Low Pneumoperitoneum Pressure Reduces Gas Embolism During Laparoscopic Liver Resection: A Randomized Controlled Trial.

OBJECTIVE: To compare the effect of low and standard pneumoperitoneal pressure (PP) on the occurrence of gas embolism during laparoscopic liver resection (LLR). BACKGROUND: LLR has an increased risk of gas embolism. Although animal studies have shown that low PP reduces the occurrence of gas embolism, clinical evidence is lacking. METHODS: This parallel, dual-arm, double-blind, randomized controlled trial included 141 patients undergoing elective LLR. Patients were randomized into standard ("S," 15 mm Hg; n = 70) or low ("L," 10 mm Hg; n = 71) PP groups. Severe gas embolism (≥ grade 3, based on the Schmandra microbubble method) was detected using transesophageal echocardiography and recorded as the primary outcome. Intraoperative vital signs and postoperative recovery profiles were also evaluated. RESULTS: Fewer severe gas embolism cases (n = 29, 40.8% vs n = 47, 67.1%, P = 0.003), fewer abrupt decreases in end-tidal carbon dioxide partial pressure, shorter severe gas embolism duration, less peripheral oxygen saturation reduction, and fewer increases in heart rate and lactate during gas embolization episodes was found in group L than in group S. Moreover, a higher arterial partial pressure of oxygen and peripheral oxygen saturation were observed, and fewer fluids and vasoactive drugs were administered in group L than in group S. In both groups, the distensibility index of the inferior vena cava negatively correlated with central venous pressure throughout LLR, and a comparable quality of recovery was observed. CONCLUSIONS: Low PP reduced the incidence and duration of severe gas embolism and achieved steadier hemodynamics and vital signs during LLR. Therefore, a low PP strategy can be considered a valuable choice for the future LLR.

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.

Effect of low-pressure pneumoperitoneum on pain and inflammation in laparoscopic cholecystectomy: a randomized controlled clinical trial.

OBJECTIVE: We aim to assess the effect of low-pressure pneumoperitoneum on post operative pain and ten of the known inflammatory markers. BACKGROUND: The standard of care pneumoperitoneum set pressure in laparoscopic cholecystectomy is set to 12-14 mmHg, but many societies advocate to operate at the lowest pressure allowing adequate exposure of the operative field. Many trials have described the benefits of operating at a low-pressure pneumoperitoneum in terms of lower post operative pain, and better hemodynamic stability. But only few describe the effects on inflammatory markers and cytokines. METHODS: A prospective, double-blinded, randomised, controlled clinical trial, including patients who underwent elective laparoscopic cholecystectomy. Patients randomised into low-pressure (8-10 mmHg) vs. standard-pressure (12-14 mmHg) with an allocation ratio of 1:1. Perioperative variables were collected and analysed. RESULTS: one hundred patients were allocated, 50 patients in each study arm. Low-pressure patients reported lower median pain score 6-hour post operatively (5 vs. 6, p-value = 0.021) in comparison with standard-pressure group. Eight out of 10 inflammatory markers demonstrated better results in low-pressure group in comparison with standard-pressure, but the effect was not statistically significant. Total operative time and surgery difficulty was not significantly different between the two groups even in the hands of inexperienced surgeons. CONCLUSION: low-pressure laparoscopic cholecystectomy is associated with less post operative pain and lower rise of inflammatory markers. It is feasible with comparable complications to the standard of care. Registered on ClinicalTrials.gov (NCT05530564/ September 7th, 2022).

Effect of duration of pneumoperitoneum on renal function in patients undergoing laparoscopic surgeries: a prospective observational study.

This study aimed to assess the effect of pneumoperitoneum and, thereby, raised intra-abdominal pressure for different durations (≤ 1 h, 1-3 h and > 3 h) on renal function. One hundred and twenty adult patients were allocated to four groups-the Control Group A (N = 30; patients undergoing non-laparoscopic surgery) or Group B (N = 30; patients undergoing laparoscopic surgery with duration of pneumoperitoneum < 1 h) or Group C (N = 30; patients undergoing laparoscopic surgery with duration of pneumoperitoneum 1-3 h) or Group D (N = 30; patients undergoing laparoscopic surgery with duration of pneumoperitoneum > 3 h). The baseline, intraoperative (at the end of pneumoperitoneum/surgery), and postoperative (after 6 h) values of blood urea levels, creatinine clearance, and serum cystatin C were compared. The results showed that the raised IAP (10-12 mmHg) and varying durations of pneumoperitoneum (from less than 1 h to more than 3 h) did not significantly affect renal function measured in terms of change in serum cystatin levels from baseline to 6 h in postoperative period. The varying durations of pneumoperitoneum also did not significantly affect serum creatinine or blood urea levels in the postoperative period. CTRI registration: CTRI/2016/10/007334.

