Intraperitoneal hypothermia during surgery enhances postoperative tumor growth

The role of perioperative factors in the prognosis of cancer patients: A coin has two sides

Cancer, the second leading cause of mortality globally, poses a significant health challenge. The conventional treatment for solid tumors involves surgical intervention, followed by chemo- and radio-therapies as well as target therapies, but the recurrence and metastasis of cancers remain a major issue. Anesthesia is essential for ensuring patient comfort and safety during surgical procedures. Despite its crucial role during the surgery, the precise effect of anesthesia on cancer patient outcomes is not clearly understood. This comprehensive review aims to elucidate the various anesthesia strategies used in the perioperative care of cancer patients and their potential effects on patients' prognosis, but understanding the complex relationship between anesthesia and cancer outcomes is crucial, given the complexity in cancer treaments. Examining potential implications of anesthesia strategies on cancer patient prognosis may help better understand treatment efficacy and risk factors of cancer recurrence and metastasis. Through a detailed analysis of anesthesia practices in cancer surgery, this review aims to provide insights that may lead to improving the existing anesthesia protocols and ultimately reduce risk factors for patient outcomes in the field of oncology.

Effect of Surgical Humidification on Inflammation and Peritoneal Trauma in Colorectal Cancer Surgery: A Randomized Controlled Trial

BACKGROUND

Pre-clinical studies indicate that dry-cold-carbon-dioxide (DC-CO2) insufflation leads to more peritoneal damage, inflammation and hypothermia compared with humidified-warm-CO₂ (HW-CO2). Peritoneum and core temperature in patients undergoing colorectal cancer (CRC) surgery were compared.

METHODS

Sixty-six patients were randomized into laparoscopic groups; those insufflated with DC-CO2 or HW-CO2. A separate group of nineteen patients undergoing laparotomy were randomised to conventional surgery or with the insertion of a device delivering HW-CO2. Temperatures were monitored and peritoneal biopsies and bloods were taken at the start of surgery, at 1 and 3 h. Further bloods were taken depending upon hospital length-of-stay (LOS). Peritoneal samples were subjected to scanning electron microscopy to evaluate mesothelial damage.

RESULTS

Laparoscopic cases experienced a temperature drop despite Bair-Hugger^TM use. HW-CO2 restored normothermia (≥ 36.5 °C) by 3 h, DC-CO2 did not. LOS was shorter for colon compared with rectal cancer cases and if insufflated with HW-CO2 compared with DC-CO2; 5.0 vs 7.2 days, colon and 11.6 vs 15.4 days rectum, respectively. Unexpectedly, one third of patients had pre-existing damage. Damage increased at 1 and 3 h to a greater extent in the DC-CO2 compared with the HW-CO2 laparoscopic cohort. C-reactive protein levels were higher in open than laparoscopic cases and lower in both matched HW-CO2 groups.

CONCLUSIONS

This prospective RCT is in accord with animal studies while highlighting pre-existing damage in some patients. Peritoneal mesothelium protection, reduced inflammation and restoration of core-body temperature data suggest benefit with the use of HW-CO2 in patients undergoing CRC surgery.

Circulating Tumor Cells Correlate With Prognosis in Head and Neck Squamous Cell Carcinoma

Background:

To investigate the relationship of circulating tumor cells (CTCs) and the clinical characteristic parameters and prognosis in patients with head and neck squamous cell carcinoma (HNSCC).

Methods:

The retrospective clinical study included 95 patients with HNSCC who after surgery in Shanghai Ninth People’s Hospital affiliated to Shanghai Jiao Tong University School of Medicine between December 2015 and December 2016. All patients were followed up for survival until the end of June 2019. The CTCs detection was performed by negative enrichment (NE) immunofluorescence-in situ hybridization (im-FISH) of chromosome 8.

Results:

Patients with higher CTCs counts are associated with a worse prognosis with an area under the receiver operator characteristic (ROC) curve of 0.756 [95% confidence interval (CI) 0.640-0.872, p = 0.001]. The CTCs-positive rate of HNSCC patients was 58.9% (56/95) by using the cut-point of 3. Both the chi-square test and binary logistic regression analysis showed that the N stage and clinical stage were significantly associated with CTCs-positive in patients with HNSCC (p < 0.05). Further Non-parametric test analysis indicated that more CTCs counts were detected in late N and clinical stages patients (p < 0.001). The Kaplan-Meier survival analysis indicated that CTCs-positive were correlated with shorter progression-free survival (PFS) (p < 0.001) and overall survival (OS) (p = 0.001). Further, the CTCs-positive was an independent prognostic factor for PFS and OS according to the Cox multivariate regression analysis (p < 0.05).

