Reduction of CO(2)-pneumoperitoneum-induced metabolic hypoxaemia by the addition of small amounts of O(2) to the CO(2) in a rabbit ventilated model. A preliminary study

Global recommendations on adhesion prophylaxis in gynaecological laparoscopic surgery

Adhesions are recognised as one of the most common complications of abdominal surgery; their diagnosis and prevention remains a significant unmet need in surgical therapy, affecting negatively a patient's quality of life and healthcare budgets. In addition, postoperative pelvic adhesions pose a high risk of reduced fertility in women of childbearing age. These 2023 Global Recommendations on Adhesion Prevention in Gynaecological Laparoscopic Surgery provide agreed-upon statements to guide clinical practice, with the ultimate goal of improving patient outcomes.

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.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Peritoneal full-conditioning reduces postoperative adhesions and pain: a randomised controlled trial in deep endometriosis surgery

BACKGROUND

To translate the concept of full-conditioning (FC) from animal experiments to the human, and to evaluate the efficacy for adhesion prevention. FC consisted of decreasing acute inflammation by 86% CO2+ 10% N2O + 4% O2 for the pneumoperitoneum, cooling of the peritoneal cavity, humidification, heparinized rinsing solution and 5 mg of dexamethasone as demonstrated in animal models.

METHODS

A randomized controlled trial (RCT: NCT01344486) comparing standard laparoscopy with full conditioning together with a barrier in a 2/3 ratio in 44 women undergoing deep endometriosis surgery at KULeuven. The primary aim was reduction of adhesions. Secondary aims were CO2 resorption, postoperative pain and recovery. Randomization was performed after signing informed consent. Adhesion scoring during second look laparoscopy and pain scoring were done blindly.

RESULTS

In the FC group (n = 16) adhesions were completely prevented in 12/16 women whereas in the control group (n = 11) all women had severe adhesions (P < 0.0005). Also the area, density and severity of adhesions were less. (P <0.001). In the control group, severity, density and area of adhesions were strongly interrelated (P = 0.0001 for all areas) suggesting a common enhancing factor. In the FC group CO2 resorption (P < 0.001), postoperative pain (P < 0.001), and CRP concentrations (P < 0.01) were lower while clinical recovery was faster (P < 0.0001) and time to first flatus (P < 0.002) shorter.

IN CONCLUSION

This translational research confirms in the human the efficacy of FC in reducing CO2 resorption and adhesions with in addition less postoperative pain, lower postoperative CRP concentrations and an accelerated recovery.

Severe inflammatory reaction induced by peritoneal trauma is the key driving mechanism of postoperative adhesion formation

BACKGROUND

Many factors have been put forward as a driving mechanism of surgery-triggered adhesion formation (AF). In this study, we underline the key role of specific surgical trauma related with open surgery (OS) and laparoscopic (LS) conditions in postoperative AF and we aimed to study peritoneal tissue inflammatory reaction (TIR), remodelling specific complications of open surgery (OS) versus LS and subsequently evaluating AF induced by these conditions.

METHODS

A prospective randomized study was done in 80 anaesthetised female Wistar rats divided equally into 2 groups. Specific traumatic OS conditions were induced by midline incision line (MIL) extension and tissue drying and specific LS conditions were remodelled by intraperitoneal CO2 insufflation at the 10 cm of water. TIR was evaluated at the 24th, 72nd, 120th and 168th hour by scoring scale. Statistical analysis was performed by the non-parametric t test and two-way ANOVA using Bonferroni post-tests.

RESULTS

More pronounced residual TIR was registered after OS than after LS. There were no significant TIR interactions though highly significant differences were observed between the OS and LS groups (p < 0.0001) with regard to surgical and time factors. The TIR change differences between the OS and LS groups were pronounced with postoperative time p < 0.05 at the 24th and 72nd; p < 0.01--120th and p < 0.001--168th hrs. Adhesion free wounds were observed in 20.0 and 31.0% of cases after creation of OS and LS conditions respectively; with no significant differences between these values (p > 0.05). However larger adhesion size (41.67 ± 33.63) was observed after OS in comparison with LS (20.31 ± 16.38). The upper-lower 95% confidential limits ranged from 60.29 to 23.04 and from 29.04 to 11.59 respectively after OS and LS groups with significant differences (p = 0.03). Analogous changes were observed in adhesion severity values. Subsequently, severe TIR parameters were followed by larger sizes of severe postoperative adhesions in the OS group than those observed in the LS group.

