Effect of temperature of insufflated CO2 during and after prolonged laparoscopic surgery

Hemodynamic derangement associated with tension pneumomediastinum during minimally invasive esophagectomy: A case report

RATIONALE

Surgery is the treatment of choice for esophageal cancer. Since the 1990s, minimally invasive esophagectomy (MIE) has been developed using videoscope. Although MIE lowers mortality by reducing postoperative complications, the risk of carbon dioxide (CO2) insufflation related complications still exists.

PATIENT CONCERNS

A 56-years-old male patient underwent elective MIE. The patient (body mass index, 15 kg/m2) had well-controlled hypertension, cardiomegaly, and severe emphysematous lungs. He had iatrogenic pneumothorax during central venous catheterization 3 weeks prior; however, the pneumothorax was resolved before surgery.

DIAGNOSIS

During thoracoscopic surgery, respiratory acidosis was not corrected despite rapid respiratory rate and positive end-expiratory pressure. Intrathoracic CO2 pressure was lowered from 12 to 8 mm Hg, and laparoscopic surgery was performed through the diaphragm in the reverse Trendelenburg position. In 15 minutes at this position, pulseless electrical activity with respiratory failure and high peak inspiratory pressure developed.

INTERVENTIONS

CO2 insufflation was stopped and drained as soon as hypotension developed. The patient was placed in the supine neutral position, and cardiopulmonary circulation was restored without further treatment.

OUTCOMES

After the pneumomediastinum event, surgery was successfully performed. Respiratory acidosis due to CO2 insufflation was not corrected during surgery and the patient was transferred to intensive care unit without extubation. After 14 days, the patient was discharged without cardiopulmonary complications. However, the patient expired 2 years later due to cardiovascular disease.

LESSONS

In MIE, there is always a risk of catastrophic tension pneumomediastinum along with intravascular volume depletion, surgical position, and ventilatory strategy depending on the surgical characteristics.

Effects of Intraoperative Insufflation With Warmed, Humidified CO2 during Abdominal Surgery: A Review

PURPOSE

During a laparotomy, the peritoneum is exposed to the cold, dry ambient air of the operating room (20°C, 0%-5% relative humidity). The aim of this review is to determine whether the use of humidified and/or warmed CO2 in the intraperitoneal environment during open or laparoscopic operations influences postoperative outcomes.

METHODS

A review was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The PubMed, OVID MEDLINE, Cochrane Central Register of Controlled Trials and Embase databases were searched for articles published between 1980 and 2016 (October). Comparative studies on humans or nonhuman animals that involved randomized controlled trials (RCTs) or prospective cohort studies were included. Both laparotomy and laparoscopic studies were included. The primary outcomes identified were peritoneal inflammation, core body temperature, and postoperative pain.

RESULTS

The literature search identified 37 articles for analysis, including 30 RCTs, 7 prospective cohort studies, 23 human studies, and 14 animal studies. Four studies found that compared with warmed/humidified CO2, cold, dry CO2 resulted in significant peritoneal injury, with greater lymphocytic infiltration, higher proinflammatory cytokine levels and peritoneal adhesion formation. Seven of 15 human RCTs reported a significantly higher core body temperature in the warmed, humidified CO2 group than in the cold, dry CO2 group. Seven human RCTs found lower postoperative pain with the use of humidified, warmed CO2.

CONCLUSION

While evidence supporting the benefits of using humidified and warmed CO2 can be found in the literature, a large human RCT is required to validate these findings.

Renal Physiology and Robotic Urological Surgery

The use of robotic-assisted laparoscopic techniques has transformed the face of urological surgery in the last decade, with demonstrable benefits over both unassisted laparoscopic and traditional open approaches. For example, robotic-assisted partial nephrectomy is associated with lower morbidity, improved convalescence, reduced postoperative pain, shorter length of hospital stay, and a superior cosmetic result when compared to an open procedure. This review discusses the various perioperative influences on the renal physiology of patients undergoing robotic-assisted urological procedures.