Major and minor complications in Veress needle (VN) and direct trocar insertion (DTI) for laparoscopic closed-entry techniques: an updated systematic review and meta-analysis.

OBJECTIVE: Direct insertion of the trocar is an alternative method to Veress needle insertion for the creation of pneumoperitoneum. We conducted a systematic review and meta-analysis to compare these two entry closed techniques. DATA SOURCE: A systematic review of the literature was done on PubMed, MEDLINE, Embase, Scopus, and EBSCO. METHODS: The literature search was constructed until May 01, 2022, around search terms for "Veress," "direct trocar," "needle," "insertion," and "laparoscopic ways of entry." This systematic review was reported according to the PRISMA Statement 2020. RESULTS: Sixteen controlled trials (RCTs) and 5 observational studies were included in the systematic review. We found no significant differences in the risk of major complication during the access manoeuvres between DTI and VN: bowel injuries (OR = 0.76, 95% CI: 0.24-2.36, P = 0.63), major vascular injuries (OR = 1.74, 95% CI 0.56-5.38, P = 0.34), port site hernia (OR = 2.41, 95% CI: 0.28-20.71, P = 0.42). DTI has a lower risk of minor complications such as subcutaneous emphysema (OR = 5.19 95% CI: 2.27-11.87, P < 0.0001), extraperitoneal insufflation (OR = 5.93 95% CI: 1.69-20.87, P = 0.006), omental emphysema (OR = 18.41, 95% CI: 7. 01-48.34, P < 0.00001), omental bleeding (OR = 2.32, 95% CI: 1.18-4.55, P = 0.01), and lower number of unsuccessful entry or insufflation attempts (OR = 2.25, 95% CI: 1.05-4.81, P = 0.04). No significant differences were found between the two groups in terms of time required to achieve complete insufflation (MD = - 15.53, 95% CI: - 91.32 to 60.27, P = 0.69), trocar site bleeding (OR = 0.66, 95% CI, 0.25-1.79, P = 0.42), and trocar site infection (OR = 1.19, 95% CI, 0.34-4.20, P = 0.78). CONCLUSION: There were no statistically significant differences in the risk of major complications during the access manoeuvres between DTI and VN. A lower number of minor complications were observed in DTI compared with those in Veress access.

Impact of pneumoperitoneum pressure during laparoscopic hysterectomy: A randomized controlled trial.

OBJECTIVE: Minimally invasive hysterectomy is a commonly performed gynecologic procedure with associated postoperative pain managed with opioid medications. Uncontrolled postoperative pain leads to increased opioid use/abuse, longer hospital stays, increase in healthcare visits, and may negatively affect patient satisfaction. Current data suggests that reduced pneumoperitoneum insufflation pressure during laparoscopic surgery may impact postoperative pain. Given the current opioid epidemic, surgeons are proactively finding ways to reduce postoperative pain. It is unclear how reduced pneumoperitoneum pressure impacts the surgeon. We investigated the impact of reduced pneumoperitoneum insufflation pressure on surgeon satisfaction. STUDY DESIGN: This was a pilot, double-blinded, randomized controlled trial from March 2020 to July 2021 comparing pneumoperitoneum pressure of 15 mmHg to reduced pressures of 12 mmHg and 10 mmHg during laparoscopic hysterectomy. RESULTS: A total of 40 patients were randomized (13 - 15 mmHg, 13 - 12 mmHg, and 14 - 10 mmHg). The primary outcome was surgeon satisfaction. Secondary outcomes included patient satisfaction, operative time, blood loss, postoperative pain, opioid usage, and discharge timing. There were no differences in baseline demographics or perioperative characteristics. Surgeon satisfaction was negatively impacted with lower pneumoperitoneum pressures greatest with 10 mmHg, including overall satisfaction (p =.01), overall effect of the pneumoperitoneum (p =.04), and quality of visualization (p =.01). There was an apparent although not statistically significant difference in operative time (p =.06) and blood loss (p =.054). There was no difference in patient satisfaction, postoperative pain scores, opioid usage, or time to discharge. CONCLUSION(S): Reduced pneumoperitoneum insufflation pressure during laparoscopic hysterectomy negatively impacted surgeon satisfaction with a trend towards longer operative times and greater blood loss, and did not positively impact patient satisfaction, postoperative pain, opioid demand, or discharge timing.

