Pneumoperitoneum and peritoneal surface changes: a review

Underneath Images and Robots, Looking Deeper into the Pneumoperitoneum: A Narrative Review

Laparoscopy offers numerous advantages over open procedures, minimizing trauma, reducing pain, accelerating recovery, and shortening hospital stays. Despite other technical advancements, pneumoperitoneum insufflation has received little attention, barely evolving since its inception. We explore the impact of pneumoperitoneum on patient outcomes and advocate for a minimally invasive approach that prioritizes peritoneal homeostasis. The nonlinear relationship between intra-abdominal pressure (IAP) and intra-abdominal volume (IAV) is discussed, emphasizing IAP titration to balance physiological effects and surgical workspace. Maintaining IAP below 10 mmHg is generally recommended, but factors such as patient positioning and surgical complexity must be considered. The depth of neuromuscular blockade (NMB) is explored as another variable affecting laparoscopic conditions. While deep NMB appears favorable for surgical stillness, achieving a balance between IAP and NMB depth is crucial. Temperature and humidity management during pneumoperitoneum are crucial for patient safety and optical field quality. Despite the debate over the significance of temperature drop, humidification and the warming of insufflated gas offer benefits in peritoneal homeostasis and visual clarity. In conclusion, there is potential for a paradigm shift in pneumoperitoneum management, with dynamic IAP adjustments and careful control of insufflated gas temperature and humidity to preserve peritoneal homeostasis and improve patient outcomes in minimally invasive surgery.

Impact of Standard Versus Low Pneumoperitoneum Pressure on Peritoneal Environment in Laparoscopic Cholecystectomy. Randomized Clinical Trial

BACKGROUND

High CO 2 pneumoperitoneum pressure during laparoscopy adversely affects the peritoneal environment. This study hypothesized that low pneumoperitoneum pressure may be linked to less peritoneal damage and possibly to better clinical outcomes.

MATERIALS AND METHODS

One hundred patients undergoing scheduled laparoscopic cholecystectomy were randomized 1:1 to low or to standard pneumoperitoneum pressure. Peritoneal biopsies were performed at baseline time and 1 hour after peritoneum insufflation in all patients. The primary outcome was peritoneal remodeling biomarkers and apoptotic index. Secondary outcomes included biomarker differences at the studied times and some clinical variables such as length of hospital stay, and quality and safety issues related to the procedure.

RESULTS

Peritoneal IL6 after 1 hour of surgery was significantly higher in the standard than in the low-pressure group (4.26±1.34 vs. 3.24±1.21; P =0.001). On the contrary, levels of connective tissue growth factor and plasminogen activator inhibitor-I were higher in the low-pressure group (0.89±0.61 vs. 0.61±0.84; P =0.025, and 0.74±0.89 vs. 0.24±1.15; P =0.028, respectively). Regarding apoptotic index, similar levels were found in both groups and were 44.0±10.9 and 42.5±17.8 in low and standard pressure groups, respectively. None of the secondary outcomes showed differences between the 2 groups.

CONCLUSIONS

Peritoneal inflammation after laparoscopic cholecystectomy is higher when surgery is performed under standard pressure. Adhesion formation seems to be less in this group. The majority of patients undergoing surgery under low pressure were operated under optimal workspace conditions, regardless of the surgeon's expertise.

Minimally Invasive Surgery for Cervical Cancer in Light of the LACC Trial: What Have We Learned?

Cervical cancer is the most common gynecologic malignancy and the fourth most common cancer in women worldwide. Over the last two decades, minimally invasive surgery (MIS) emerged as the mainstay in the surgical management of cervical cancer, bringing advantages such as lower operative morbidity and shorter hospital stay compared to open surgery while maintaining comparable oncologic outcomes in numerous retrospective studies. However, in 2018, a prospective phase III randomized controlled trial, “Laparoscopic Approach to Carcinoma of the Cervix (LACC)”, unexpectedly reported that MIS was associated with a statistically significant poorer overall survival and disease-free survival compared to open surgery in patients with early-stage cervical cancer. Various hypotheses have been raised by the authors to try to explain these results, but the LACC trial was not powered to answer those questions. In this study, through an exhaustive literature review, we wish to explore some of the potential causes that may explain the poorer oncologic outcomes associated with MIS, including the type of MIS surgery, the size of the lesion, the impact of CO2 pneumoperitoneum, prior conization, the use of uterine manipulator, the use of protective measures, and the effect of surgical expertise/learning curve.

Proteomic analysis of the influence of CO2 pneumoperitoneum in cervical cancer cells

Objective

The effect of CO₂ pneumoperitoneum (CDP) on the oncology outcomes of patients undergoing laparoscopic radical hysterectomy for cervical cancer remains unclear. In this study, we investigated the effects of CDP on the proliferation of cervical cancer cells and examined the molecular mechanism.

Materials and Methods

We established an in vitro CDP model to study the effects of CDP on the proliferation of cervical cancer cells by Cell Counting Kit-8 (CCK-8) assay, xenografted tumor assay. Tandem mass tag-based quantitative proteomics were used to study the proteomic changes in HeLa cells after CDP treatment. Western blot assay was used to detect the expressions of PI3K/Akt signaling pathway proteins.

Results

CDP increased cell proliferation after a short period of inhibition in vitro and promoted tumorigenesis in vivo. Proteomic analysis showed that the expression levels of 177 and 309 proteins were changed significantly 24 and 48 h after CDP treatment, respectively. The acidification caused by CO₂ inhibited the proliferation of cervical cancer cells by inhibiting the phosphorylation of PI3K and Akt.

Conclusions

CDP promoted the proliferation of human cervical cancer cells after a short time of inhibition. The mechanism of which is related to the inhibition of phosphorylation of the PI3K/Akt signaling pathway.

Should be a locally advanced colon cancer still considered a contraindication to laparoscopic resection?

BACKGROUND

The role of elective laparoscopic resection (LR) for the treatment of locally advanced colon cancer (LACC) is unclear. Most studies have retrospectively investigated the outcomes of LR for pT4 cancers, while clinical T4 (cT4) cancers are excluded in the large randomized controlled trials comparing LR and open resection (OR). The aim of this study was to investigate the outcomes in patients undergoing elective LR for LACC.