CONCLUSIONS

MIL extension and tissue drying seem to be the key factors in the pathogenesis of adhesion formation, triggering severe inflammatory reactions of the peritoneal tissue surrounding the MIL resulting in local and systemic consequences. CO2 insufflation however, led to moderate inflammation and less adhesion formation.

Effects of adding small amounts of oxygen to a carbon dioxide-pneumoperitoneum of increasing pressure in rabbit ventilation models

OBJECTIVE

To evaluate the metabolic consequences of the addition of oxygen to the CO(2)-pneumoperitoneum.

DESIGN

Prospective randomized study in rabbits. After 30 minutes of ventilation pneumoperitoneum was maintained for 90 minutes with pure CO(2) or CO(2) with 2% or 6% of oxygen. The intraperitoneal pressure was increased from 10 to 15 and 20 mm Hg every 30 minutes. Ventilation rate was either fixed or a progressive hyperventilation. End points were changes in arterial blood gases (Pco(2), Po(2)), pH, acid-base balance (actual base excess [ABE], standard bicarbonate [SBC], standard base excess [SBE], hydrogen carbonate [HCO(3)(-)], concentration of total carbon dioxide [Tco(2)]); oxygen and oximetry (oxyhemoglobin [O(2)Hb], oxygen saturation [So(2)], reduced hemoglobin [RHb], total oxygen concentration [To(2)], and oxygen tension at half saturation assessing hemoglobin oxygen affinity [p50]); and lactate concentrations assayed every 15 minutes.

SETTING

University research center.

ANIMALS

Twenty-four adult female New Zealand white rabbits.

INTERVENTION(S)

Anesthesia, mechanical ventilation, and pneumoperitoneum.

RESULT(S)

The effects of CO(2)-pneumoperitoneum on all end points increased with the elevated intraperitoneal pressure and were more pronounced when ventilation was fixed. Changes were less when 2% or 6% of oxygen had been added to the CO(2)-pneumoperitoneum. With use of logistic regression, the addition of oxygen, intraperitoneal pressure, and ventilation were found to be independent variables affecting Pco(2), pH, ABE, SBE, HCO(3)(-), O(2)Hb, So(2), p50, and end-tidal CO(2).

CONCLUSION(S)

The metabolic consequences of the combined effect of increased intraperitoneal pressure and CO(2)-pneumoperitoneum were less when 2% to 6% of oxygen was added or when animals were hyperventilated. We suggest that metabolic and mesothelial hypoxemia caused by CO(2) absorption can be reduced by adding small amounts of oxygen and by hyperventilation.

Effect of reactive oxygen species scavengers, antiinflammatory drugs, and calcium-channel blockers on carbon dioxide pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

BACKGROUND

Postoperative adhesions are a clinical problem. They can cause female infertility, intestinal obstruction, chronic pelvic pain, and difficulties at the time of reoperation. A variety of approaches described to prevent adhesions have shown variable and inconsistent results. Therefore, this study aimed to evaluate most known substances in a laparoscopic mouse model to obtain quantitative and comprehensive information on adhesion prevention. Specifically, this first study aimed to investigate the effects of reactive oxygen species (ROS) scavengers, antiinflammatory agents, and a calcium-channel blocker on pneumoperitoneum-enhanced adhesions.

METHODS

Adhesions were induced during laparoscopy in BALB/c female mice by creation of a bipolar lesion. Carbon dioxide (CO2) pneumoperitoneum was maintained for 60 min using humidified CO2. Six experiments were conducted to evaluate the effects of ROS scavengers (superoxide dismutase [SOD], catalase, melatonin, and ascorbic acid), antiinflammatory agents (dexamethasone, tenoxicam, ibuprofen, parecoxib, nimesulide, anti-tumor necrosis factor [TNF]-alpha), and a calcium-channel blocker (diltiazem). Adhesions were scored after 7 days during laparotomy.

RESULTS

Adhesions were reduced by SOD (p < 0.01, proc general linear methods (GLM) of experiments 1 and 2), diltiazem (p = 0.05, Wilcoxon), and dexamethasone (p < 0.03), but not by nonsteroidal antiinflammatory drugs (NSAIDs) nor by anti-TNF-alpha. When all the experiments were grouped for analysis, adhesions also decreased with one and three doses of SOD (p < 0.01 and p < 0.01, respectively) and with one and three doses of ascorbic acid (p < 0.02 and p = 0.05, respectively).

CONCLUSIONS

These experiments confirm that SOD, diltiazem, and dexamethasone can decrease adhesion formation. The absence of effect from the other antiinflammatory drugs and anti-TNF-alpha is surprising.