Prediction of blood pressure changes associated with abdominal pressure changes during robotic laparoscopic low abdominal surgery using deep learning.

BACKGROUND: Intraoperative hypertension and blood pressure (BP) fluctuation are known to be associated with negative patient outcomes. During robotic lower abdominal surgery, the patient's abdominal cavity is filled with CO2, and the patient's head is steeply positioned toward the floor (Trendelenburg position). Pneumoperitoneum and the Trendelenburg position together with physiological alterations during anesthesia, interfere with predicting BP changes. Recently, deep learning using recurrent neural networks (RNN) was shown to be effective in predicting intraoperative BP. A model for predicting BP rise was designed using RNN under special scenarios during robotic laparoscopic surgery and its accuracy was tested. METHODS: Databases that included adult patients (over 19 years old) undergoing low abdominal da Vinci robotic surgery (ovarian cystectomy, hysterectomy, myomectomy, prostatectomy, and salpingo-oophorectomy) at Soonchunhyang University Bucheon Hospital from October 2018 to March 2021 were used. An RNN-based model was designed using Python3 language with the PyTorch packages. The model was trained to predict whether hypertension (20% increase in the mean BP from baseline) would develop within 10 minutes after pneumoperitoneum. RESULTS: Eight distinct datasets were generated and the predictive power was compared. The macro-average F1 scores of the datasets ranged from 68.18% to 72.33%. It took only 3.472 milliseconds to obtain 39 prediction outputs. CONCLUSIONS: A prediction model using the RNN may predict BP rises during robotic laparoscopic surgery.

Benefits of AirSeal System in Laparoscopic Hysterectomy for Benign Condition: A Randomized Controlled Trial.

STUDY OBJECTIVE: To compare the AirSeal insufflation system with the standard insufflation system for postoperative abdominal pain after laparoscopic hysterectomy for benign pathology. DESIGN: Randomized controlled trial. SETTING: Teaching Hospital La Conception, Marseille, France, February 2018 to July 2020. PATIENTS: A total of 80 patients scheduled for a laparoscopic hysterectomy for benign pathology (40 per group). INTERVENTION: Laparoscopic hysterectomy using the AirSeal insufflation system with a pneumoperitoneum between 8 and 10 mm Hg compared with the standard insufflation system with a pneumoperitoneum between 12 and 15 mm Hg. MEASUREMENTS AND MAIN RESULTS: The primary end point was abdominal pain at 6 hours after the end of surgery, assessed by a Simple Numerical Scale from 0 to 10. The secondary end points were intraoperative (operating time and difficulty of the surgery felt by the operator), early postoperative (intensity of abdominal and scapular pain at H0 [end of surgery], H2 [two hours after the end of surgery, H12 [twelve hour after the end of surgery], H24 [twenty four hours after the end of surgery], H48 [fourty eight hours after the end of surgery]), and late postoperative (late postoperative complication, estimated time to return to normal life, and overall patient satisfaction assessed by the SF-12 general health survey). The median values for abdominal pain were not different between the 2 groups at 6 hours (AirSeal group median, 0; interquartile range, 2 vs standard laparoscopy group median, 1; interquartile range, 2; p = .41). The abdominal and scapular pain values were similar in both groups at all postoperative times. There were no differences between the groups regarding secondary end points. CONCLUSION: Use of the AirSeal insufflation system with low-pressure pneumoperitoneum in laparoscopic hysterectomy for a benign indication did not reduce postoperative abdominal and scapular pain.

Randomized Trial of Ultralow vs Standard Pneumoperitoneum during Robotic Prostatectomy.