METHODS

A prospective single-institution database including consecutive patients undergoing elective LR for clinical LACC (high-risk T3 or T4 N0-2) between March 1996 and March 2017 was retrospectively reviewed. A multivariate analysis was performed to identify predictors of conversion to OR and risk factors for adverse oncologic outcomes.

RESULTS

A total of 300 patients undergoing LR for LACC were included. A multi-visceral resection was needed in 17 (5.7%) patients. A total of 63 (21%) LRs were converted to OR, mainly due to suspected adjacent organ invasion (82.5%) or obesity (9.5%). Overall postoperative Clavien-Dindo 3-4 complication rate was 4.7%, with no significant differences between completed and converted LRs. Final pathology showed 18 (6%) pT2, 215 (71.7%) pT3, 54 (18%) pT4a, and 13 (4.3%) pT4b cancers. A R0 resection was achieved in 98.3% of patients. On multivariate analysis, tumor size ≥ 7 cm and tumor site (splenic flexure) were the independent risk factors for conversion to OR. A pT4 colon cancer and LNR of 0.25 or greater, but not conversion to OR, were independently associated with both poorer OS and DFS.

CONCLUSION(S)

Clinical LACC should not be considered a contraindication to LR itself. Bulky tumors ≥ 7 cm and splenic flexure cancers are at higher risk of conversion to OR; however, there is no increased postoperative morbidity or adverse oncologic outcomes in converted patients.

Modes of carbon dioxide delivery during laparoscopy generate distinct differences in peritoneal damage and hypoxia in a porcine model

BACKGROUND

Insufflation with CO₂ can employ continuous flow, recirculated gas and/or additional warming and humidification. The ability to compare these modes of delivery depends upon the assays employed and opportunities to minimize subject variation. The use of pigs to train colorectal surgeons provided an opportunity to compare three modes of CO₂ delivery under controlled circumstances.

METHODS

Sixteen pigs were subjected to rectal resection, insufflated with dry-cold CO₂ (DC-CO₂) (n = 5), recirculated CO₂ by an AirSeal device (n = 5) and humidification and warming (HW-CO2) by a HumiGard device (n = 6). Peritoneal biopsies were harvested from the same region of the peritoneum for fixation for immunohistochemistry for hypoxia-inducible factor 1 alpha (HIF-1α) and scanning electron microscopy (SEM) to evaluate hypoxia induction or tissue/cellular damage, respectively.

RESULTS

DC-CO₂ insufflation by both modes leads to significant damage to mesothelial cells as measured by cellular bulging and retraction as well as microvillus shortening compared with HW-CO₂ at 1 to 1.5 h. DC-CO₂ also leads to a rapid and significant induction of HIF-1α compared with HW-CO₂.

CONCLUSIONS

DC-CO₂ insufflation induces substantive cellular damage and hypoxia responses within the first hour of application. The use of HW-CO₂ insufflation ameliorates these processes for the first one to one and half hours in a large mammal used to replicate surgery in humans.

Laparoscopic surgery for T4 colon cancer: a risk factor for peritoneal recurrences?

BACKGROUND

Although some preclinical studies have inferred that laparoscopic surgery for advanced cancer may increase the risk of peritoneal metastasis, this potential hazard has not been fully evaluated in the clinical setting. This study aimed to clarify whether laparoscopic surgery is associated with an increased risk of postoperative peritoneal recurrence after resection of T4 colon cancer.

METHODS

This study included 272 patients who underwent curative resection for pathological T4a colon cancer without distant metastases at the University of Tokyo Hospital between 1997 and 2017. Multivariable Fine-Gray analysis was performed to evaluate whether the use of laparoscopy was an independent risk factor for postoperative peritoneal recurrence. Thereafter, oncological outcomes (overall and relapse-free survival, and organ-specific recurrence) were compared between laparoscopic colectomy and open colectomy using propensity score matching.

RESULTS

Multivariable analysis found that laparoscopic surgery was a significant risk factor for postoperative peritoneal recurrence (hazard ratio: 1.89; 95% confidence interval: 1.01-3.65; P = .046). Comparison after propensity score matching revealed that the incidence of peritoneal recurrence was significantly higher after laparoscopic colectomy than after open colectomy (5-year cumulative incidence: 28.1% vs 12.1%; P = .003).

CONCLUSION

This study suggested that laparoscopic surgery may be related to an increased risk of peritoneal recurrence in patients with pathological T4a colon cancer. Clinicians should be fully aware of this potential risk and seek an optimal treatment plan for the prevention and early detection of peritoneal metastasis.

Robot-assisted laparoscopic cystectomy with intracorporeal urinary diversion vs. open mini-laparotomy cystectomy: evaluation of surgical inflammatory response and immunosuppressive ability of CO2-pneumoperitoneum in an experimental porcine study

OBJECTS

To compare surgical inflammatory response (SIR) after radical cystectomy (RC) in a porcine model using minimal invasive techniques. Additionally we aimed to investigate the potential immunosuppressive ability of preoperative CO₂-pneumoperitoneum (CO₂P).

MATERIALS AND METHODS

Forty female landrace pigs were randomized to five groups: Three intervention groups all having a cystectomy and an ileal conduit either done by robot-assisted laparoscopic technique with intracorporeal urinary diversion (RALC) or an open mini-laparotomy with or without prior CO₂P (OMC ± CO₂P). Two control sham groups with or without prior CO₂P (S ± CO₂P). Serum samples were obtained preoperatively, immediately postoperative, 24, 48 and 72 hours postoperatively, and the inflammatory mediators CRP, Haptoglobin, Ceruloplasmin, Albumin, Cortisol, IL-4, IL-6, IL-12 and IFN-α were measured.