Conclusion:

More CTCs were associated with N stage, clinical stage, poor prognosis in patients with HNSCC, which might be used as a prognostic biomarker.

Association of intraoperative hypothermia with oncologic outcomes following radical cystectomy

INTRODUCTION

Intraoperative hypothermia (IOH) has been suggested to adversely impact outcomes following surgery. The objective of this study was to evaluate the association between IOH and survival following radical cystectomy (RC).

METHODS

Patients who underwent RC for bladder cancer from 2003 to 2018 were identified in our cystectomy registry. Intraoperative temperatures were extracted from the anesthesia record. IOH was defined as a median intraoperative temperature <36°C, and severe IOH as ≤ 35°C. Time under 36°C was assessed as a continuous variable. Recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS) were estimated using the Kaplan-Meier method. Associations between IOH and outcomes were assessed with multivariable Cox proportional hazards models.

RESULTS

A total of 852 patients were identified, among whom 274 (32%) had IOH. Median follow up among survivors was 4.9 years (IQR 2.4-8.7), during which time 483 patients died, including 343 from bladder cancer. Two-year survival was not significantly different between patients with and without IOH (CSS: 74% vs. 71%, P= 0.31; OS: 68% vs. 67%, P= 0.13). Following multivariable adjustment, neither IOH nor time under 36°C was significantly associated with survival. A total of 37 patients (4.3%) had severe IOH. These patients were observed to have significantly lower 2-year OS (56% vs. 68%, P= 0.005); however, this association did not remain statistically significant after multivariable adjustment (P= 0.92).

CONCLUSION

IOH was not independently associated with survival following RC. These data do not support IOH as a prognostic factor for cancer outcomes among patients undergoing RC.

Case series - Peritoneal and port-site metastasis following roboticassisted radical prostatectomy

N/A

A simplified enriched environment increases body temperature and suppresses cancer progression in mice

Mice housed in an enriched environment (EE) have inhibited tumor development because of eustress (positive stress) stimulation. However, the mechanisms underlying increased cancer resistance in EEs remain unclear; this may be due to poor reproducibility of the results because of the complicated EE assembly requirements. In this study, we examined the effects of a simplified EE (sEE) model, consisting only of a nesting shelter and a running wheel, on cancer development in mice. We found that, similar to the complex EE, the sEE promoted motor function and alleviated anxiety in mice. Moreover, the mice housed in the sEE showed inhibited tumor growth and metastasis in addition to a higher average body temperature (especially at the point of transition from light to darkness). Furthermore, mice in the sEE had a decreased brown adipose tissue (BAT) mass, with a significant upregulation of the Ucp1 and Adrb3 genes (which encode uncoupling protein 1 and β-adrenergic receptor, respectively) observed in the BAT at the point of transition from light to darkness. An antibody against the immune checkpoint protein programmed cell death 1 was also found to have an additive effect with the sEE against tumor development. Our findings indicate that the established sEE model may be a useful tool for studying the antitumor effects of eustress and can potentially introduce new avenues for cancer prevention and treatment.

New Concept Air Conditioning System for the Operating Room to Minimize Patient Cooling and Surgeon Heating: A Historical Control Cohort Study

BACKGROUND

Intraoperative hypothermia is a common adverse event. For avoiding the complication due to hypothermia, many warming devices and methods have been used in perioperative period. It has been reported that more patients undergoing laparoscopic surgery tend to have hypothermia than with open surgery. To avoid intraoperative hypothermia, many kinds of warming tools have been used. But, it was also reported that some warming methods increased perceptions of distraction and physical demand.

METHODS

To achieve both patients' normothermia and surgeons' comfort, new air conditioning (AC) system was designed with considering the characteristics of laparoscopic surgery. The temperature of the airflows to the patient and to the surgeons can be adjusted independently in this new system. The new system has two parts. One controls the temperature of the central area over the operation table. The air from this part falls on the patients. The other part is the lateral area beside the operating table; the air from this part falls on the surgeons. The subjects of this study were 160 gastric cancer patients and 316 colorectal cancer patients undergoing laparoscopic surgery. The temperature of the central flow was set 23.5 °C, and the temperature of the lateral flow was set 22 °C just after the anesthesia. The number of timepoints the patient spent in hypothermic state, defined as a temperature cooler by 0.5 °C or more than that at the starting point of surgery, was determined in each patient.