PURPOSE: Laparoscopic and robotic surgery have traditionally been performed with pneumoperitoneum of 12-15 mmHg. Based upon our previous retrospective study showing an advantage to using ultralow pneumoperitoneum during robotic prostatectomy (RP), we performed a randomized, double-blinded, controlled trial of RP at 6 mmHg vs 15 mmHg to assess postoperative pain and opioid use. MATERIALS AND METHODS: Patients undergoing RP with lymphadenectomy by a single surgeon were randomized to pneumoperitoneum pressures of 6 mmHg vs 15 mmHg. Pain scores and opioid use were recorded every 2 hours until discharge. Groups underwent intention-to-treat analysis on the primary outcome of pain scores up to 8 hours after post-anesthesia care unit. RESULTS: A total of 138 patients were randomized to RP at 6 mmHg or 15 mmHg (67 and 71, respectively). Mean console time was 7 minutes longer at 6 mmHg (135 vs 128 minutes, p=0.02). Mean estimated blood loss was similar (p=0.4) with no transfusions in either group. Most patients were discharged on the same day as surgery (88% vs 84%, p=0.5). There was no statistically significant difference observed in morphine equivalents administered during surgery or used postoperatively, yet 6 mmHg patients had lower immediate (0-4 hours) mean pain scores (2.1 vs 3.5, p <0.01) and lower maximum pain scores (3.0 vs 5.2, p <0.01). Shoulder pain was lower in 6 mmHg patients (0.03 vs 0.15, p=0.01), as was groin pain (0.6 vs 1.2 p=0.01). Patients reported flatus earlier with 6 mmHg (mean 1.0 day vs 1.3 days, p <0.01). CONCLUSIONS: Pneumoperitoneum pressure of 6 mmHg during RP has several advantages over the commonly used level of 15 mmHg without any identified disadvantages. Surgeons should consider using lower insufflation pressures.

Accidental peritoneum-cutaneous fistula after insufflation of preoperative progressive pneumoperitoneum in a large incisional hernia with loss of domain.

Preoperative progressive pneumoperitoneum has represented an important advancement in achieving the reintroduction of large herniated volumes into the abdominal cavity. However, this technique is not free of complications. We present a case of a man in his 70s with an accidental peritoneal-cutaneous fistula, secondary to the excessive pressure of the pneumoperitoneum, during the preparation of a large incisional hernia with loss of domain intervention.

Active aspiration versus simple compression to remove residual gas from the abdominal cavity after laparoscopic cholecystectomy: a randomized clinical trial.

PURPOSE: After laparoscopic surgical procedures, residual gas in the abdominal cavity can cause post-operative pain, which is commonly located in the shoulder region. Previous studies suggested that post-laparoscopy pain can be prevented by active suctioning of intraabdominal gas at the end of surgery. METHODS: This randomized controlled trial (registered at DRKS 00,023,286) compared active suctioning versus manual compression in their ability to reduce pain after laparoscopic cholecystectomy. Patients scheduled for laparoscopic cholecystectomy were eligible for trial participation. The primary outcome measure was post-operative pain intensity after 12 h. All the patients were examined by MRI scanning to quantify the intraabdominal gas volume after the intervention. RESULTS: As planned, 60 patients were recruited. The two groups (n = 30 each) were very similar at the end of surgery. Active suctioning reduced the amount of residual pneumoperitoneum more than simple compression (median volume 1.5 versus 3.0 ml, p = 0.002). The primary outcome measure, abdominal pain after 12 h, was slightly lower in the intervention group (- 0.5 points, 95% confidence interval + 0.5 to - 1.7), but without reaching statistical significance (p = 0.37). After 12 h, shoulder pain was present in 10 patients in each group (p = 1.0). Independent of group assignment, however, residual gas volume was significantly associated with higher pain intensity. CONCLUSIONS: Active suctioning appears to have only a minor preventive effect on post-laparoscopy pain, probably because evacuation of the pneumoperitoneum remains incomplete in some patients. Other more effective maneuvers for gas removal should be preferred.

Review of Outcomes of Low Verses Standard Pressure Pneumoperitoneum in Laparoscopic Surgery.