RESULTS

Operative time was significantly longer in RALC compared to open groups (OMC ± CO₂P) (p's < .0001). CRP and Haptoglobin levels were significantly higher for surgical intervention groups (SIG) compared to controls 24, 48 and 72 hours postoperatively (p's < .001). At 48 hours, CRP was higher for RALC vs OMC + CO₂P (p = .029). At 72 hours, Haptoglobin was higher for RALC vs open groups (p's < .024). Ceruloplasmin, cortisol, albumin, IL-4, IL-6, IL-12 and IFN-α, revealed no significant differences between SIG.

CONCLUSIONS

No major differences were found between RALC and OMC regarding the degree of tissue trauma quantified by inflammatory markers. Thirty minutes of CO_2-insufflation preoperative appears to have a transient immunosuppressive effect of the innate postoperative SIR, whereas prolonged CO₂P apparently diminishes this effect.

Effects of low intraperitoneal pressure and a warmed, humidified carbon dioxide gas in laparoscopic surgery: a randomized clinical trial

Laparoscopic surgery technology continues to advance. However, much less attention has been focused on how alteration of the laparoscopic surgical environment might improve clinical outcomes. We conducted a randomized, 2 × 2 factorial trial to evaluate whether low intraperitoneal pressure (IPP) (8 mmHg) and/or warmed, humidified CO₂ (WH) gas are better for minimizing the adverse impact of a CO₂ pneumoperitoneum on the peritoneal environment during laparoscopic surgery and for improving clinical outcomes compared to the standard IPP (12 mmHg) and/or cool and dry CO₂ (CD) gas. Herein we show that low IPP and WH gas may decrease inflammation in the laparoscopic surgical environment, resulting in better clinical outcomes. Low IPP and/or WH gas significantly lowered expression of inflammation-related genes in peritoneal tissues compared to the standard IPP and/or CD gas. The odds ratios of a visual analogue scale (VAS) pain score >30 in the ward was 0.18 (95% CI: 0.06, 0.52) at 12 hours and 0.06 (95% CI: 0.01, 0.26) at 24 hours in the low IPP group versus the standard IPP group, and 0.16 (95% CI: 0.05, 0.49) at 0 hours and 0.29 (95% CI: 0.10, 0.79) at 12 hours in the WH gas group versus the CD gas group.

Postoperative C-reactive protein concentration and clinical outcome: comparison of open cystectomy to robot-assisted laparoscopic cystectomy with extracorporeal or intracorporeal urinary diversion in a prospective study

OBJECTIVE

This study aimed to compare clinical outcome and postoperative systemic inflammatory response using C-reactive protein (CRP) levels, to quantify the degree of tissue injury in open mini-laparotomy cystectomy (OMC) versus robot-assisted laparoscopic cystectomy with extracorporeal (RALC-EUD) or intracorporeal urinary diversion (RALC-IUD).

MATERIALS AND METHODS

From September 2012 to September 2015, 309 patients diagnosed with bladder cancer underwent radical cystectomy with urinary diversion. Of these, 175 patients were eligible for the study and underwent OMC (n = 125), RALC-EUD (n = 12) or RALC-IUD (n = 38). Blood samples were obtained preoperatively and postoperatively on days 1-7. Clinical and perioperative parameters, including demographics, comorbidity, tumour stage and postoperative outcomes, were collected from medical records.

RESULTS

Age, American Society of Anesthesiologists score and Charlson score were significantly higher in OMC than in the robotic groups (p = 0.020, 0.012 and 0.008, respectively). Other demographic data showed no significant group differences. Estimated blood loss and blood transfusion volume were higher in OMC (p < 0.001) and operative time was longer in the robotic groups (p < 0.001); no difference was found between RALC groups. Postoperative CRP levels changed over time (p < 0.001) and RALC-IUD appeared to have significantly higher CRP levels on postoperative days 3-7 compared to OMC and RALC-EUD (p < 0.031), but OMC CRP levels were higher than RALC-EUD.

CONCLUSIONS

In this study, robotic techniques seem less traumatic overall than open surgery, as OMC had higher postoperative CRP levels than RALC-EUD. The higher CRP levels in RALC-IUD may be more reflective of the urinary diversion technique than the true tissue trauma.

POstLAparoscopic Reduction of pain By combining intraperitoneal normal salinE And the pulmonary Recruitment maneuver (POLAR BEAR trial). RCT to estimate reduction in pain after laparoscopic surgery when using a combination therapy of intraperitoneal normal saline and the pulmonary recruitment maneuver

Background

Shoulder pain and pain in the upper abdomen are common complaints after laparoscopy, sometimes surpassing the pain at incision sites. The incidence of shoulder pain ranges from 35 to 80%. Post-laparoscopic pain is caused by retention of carbon dioxide in the abdomen, which irritates the phrenic nerve and diaphragm, causing referred pain in the shoulder and in the upper abdomen. A promising strategy to reduce this post-laparoscopic pain is the pulmonary recruitment maneuver, which indirectly increases intraperitoneal pressure and thereby facilitates removal of residual carbon dioxide. An alternative strategy is the infusion of intraperitoneal normal saline. With normal saline infusion, carbon dioxide rises and escapes through the port sites. In addition, normal saline offers a physiologic buffer system to dissolve excess carbon dioxide.

Methods/Design

This multicenter randomized controlled trial is conducted in two teaching hospitals in the Netherlands. Women between 18 and 65 years of age, with an ASA classification of I-II who are scheduled to undergo an elective laparoscopic procedure with benign gynecologic indication can participate. Following informed consent, participants are randomly allocated into two groups at the end of the surgical procedure. In the intervention group, the upper abdomen is filled with normal saline infusion with the patient in the Trendelenburg position. Then the anesthesiologist performs a standardized pulmonary recruitment maneuver with a pressure of 40 cm H₂O. The trocar sleeve valves will be left open, so carbon dioxide can escape the abdominal cavity. With the patient in a neutral position the instruments are removed from the abdomen. In the control group, carbon dioxide is removed from the abdominal cavity at the end of surgery, with gentle abdominal pressure and passive exsufflation through the port sites, with open sleeve valves.

The primary outcomes are the incidence and intensity of post-laparoscopic pain in the shoulder, upper abdomen and at the operation sites, at 8, 24 and 48 h after surgery. Secondary outcomes are postoperative use of analgesics, nausea, vomiting and pulmonary complications.