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.

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.

A computerized tomography scan method for calculating the hernia sac and abdominal cavity volume in complex large incisional hernia with loss of domain

Preoperative progressive pneumoperitoneum (PPP) is a safe and effective procedure in the treatment of large incisional hernia (size > 10 cm in width or length) with loss of domain (LIHLD). There is no consensus in the literature on the amount of gas that must be insufflated in a PPP program or even how long it should be maintained. We describe a technique for calculating the hernia sac volume (HSV) and abdominal cavity volume (ACV) based on abdominal computerized tomography (ACT) scanning that eliminates the need for subjective criteria for inclusion in a PPP program and shows the amount of gas that must be insufflated into the abdominal cavity in the PPP program. Our technique is indicated for all patients with large or recurrent incisional hernias evaluated by a senior surgeon with suspected LIHLD. We reviewed our experience from 2001 to 2008 of 23 consecutive hernia surgical procedures of LIHLD undergoing preoperative evaluation with CT scanning and PPP. An ACT was required in all patients with suspected LIHLD in order to determine HSV and ACV. The PPP was performed only if the volume ratio HSV/ACV (VR = HSV/ACV) was >or=25% (VR >or= 25%). We have performed this procedure on 23 patients, with a mean age of 55.6 years (range 31-83). There were 16 women and 7 men with an average age of 55.6 years (range 31-83), and a mean BMI of 38.5 kg/m(2) (range 23-55.2). Almost all patients (21 of 23 patients-91.30%) were overweight; 43.5% (10 patients) were severely obese (obese class III). The mean calculated volumes for ACV and HSV were 9,410 ml (range 6,060-19,230 ml) and 4,500 ml (range 1,850-6,600 ml), respectively. The PPP is performed by permanent catheter placed in a minor surgical procedure. The total amount of CO(2) insufflated ranged from 2,000 to 7,000 ml (mean 4,000 ml). Patients required a mean of 10 PPP sessions (range 4-18) to achieve the desired volume of gas (that is the same volume that was calculated for the hernia sac). Since PPP sessions were performed once a day, 4-18 days were needed for preoperative preparation with PPP. The mean VR was 36% (ranged from 26 to 73%). We conclude that ACT provides objective data for volume calculation of both hernia sac and abdominal cavity and also for estimation of the volume of gas that should be insufflated into the abdominal cavity in PPP.

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.

Heating and humidifying of carbon dioxide during pneumoperitoneum is not indicated

BACKGROUND

Carbon dioxide (CO2) pneumoperitoneum usually is created by a compressed gas source. This exposes the patient to cool dry gas delivered at room temperature (21 degrees C) with 0% relative humidity. Various delivery methods are available for humidifying and heating CO2 gas. This study was designed to determine the effects of heating and humidifying gas for the intraabdominal environment.

METHODS

For this study, 44 patients undergoing laparoscopic Roux-en-Y gastric bypass were randomly assigned to one of four arms in a prospective, randomized, single-blinded fashion: raw CO2 (group 1), heated CO2 (group 2), humidified CO2 (group 3), and heated and humidified CO2 (group 4). A commercially available CO2 heater-humidifier was used. Core temperatures, intraabdominal humidity, perioperative data, and postoperative outcomes were monitored. Peritoneal biopsies were taken in each group at the beginning and end of the case. Biopsies were subjected staining protocols designed to identify structural damage and macrophage activity. Postoperative narcotic use, pain scale scores, recovery room time, and length of hospital stay were recorded. One-way analysis of variance (ANOVA) and the nonparametric Kruskal-Wallis test were used to compare the groups.

RESULTS

Demographics, volume of CO2 used, intraabdominal humidity, bladder temperatures, lens fogging, and operative times were not significantly different between the groups. Core temperatures were stable, and intraabdominal humidity measurements approached 100% for all the patients over the entire procedure. Total narcotic dosage and pain scale scores were not statistically different. Recovery room times and length of hospital stay were similar in all the groups. Only one biopsy in the heated-humidified group showed an increase in macrophage activity.