BACKGROUND: Carbon dioxide pneumoperitoneum during laparoscopy changes cardiorespiratory physiology and contributes to post-op pain. We studied outcomes before and after implementing low-pressure pneumoperitoneum QI project. METHODS: Forty-two patients were insufflated at standard pressures (15 mmHg) while 41 were insufflated using low (8-12 mmHg) during laparoscopic procedures. These variables were obtained from the patient chart: pain scores, intravenous morphine milligram equivalents (MME), peak inspiratory pressures (PIP), end-tidal CO2 (EtCO2), surgery duration, and patient demographics. The study was conducted after IRB approval. RESULTS: Low-pressure pneumoperitoneum is feasible and the surgeon can increase to 10-12 mmHg as needed. The mean post-op IV MME was significantly decreased in the low-pressure group (11.75 ± 10.41) compared to the standard pressure group (17.36 ± 18.1) (t-test, P = .047). Mean peak inspiratory pressures during insufflation were significantly higher for procedures conducted at standard pressure (31.40 ± 4.82) compared to the 8 mmHg (24.68 ± 4.19) and 12 mmHg (27.33± 3.85) low pressure groups (one-way ANOVA, P < .0001). During insufflation, there was a significant increase in the average EtCO2 in the standard pressure group (42.07 ± 5.60) compared to the 8 mmHg low pressure group (37.59 ± 5.05) (ANOVA, P = .0096). Constant flow insufflation was more likely to be performed at low pressure than demand mode (58% v. 33%). CONCLUSION: Low pressure pneumoperitoneum decreases PIP pressure and CO2 absorption evidenced by lower ETCO2 intra-operatively. Patients have significant improvement in postoperative pain evidenced by decreased narcotics needed. Low pressure pneumoperitoneum using a constant flow insufflator is safe and results in improved patient outcomes.

Shall we use low-pressure CO2 pneumoperitoneum in laparoscopic cholecystectomy?

BACKGROUND E AIMS: We aimed to determine whether intraabdominal pressure change caused by pneumoperitoneum created during laparoscopic cholecystectomy (LC) has effects on abdominal and shoulder pain, nausea, vomiting, bowel movements, time of first flatus and defecation, and biochemical parameters. METHODS: Seventy patients that were diagnosed with cholelithiasis and would undergo LC, between the ages of 18-75, with the Society of Anesthesia Physical Status (ASA) I-III classifications were included in the study. Patients were divided into two groups as whose intervention was defined as low pressure (8-10 mm/hg) and whose intervention was defined as high pressure (14-16 mm/hg). Differences in the prognoses of patients in both groups were observed for statistical significance. RESULTS: Shoulder pain- visual analogue scale (VAS) values in 6th and 24th hours were lower in Group 1(p<0.005). There was no significant difference in abdominal pain-VAS values(p≥0.05). Mean intraoperative end-tidal carbon dioxide (ETCO2) values were higher in Group 2 (p<0.005). Differences in nausea and vomiting were not significant(p≥0.05). There was no significant difference in the first flatus times(p≥0.05). Bowel movements resumed earlier in Group 1(p<0.005). Changes were not significant for biochemical blood parameters in the preoperative and postoperative periods( p≥0.05). CONCLUSION: The use of low-pressure and high pressure carbon-dioxide (CO2)-pneumoperitoneum created during LC does not cause a significant difference in terms of clinical and laboratory results. Therefore, the surgical team should prefer an easy-to-apply pressure level which they are used to and in which they have low complication rates. KEY WORDS: Cholecystectomy, Pneumoperitoneum, Low-pressure CO2.

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.

The role of Cushing's reflex and the vasopressin-mediated oligoanuric response to intracranial hypertension in patients with abdominal compartment syndrome.

BACKGROUND: We examined the link between increased intra-abdominal pressure, intracranial pressure, and vasopressin release as a potential mechanism. Intra-abdominal pressure, produced by abdominal-cavity insufflation with carbon dioxide (CO2) during laparoscopic abdominal procedures to facilitate visualization, is associated with various complications, including arterial hypertension and oliguria. METHODS: Mean arterial pressure, optic nerve sheath diameter, measured as a proxy for intracranial pressure, plasma vasopressin, serum and urine osmolarity, and urine output were measured 4 times during laparoscopic sleeve gastrectomy in 42 patients: before insufflation with CO2 (T0); after insufflation to 15 cm water (H2O) pressure, with 5 cm H2O positive end-expiratory pressure (T1); after positive end-expiratory pressure was raised to 10 cm H2O (T2); and after a return to the baseline state (T3). Mean values at T0 to T3 and the directional consistency of changes (increase/decrease/ unchanged) were compared among the 4 data-collection points. RESULTS: Statistically significant elevations (all P ≤ .001) were noted from T0 to T1 and from T0 to T2 in mean arterial pressure, optic nerve sheath diameter, and vasopressin, followed by decreases at T3. For optic nerve sheath diameter and vasopressin, the increases at T1 and T2 occurred in 98% and 100% of patients, ultimately exceeding normal levels in 88 and 97%, respectively. Conversely, urine output fell from T0 to T1 and T2 by 60.9 and 73.4%, decreasing in 88.1% of patients (all P < .001). Patients with class II obesity exhibited statistically greater increases in optic nerve sheath diameter and vasopressin, but statistically less impact on urine output, than patients with class III obesity. CONCLUSION: Increased mean arterial pressure, intracranial pressure, and vasopressin release appear to be intermediary steps between increased intra-abdominal pressure and oliguria. Further research is necessary to determine any causative links between these physiological changes.