Discussion

This study may reduce post-laparoscopic pain in women undergoing laparoscopy.

Trial registration

Dutch trial register, number NTR4812.

Comparative evaluation of colonoscopy-assisted transanal minimally invasive surgery via glove port and endoscopic submucosal dissection for early rectal tumor

BACKGROUND

Early rectal tumor is usually managed by local excision. A novel method-colonoscopy-assisted transanal minimally invasive surgery via glove port (CA-TAMIS-GP)-for resecting early rectal tumor was developed and compared with endoscopic submucosal dissection (ESD).

MATERIALS AND METHODS

We performed CA-TAMIS-GP surgery on 26 patients from January 2014 to February 2016. For better analysis, we retrospectively collected data from 31 patients who underwent ESD between October 2012 and December 2013; overall, 57 patients diagnosed with early rectal tumor were included in this study. Perioperative conditions and long-term outcomes of both groups were compared.

RESULTS

All lesions were dissected completely and successfully without conversion to open surgery or major complications. On histopathologic examination, all specimens in this study had negative margins. All patients had uneventful postoperative recoveries, except 3 patients of CA-TAMIS-GP with minor hematochezia, which resolved spontaneously; 7 ESD patients had late-onset bleeding and 3 needed colonoscopic hemostasis; 2 patients in each group had mild fever. The CA-TAMIS-GP group had a shorter operation time, less hemorrhage, and a lower average consumable cost than the ESD group (P < 0.05); moreover, the CA-TAMIS-GP group had no recurrence or long-term complications during a follow-up of 10-32 months, whereas3 patients in the ESD group developed local recurrence during a follow-up of 24-36 months.

CONCLUSIONS

The CA-TAMIS-GP is a new method that is safe and effective in patients with early rectal tumor and appears to have a shorter operation time and less blood loss as compared with ESD.

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.

Advantages of laparoscopic compared to conventional surgery are not related to an innate immune response of peritoneal immune activation: an animal study in rats

PURPOSE

Laparoscopic surgery (LS) has proved superior compared to conventional surgery (CS) regarding morbidity, length of hospital stay, rate of wound infection and time until recovery. An improved preservation of the postoperative immune function is assumed to contribute to these benefits though the role of the local peritoneal immune response is still poorly understood. Our study investigates the peritoneal immune response subsequent to abdominal surgery and compares it between laparoscopic and conventional surgery to find an immunological explanation for the clinically proven benefits of LS.

METHODS

Wistar rats (N = 140) underwent laparoscopic cecum resection (LCR; N = 28), conventional cecum resection (CCR; N = 28), laparoscopic sham operation (LSO; N = 28), conventional sham operation (CSO; N = 28), or no surgical treatment (CTRL; N = 28). Postoperatively, peritoneal lavages were performed, leukocytes isolated and analyzed regarding immune function and phagocytosis activity.

RESULTS

Immune function was inhibited postoperatively in animals undergoing LCR or CCR compared to CTRL reflected by a lower TNF-α (CTRL 3956.65 pg/ml, LCR 2018.48 pg/ml (p = 0.023), CCR 2793.78 pg/ml (n.s.)) and IL-6 secretion (CTRL 625.84 pg/ml, LCR 142.84 pg/ml (p = 0.009), CCR 169.53 pg/ml (p = 0.01)). Phagocytosis was not affected in rats undergoing any kind of surgery compared to CTRL. Neither cytokine secretion nor phagocytosis activity differed significantly between laparoscopic and conventional surgery.

CONCLUSIONS

According to our findings the benefits associated with LS compared to CS cannot be explained by differences in the postoperative peritoneal innate immune response. Further studies are needed to elucidate the causes for a more favorable postoperative outcome in patients after LS compared to CS.

Evidence for the absence of visceral pain in C57BL6/N mice subjected to therapeutically relevant O3/O2-pneumoperitoneum

Each different gas that is used to induce a pneumoperitoneum (PP) exhibits individual effects within the peritoneal cavity. This might include adverse effects such as pain and/or inflammatory reactions. The acute effects of ozonized oxygen (O₃/O₂), a highly oxidative gas mixture, after being insufflated into the peritoneal cavity are analysed in this study. Using the abdominal constriction response ('writhing') assay of chemical nociception in C57BL6/N mice, O₃/O₂-PP was found not to be associated with visible pain responses and did not alter the c-fos expression in the spinal cord. In addition, mRNA expression levels of the pro-inflammatory cytokines, interleukin (IL)-1β and IL-6, were found unaltered in the spleen 2 h after insufflation. In conclusion, O₃/O₂-PP is free of adverse pain and does not trigger inflammatory immune responses.

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.

Attenuation of Oxidative Stress by Ischemic Preconditioning in an Experimental Model of Intraabdominal Hypertension

PURPOSE

Increased intra-abdominal pressure, as used in laparoscopic surgery or seen in intraabdominal hypertension (IAH), is associated with tissue ischemia and oxidative stress. Ischemic preconditioning (IP) is a method successfully used in liver and transplant surgery, in order to attenuate the detrimental effects of ischemia and reperfusion. In this experimental study, we tested the ability of IP to modify oxidative stress induced by extremely high intraabdominal pressures.

METHODS

Twenty-five female pigs were studied and divided in three groups: a control group, a pneumoperitoneum group (with pressure of 30 mmHg), and an ischemic preconditioning group (initially subjected to preconditioning with pressure of 25 mmHg for 15 min and desufflation for 15 min and then to pneumoperitoneum as in pneumoperitoneum group). Blood samples were obtained at identical time intervals in the three groups. Total oxidative capacity, total antioxidative capacity and total nitric oxide (NO), nitrite and nitrate concentrations were measured and compared between groups.

RESULTS

IP increased total antioxidative capacity (p = .045) and protective mediators like nitrite (p = .022). It was also associated with a trend toward lower levels of total oxidative capacity at the end of the abdominal desufflation period but statistical significance was not met.