CONCLUSIONS

The intraabdominal environment in terms of temperature and humidity was similar in all the groups. There was no significant difference in the intraoperative body temperatures or the postoperative variable measured. No histologic changes were identified. Heating or humidifying of CO2 is not justified for patients undergoing laparoscopic bariatric surgery.

Laparoscopic surgery: pitfalls due to anesthesia, positioning, and pneumoperitoneum

BACKGROUND

Laparoscopic procedures are increasing in number and extensiveness. Many patients undergoing laparoscopic surgery have coexisting disease. Especially in patients with cardiopulmonary comorbidity, pneumoperitoneum and positioning can be deleterious. This article reviews possible pitfalls related to the combination of anesthesia, positioning of the patient, and the influence of pneumoperitoneum in the course of laparoscopic interventions.

METHODS

A literature search using Medline's MESH terms was used to identify recent key articles. Cross-references from these articles were used as well.

RESULTS

Patient positioning and pneumoperitoneum can induce hemodynamic, pulmonary, renal, splanchnic, and endocrine pathophysiological changes, which will affect the entire perioperative period of patients undergoing laparoscopic procedures.

CONCLUSION

Perioperative management for the estimation and reduction of risk of morbidity and mortality due to surgery and anesthesia in laparoscopic procedures must be based on knowledge of the pathophysiological disturbances induced by the combination of general anesthesia, pneumoperitoneum, and positioning of the patient.

Heated and humidified insufflation during laparoscopic gastric bypass surgery: effect on temperature, postoperative pain, and recovery outcomes

BACKGROUND

Controversy exists regarding the efficacy of heated and humidified intraperitoneal gases in maintaining core body temperature. We performed a sham-controlled study to test the hypothesis that active warming and humidification of the insufflation gas reduces intraoperative heat loss and improves recovery outcomes.

PATIENTS AND METHODS

Fifty morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass procedures using a standardized anesthetic technique were randomly assigned to either a control (sham) group receiving room temperature insufflation gases with an inactive Insuflow (Lexion Medical, St. Paul, MN) device, or an active (Insuflow) group receiving warmed and humidified intraperitoneal gases. Esophageal and/or tympanic membrane temperature was measured perioperatively. Postoperative pain was assessed at 15 minute intervals using an 11-point verbal rating scale, with 0 = none to 10 = maximal. In addition, postoperative opioid requirements, incidence of nausea and vomiting, as well as the quality of recovery, were recorded.

RESULTS

Use of the active Insuflow device was associated with significantly higher mean +/- standard deviation (SD) intraoperative core body temperatures (35.5 +/- 0.5 vs. 35.0 +/- 0.4 degrees C). Postoperative shivering (0 vs. 19%) and the requirement for morphine in the postanesthesia care unit (5 +/- 4 vs. 10 +/- 5 mg) were both significantly lower in the Insuflow vs. control groups. Patients in the Insuflow group also reported a higher quality of recovery 48 hours after surgery (15 vs. 13, P < 0.05).

CONCLUSION

The Insuflow device modestly reduced shivering and heat loss, as well as the need for opioid analgesics in the early postoperative period. However, it failed to improve laparoscopic visualization due to fogging, and provided improvement in the quality of recovery only on postoperative day 2.

The Effects of Intraabdominally Insufflated Carbon Dioxide on Hepatic Blood Flow During Laparoscopic Surgery Assessed by Transesophageal Echocardiography