Severe portal and systemic acidosis during CO2-laparoscopy compared to helium or gasless laparoscopy and laparotomy in a rodent model: an experimental study.

BACKGROUND AND AIMS: This experimental study assesses the influence of different gases and insufflation pressures on the portal, central-venous and peripheral-arterial pH during experimental laparoscopy. METHODS: Firstly, 36 male WAG/Rij rats were randomized into six groups (n = 6) spontaneously breathing during anaesthesia: laparoscopy using carbon dioxide or helium at 6 and 12 mmHg, gasless laparoscopy and laparotomy. 45 and 90 min after setup, blood was sampled from the portal vein, vena cava and the common femoral artery with immediate blood gas analysis. Secondly, 12 animals were mechanically ventilated at physiological arterial pH during 90 min of laparotomy (n = 6) or carbon dioxide laparoscopy at 12 mmHg (n = 6) with respective blood gas analyses. RESULTS: Over time, in spontaneously breathing rats, carbon dioxide laparoscopy caused significant insufflation pressure-dependent portal acidosis (pH at 6 mmHg, 6.99 [6.95-7.04] at 45 min and 6.95 [6.94-6.96] at 90 min, pH at 12 mmHg, 6.89 [6.82-6.90] at 45 min and 6.84 [6.81-6.87] at 90 min; p < 0.05) compared to laparotomy (portal pH 7.29 [7.23-7.30] at 45 min and 7.29 [7.20-7.30] at 90 min; p > 0.05). Central-venous and peripheral-arterial acidosis was significant but less severely reduced during carbon dioxide laparoscopy. Laparotomy, helium laparoscopy and gasless laparoscopy showed no comparable acidosis in all vessels. Portal and central-venous acidosis during carbon dioxide laparoscopy at 12 mmHg was not reversible by mechanical hyperventilation maintaining a physiological arterial pH (pH portal 6.85 [6.84-6.90] (p = 0.004), central-venous 6.93 [6.90-6.99] (p = 0.004), peripheral-arterial 7.29 [7.29-7.31] (p = 0.220) at 90 min; Wilcoxon-Mann-Whitney test). CONCLUSION: Carbon dioxide laparoscopy led to insufflation pressure-dependent severe portal and less severe central-venous acidosis not reversible by mechanical hyperventilation.

Preperitoneal insufflation pressure of the abdominal wall in a porcine model.

BACKGROUND: Most complications and adverse events during laparoscopic surgery occur during initial entry into the peritoneal cavity. Among them, preperitoneal insufflation occurs when the insufflation needle is incorrectly placed, and the abdominal wall is insufflated. The objective of this study was to find a range for static pressure which is low enough to allow placement of a Veress needle into the peritoneal space without causing preperitoneal insufflation, yet high enough to separate abdominal viscera from the parietal peritoneum. METHODS: A pressure test was performed on twelve fresh porcine carcasses to determine the minimum preperitoneal insufflation pressure and the minimum initial peritoneal cavity insufflation pressure. Each porcine model had five needle placement categories. One category tested the initial peritoneal cavity insufflation pressure beneath the umbilicus. The four remaining categories tested the preperitoneal insufflation pressure at four different anatomical locations on the abdomen that can be used for initial entry. The minimum initial insufflation pressures from each carcass were then compared to the preperitoneal insufflation pressures to obtain an optimal range for initial insufflation. RESULTS: Increasing the insufflation pressure increased the probability of preperitoneal insufflation. Also, there was a statistically significant difference (p < 0.05) between the initial peritoneal cavity insufflation pressures (8.83 ± 4.19 mmHg) and the lowest preperitoneal pressures (32.54 ± 7.84 mmHg) (mean ± SD). CONCLUSION: Pressures greater than 10 mmHg resulted in initial cavity insufflation and pressures greater than 20 mmHg resulted in preperitoneal insufflation in porcine models. By knowing the minimum pressure required to separate the layers of the abdominal wall, the risk of preperitoneal insufflation can be mitigated while obtaining safe and efficient entry into the peritoneal cavity. The findings in this research are not a guideline for trocar or Veress needle placement, but instead reveal preliminary data which may lead to more studies, technology, etc.