CONCLUSIONS

IP attenuated oxidative stress induced by IAH, mainly by increasing antioxidative capacity and the levels of protective mediators. The fact that IP was effective, even when used at extremely high levels of intraabdominal pressure, reinforces the interest on this method but further studies are needed to clarify its mechanism of action and potential clinical applications.

Effects of carbon dioxide pneumoperitoneum on postoperative adhesion formation and oxidative stress in a rat cecal abrasion model

INTRODUCTION

It is claimed that CO2 pneumoperitoneum (CP) is less adhesiogenic than laparotomy. Our aim in this study was to investigate the local oxidative stress responses and related adhesion formation resulting from exposure to CP.

METHODS

Forty-five rats were randomised into six groups. Group 1 underwent laparotomy only; in group 2, 6 mmHg CP was performed for 60 min; in group 3, the same procedure was carried out using 12 mmHg CP; in group 4, laparotomy and cecal-peritoneal abrasion were performed; in group 5, 6 mmHg CP was performed for 60 min, followed by laparotomy and cecal-peritoneal abrasion; in group 6, the same procedure was carried out using 12 mmHg CP. Groups 1, 2 and 3 were sacrificed immediately and used only for biochemical examination. The other groups were sacrificed on the 14th postoperative day.

RESULTS

The total adhesion scores, thickness, quantity, extent and type of adhesions decreased steadily in groups 4, 5 and 6 (p < 0.05). The median values for neutrophil and monocyte infiltration, and for capillary and fibroblast proliferation decreased steadily in groups 4, 5 and 6 (p < 0.05). CAT, SOD and GSHPx levels decreased significantly in line with increasing pressure in groups 1, 2 and 3. SOD and GSHPx levels were similar in groups 4, 5 and 6, while CAT levels decreased with increasing pressure in groups 4, 5 and 6.

CONCLUSION

It was found that CP is associated with less adhesion formation than laparotomy in the presence of similar antioxidant levels. The reduced adhesion formation is probably caused by a decreased inflammatory response.

Does thermodynamic stability of peritoneal collagen change during laparoscopic cholecystectomies? A differential scanning calorimetry (DSC) study

Background

Carbon dioxide pneumoperitoneum used during laparoscopic surgeries alters the integrity of the peritoneum and results in denudation of the basal lamina that might cause altered immune response, inhibited fibrinolysis, hypoxia, and acidosis. The changes in the structure of pneumoperitoneum were described as bulging of mesothelial cells, irregular cell junction’s cell membrane degradation, and mesodermal edema. As denaturation of peritoneal proteins reflects overall condition of its structure and interactions with the surrounding molecules, the physical status of collagen was assessed on the basis of parameters of thermal denaturation measured by DSC method.

Methods

Twenty-four female patients operated on due to cholelithiasis were enrolled in this study. Laparoscopic cholecystectomy was performed using standard four-trocar technique, and standard values of insufflated carbon dioxide pneumoperitoneum were used. After trocar placement, the first collection of peritoneal sample (sample A) was performed. The second peritoneal sample (sample B) was collected after the removal of gall bladder. Differential scanning calorimetry (Q200 calorimeter, TA Instruments) was performed on samples defrosted at room temperature.

Results

In all samples of peritoneum, a nonreversible endothermal process recognized as denaturation was observed. Sample B obtained at the end of surgery did not differ from sample A obtained at the beginning in terms of all parameters under study. Temperature of denaturation in A and B was correlated only marginally, but enthalpy and specific heat were significantly correlated. The analysis of data from DSC measurements did not reveal differences in physical stability of collagen in peritoneal samples obtained at the beginning and at the end of surgery. Significant negative correlations between duration of CO₂ pneumoperitoneum and enthalpy of denaturation in sample B were found.

Conclusions

Differences in enthalpy of denaturation may reflect a quantitative relation between amount of native collagen molecules in the sample and other, non-collagenous components or impaired collagen.

Randomized comparison of surgical stress and the nutritional status between laparoscopy-assisted and open distal gastrectomy for gastric cancer

BACKGROUND

Laparoscopy-assisted distal gastrectomy (LADG) for gastric cancer may prevent the development of an impaired nutritional status due to reduced surgical stress compared with open distal gastrectomy (ODG).

METHODS

This study was performed as an exploratory analysis of a phase III trial comparing LADG and ODG for stage I gastric cancer during the period between May and December of 2011. All patients received the same perioperative care via fast-track surgery. The level of surgical stress was evaluated based on the white blood cell count and the interleukin-6 (IL-6) level. The nutritional status was measured according to the total body weight, amount of lean body mass, lymphocyte count, and prealbumin level.

RESULTS

Twenty-six patients were randomized to receive ODG (13 patients) or LADG (13 patients). The baseline characteristics and surgical outcomes were similar between the two groups. The median IL-6 level increased from 0.8 to 36.3 pg/dl in the ODG group and from 1.5 to 53.3 pg/dl in the LADG group. The median amount of lean body mass decreased from 48.3 to 46.8 kg in the ODG group and from 46.6 to 46.0 kg in the LADG group. There are no significant differences between two groups.

CONCLUSIONS

The level of surgical stress and the nutritional status were found to be similar between the ODG and LADG groups in a randomized comparison using the same perioperative care of fast-track surgery.

A randomized comparison of gasless laparoscopic appendectomy and conventional laparoscopic appendectomy

Introduction

The purpose of this study was to compare the clinical outcomes and cost effectiveness of the gasless laparoscopic appendectomy (GLA) and conventional laparoscopic appendectomy (LA).

Methods

From Aug 2010 to Feb 2012, 100 patients with a clinical diagnosis of acute appendicitis in Shanghai Tongji hospital were included in the study and randomly divided into the LA and GLA groups, fifty in the GLA group and 50 in the LA group. The two groups were comparable in age, gender, body mass index, symptom duration, ASA score, and white blood cell count.