Conflicting results have been published about the effects of carbon dioxide (CO(2)) pneumoperitoneum on splanchnic and liver perfusion. Several experimental studies described a pressure-related reduction in hepatic blood flow, whereas other investigators reported an increase as long as the intraabdominal pressure (IAP) remained less than 16 mm Hg. Our goal in the present study was to investigate the effects of insufflated CO(2) on hepatic blood flow during laparoscopic surgery in healthy adults. Blood flow in the right and middle hepatic veins was assessed in 24 patients undergoing laparoscopic surgery by use of transesophageal Doppler echocardiography. Hepatic venous blood flow was recorded before and after 5, 10, 20, 30, and 40 min of pneumoperitoneum, as well as 1 and 5 min after deflation. Twelve patients undergoing conventional hernia repair served as the control group. The induction of pneumoperitoneum produced a significant increase in blood flow of the right and middle hepatic veins. Five minutes after insufflation of CO(2) the median right hepatic blood flow index increased from 196 mL/min/m(2) (95% confidence interval (CI), 140-261 mL/min/m(2)) to 392 mL/min/m(2) (CI, 263-551 mL/min/m(2)) (P < 0.05) and persisted during maintenance of pneumoperitoneum. In the middle hepatic vein the blood flow index increased from 105 mL/min/m(2) (CI, 71-136 mL/min/m(2)) to 159 mL/min/m(2) (CI, 103-236 mL/min/m(2)) 20 min after insufflation of CO(2). After deflation blood flow returned to baseline values in both hepatic veins. Conversely, in the control group hepatic blood flow remained unchanged over the entire study period. We conclude that induction of CO(2) pneumoperitoneum with an IAP of 12 mm Hg is associated with an increase in hepatic perfusion in healthy adults.

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.

Anaesthetic considerations for laparoscopic surgery in neonates and infants: a practical review

Minimally invasive surgery is being applied to an increasing number of neonates and infants undergoing abdominal surgeries. Knowledge of specific implications, patient's health status and pathophysiological changes induced by the surgery allow the anaesthesiologist to provide safe anaesthesia to these high-risk patients. This chapter describes the specific pathophysiological effects, peri-operative management, major complications and contraindications related to endoscopic procedures.

Circulatory and respiratory complications of carbon dioxide insufflation

BACKGROUND

Although providing excellent outcome results, laparoscopy also induces particular pathophysiological changes in response to pneumoperitoneum. Knowledge of the pathophysiology of a CO(2) pneumoperitoneum can help minimize complications while profiting from the benefits of laparoscopic surgery without concerns about its safety.

METHODS

A review of articles on the pathophysiological changes and complications of carbon dioxide pneumoperitoneum as well as prevention and treatment of these complications was performed using the Medline database.

RESULTS

The main pathophysiological changes during CO(2) pneumoperitoneum refer to the cardiovascular system and are mainly correlated with the amount of intra-abdominal pressure in combination with the patient's position on the operating table. These changes are well tolerated even in older and more debilitated patients, and except for a slight increase in the incidence of cardiac arrhythmias, no other significant cardiovascular complications occur. Although there are important pulmonary pathophysiological changes, hypercarbia, hypoxemia and barotraumas, they would develop rarely since effective ventilation monitoring and techniques are applied. The alteration in splanchnic perfusion is proportional with the increase in intra-abdominal pressure and duration of pneumoperitoneum.

CONCLUSION

A moderate-to-low intra-abdominal pressure (<12 mm Hg) can help limit the extent of the pathophysiological changes since consecutive organ dysfunctions are minimal, transient and do not influence the outcome.

Insufflation profile and body position influence portal venous blood flow during pneumoperitoneum

BACKGROUND

We investigated changes in portal venous blood flow (PVBF) during carbon dioxide (CO2) pneumoperitoneum to evaluate the effects of different insufflation profiles and body positions.

METHODS

An established rat model was extended by implanting a portal vein flow probe that would enable us to measure PVBF for 60 min [t0-t60] in animals subjected to a CO2 pneumoperitoneum with an intraabdominal pressure (IAP) of 9 mmHg. Forty-eight male Sprague-Dawley rats were randomized into the following four experimental and two control groups: decompression group D1 ( n = 8), desufflation for 1 min every 14 min; decompression group D2 ( n = 8), desufflation for 5 min, after 27 min; position group P1 ( n = 8), 35 degrees head-up position; position group P2 ( n = 8), 35 degrees head-down position; negative control group C1 ( n = 8), no insufflation; positive control group C2 ( n = 8), constant IAP of 9 mmHg for 60 min.

