But the puncture should be avoided whenever possible. The surgical treatment of invasive ovarian cancer should be performed by laparotomy whatever the stage. In contrast restaging of an early ovarian cancer initially managed as a benign mass, is a good indication of the laparoscopic approach. The laparoscopic management of low malignant potential tumors should include a complete staging of the peritoneum. Knowledge of the principles of endoscopy and of oncologic surgery is required. Teaching and diffusion of endoscopic oncological techniques are among the major challenges of gynecologic surgery within the next few years.

[Immediate peritoneal response to contamination during laparoscopic surgery in an experimental mouse model]

INTRODUCTION

Several studies have shown that laparoscopic surgery (LS) minimizes surgical trauma and preserves immune response. Another advantage is the lower incidence of infectious complications. However, several in vitro studies have shown that an atmosphere with CO2 affects macrophage physiology, which would affect the response to peritoneal contamination. This observation is controversial, given the experimental evidence of a better conserved response to peritoneal contamination. The aim of the present study was to investigate the immediate response of the peritoneum to contamination in an atmosphere with CO2.

MATERIAL AND METHOD

A total of 192 CD-1 rats were distributed into three groups: group I, LP, n= 64, (laparotomy); group II, LC-CO2, n= 64, (laparoscopy-CO2), group III, LC-T, n= 64, (laparoscopy-traction). The rats were randomized to receive 1 ml of a suspension of Escherichia coli (1x10(4) CFU/ml) (contamination [C]) or saline serum (no contamination [NC]). Peritoneal fluid was obtained at 1.5, 3, 6, and 12 h after surgery. Monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-6 and prostaglandin.E2 (PGE2) were determined.

RESULTS

MCP-1 levels were significantly higher and increased earlier in group II (LC-CO2-NC) than in group I (LP-NC) (p< .007). Simultaneously, the increase in the traction group was significantly higher (p< .002) than after laparotomy, without differences with respect to group II (LC-CO2-NC). When contamination was added, there was a significant increase in the three groups (p< .5). The modifications in MCP-1 in the LP-C group were statistically significantly greater and appeared earlier than those in the traction groups, LC-T-C (p< .002) and LC-CO2-C (p< .02). Interleukin 6: the three models showed a significant increase, which appeared later in the LP-NC group. Simultaneously, the increase in IL-6 appeared earlier and was significantly greater in the LC-T-NC group than in the LP group (p< .003), with no differences between the LC-CO2-NC and LC-T-NC groups. There was a significant difference between contaminated and uncontaminated groups in the LC-CO2 model. The traction model (LC-T-C group) showed a greater increase than the LP-C and LC-CO2-C groups (p< .001). PGE2: a significant increase was observed in the three models without contamination. However, when contamination was added, no differences were observed.

CONCLUSION

Pneumoperitoneum with CO2 provokes a peritoneal response that is qualitatively different from open surgery and modifies the response to contamination with a greater increase in MCP-1 and IL-6.

Laparoscopic surgery in children is associated with an intraoperative hypermetabolic response

BACKGROUND

Laparoscopic surgery is thought to be associated with a reduced metabolic response compared to open surgery. Oxygen consumption (VO2) and energy metabolism during laparoscopic surgery have not been characterized in children.

METHODS

We measured respiratory gas exchange intraoperatively in children undergoing 19 open and 20 laparoscopic procedures. Premature infants and patients with metabolic, renal, and cardiac abnormalities were excluded. Anesthesia was standardized. Unheated carbon dioxide was used for insufflation. VO2 was measured by indirect calorimetry. Core temperature was measured using an esophageal temperature probe.

RESULTS

We found a steady increase in VO2 during laparoscopy. The increase in VO2 was more marked in younger children and was associated with a significant rise in core temperature. Open surgery was not associated with significant changes in core temperature or VO2.

CONCLUSIONS

Laparoscopy in children is associated with an intraoperative hypermetabolic response characterized by increased oxygen consumption and core temperature. These changes are more marked in younger children.

Immediate peritoneal response to bacterial contamination during laparoscopic surgery

BACKGROUND

Several studies have shown that laparoscopic surgery (LS) minimizes surgical trauma and the immune function is better preserved. Another major advantage of LS is the lower incidence of septic complications. However, several in vitro studies have shown that CO(2) severely impairs macrophage physiology. In theory, this would reduce the ability to respond to peritoneal contamination. However, there is some controversy in view of the evidence of a better preserved peritoneal response to sepsis. This study analyzed the early response of the peritoneum to contamination in a CO(2) ambience.