Results

The mean surgical duration was 70.6 ± 30.8 min in the GLA group and 62.6 ± 22.0 min in the LA group (P = 0.138). The total conversion rate was 8% in the GLA group, while no conversions occurred in the LA group. Postoperative complications did not significantly differ between the two groups. Fentanyl consumption was decreased significantly in the GLA group (P = 0.019) postoperatively. The length of the total hospital stay was 4.36 ± 1.74 days in the GLA group compared with 5.68 ± 4.44 days in the LA group (P = 0.053). There was a significant decrease in the total hospital cost when the GLA group was compared with the LA group (6659 ± 1782 vs. 9056 ± 2680 Yuan, respectively, P < 0.001).

Conclusion

GLA and conventional LA are comparable in terms of operative duration, complications, and total hospital stay. The obvious advantage of GLA is the significantly reduced hospital cost. The demand for postoperative analgesics may also decrease following GLA. In conclusion, GLA is a safe and feasible procedure in selected patients.

Trial registration

Chinese Clinical Trial Register ChiCTR-TRC-10001203.

Randomized clinical trial of a simple pulmonary recruitment manoeuvre to reduce pain after laparoscopy

Background

Shoulder tip and abdominal pain following laparoscopic procedures are well recognized causes of postoperative morbidity. In this double-blind randomized clinical trial attempts were made to reduce postoperative pain in patients undergoing laparoscopic surgery by implementing a simple intraoperative technique.

Methods

Patients undergoing elective laparoscopic cholecystectomy or laparoscopic transabdominal preperitoneal inguinal hernia repair were randomized to receive either the current standard treatment (control group) or an intervention to remove residual carbon dioxide. In the intervention group, the pneumoperitoneum was removed at the end of the operation by placing the patient in the Trendelenburg position and utilizing a pulmonary recruitment manoeuvre consisting of two manual inflations to a maximum pressure of 60 cmH2O. In the control group, residual pneumoperitoneum was evacuated at the end of the procedure by passive decompression via the open operative ports.

Results

Seventy-six randomly assigned patients, 37 in the intervention group and 39 in the control group, were recruited. Overall postoperative pain scores were significantly lower in the intervention group (P = 0·001). Median (interquartile range) pain scores were significantly lower in the intervention group compared with the control group at both 12 h (3·5 versus 5; P &lt; 0·010) and 24 h (3 versus 4·5; P &lt; 0·010).

Conclusion

Active evacuation of residual pneumoperitoneum following laparoscopic procedures, by means of two pulmonary recruitment manoeuvres in the Trendelenburg position, reduces postoperative pain significantly. This simple and safe technique can be implemented routinely after abdominal laparoscopy. Registration number: NCT01720433 (http://www.clinicaltrials.gov).

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).

Structural deteriorations of the human peritoneum during laparoscopic cholecystectomy. A transmission electron microscopic study

BACKGROUND

In previous studies, changes in the surface of the peritoneum during laparoscopic surgery are well defined. Nevertheless, almost all of these studies were performed on rodents via scanning electron microscopy. In the present study, structural alterations of the mesothelial cells of peritoneum were examined during laparoscopic cholecystectomy using transmission electron microscopy.

METHODS

Twenty patients with symptomatic cholelithiasis were included in the study. Peritoneal biopsy was performed immediately after CO2 pneumoperitoneum creation and at the end of surgery just before gallbladder removal. Biopsies were taken from the right upper quadrant, i.e., apart from operative manipulation. Peritoneal sample cross-sections were compared using transmission electron microscopy.

RESULTS

The carbon dioxide pneumoperitoneum during laparoscopic cholecystectomy caused deteriorations of the peritoneal mesothelium. Apoptosis were developed in mesothelial cells. Bulging of mesothelial cells, irregular cell junctions, focal intercellular clefts, apical cell membrane degeneration, deep nuclear invaginations, and lipid droplets in the cytoplasm of the mesothelial cells were other remarkable findings. Mesothelial edema also was determined.

DISCUSSION

As seen in previous studies, basement membrane nudity appeared after carbon dioxide pneumoperitoneum could be attributable to mesothelial cell apoptosis, deterioration of the cell structure, and cell organelles.

Transcutaneous application of carbon dioxide (CO2) induces mitochondrial apoptosis in human malignant fibrous histiocytoma in vivo

Mitochondria play an essential role in cellular energy metabolism and apoptosis. Previous studies have demonstrated that decreased mitochondrial biogenesis is associated with cancer progression. In mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) regulates the activities of multiple nuclear receptors and transcription factors involved in mitochondrial proliferation. Previously, we showed that overexpression of PGC-1α leads to mitochondrial proliferation and induces apoptosis in human malignant fibrous histiocytoma (MFH) cells in vitro. We also demonstrated that transcutaneous application of carbon dioxide (CO₂) to rat skeletal muscle induces PGC-1α expression and causes an increase in mitochondrial proliferation. In this study, we utilized a murine model of human MFH to determine the effect of transcutaneous CO₂ exposure on PGC-1α expression, mitochondrial proliferation and cellular apoptosis. PGC-1α expression was evaluated by quantitative real-time PCR, while mitochondrial proliferation was assessed by immunofluorescence staining and the relative copy number of mitochondrial DNA (mtDNA) was assessed by real-time PCR. Immunofluorescence staining and DNA fragmentation assays were used to examine mitochondrial apoptosis. We also evaluated the expression of mitochondrial apoptosis related proteins, such as caspases, cytochorome c and Bax, by immunoblot analysis. We show that transcutaneous application of CO₂ induces PGC-1α expression, and increases mitochondrial proliferation and apoptosis of tumor cells, significantly reducing tumor volume. Proteins involved in the mitochondrial apoptotic cascade, including caspase 3 and caspase 9, were elevated in CO₂ treated tumors compared to control. We also observed an enrichment of cytochrome c in the cytoplasmic fraction and Bax protein in the mitochondrial fraction of CO₂ treated tumors, highlighting the involvement of mitochondria in apoptosis. These data indicate that transcutaneous application of CO₂ may represent a novel therapeutic tool in the treatment of human MFH.

Evaluation of the effects of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats undergoing segmental resection and anastomosis of the left colon

PURPOSE

To evaluate the influence of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats.