RESULTS

Pneumoperitoneum and body positions, respectively, reduced PVBF [t1-t60] significantly ( p < 0.001) by 32.0% C2, 32.8% D1, 31.1% D2, 40.8% P1, and 48.5% P2, as compared to PVBF at t0 in each group. There was a significant difference in PVBF reduction between P1 and P2 and also between C2 and both P1 and P2 ( p < 0.04).

CONCLUSIONS

CO2 pneumoperitoneum reduces PVBF significantly (>30%). Extreme body positions (35 degrees tilt) significantly intensify PVBF reduction. PVBF reduction is significantly more dramatic in subjects placed in a 35 degrees head-down position. Short desufflation periods did not improve mean PVBF, but it may have beneficial immunological and oncological effects that warrant further investigation.

Insufflation profile and body position influence portal venous blood flow during pneumoperitoneum

BACKGROUND

We investigated changes in portal venous blood flow (PVBF) during carbon dioxide (CO2) pneumoperitoneum to evaluate the effects of different insufflation profiles and body positions.

METHODS

An established rat model was extended by implanting a portal vein flow probe that would enable us to measure PVBF for 60 min [t0-t60] in animals subjected to a CO2 pneumoperitoneum with an intraabdominal pressure (IAP) of 9 mmHg. Forty-eight male Sprague-Dawley rats were randomized into the following four experimental and two control groups: decompression group D1 ( n = 8), desufflation for 1 min every 14 min; decompression group D2 ( n = 8), desufflation for 5 min, after 27 min; position group P1 ( n = 8), 35 degrees head-up position; position group P2 ( n = 8), 35 degrees head-down position; negative control group C1 ( n = 8), no insufflation; positive control group C2 ( n = 8), constant IAP of 9 mmHg for 60 min.

RESULTS

Pneumoperitoneum and body positions, respectively, reduced PVBF [t1-t60] significantly ( p < 0.001) by 32.0% C2, 32.8% D1, 31.1% D2, 40.8% P1, and 48.5% P2, as compared to PVBF at t0 in each group. There was a significant difference in PVBF reduction between P1 and P2 and also between C2 and both P1 and P2 ( p < 0.04).

CONCLUSIONS

CO2 pneumoperitoneum reduces PVBF significantly (>30%). Extreme body positions (35 degrees tilt) significantly intensify PVBF reduction. PVBF reduction is significantly more dramatic in subjects placed in a 35 degrees head-down position. Short desufflation periods did not improve mean PVBF, but it may have beneficial immunological and oncological effects that warrant further investigation.

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.

Effects of prolonged pneumoperitoneum on hemodynamics and acid-base balance during totally endoscopic robot-assisted radical prostatectomies

Laparoscopic techniques have become a standard approach for diagnostic and therapeutic procedures in many surgical disciplines. Recent progress in endoscopic surgery is based on the integration of computer-enhanced telemanipulation systems. Because robot-assisted radical prostatectomies take up to 10 hours, the present study was performed to evaluate the effects of prolonged intraperitoneal CO2 insufflation on hemodynamics and gas exchange in 15 patients with prostate cancer. When CO2 insufflation was initiated, peak inspiratory pressure increased and reached significant values after a 1.5-hour period of intraperitoneal CO2 insufflation. With the release of CO2, peak inspiratory pressure decreased close to baseline values. A significant increase in heart rate was observed after a 4-hour period of increased intraabdominal pressure. Mean arterial blood pressure and central venous pressure remained stable during CO2 insufflation. Minute ventilation was adjusted according to repeated blood gas analyses to maintain pH, base excess (BE), bicarbonate (HCO3?), and PaCO2 within physiologic ranges. The present data show, that prolonged CO2 insufflation during totally endoscopic robot-assisted radical prostatectomy results in only minor changes in hemodynamics and acid-base status. Because of the limited experience with long-term pneumoperitoneum, we consider invasive haemodynamic monitoring and repeat blood gas analysis essential for such operations.

