Modeling intra-abdominal volume and respiratory driving pressure during pneumoperitoneum insufflation-a patient-level data meta-analysis

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.

Physiological and Anesthetic Considerations of Safe and Optimal Pneumoperitoneal Pressures for Laparoscopic Surgeries in Children

Context

In the era of minimally invasive surgeries, pediatric laparoscopic surgeries are now becoming the standard of care.

Aim

In this study, we aim to determine the safe and optimal pneumoperitoneal pressures (PPs) for laparoscopic surgery in children aged 1-5 years, along with the technical ease for the surgeon.

Settings and Design

Prospective, randomized, single-blinded study was conducted at SGPGI Lucknow.

Materials and Methods

Children aged 1-5 years were randomized into Group I (n = 24): PP = 6-8 mmHg and Group II: (PP) = 9-10 mmHg. Hemodynamic, ventilatory, and blood gas changes were measured before CO2 insufflation (T0), 20 min after insufflation (T1), before desufflation (T2), and 10 min after desufflation (T3). Surgeon's technical ease of surgery, postoperative pain, the requirement of rescue analgesia, time to resume feeding, and complications were recorded and analyzed.

Statistical Analysis Used

Paired t-test, Mann-Whitney test, and Wilcoxon signed-rank test were used for nonparametric/parametric data. Chi-square/Fisher's test was used for nominal data.

Results

Partial pressure of CO2 (PaCO2) was significantly higher in Group II at T1, T2, and T3, requiring frequent changes in ventilatory settings. Postoperative pain scores were higher in Group II at 1, 6, and 12 h, requiring rescue analgesia. Surgeon's scores and hemodynamics were similar in both groups.

Conclusions

Higher PP in Group II caused significant changes in PaCO2, end-tidal CO2, and postoperative pain requiring rescue analgesia, but blood gas changes were clinically insignificant and there were no significant changes in hemodynamic parameters. Since the surgeon's ease of performing surgery was similar in both groups, we recommend that laparoscopy in children aged 1-5 years can be started with lower PPs of 6-8 mmHg, which can be increased if needed based on the surgeon's comfort and the patient's body habitus.

Escape of surgical smoke particles, comparing conventional and valveless trocar systems

BACKGROUND

During minimal access surgery, surgical smoke is produced which can potentially be inhaled by the surgical team, leading to several health risks. This smoke can escape from the abdominal cavity into the operating room due to trocar leakage. The trocars and insufflator that are used during surgery influence gas leakage. Therefore, this study compares particle escape from a valveless (Conmed AirSeal iFS), and a conventional (Karl Storz Endoflator) system.

MATERIALS AND METHODS

Using an in vitro model, a conventional and a valveless trocar system were compared. A protocol that simulated various surgical phases was defined to assess the surgical conditions and particle leakage. Insufflation pressures and instrument diameters were varied as these are known to affect gas leakage.

RESULTS

The conventional trocar leaked during two distinct phases. Removal of the obturator caused a sudden release of particles. During instrument insertion, an average of 211 (IQR 111) particles per second escaped when using the 5 mm diameter instrument. With the 10 mm instrument, 50 (IQR 13) particles per second were measured. With the conventional trocar, a higher abdominal pressure increased particle leakage. The valveless trocar demonstrated a continuously high particle release during all phases. After the obturator was removed, particle escape increased sharply. Particle escape decreased to 1276 (IQR 580) particles per second for the 5 mm instrument insertion, and 1084 (IQR 630) particles per second for 10 mm instrument insertion. With the valveless trocar system, a higher insufflation pressure lowered particle escape.

CONCLUSIONS

This study shows that a valveless trocar system releases more particles into the operating room environment than a conventional trocar. During instrument insertion, the leakage through the valveless system is 6 to 20 times higher than the conventional system. With a valveless trocar, leakage decreases with increasing pressure. With both trocar types leakage depends on instrument diameter.

Effect of driving pressure-guided positive end-expiratory pressure on postoperative pulmonary complications in patients undergoing laparoscopic or robotic surgery: a randomised controlled trial

BACKGROUND

Individualised positive end-expiratory pressure (PEEP) improves respiratory mechanics. However, whether PEEP reduces postoperative pulmonary complications (PPCs) remains unclear. We investigated whether driving pressure-guided PEEP reduces PPCs after laparoscopic/robotic abdominal surgery.

METHODS

This single-centre, randomised controlled trial enrolled patients at risk for PPCs undergoing laparoscopic or robotic lower abdominal surgery. The individualised group received driving pressure-guided PEEP, whereas the comparator group received 5 cm H2O fixed PEEP during surgery. Both groups received a tidal volume of 8 ml kg-1 ideal body weight. The primary outcome analysed per protocol was a composite of pulmonary complications (defined by pre-specified clinical and radiological criteria) within 7 postoperative days after surgery.

RESULTS

Some 384 patients (median age: 67 yr [inter-quartile range: 61-73]; 66 [18%] female) were randomised. Mean (standard deviation) PEEP in patients randomised to individualised PEEP (n=178) was 13.6 cm H2O (2.1). Individualised PEEP resulted in lower mean driving pressures (14.7 cm H2O [2.6]), compared with 185 patients randomised to standard PEEP (18.4 cm H2O [3.2]; mean difference: -3.7 cm H2O [95% confidence interval (CI): -4.3 to -3.1 cm H2O]; P<0.001). There was no difference in the incidence of pulmonary complications between individualised (25/178 [14.0%]) vs standard PEEP (36/185 [19.5%]; risk ratio [95% CI], 0.72 [0.45-1.15]; P=0.215). Pulmonary complications as a result of desaturation were less frequent in patients randomised to individualised PEEP (8/178 [4.5%], compared with standard PEEP (30/185 [16.2%], risk ratio [95% CI], 0.28 [0.13-0.59]; P=0.001).