METHODS

A total of 192 CD-1 mice were distributed in three groups: group 1, laparotomy (LAP, n = 64); group 2, CO(2) laparoscopy (CO(2)-LC, n = 64); and group 3, wall lift laparoscopy (WL-LC, n = 64). Mice in each group were randomized to receive 1 ml of Escherichia coli suspension (1 x 10(4) colony-forming units/ml) or saline. Peritoneal fluid was obtained at 1.5, 3, 6, and 12 h after surgery. Monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and prostaglandin E(2) (PGE(2)) were measured.

RESULTS

MCP-1 levels were significantly greater and higher earlier in group 2 (CO(2)-LC) than in group 1 (LAP) (p < 0.007). Simultaneously, the increment in the traction group (WL-LC, group 3) was significantly higher (p < 0.002) than after laparotomy, with no differences in group 2 (CO(2)-LC). When a contamination was added to the laparotomy subgroup, there was a significant increase compared to the group without contamination (p < 0.5). MCP-1 modifications after contamination in the LAP group were statistically significant and appeared later than in the WL-LC (p < 0.002) and CO(2)-LC groups (p < 0.02). For IL-6, the three models presented a significant increase in the noncontaminated groups. This occurred significantly later in the LAP group. Simultaneously, the increase in IL-6 occurred earlier and was significantly higher in the WL-LC group compared to the LAP group (p < 0.003), without differences between CO(2)-LC and wall lift groups. Significant differences between contaminated and noncontaminated subgroups were only observed in the LC-CO(2) groups. When contaminated, the traction model sustained a higher and earlier rise in IL-6 levels compared to the LAP and LC-CO(2) groups (p < 0.001). For PGE(2), The three models showed a significant increase in PGE(2) levels in the noncontaminated groups. However, there were no significant differences between them. In the contaminated groups, there was no statistical difference between the groups.

CONCLUSION

Despite a transient impairment of the immediate peritoneal response to a septic challenge, the degree of injury with LS is lower than that with open surgery, and abdominal infection can therefore be better controlled.

Effect of warmed, humidified insufflation gas and anti-inflammatory agents on cytokine response to laparoscopic nephrectomy: porcine model

PURPOSE

We evaluated the effects of warmed, humidified CO2 and anti-inflammatory agents on the local and systemic cytokine response after laparoscopic nephrectomy.

MATERIALS AND METHODS

A total of 15 pigs were randomized to undergo standard laparoscopic nephrectomy, laparoscopic nephrectomy with warmed, humidified CO2 gas or laparoscopic nephrectomy with perioperative administration of intravenous dexamethasone and oral rofecoxib. At baseline, and 1, 4, 24 and 48 hours after surgery duplicate blood and peritoneal samples were drawn to analyze cortisol, glucose, tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and IL-6 via a microassay technique. Body temperature was determined at operation, intraoperatively and 1 hour postoperatively. Surgical parameters, including operative time, gas volume used and blood loss, were recorded.

RESULTS

Pigs in the warmed, humidified CO2 and anti-inflammatory arms maintained higher intraoperative and postoperative core body temperatures than controls. Warmed, humidified CO2 did not affect peritoneal or systemic cytokine levels. Peak peritoneal TNF-alpha levels in the anti-inflammatory group were significantly higher than in controls at 4 hours. Considerably higher serum TNF-alpha levels in the anti-inflammatory group were observed at 48 hours. Peritoneal IL-1beta and IL-6 levels in the anti-inflammatory group remained similar to those in controls, while serum levels were noticeably lower. There was no observable difference in serum cortisol or the glucose response to laparoscopic nephrectomy among the groups.

CONCLUSIONS

While preserving core body temperature, humidified, warmed CO2 did not affect local or systemic trends of pro-inflammatory mediators. The administration of perioperative anti-inflammatory agents produced conflicting local and systemic cytokine response of uncertain clinical significance.

A procedure-specific systematic review and consensus recommendations for postoperative analgesia following laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy has advantages over the open procedure for postoperative pain. However, a systematic review of postoperative pain management in this procedure has not been conducted.

METHODS

A systematic review was conducted according to the guidelines of the Cochrane Collaboration. Randomized studies examining the effect of medical or surgical interventions on linear pain scores in patients undergoing laparoscopic cholecystectomy were included. Qualitative and quantitative analyses were performed. Recommendations for patient care were derived from review of these data, evidence from other relevant procedures, and clinical practice observations collated by the Delphi method among the authors.