RESULTS

In the results, the rate of hypothermic state in old operation rooms was 23.8% and that in new operation rooms was 2.7% in male gastric cancer patients (p < 0.01). And those were 37.1% in old operation rooms and 0.9% in new operation rooms in female gastric cancer patients (p < 0.01). The rate of hypothermic state in old operation rooms was 30.0% and that in new operation rooms was 9.5% in male colorectal cancer patients (p < 0.01). And those were 41.6% in old operation rooms and 8.9% in new operation rooms in female colorectal cancer patients (p < 0.01). The similar results were showed in the study, which subjects were limited the patients undergoing surgery in 2015 and 2016; which were the last year the old operation rooms were used and the first year the new operation rooms were used.

CONCLUSIONS

Thus, the usefulness of the new air conditioning system for achieving both patients' normothermia and comfort of surgeons could be verified in this study.

Combining surgery and immunotherapy: turning an immunosuppressive effect into a therapeutic opportunity

Background

Cancer surgery is necessary and life-saving. However, the majority of patients develop postoperative recurrence and metastasis, which are the main causes of cancer-related deaths. The postoperative stress response encompasses a broad set of physiological changes that have evolved to safeguard the host following major tissue trauma. These stress responses, however, intersect with cellular mediators and signaling pathways that contribute to cancer proliferation.

Main

Previous descriptive and emerging mechanistic studies suggest that the surgery-induced prometastatic effect is linked to impairment of both innate and adaptive immunity. Existing studies that combine surgery and immunotherapies have revealed that this combination strategy is not straightforward and patients have experienced both therapeutic benefit and drawbacks. This review will specifically assess the immunological pathways that are disrupted by oncologic surgical stress and provide suggestions for rationally combining cancer surgery with immunotherapies to improve immune and treatment outcomes.

Short conclusion

Given the prevalence of surgery as frontline therapy for solid cancers, the emerging data on postoperative immunosuppression and the rapid development of immunotherapy for oncologic treatment, we believe that future targeted studies of perioperative immunotherapy are warranted.

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.

Experimental study of delivery of humidified-warm carbon dioxide during open abdominal surgery

Background

The aim of this study was to monitor the effect of humidified‐warm carbon dioxide (HWCO₂) delivered into the open abdomen of mice, simulating laparotomy.

Methods

Mice were anaesthetized, ventilated and subjected to an abdominal incision followed by wound retraction. In the experimental group, a diffuser device was used to deliver HWCO₂; the control group was exposed to passive air flow. In each group of mice, surgical damage was produced on one side of the peritoneal wall. Vital signs and core temperature were monitored throughout the 1‐h procedure. The peritoneum was closed and mice were allowed to recover for 24 h or 10 days. Tumour cells were delivered into half of the mice in each cohort. Tissue was then examined using scanning electron microscopy and immunohistochemistry.

Results

Passive air flow generated ultrastructural damage including mesothelial cell bulging/retraction and loss of microvilli, as assessed at 24 h. Evidence of surgical damage was still measurable on day 10. HWCO₂ maintained normothermia, whereas open surgery alone led to hypothermia. The degree of tissue damage was significantly reduced by HWCO₂ compared with that in controls. Peritoneal expression of hypoxia inducible factor 1α and vascular endothelial growth factor A was lowered by HWCO₂. These effects were also evident at the surgical damage sites, where protection from tissue trauma extended to 10 days. HWCO₂ did not reduce tumorigenesis in surgically damaged sites compared with passive air flow.

Conclusion

HWCO₂ diffusion into the abdomen in the context of open surgery afforded tissue protection and accelerated tissue repair in mice, while preserving normothermia.

Warmed, humidified CO2 insufflation benefits intraoperative core temperature during laparoscopic surgery: A meta-analysis

BACKGROUND

Intraoperative hypothermia is linked to postoperative adverse events. The use of warmed, humidified CO₂ to establish pneumoperitoneum during laparoscopy has been associated with reduced incidence of intraoperative hypothermia. However, the small number and variable quality of published studies have caused uncertainty about the potential benefit of this therapy. This meta-analysis was conducted to specifically evaluate the effects of warmed, humidified CO₂ during laparoscopy.

METHODS

An electronic database search identified randomized controlled trials performed on adults who underwent laparoscopic abdominal surgery under general anesthesia with either warmed, humidified CO₂ or cold, dry CO₂ . The main outcome measure of interest was change in intraoperative core body temperature.