CONCLUSIONS

Driving pressure-guided PEEP did not decrease the incidence of pulmonary complications within 7 days of laparoscopic or robotic lower abdominal surgery, although uncertainty remains given the lower than anticipated event rate for the primary outcome.

CLINICAL TRIAL REGISTRATION

KCT0004888 (http://cris.nih.go.kr, registration date: April 6, 2020).

Clinical outcomes of low-pressure pneumoperitoneum in minimally invasive urological surgery

The adoption of minimally invasive laparoscopic techniques has revolutionised urological practice. This necessitates a pneumoperitoneum (PNP) and the impact the PNP pressure has on post-operative outcomes is uncertain. During the current COVID-19 era guidance has suggested the utilisation of lower PNP pressures to mitigate the risk of intra-operative viral transmission. Review the current literature regarding the impact of pneumoperitoneum pressure, within the field of urology, on post-operative outcomes. A search of the PubMed, Medline and EMBASE databases was undertaken to identify studies that met the inclusion criteria. The Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines were adhered to. Ten studies, that included both randomised controlled trials and retrospective case series reviews, were identified that met the inclusion criteria. The effect of PNP pressure on outcomes following prostatectomy, live donor nephrectomy, partial nephrectomy and a variety of benign upper tract procedures were discussed. Low pressure PNP appears safe when compared to high pressure PNP, potentially reducing post-operative pain and rates of ileus. When compared to general surgery, there is a lack of quality evidence investigating the impact of PNP pressures on outcomes within urology. Low pressure PNP appears non-inferior to high pressure PNP. More research is required to validate this finding, particularly post-cystectomy and nephrectomy.

A novel method for monitoring abdominal compliance to optimize insufflation pressure during laparoscopy

BACKGROUND

Abdominal compliance describes the ease of expansion of the abdominal cavity. Several studies highlighted the importance of monitoring abdominal compliance (Cab) during the creation of laparoscopic workspace to individualize the insufflation pressure. The lack of validated clinical monitoring tools for abdominal compliance prevents accurate tailoring of insufflation pressure. Oscillometry, also known as the forced oscillation technique (FOT), is currently used to measure respiratory mechanics and has the potential to be adapted for monitoring abdominal compliance. This study aimed to define, develop and evaluate a novel approach which can monitor abdominal compliance during laparoscopy using endoscopic oscillometry.

MATERIALS AND METHODS

Endoscopic oscillometry was evaluated in a porcine model for laparoscopy. A custom-built insufflator was developed for applying an oscillatory pressure signal superimposed onto a mean intra-abdominal pressure. This insufflator was used to measure the abdominal compliance at insufflation pressures ranging from 5 to 20 hPa (3.75 to 15 mmHg). The measurements were compared to the static abdominal compliance, which was measured simultaneously with computed tomography imaging.

RESULTS

Endoscopic oscillometry recordings and CT images were obtained in 10 subjects, resulting in 76 measurement pairs for analysis. The measured dynamic Cab ranged between 0.0216 and 0.261 L/hPa while the static Cab based on the CT imaging ranged between 0.0318 and 0.364 L/hPa. The correlation showed a polynomial relation and the adjusted R-squared was 97.1%.

CONCLUSIONS

Endoscopic oscillometry can be used to monitor changes in abdominal compliance during laparoscopic surgery, which was demonstrated in this study with a comparison with CT imaging in a porcine laparoscopy model. Use of this technology to personalize the insufflation pressure could reduce the risk of applying excessive pressure and limit the drawbacks of insufflation.

The effect of different pressures of pneumoperitoneum on the dimensions of internal jugular vein – A prospective double-blind, randomised study

Background and Aims:

During laparoscopic surgeries, pneumoperitoneum increases intraabdominal pressure (IAP) which can increase the central venous pressure (CVP), and significant haemodynamic changes. In this study, we evaluated the effect of two different pressures of pneumoperitoneum, standard (13-15 mmHg), and low (6-8 mmHg) on the cross-sectional area (CSA) of the internal jugular vein (IJV) using ultrasonography, haemodynamic changes and duration of surgery. Surgeon’s comfort and feasibility of performing laparoscopic surgeries with low pressure pneumoperitoneum was also studied.

Methods:

This prospective, double-blind, randomised study included 148 patients of American Society of Anesthesiologists physical status class I and II undergoing laparoscopic surgeries. They were allocated into two groups: group S (standard) (number (n) = 73) had the IAP maintained between 13-15 mmHg; group L (low) had an IAP of 6-8 mmHg (n = 75). CSA of right IJV was measured before induction of anaesthesia (T1), 5 min after intubation (T2), 5 min after pneumoperitoneum (T3), before desufflation (T4) and 5 min prior to extubation (T5). Chi-square test, and Student’s paired and unpaired t test were used for statistical analysis.

Results:

The increase in IJV CSA at T3 when compared to T2 was statistically significant in both the groups (P < 0.001). On desufflation, the change in IJV CSA showed significant decrease in T5 value than T4 value in both the groups (P < 0.001). However, the percentage change in the IJV CSA was more in group S (35.4%) than group L (21.2%).

Conclusion:

CSA of IJV increased significantly even with lower IAP of 6-8 mmHg. Laparoscopic surgery can be performed conveniently even at low IAP.

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.