RESULTS

Sixty-nine randomized trials were included and 77 reports were excluded. Recommendations are provided for preoperative analgesia, anesthetic and operative techniques, and intraoperative and postoperative analgesia.

CONCLUSIONS

A step-up approach to the management of postoperative pain following laparoscopic cholecystectomy is recommended. This approach has been designed to provide adequate analgesia while minimizing exposure to adverse events.

The increased incidence of intraabdominal infections in laparoscopic procedures: potential causes, postoperative management, and prospective innovations

We conducted a review of the literature to identify some potential causes for the increased incidence of intraabdominal infections seen after laparoscopic procedures. We also discuss the postoperative management of this condition and provide a prospective overview of innovations that may be helpful in such cases in the future.

Thermal response of rats to different types of trauma

BACKGROUND

Hypothermia is commonly observed in victims of trauma, and it is generally combined with shock caused by either hemorrhagic or nonhemorrhagic mechanisms. This study deals with phenomena related to nonhemorrhagic mechanisms. The objective is to document through experimental evidence the existence of a natural mechanism in rats that compensates for the inadequate tissue perfusion in the presence of shock by reducing body temperature (hypothermia).

METHODS

Different types of trauma are analyzed (i.e., abdominal cavity and bowel exposure) and compared with other groups that suffered, additionally, femur fracture and partial hepatectomy. Further thermal alterations are also studied as consequences of vascular phenomena involving the elevation of intra-abdominal pressure and clamping of arteries and veins, such as the aorta and inferior vena cava. The loss of energy and temperature response of the animals is documented in time through charts with experimental uncertainties.

RESULTS

It is concluded that exposure of the bowels is the main factor involved in the genesis of hypothermia, regardless of the associated trauma. Plastic film is shown to be the most effective way to avoid heat loss in bowel exposure. An optimal intra-abdominal pressure, Popt congruent with 12 mm Hg, is found such that heat flux loss is minimum in pneumoperitoneal procedures.

CONCLUSION

Aortic and inferior vena cava clamping induces hypothermia at levels comparable to bowel exposure.

Effect of Humidified and Heated CO2 During Gynecologic Laparoscopic Surgery on Analgesic Requirements and Postoperative Pain

STUDY OBJECTIVE

To determine the effect of humidified and heated CO(2) for pneumoperitoneum during laparoscopic surgery on analgesic requirements, postoperative pain, and patient satisfaction.

DESIGN

Prospective, randomized, double-blind, controlled study (Canadian Task Force classification I).

SETTING

University hospital.

PATIENTS

Ninety consecutive women scheduled for gynecologic laparoscopic surgery.

INTERVENTION

Operative laparoscopic management of adnexa surgery or adhesiolysis.

MEASUREMENTS AND MAIN RESULTS

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.

CONCLUSION

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.

Effect of temperature upon adhesion formation in a laparoscopic mouse model

BACKGROUND

Pneumoperitoneum can be a cofactor in adhesion formation. Pneumoperitoneum with non-humidified gas causes desiccation in the peritoneal cavity which decreases temperature. The effect of desiccation upon adhesion formation is widely accepted. The specific effect of the associated cooling upon adhesion formation remains unexplored, and was addressed specifically in our laparoscopic mouse model.

METHODS

Adhesions were induced during laparoscopy and scored after 7 days during laparotomy. Pneumoperitoneum was performed using CO2 or CO2 with oxygen with or without humidification. Animals were placed at different environmental temperatures to modulate body and intraperitoneal temperature.

RESULTS

Anaesthesia, environment with a lower temperature and pneumoperitoneum all independently decrease body temperature. A decrease in body temperature decreases adhesion formation (P=0.004). Therefore, at 37 degrees C, pneumoperitoneum-enhanced adhesion formation is more important than at room temperature (P=0.04). As was observed at room temperature, adhesion formation at 37 degrees C increases with the duration (P=0.01) of pneumoperitoneum and decreases with the addition of 3% of oxygen (P=0.03).

CONCLUSIONS

Hypothermia reduces pneumoperitoneum-enhanced adhesion formation, which supports hypoxia as a driving mechanism, since hypothermia decreases the toxic effects of hypoxia and of the ischaemia-reperfusion process. These data could open up new possibilities for adhesion prevention in laparoscopic surgery.