RESULTS

The database search identified 320 studies as potentially relevant, and of these, 13 met the inclusion criteria and were included in the analysis. During laparoscopic surgery, use of warmed, humidified CO₂ is associated with a significant increase in intraoperative core temperature (mean temperature change, 0.3°C), when compared with cold, dry CO₂ insufflation_. CONCLUSION: Warmed, humidified CO₂ insufflation during laparoscopic abdominal surgery has been demonstrated to improve intraoperative maintenance of normothermia when compared with cold, dry CO_2.

Exploiting the critical perioperative period to improve long-term cancer outcomes

Evidence suggests that the perioperative period and the excision of the primary tumour can promote the development of metastases—the main cause of cancer-related mortality. This Review first presents the assertion that the perioperative timeframe is pivotal in determining long-term cancer outcomes, disproportionally to its short duration (days to weeks). We then analyse the various aspects of surgery, and their consequent paracrine and neuroendocrine responses, which could facilitate the metastatic process by directly affecting malignant tissues, and/or through indirect pathways, such as immunological perturbations. We address the influences of surgery-related anxiety and stress, nutritional status, anaesthetics and analgesics, hypothermia, blood transfusion, tissue damage, and levels of sex hormones, and point at some as probable deleterious factors. Through understanding these processes and reviewing empirical evidence, we provide suggestions for potential new perioperative approaches and interventions aimed at attenuating deleterious processes and ultimately improving treatment outcomes. Specifically, we highlight excess perioperative release of catecholamines and prostaglandins as key deleterious mediators of surgery, and we recommend blockade of these responses during the perioperative period, as well as other low-risk, low-cost interventions. The measures described in this Review could transform the perioperative timeframe from a prominent facilitator of metastatic progression, to a window of opportunity for arresting and/or eliminating residual disease, potentially improving long-term survival rates in patients with cancer.

Peritoneal Tumorigenesis and Inflammation are Ameliorated by Humidified-Warm Carbon Dioxide Insufflation in the Mouse

Background

Conventional laparoscopic surgery uses CO₂ that is dry and cold, which can damage peritoneal surfaces. It is speculated that disseminated cancer cells may adhere to such damaged peritoneum and metastasize. We hypothesized that insufflation using humidified-warm CO₂, which has been shown to reduce mesothelial damage, will also ameliorate peritoneal inflammation and tumor cell implantation compared to conventional dry-cold CO₂.

Methods

Laparoscopic insufflation was modeled in mice along with anesthesia and ventilation. Entry and exit ports were introduced to maintain insufflation using dry-cold or humidified-warm CO₂ with a constant flow and pressure for 1 h; then 1000 or 1 million fluorescent-tagged murine colorectal cancer cells (CT26) were delivered into the peritoneal cavity. The peritoneum was collected at intervals up to 10 days after the procedure to measure inflammation, mesothelial damage, and tumor burden using fluorescent detection, immunohistochemistry, and scanning electron microscopy.

Results

Rapid temperature control was achieved only in the humidified-warm group. Port-site tumors were present in all mice. At 10 days, significantly fewer tumors on the peritoneum were counted in mice insufflated with humidified-warm compared to dry-cold CO₂ (p < 0.03). The inflammatory marker COX-2 was significantly increased in the dry-cold compared to the humidified-warm cohort (p < 0.01), while VEGFA expression was suppressed only in the humidified-warm cohort. Significantly less mesothelial damage and tumor cell implantation was evident from 2 h after the procedure in the humidified-warm cohort.

Conclusions

Mesothelial cell damage and inflammation are reduced by using humidified-warm CO₂ for laparoscopic oncologic surgery and may translate to reduce patients’ risk of developing peritoneal metastasis.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-015-4508-1) contains supplementary material, which is available to authorized users.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model

Purpose

The addition of 4 % O₂ and 10 % N₂O to the CO₂ pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation.

Methods

In Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO₂PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N₂O, humidification + 10 % N₂O + 4 % O₂, and conditioning, respectively.

Results

In Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO₂PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO₂ (p = 0.032) or conditioning (p = 0.026).

Conclusions

Tumor implantation was enhanced by peritoneal damage (60 min of dry CO₂PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

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.

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.