Peritoneal tissue-oxygen tension during a carbon dioxide pneumoperitoneum in a mouse laparoscopic model with controlled respiratory support

BACKGROUND

Previous animal studies suggested that the peritoneal environment during a carbon dioxide (CO(2)) pneumoperitoneum is hypoxic and that this may contribute to the formation of intra-abdominal adhesions or the growth of malignant cells. There is no study, however, that investigates the relationship between anaesthesia, ventilation and the laparoscopic peritoneal environment to the development of hypoxia. The objective of this study is to monitor the peritoneal tissue-oxygen tension (PitO(2)) under various conditions including anaesthesia alone, during a CO(2) pneumoperitoneum at both low and high intraperitoneal pressure (IPP), and laparotomy, in animal models with controlled respiratory support (CRS).

METHODS

C57BL6 mice were divided into eight groups (n = 5) consisting of anaesthesia alone or with CO(2) pneumoperitoneum at low (2 mmHg) or high (8 mmHg) IPP or undergoing laparotomy. Groups were further subdivided into those with or without CRS with endotracheal intubation and mechanical ventilation. Over the course of the 1 h procedure, PitO(2) was continuously monitored.

RESULTS

Protocol 1. The PitO(2) levels (104.2 +/- 7.8 mmHg, mean +/- SEM) in non-injured peritoneum during a CO(2) pneumoperitoneum at a low IPP were elevated approximately 2-fold over the levels during laparotomy (49.8 +/- 15.0 mmHg) in ventilated mice. Protocol 2. After insufflation with CO(2), the PitO(2) was immediately elevated and maintained at a higher level. Following laparotomy, it decreased immediately. This elevation was not seen with air insufflation.

CONCLUSION

In mice, a significant elevation in PitO(2) occurs during a CO(2) pneumoperitoneum at low IPP with CRS.

The Addition of O2 to the CO2 Does Not Prevent the Systemic Effects of the CO2 Pneumoperitoneum in a Rabbit Model

CO2 pneumoperitoneum used in endoscopic surgery induces systemic effects by CO2 absorption. It was claimed that a reduction in CO2 pneumoperitoneum-induced metabolic hypoxemia was achieved by the addition of small amounts of O2 to the CO2 in a rabbit ventilated model. We reevaluated the effects of the addition of O2 to the CO2 pneumoperitoneum upon CO2 absorption in a rabbit model. The effects of a pneumoperitoneum using 100% CO2, 90% CO2 + 10% O2, 95% CO2 + 5% O2, or 100% O2 on arterial blood gases, acid base and O2 homeostasis were evaluated in nonintubated rabbits. A pneumoperitoneum pressure of 10 cm H2O (approximately 7.35 mm Hg) was used. CO2 pneumoperitoneum of 120 minutes affected blood gases and acid base homeostasis. Whereas partial pressure of CO2 and HCO3 increased (P < 0.001) during pneumoperitoneum, pH and partial pressure of O2 decreased (P < 0.001). Similar results were obtained in O2-CO2 pneumoperitoneum (P > 0.05). CO2 pneumoperitoneum profoundly affected blood gases and acid base homeostasis, resulting in metabolic hypoxemia. The addition of O2 to the CO2 did not prevent the systemic effects of CO2 pneumoperitoneum in nonintubated animals.

Molecular Characterization of Postoperative Adhesions: The Adhesion Phenotype

Postoperative adhesion development remains a very frequent occurrence, which is often unrecognized by surgeons because of limited ability to conduct early second-look laparoscopies. The consequences include infertility, pelvic pain, bowel obstruction, and difficult reoperative procedures. To date, approaches to limit adhesions primarily have involved barriers to separate tissue during reepithelization. Future progress in regulating adhesion development and tissue fibrosis likely will require an improved understanding of the molecular processes involved in normal peritoneal repair and its aberrations leading to adhesion development. We hypothesize that tissue hypoxia (in part resulting from tissue incision, fulguration, suture ligation, etc.) is the major inciting event, which leads to a coordinated series of molecular events that promote an inflammatory response leading to enhanced tissue fibrosis. These events are reduced plasminogen activator activity, extracellular matrix deposition, increased cytokine production, increased angiogenesis, and reduced apoptosis (programmed cell death). Improved understanding of these events and their regulation will provide the opportunity to regulate better postoperative adhesion development and tissue fibrosis, thereby reducing the morbidity and mortality they cause.