Physiologic changes during laparoscopy

The short-term benefits of minimal access techniques include less pain, early mobilization, and shorter hospital stay. Nonetheless, significant data have accumulated regarding the complications associated with laparoscopic techniques, including those that are unique to laparoscopic surgery such as bile duct injury and disruption of major blood vessels. Other problems such as myocardial ischemia and respiratory acidosis are associated with the cardiopulmonary effects of pneumoperitoneum and systemic CO2 absorption. These physiologic changes, although tolerated by healthy patients, could have particular adverse consequences for infirm and critically ill patients. It would appear that minimizing IAP during insufflation decreases the risk of potentially marked cardiovascular changes and regional blood flow alterations. In turn, this could arguably decrease the risk of perioperative myocardial events, or organ dysfunction or failure. Laparoscopy in the critically ill patient is questionable because the role is not established. An ICU patient has little to gain from the benefits of early mobilization. Conversely, in the presence of raised ICP or borderline organ function, the physiologic changes associated with pneumoperitoneum and laparoscopy could have profound detrimental effects.

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.

Renal physiology. Laparoscopic considerations

Oliguria is a recognized component of the physiologic effect of increased intra-abdominal or retroperitoneal pressure. The cause is multifactorial, emanating from vascular and parenchymal compression, and is associated with systemic hormonal effects. Ureteral obstruction does not play a significant role. These changes are pressure-dependent and are usually not apparent until pressures reach 15 mm Hg or more. This effect is not associated with any histologic pathology or evidence of renal tubular damage. After the release of the pneumoperitoneum or pneumoretroperitoneum, the renal function and urine output return to normal with no long-term sequelae, even in patients with pre-existing renal disease. The entire operative team must understand the physiologic effects of CO2 insufflation, which allows appropriate intraoperative monitoring and management and minimizes intraoperative and postoperative complications.

Pain after laparoscopic cholecystectomy

BACKGROUND

Although laparoscopic cholecystectomy (LC) results in less pain than open chole-cystectomy, it is not a pain-free procedure. Many methods of analgesia for pain after laparoscopy have been evaluated.

METHODS

Forty-two randomized controlled trials assessing interventions to reduce pain after LC are reviewed, as are the mechanisms and nature of pain after this procedure.

RESULTS

Non-steroidal anti-inflammatory drugs, wound local anaesthetic, intraperitoneal local anaesthetic, intraperitoneal saline, a gas drain, heated gas, low-pressure gas and nitrous oxide pneumo-peritoneum have been shown to reduce pain after LC. The clinical significance of this pain reduction is questionable.

CONCLUSION

Pain after LC is multifactorial. Although many methods of analgesia produce short-term benefit, this does not equate with earlier discharge or improved postoperative function. However, single trials evaluating low-pressure insufflation, heated gas and multimodal analgesia suggest that clinically relevant benefits can be achieved.

Acute renal failure following laparoscopic cholecystectomy: a case report

The carbon dioxide (CO2) pneumoperitoneum of laparoscopic surgery is a complex physiologic event associated with neuroendocrine, respiratory, cardiovascular, and renal disturbances, as well as compromised organ blood flow. A case is presented of a 67-year-old man with a history of chronic renal failure, renal tubular acidosis, and hypertension, who underwent an uneventful elective laparoscopic cholecystectomy that included 75 minutes of CO2 pneumoperitoneum of 15 mmHg pressure. Postoperatively, the patient developed acute renal failure from which he recovered within 2 weeks. In the absence of other evident precipitating factors, we suspect that the CO2 pneumoperitoneum played a causal role in the development of his acute renal failure. The potential seriousness of the physiologic insult of conventional CO2 pneumoperitoneum suggests that "minimal access" surgery is not necessarily "minimally invasive."