Effects of perioperative hypothermia and warming in surgical practice

Perioperative hypothermia is common and adversely affects clinical outcomes due to its effect on a range of homeostatic functions. Many of these adverse consequences are preventable by the use of warming techniques. A literature search was conducted to identify relevant published articles on perioperative hypothermia and warming. The databases searched include MEDLINE (1966 to February 2005), EMBASE (1974 to February 2005), CINAHL, the Cochrane library and the health technology assessment database. Reference lists of key articles were also searched. The primary beneficial effects of warming are mediated through increased blood flow and oxygen tension at tissue level. Reduction in wound infection, blood loss and perioperative pain with warming is promising. However, more evidence from good-quality prospective randomised controlled trials is needed to evaluate the role of warming in improving overall morbidity, mortality and hospital stay as well as to clarify its role as an adjunct to resuscitation and during the pre-hospital transport phase of critically ill patients. Awareness of the risks of perioperative hypothermia is the key to prevention. Achieving normothermia throughout the patient's journey is a worthwhile goal in surgical patients.

Peritoneal pH during laparoscopy is dependent on ambient gas environment: helium and nitrous oxide do not cause peritoneal acidosis

BACKGROUND

Little is know about the effects of different insufflation gases on peritoneal pH during laparoscopy. However, these changes may influence the intracellular signalling system, resulting in altered cell growth or adhesiveness. The aim of this study was to determine the effects of carbon dioxide (CO(2)), nitrous oxide (N(2)O), and helium (He) on parietal and visceral peritoneal pH. The effect of different intraabdominal pressures on parietal and visceral peritoneal pH was also examined.

METHODS

We conducted both an ambient gas study and a pressure study. For the ambient gas study, 20 pigs were divided into the following four groups: (a) CO(2), (b) He, (c) N(2)O, and (d) abdominal wall lift (Lift) laparoscopy. Parietal and visceral peritoneal pH were measured at 15 min intervals for 180 min. For the pressure study, 15 pigs were divided into the following three groups: (a) CO(2), (b) He, (c) N(2)O laparoscopy. Baseline values were established for parietal and visceral peritoneal pH. Intraabdominal pressure was then increased stepwise at 1-mmHg intervals to 15 mmHg. After pressure was maintained for 15 min at each setting, parietal and visceral peritoneal pH were measured.

RESULTS

Ambient gas environment was the major determinant of parietal peritoneal pH. Carbon dioxide caused parietal peritoneal acidosis. Helium, N(2)O, and Lift caused alkalotic parietal peritoneal pH. Intraabdominal pressure had a minor effect on parietal peritoneal pH. At higher intraabdominal pressure (12-15 vs 5-8 mmHg), CO(2) caused a slight decrease in parietal peritoneal pH, whereas N(2)O and He caused a slight increase in parietal peritoneal pH. Visceral peritoneal pH remained relatively unaffected during all studies.

CONCLUSIONS

Parietal peritoneal pH during laparoscopy was highly dependent on the ambient gas environment. The effect of intraabdominal pressure on parietal peritoneal pH was of minor significance. Carbon dioxide caused a slight worsening of parietal peritoneal acidosis at higher intraabdominal pressure, whereas, N(2)O, He, and Lift did not cause parietal peritoneal acidosis.

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.

Decrease in core liver temperature with 10°C by in situ hypothermic perfusion under total hepatic vascular exclusion reduces liver ischemia and reperfusion injury during partial hepatectomy in pigs

OBJECTIVE

We attempted to assess liver ischemia/reperfusion injury under a mild decrease in core liver temperature of 10 degrees C by in situ hypothermic perfusion during ischemia.

METHODS

Liver ischemia was induced in pigs by total hepatic vascular exclusion with concomitant in situ perfusion with hypothermic (4 degrees C) Ringer-glucose (cold perfused group, core liver temperature maintained at 28 degrees C), with normothermic (38 degrees C) Ringer-glucose (warm perfused group) or without in situ perfusion (control group).

RESULTS

In the cold perfused, warm perfused, and control groups, 24-hour survival was 5/5, 0/5, and 3/5, respectively. Hemodynamic parameters in the cold perfused group remained stable, whereas pigs in both other groups required circulatory support. Plasma AST and interleukin-6 levels were lower in the cold perfused group than in both other groups. Hepatocellular function was best preserved in the cold perfused group as indicated by complete recovery of bile production during reperfusion and no loss of indocyanine green clearance capacity. In both other groups, bile production and indocyanine green clearance capacity were reduced significantly. The hyaluronic acid uptake capacity of pigs in the cold perfused group or control group did not differ, indicating preserved sinusoidal endothelial cell function. Histopathologic injury scores during reperfusion were significantly lower in the cold perfused group when compared to both other groups.

CONCLUSIONS

A mild decrease in core liver temperature of 10 degrees C by in situ hypothermic liver perfusion during ischemia protects the liver from ischemia/reperfusion injury. This protection appears to be related to cooling of the liver rather than to the washout of blood during perfusion.