METHODS

Eighty rats underwent laparotomy, segmental left colon resection, and anastomosis. The animals were divided into three experimental groups and one control group: EI = pneumoperitoneum for 30 minutes before laparotomy (n=20); EII = pneumoperitoneum for 30 minutes after abdominal closure (n=20); EIII = pneumoperitoneum for 30 minutes before laparotomy and 30 minutes after abdominal closure (n=20); C = control group, without pneumoperitoneum (n=20). In each group, 10 animals were killed 7 days and 10 animals 14 days postoperatively. A segment of the abdominal wall was resected and subjected to tensile strength testing. Another segment of abdominal muscle was used for histopathological analysis; the specimens were fixed in formalin and stained with hematoxylin and eosin.

RESULTS

There were no differences in histopathology and tensile strength values among animals in the experimental and control groups 7 or 14 days after surgery.

CONCLUSION

Under the present experimental conditions, carbon dioxide pneumoperitoneum did not interfere with abdominal wall wound healing.

Minilaparoscopic versus conventional laparoscopic hysterectomy: results of a randomized trial

STUDY OBJECTIVE

To compare operative outcomes and postoperative pain of laparoscopic hysterectomy (LH) versus minilaparoscopic hysterectomy (MLH).

DESIGN

Randomized controlled trial (Canadian Task Force Classification I).

SETTING

Tertiary care center.

PATIENTS

Seventy-six women scheduled to undergo a hysterectomy for a supposed benign gynecologic condition.

INTERVENTIONS

Participants were randomly assigned to LH (n = 38) or MLH (n = 38). MLH was performed with use of 3-mm ports. Both patients and assessors of the postoperative outcomes were blinded to the size of port used, and patients' wounds were concealed by standard-size nontransparent dressings.

MEASUREMENTS

Primary outcome was postoperative pain (both rest and incident on coughing and abdominal pain, as well as shoulder pain) by use of a 100-mm visual analogue scale.

MAIN RESULTS

The two groups were similar in terms of operative outcomes. No intraoperative conversion from MLH to both LH and open surgery occurred. No significant difference in pain scores at 1, 3, 8, and 24 hours after surgery between groups was found. Rescue analgesic requirement was similar in the MLH and LH groups (21.1% vs 13.2%, p =.54).

CONCLUSIONS

Ports can safely be reduced in size without a negative impact on the surgeon's ability to perform LH. MLH appears to have no advantage over LH in terms of postoperative pain.

Warming and humidification have no effect on oxidative stress during pneumoperitoneum in rats

Pneumoperitoneum is reported to induce oxidative stress due to the desiccative effect of cold, dry gas insufflation. The aim of this study is to compare the effect of warmed, humidified insufflation to standard gas, by measuring oxidative stress markers in a physiologically relevant animal model. Twenty male Wistar rats (330?650 g) were alternately assigned to the Warm Humidified group (WH, n = 10) and Control group (n = 10). All rats underwent pneumoperitoneum at 5 mmHg and a controlled flow rate for 110 min. The WH group received warmed (37?C) and humidified (98% Relative Humidity (RH)) gas and the control group received standard gas at room temperature (19?C) and 0% RH. At the end of pneumoperitoneum, samples of liver, kidney, pancreas, jejunum, and lung were excised. Levels of plasma and tissue malondialdehyde (MDA) and protein carbonyls (PC) were measured. Organ light microscopy was performed. There were no differences between groups for MDA or PC concentrations in plasma, liver, kidney, jejunum, or lung tissue. There were no differences in histological score between groups. Warming and humidification of pneumoperitoneum insufflation gas have no effect on measures of oxidative stress compared to non-warmed, non-humidified controls.

Impact of intraperitoneal pressure and duration of surgery on levels of tissue plasminogen activator and plasminogen activator inhibitor-1 mRNA in peritoneal tissues during laparoscopic surgery

BACKGROUND

Our objective was to evaluate the impact of intraperitoneal pressure (IPP) and duration of a CO(2) pneumoperitoneum on the peritoneal fibrinolytic system during laparoscopic surgery.

METHODS

Human study: Patients undergoing laparoscopic surgery were divided into two groups: low (8 mmHg, n= 32) or standard (12 mmHg, n= 36) IPP. Normal peritoneum was collected from the parietal wall at the beginning of surgery and every 60 min thereafter. Mouse study: Mice were divided into three groups: low (2 mmHg) or high (8 mmHg) IPP or laparotomy. Peritoneal tissue was collected at 0, 4, 8, 24, 48 and 72 h, and 5 and 7 days after surgery. Real-time RT-PCR was performed in humans and mice to measure the levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) mRNA in peritoneal tissues.

RESULTS

Human study: The tPA/PAI-1 mRNA ratio was significantly decreased in the 12 mmHg group at 1 h [P < 0.0001 versus matched initial peritoneal biopsies (MI)]. The tPA/PAI-1 mRNA ratio decreased in both groups at 2 h (P < .0.01 versus MI). Mouse study: The tPA/PAI-1 ratio was decreased at 0 h, and the difference was significant at 4 h in both the laparotomy (P < 0.001 versus controls, 0 h, 5 and 7 days) and high-IPP (P < 0.0001 versus 0, 48 and 72 h, 5 and 7 days) groups. No changes in tPA/PAI-1 ratio were observed in the low-IPP group.

CONCLUSIONS

A low IPP and shorter duration of surgery appear to minimally impact the fibrinolytic system during a CO₂ pneumoperitoneum.

Gut oxygenation and oxidative damage during and after laparoscopic and open left-sided colon resection: a prospective, randomized, controlled clinical trial

BACKGROUND

Pneumoperitoneum (PP), established for laparoscopic (LPS) operation, has been associated with potential detrimental effects, such as mesenteric ischemia-reperfusion injury. The objective of the trial was to measure intestinal tissue oxygen pressure (PtiO2) and oxidative damage during laparoscopic (LPS) and open colon surgery and during the postoperative course.

METHODS

Forty patients candidate to left-sided colectomy were randomized to undergo open or LPS resection (20 patients/group). During the operation, PtiO2 was measured at established changes of PP pressure (from 0-15 mmHg) and for 6 days postoperatively. PtiO2 was determined by a polarographic microprobe implanted in the colon wall. Ischemia-reperfusion injury was assessed by plasma malondialdehyde (MDA). ClinicalTrial.gov registration number: NCT01040013.

