Increased tumor growth after high pressure pneumoperitoneum with helium and air

The effect of CO2 pressure and flow variation on carbon particles spread during pneumoperitoneum: an experimental study

BACKGROUND

A correlation between atypical recurrences and minimally-invasive surgery has been suggested in case of urothelial cancer; however, very few data are available on the role of pneumo peritoneum in terms of gas flow and intra-abdominal pressure. The objective of the study is to analyze the impact of CO2 pneumoperitoneum variation on an inert material as surrogate of neoplastic cells.

MATERIAL AND METHODS

We designed an experimental model mimicking pneumoperitoneum in three settings: sealed flow (no leakage), pulsatile flow (alternating efflux and influx) and continuous flow (AirSeal® insufflator). Each experiment was characterized by a pre-determined gas flow and pressure, trocar distance and position from the particles. Hounsfield density (HD) variation in the areas of interest was measured as index of graphite powder dispersion. A Linear regression model was employed to measure the correlation between modifiable variables and HD.

RESULTS

HD was lower in the pulsatile compared to both the sealed and continuous flows (p < 0.03). On multivariate analysis for sealed setting, flow and total gas liters delivered (i.e. gas leakage) were inversely and independently related to HD (all p <0.03). In pulsatile setting, trocar position, trocar distance and gas flow independently predicted HD (all p <0.03). In continuous setting, gas pressure was directly and independently related to HD (p = 0.004) due to decreased pneumoperitoneum stability and increased CO2 liters delivered. In case of in-flow trocar positioned laterally to the particles, low flow (1 L/min) or low pressure (8 mmHg), HD values recorded in the three settings were all overlapping (all p > 0.05).

CONCLUSIONS

Flow and pressure setting, in-flow trocar distance and contiguity from the tumor, and pneumoperitoneum stability may be all crucial component in minimally invasive surgery. In vivo, these variables should be considered as potential risk factors for tumor cells spread within the abdominal cavity.

What is the evidence for the use of low-pressure pneumoperitoneum? A systematic review

Background

Laparoscopic surgery has several advantages when compared to open surgery, including faster postoperative recovery and lower pain scores. However, for laparoscopy, a pneumoperitoneum is required to create workspace between the abdominal wall and intraabdominal organs. Increased intraabdominal pressure may also have negative implications on cardiovascular, pulmonary, and intraabdominal organ functionings. To overcome these negative consequences, several trials have been performed comparing low- versus standard-pressure pneumoperitoneum.

Methods

A systematic review of all randomized controlled clinical trials and observational studies comparing low- versus standard-pressure pneumoperitoneum.

Results and conclusions

Quality assessment showed that the overall quality of evidence was moderate to low. Postoperative pain scores were reduced by the use of low-pressure pneumoperitoneum. With appropriate perioperative measures, the use of low-pressure pneumoperitoneum does not seem to have clinical advantages as compared to standard pressure on cardiac and pulmonary function. Although there are indications that low-pressure pneumoperitoneum is associated with less liver and kidney injury when compared to standard-pressure pneumoperitoneum, this does not seem to have clinical implications for healthy individuals. The influence of low-pressure pneumoperitoneum on adhesion formation, anastomosis healing, tumor metastasis, intraocular and intracerebral pressure, and thromboembolic complications remains uncertain, as no human clinical trials have been performed. The influence of pressure on surgical conditions and safety has not been established to date. In conclusion, the most important benefit of low-pressure pneumoperitoneum is lower postoperative pain scores, supported by a moderate quality of evidence. However, the quality of surgical conditions and safety of the use of low-pressure pneumoperitoneum need to be established, as are the values and preferences of physicians and patients regarding the potential benefits and risks. Therefore, the recommendation to use low-pressure pneumoperitoneum during laparoscopy is weak, and more studies are required.

What is the effect of laparoscopic colectomy on pattern of colon cancer recurrence? A propensity score and competing risk analysis compared with open colectomy

BACKGROUND

Variability in colon cancer recurrence after laparoscopic colectomy (LAC) remains poorly understood. The aim of our study was to quantify the influence of LAC on colon cancer recurrence patterns.

METHODS

We included 986 patients undergoing curative colectomy at our institution between 1992 and 2008. Kaplan-Meier, multivariable Cox regression, propensity score adjustment, and competing risks modeling were used to evaluate the influence of laparoscopic surgery on the site of colon cancer recurrence, including the following: liver metastasis, lung metastasis, local recurrence, peritoneal dissemination, other, and multiple sites. We estimated the risk factors for each recurrence site.

RESULTS

Laparoscopic surgery was used in 419 (42.5 %) of 986 patients, with an overall median follow-up time of 5.0 years (interquartile range 3.5). The overall 5-year disease-free survival rate was 86.1 % (open surgery 81.8 % vs. laparoscopic surgery 92.0 %; p < 0.001). However, after covariates and propensity score adjustment, laparoscopic surgery was not a significant risk factor for each type of recurrence: liver hazard ratio (HR) 0.93 (95 % CI 0.45-1.89), p = 0.84; lung HR 0.67 (95 % CI 0.26-1.70), p = 0.39; local HR 0.56 (95 % CI 0.12-2.63), p = 0.46; peritoneal HR 2.49 (95 % CI 0.75-8.27), p = 0.14; others HR 0.47 (95 % CI 0.04-5.13), p = 0.53; multiple HR 0.88 (95 % CI 0.25-3.14), p = 0.84. The risk factors for each type of recurrence were variable and characterized by specific clinicopathological features.

CONCLUSION

Our study reveals that LAC and open colectomy demonstrate comparable overall colon cancer recurrence rates and recurrence sites. Specific clinicopathological characteristics may have a stronger influence on colon cancer recurrence site compared with the surgical technique.