Mild hyperthermia down-regulates receptor-dependent neutrophil function

Mild hypothermia impairs resistance to infection and, reportedly, impairs phagocytosis and oxidative killing of unopsonized bacteria. We evaluated various functions at 33 degrees-41 degrees C in neutrophils taken from volunteers. Adhesion on endothelial cells was determined using light microscopy. Adhesion molecule expression and receptors, phagocytosis, and release of reactive oxidants were assessed using flow cytometric assays. Adhesion protein CD11b expression on resting neutrophils was temperature-independent. However, up-regulation of CD11b with tumor necrosis factor (TNF)-alpha was increased by hypothermia and decreased with hyperthermia. Neutrophil adhesion to either resting or activated endothelial cells was not temperature-dependent. Bacterial uptake was inversely related to temperature, more so with Escherichia coli than Staphylococcus aureus. Temperature dependence of phagocytosis occurred only wi thopsonized bacteria. Hypothermia slightly increased N-formyl-L-methionyl-L-leucyl-phenylalanine receptors on neutrophils: hyperthermia decreased expression, especially with TNF-alpha. N-formyl-L-methionyl-L-leucyl-phenylalanine-induced H2O2 production was inversely related to temperature, especially in the presence of TNF-alpha. Conversely, phorbol-13-myristate-12-acetate, an activator of protein kinase C, induced an extreme and homogenous release of reactive oxidants that increased with temperature. In contrast to nonreceptor-dependent phagocytosis and oxidative killing, several crucial receptor-dependent neutrophil activities show temperature-dependent regulation, with hypothermia increasing function. The temperature dependence of neutrophil function is thus more complicated than previously appreciated.

Pneumoperitoneum and peritoneal surface changes: a review

BACKGROUND

Recent evidence suggests that the use of carbon dioxide to create a pneumoperitoneum during laparoscopy can lead to adverse structural, metabolic, and immune derangements within the peritoneal cavity, and that these can be dependent on the specific insufflation gas used. These changes include structural alterations in the mesothelial lining, pH disturbances, and alterations in peritoneal macrophage responsiveness. This contrasts with an apparent systemic benefit associated with laparoscopic, as compared with open, surgery.

METHODS

Recently published clinical and experimental studies related to the effect of pneumoperitoneum on the peritoneal surface are reviewed, and their relevance is discussed.

RESULTS

Structural changes in the peritoneal mesothelial surface layer such as widening of the intercellular junctions can be demonstrated with electron microscopy. Acidification of the peritoneum in response to carbon dioxide insufflation occurs not only at the peritoneal surface, but also in the underlying connective tissue, resulting in disturbances in the electrical surface charge and the release of various immune mediators such as endotoxin. Pneumoperitoneum also affects the local peritoneal immune environment resulting in alterations in cytokine production and phagocytic function, as well as diminished antitumor cell cytotoxicity.

CONCLUSIONS

Ultrastructural, metabolic, and immune alterations are observed at the peritoneal surface in response to a pneumoperitoneum. Experimental evidence suggests that these changes are carbon dioxide-specific effects. The consequences of these alterations to the local peritoneal environment are not well understood, but they may facilitate tumor implantation within the peritoneal cavity and adversely affect the ability to clear intraperitoneal infections. Further investigation into this area is warranted.

Stress response to laparoscopic surgery: a review

BACKGROUND

Laparoscopic surgery is associated with reduced surgical trauma, and therefore with a less acute phase response, as compared with open surgery. Impairment of the immune system may enhance surgical infections, port-site metastases, and sepsis. The objectives of this review was to assess immunologic consequences of benign laparoscopic surgery and to highlight controversial aspects.

METHODS

A literature search on stress response to nonmalignant laparoscopic and open surgery was conducted using the MEDLINE and Cochrane databases. Cross-references from the reference list of major articles on the subject were used, as well as manuscripts published between 1993 and 2002.

RESULTS

Local (i.e., peritoneal) immune function is affected by carbon dioxide pneumoperitoneum. The production of tumor necrosis factor and the phagocytotic capacity of peritoneal macrophages are less lowered. The systemic stress response, as determined by delayed-type hypersensitivity response and leukocyte antigen expression on lymphocytes, shows a preservation of immune function after laparoscopic surgery, as compared with conventional surgery.

CONCLUSIONS

Intraperitoneal carbon dioxide insufflation attenuates peritoneal immunity, but laparoscopic surgery is associated with a lower systemic stress response than open surgery.

The Effect of Warm Humidified CO2 on the Dissipation of Residual Gas Following Laparoscopy in Piglets

STUDY OBJECTIVE

To determine whether residual gas volume reduces more quickly after insufflation with humidified CO(2) compared with dry CO(2).

DESIGN

Animal study (Canadian Task Force classification I).

SETTING

University.