RESULTS

LPS was associated with a higher PtiO2 at the beginning of surgery (73.9±9.4 vs. 64.3±6.4 in open; P=0.04) and at the end of the operation (57.7±7.9 vs. 53.1±4.7 in open; P=0.03). PtiO2 decreased significantly during mesentery traction vs. beginning in both groups (respectively 58.7±13.2 vs. 73.9±9.4 in LPS and 55.3±6.4 vs. 64.3±6.4 in open group; minimum P=0.02). During LPS, there was a significant decrease of PtiO2 only when PP was increased to 15 mmHg (63.2±7.5 vs. 76.6±10.7 at 10 mmHg; P=0.03). PtiO2 also was significantly better in the LPS group during the first 3 days after operation (minimum P=0.04 vs. open). MDA significantly increased in both groups after mesentery traction and at the end of operation vs. baseline levels with no difference between techniques.

CONCLUSIONS

LPS seems to be associated with a better intra- and postoperative PtiO2. High-pressure PP may impair PtiO2.

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 damage: the inflammatory response and clinical implications of the neuro-immuno-humoral axis

BACKGROUND

The peritoneum is a bilayer serous membrane that lines the abdominal cavity. We present a review of peritoneal structure and physiology, with a focus on the peritoneal inflammatory response to surgical injury and its clinical implications.

METHODS

We conducted a nonsystematic clinical review. A search of the Ovid MEDLINE database from 1950 through January 2009 was performed using the following search terms: peritoneum, adhesions, cytokine, inflammation, and surgery.

RESULTS

The peritoneum is a metabolically active organ, responding to insult through a complex array of immunologic and inflammatory cascades. This response increases with the duration and extent of injury and is central to the concept of surgical stress, manifesting via a combination of systemic effects, and local neural pathways via the neuro-immuno-humoral axis. There may be a decreased systemic inflammatory response after minimally invasive surgery; however, it is unclear whether this is due to a reduced local peritoneal reaction.

CONCLUSIONS

Interventions that dampen the peritoneal response and/or block the neuro-immuno-humoral pathway should be further investigated as possible avenues of enhancing recovery after surgery, and reducing postoperative complications.

[Minimally invasive pediatric surgery]

In recent years minimally invasive surgical techniques in children have made substantial progress. The feasibility and safety of a wide spectrum of laparoscopic and thoracoscopic procedures have been confirmed in numerous studies. Moreover, it was reported that minimally invasive pediatric surgery is associated with lower morbidity, a shorter hospital stay, lower costs, better cosmetics and clinical results similar to those achieved by open surgery. The present article reviews information on established as well as feasible but not yet established surgical procedures. The discussion of potential hemodynamic, respiratory and organ perfusion effects of the CO(2) pneumoperitoneum and the notation of special logistic aspects should support the reader in the process of decision-making to schedule infants and children for minimally invasive surgery.

Sonographic findings following appendectomy for uncomplicated appendicitis in children

BACKGROUND

Little is known about 'normal' local sonographic changes occurring in the postoperative period after an uneventful appendectomy.

OBJECTIVE

To analyse the local changes on US examination occurring after uneventful open (OA) or laparoscopic (LA) appendectomy in children with normal histology and with nonperforated acute appendicitis.

MATERIALS AND METHODS

US was prospectively performed in 82 children (54 boys and 28 girls) aged 1-16 years (mean 11.6+/-3.2 years), 3 days following LA (n=51, 62%) or OA (n=31, 38%) for nonperforated appendicitis. Multivariate analysis was performed using stepwise logistic regression, with the following starting variables: surgical technique, gender, pathological finding, appendix location, and histology.

RESULTS

Of the 82 patients, 35 (42.7%) had postoperative pathological US findings such as peritoneal fluid, oedematous mesenteric fat and thickening of the bowel wall. While the overall incidence of pathological US findings between OA and LA groups was not significantly different, multivariate logistic regression analysis showed that OA is associated with a reduction by a factor of 0.35 in the odds ratio of postoperative pathological US findings (P=0.007).

CONCLUSION

Pathological US findings are common in children after appendectomy, particularly after LA. Awareness of these pathological findings might prevent unnecessary postoperative treatment.

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.

Involvement of proton-sensing TDAG8 in extracellular acidification-induced inhibition of proinflammatory cytokine production in peritoneal macrophages

Extracellular acidification inhibited LPS-induced TNF-alpha protein production, which was associated with an inhibition of TNF-alpha mRNA expression, in mouse peritoneal macrophages. The LPS-induced cytokine production was also inhibited by G(s) protein-coupled receptor agonists prostaglandin E(1) and isoproterenol. Among OGR1 family proton-sensing GTP-binding regulatory protein-coupled receptors, TDAG8, OGR1, and G2A are expressed in the cells. The inhibitory action by acidic pH on TNF-alpha production was significantly attenuated in macrophages from TDAG8(Tp/Tp) mice but not in those from OGR1(geo/geo) mice. Moreover, small interfering RNA specific to TDAG8, but not to G2A, clearly attenuated the acidification-induced inhibition of TNF-alpha production. On the other hand, the down-regulation or deficiency of TDAG8 hardly affected prostaglandin E(1)- or isoproterenol-induced actions. LPS-induced IL-6 production was also inhibited by extracellular acidification in a manner that was sensitive to TDAG8 expression. The acidic pH-induced inhibitory action on the cytokine production was significantly reversed either by a small interfering RNA specific to G(s) proteins or by a protein kinase A (PKA)-specific inhibitor H89. Indeed, a PKA-specific cAMP derivative inhibited LPS-induced cytokine production. Moreover, acidification induced cAMP accumulation in a TDAG8-specific way. We conclude that TDAG8, at least partly, mediates the extracellular acidification-induced inhibition of proinflammatory cytokine production through the G(s) protein/cAMP/PKA signaling pathway in mouse macrophages.