Acidification during carbon dioxide pneumoperitoneum is restricted to the gas-exposed peritoneal surface: effects of pressure, gas flow, and additional intraperitoneal fluids

Moderate Intra-Abdominal Pressure Levels in Robot-Assisted Radical Prostatectomy Seem to Have No Negative Impact on Clinical Outcomes

Introduction: Radical prostatectomy is increasingly performed laparoscopically with robot assistance (RALRP). RALRP, as with all laparoscopic procedures, requires a pneumoperitoneum, which might result in peritoneal inflammatory response reactions and postoperative pain. The aim of this retrospective single-centre study was to analyse the effects of a pneumoperitoneum during RARLP on clinical outcomes. Methods: All patients who underwent robot-guided prostatectomy in our clinic were included, with the exception of patients who were converted to open prostatectomy. C-reactive protein was used as a marker for the primary outcome, namely the postoperative inflammatory response. Intra-abdominal pressure (IAP) was evaluated as a potential factor influencing inflammation. In addition, the waist-hip ratio was used to estimate the amount of visceral adipose tissue, and the administration of dexamethasone was considered as a factor influencing inflammation. The Visual Analogue Scale (VAS) was used to determine postoperative pain. Patients were consecutively recruited between 1 September 2020 and 31 March 2022. Results: A total of 135 consecutive patients were included. The median waist-hip ratio was 0.55. The median duration of the pneumoperitoneum was 143 min. The median values of the average and maximum IAP values were 10 mmHg and 15 mmHg, respectively. The mean CRP of the first postoperative day was 6.2 mg/dL. The median VAS pain level decreased from 2 to 1 from the first to the third postoperative day. On the first postoperative day, 16 patients complained of shoulder pain. In addition, 134 patients were given some form of opioid pain treatment following surgery. Conclusion: We could not identify any relevant associations between the duration and IAP of the pneumoperitoneum and the indirect markers of inflammation or indicators of pain, or between the latter and the amount of visceral adipose tissue. In addition, we found no significant effect of the administration of dexamethasone on postoperative inflammation. The results point to a noninferior tolerability of moderate pressure during the procedure compared to the commonly utilised higher pressure, yet this must be confirmed in randomised controlled trials.

CO2-Driven Nebulization of pH-Sensitive Supramolecular Polymers for Intraperitoneal Hydrogel Formation and the Treatment of Peritoneal Metastasis

Because peritoneal metastasis (PM) from ovarian cancer is characterized by non-specific symptoms, it is often diagnosed at advanced stages. Pressurized intraperitoneal aerosol chemotherapy (PIPAC) can be considered a promising drug delivery method for unresectable PM. Currently, the efficacy of intraperitoneal (IP) drug delivery is limited by the off-label use of IV chemotherapeutic solutions, which are rapidly cleared from the IP cavity. Hence, this research aimed to improve PM treatment by evaluating a nanoparticle-loaded, pH-switchable supramolecular polymer hydrogel as a controlled release drug delivery system that can be IP nebulized. Moreover, a multidirectional nozzle was developed to allow nebulization of viscous materials such as hydrogels and to reach an even IP gel deposition. We demonstrated that acidification of the nebulized hydrogelator solution by carbon dioxide, used to inflate the IP cavity during laparoscopic surgery, stimulated the in situ gelation, which prolonged the IP hydrogel retention. In vitro experiments indicated that paclitaxel nanocrystals were gradually released from the hydrogel depot formed, which sustained the cytotoxicity of the formulation for 10 days. Finally, after aerosolization of this material in a xenograft model of PM, tumor progression could successfully be delayed, while the overall survival time was significantly increased compared to non-treated animals.

The "Dark Side" of Pneumoperitoneum and Laparoscopy

Laparoscopic surgery has been one of the most common procedures for abdominal surgery at pediatric age during the last few decades as it has several advantages compared to laparotomy, such as shorter hospital stays, less pain, and better cosmetic results. However, it is associated with both local and systemic modifications. Recent evidence demonstrated that carbon dioxide pneumoperitoneum might be modulated in terms of pressure, duration, temperature, and humidity to mitigate and modulate these changes. The aim of this study is to review the current knowledge about animal and human models investigating pneumoperitoneum-related biological and histological impairment. In particular, pneumoperitoneum is associated with local and systemic inflammation, acidosis, oxidative stress, mesothelium lining abnormalities, and adhesion development. Animal studies reported that an increase in pressure and time and a decrease in humidity and temperature might enhance the rate of comorbidities. However, to date, few studies were conducted on humans; therefore, this research field should be further investigated to confirm in experimental models and humans how to improve laparoscopic procedures in the spirit of minimally invasive surgeries.

Enthusiasm, evidence and ethics: the triple E of minimally invasive pediatric surgery

Minimally invasive techniques are applicable in more than 60% of abdominal and thoracic operations in children. Enthusiasts promoted these techniques for many years. However, level 1 evidence on advantages of minimally invasive surgery in children remains limited. Randomized controlled trials have been conducted for some types of procedures such as laparoscopic appendectomy, fundoplication, pyloromyotomy, and inguinal hernia repair. The results of these studies confirm some advantages of minimally invasive surgery, but for most types of laparoscopic and all types of thoracoscopic procedures, such data remain to be established. This article also focuses on reports on complications and disadvantages which are relevant for final conclusions and recommendations. The ethical implications of the application of new techniques in children are also discussed. On the basis of evidence based data and ethical principles, minimally invasive techniques may be appropriately used in the future.

Carbon dioxide directly suppresses spontaneous migration, chemotaxis, and free radical production of human neutrophils

BACKGROUND

Carbon dioxide (CO(2)) insufflation during laparoscopy has been shown to dampen the systemic stress response to surgery. This is related to a suppression of peritoneal macrophage functions. In vivo data suggest that CO(2) can also affect neutrophils (polymorphonuclear cells, PMNs), the most abundant cell type in the inflamed peritoneal cavity. Nonetheless, the direct effects of CO(2) on PMNs have not yet been investigated.

METHOD

PMNs were isolated from peripheral blood of healthy volunteers and incubated with (1) CO(2) (100% CO(2), pH 6.2), (2) hypoxic control (95% helium/5% CO(2), pH 7.4), and (3) control (95% air/5% CO(2), pH 7.4). Spontaneous and IL-8-induced migrations (chemokinesis and chemotaxis) during 2 h of exposure to different gases were measured with a transwell chamber system. The release of reactive oxygen species (ROS, luminometry) was determined after 15-min and 2-h exposures. In other sets of experiments, PMNs were exposed for 2 h or 4 h and kept under normal conditions for 18 h with lipopolysaccharide (LPS) stimulation thereafter. Final viability and apoptosis were assessed with fluorometry.

RESULTS

Exposure to 100% CO(2) completely blocked spontaneous and IL-8 induced migration of PMNs (p < 0.001 vs. controls). Neutrophil migration was slightly diminished in the hypoxic control group. PMA-stimulated ROS production was reduced even after short exposure to 100% CO(2)(p < 0.05). We observed a slight increase of caspase-3/7 activity after exposure to 100% CO(2) and/or hypoxia; however, total viability was not affected.

CONCLUSIONS

CO(2) incubation directly and temporarily suppresses the proinflammatory functions of PMNs; this is caused only partially by the concomitant hypoxia. This effect will contribute to the dampened inflammatory response to laparoscopic surgery. Further studies are needed to investigate whether the temporary suppression of neutrophil functions could affect the clearance of bacterial contaminations.