INTERVENTION

Piglets were randomly divided into two groups of five and underwent abdominal insufflation with either cold, dry CO(2) or warm, humidified CO(2).

MEASUREMENTS AND MAIN RESULTS

Following insufflation, anteroposterior and lateral gas-bubble radiographic images were obtained at 5, 15, 30, 45, and 60 minutes, and the area of each gas-bubble profile calculated. Blood samples were obtained at 0, 2, 4, and 5 hours, and they were analyzed for IL-1beta and TNFalpha. Peritoneal tissue samples were obtained on euthanasia at 5 hours for histological analysis. The results indicate that following pneumoperitoneum, residual CO(2) dissipates more rapidly when the gas is heated and humidified compared with when it is cool and dry. This is associated with a reduction in the duration of the inflammatory response as measured by TNF alpha production, although no histologic differences in the peritoneal tissue were observed.

CONCLUSION

Heating and humidifying CO(2) leads to faster dissipation of residual gas associated with a reduced duration of inflammation, which may contribute toward a reduction in postlaparoscopic pain.

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.

Effect of laparoscopy on immune function

BACKGROUND

Laparoscopic surgery is believed to lessen surgical trauma and so cause less disturbance of immune function. This may contribute to the rapid recovery noted after many laparoscopic operations. Preservation of both systemic and intraperitoneal immunity is particularly important in surgery for sepsis or cancer and so an understanding of the impact of laparoscopy on immune function is relevant.

METHODS

Literature on immunological changes following laparoscopy and open surgery was identified from Medline, along with cross-referencing from the reference lists of major articles on the subject.

RESULTS AND DISCUSSION

Despite a few contradictory reports, systemic immunity appears to be better preserved after laparoscopic surgery than after open surgery. However, the local intraperitoneal immune system behaves in a particular way when exposed to carbon dioxide pneumoperitoneum; suppression of intraperitoneal cell-mediated immunity has been demonstrated in a number of studies. This feature may be clinically important and should be acknowledged when considering laparoscopic surgery in patients with malignancy or sepsis.

Alterations in the immune system and tumor growth in laparoscopy

BACKGROUND

The explosion in the use of therapeutic laparoscopy during the past decade has focused much research interest on finding a basic scientific support for the clinically apparent attenuation of the stress response to surgery. In particular, the potential impact that attenuation of the immune response to surgery may have on laparoscopy for the cure of malignancy has attracted much attention.

METHODS

A review of the published literature on the stress response to laparoscopic surgery and the impact of laparoscopy on tumor growth was performed.

RESULTS

Evidence favors an attenuation of the immune response to surgery with laparoscopic cholecystectomy. Whether this is true also of more major procedures such as laparoscopically assisted colectomy for malignancy is currently unclear. In animal models, tumor growth after laparoscopic surgery is less than after laparotomy and depends on the insufflation agent used.

CONCLUSIONS

Laparoscopic cholecystectomy appears to be associated with attenuation of the immune response to surgery. The implications of these findings for the future use of laparoscopic surgical techniques for malignant disease remain unclear.

A randomized controlled trial assessing the effect of heated carbon dioxide for insufflation on pain and recovery after laparoscopic fundoplication

BACKGROUND

Insufflation with heated gas for laparoscopy may reduce postoperative pain. This study assessed the effect of heated gas on outcome after fundoplication.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

[Variations in intraperitoneal temperature during laparoscopic cholecystectomy]

STUDY AIM

The aim of this study was to measure thermal variation during laparoscopy in the vicinity of heat sources such as monopolar (MC), bipolar (BC) and ultrasound coagulation (USC) and to evaluate their possible negative consequences for the patient.

METHODS

This study included 67 patients who underwent laparoscopic cholecystectomy. The temperature measurements were taken with a sterile thermal probe introduced through a 5 mm trocar, coupled with a recording monitor reading variations between 20 degrees and 80 degrees C. The variation in temperature was measured as a function of the power applied to the electrodes (20 or 30 W) and in relation to the distance (1, 2, 3, 4, and 5 cm) from the electrodes.

RESULTS

The temperature varied by 3 degrees for BC, 29 degrees for MC and only 0.2 degree for USC when the distance increased for 1 to 5 cm. Depending on the power delivered, (20 or 30 W or 1 to 5 for USC), the variations were 1 degree for BC, 17 degrees for MC and there was still no variation for USC.

CONCLUSION

The use of bipolar coagulation and ultrasonic coagulation associated with minimal temperature variations is the option of choice for operating near structures such as the common bile duct or the gastrointestinal tract.