Gas embolism under standard versus low pneumoperitoneum pressure during laparoscopic liver resection (GASES): study protocol for a randomized controlled trial.

BACKGROUND: Gas embolism induced by CO2 pneumoperitoneum is commonly identified as a risk factor for morbidity, especially cardiopulmonary morbidity, after laparoscopic liver resection (LLR) in adults. Increasing pneumoperitoneum pressure (PP) contributes to gas accumulation following laparoscopy. However, few studies have examined the effects of PP in the context of LLR. In LLR, the PP-central venous pressure (CVP) gradient is increased due to hepatic vein rupture, hepatic sinusoid exposure, and low CVP management, which together increase the risk of CO2 embolization. The aim of this study is to primarily determine the role of low PP (10 mmHg) on the incidence of severe gas embolism. METHODS: Adult participants (n = 140) undergoing elective LLR will be allocated to either a standard (15 mmHg) or low (10 mmHg) PP group. Anesthesia management, postoperative care, and other processes will be performed similarly in both groups. The occurrence of severe gas embolism, which is defined as gas embolism ≥ grade 3 according to the Schmandra microbubble method, will be detected by transesophageal echocardiography (TEE) and recorded as the primary outcome. The subjects will be followed up until discharge and followed up by telephone 1 and 3 months after surgery. Postoperative outcomes, such as the Post-Operative Quality of Recovery Scale, pain severity, and adverse events, will be assessed. Serum cardiac markers and inflammatory factors will also be assessed during the study period. The correlation between intraoperative inferior vena cava-collapsibility index (IVC-CI) under TEE and central venous pressure (CVP) will also be explored. DISCUSSION: This study is the first prospective randomized clinical trial to determine the effect of low versus standard PP on gas embolism using TEE during elective LLR. These findings will provide scientific and clinical evidence of the role of PP. TRIAL STATUS: Protocol version: version 1 of 21-08-2020 TRIAL REGISTRATION: ChiCTR2000036396 ( http://www.chictr.org.cn ). Registered on 22 August 2020.

The Impact of Incentive Spirometry on Shoulder Tip Pain in Laparoscopic Cholecystectomy: A Randomized Clinical Trial.

BACKGROUND: Shoulder pain is among the early postlaparoscopic symptoms related to carbon dioxide used for pneumoperitoneum, which remains in the abdominal cavity. Therefore, incentive spirometry (IS) is a novel technique to alleviate this pain following laparoscopic cholecystectomy (LC). The present study was designed to investigate if the use of IS after LC would relieve shoulder tip pain, and determine the amount of postoperative opioid analgesics utilized. MATERIALS AND METHODS: This randomized clinical trial was conducted on patients who were clinically diagnosed with cholecystitis, and underwent LC. Accordingly, group I patients (n=42) received IS (including 10 deep breaths with a spirometer in sitting or semisitting positions) in full consciousness every 2 hours starting at 2 hours after surgery, but group II patients (n=42) did not have respiratory physiotherapy. The postoperative shoulder pain after the surgery was further evaluated by a numerical rating scale (NRS). RESULTS: At 4, 8, 12, 24, and 48 hours following LC, the NRS pain scores significantly reduced in group I compared with group II. In addition, the results of the repeated measures analysis of variance indicated significantly lower NRS pain scores within the first 48 hours after LC in group I compared with group II. Consequently, the study findings showed a significantly higher percentage of cases in group II, requiring postoperative analgesics, in comparison with group I. CONCLUSIONS: IS decreased the severity of shoulder tip pain after LC with no complications. Thus, IS may be considered as a viable alternative to other laparoscopic interventions. However, still further studies are necessary to evaluate its efficacy compared with other techniques.