Optimizing working space in laparoscopy: CT measurement of the effect of pre-stretching of the abdominal wall in a porcine model

Comparison of low versus high (standard) intraabdominal pressure during laparoscopic colorectal surgery: systematic review and meta-analysis

BACKGROUND

To evaluate outcomes of low with high intraabdominal pressure during laparoscopic colorectal resection surgery.

METHODS

A systematic search of multiple electronic data sources was conducted, and all studies comparing low with high (standard) intraabdominal pressures were included. Our primary outcomes were post-operative ileus occurrence and return of bowel movement/flatus. The evaluated secondary outcomes included: total operative time, post-operative haemorrhage, anastomotic leak, pneumonia, surgical site infection, overall post-operative complications (categorised by Clavien-Dindo grading), and length of hospital stay. Revman 5.4 was used for data analysis.

RESULTS

Six randomised controlled trials (RCTs) and one observational study with a total of 771 patients (370 surgery at low intraabdominal pressure and 401 at high pressures) were included. There was no statistically significant difference in all the measured outcomes; post-operative ileus [OR 0.80; CI (0.42, 1.52), P = 0.50], time-to-pass flatus [OR -4.31; CI (-12.12, 3.50), P = 0.28], total operative time [OR 0.40; CI (-10.19, 11.00), P = 0.94], post-operative haemorrhage [OR 1.51; CI (0.41, 5.58, P = 0.53], anastomotic leak [OR 1.14; CI (0.26, 4.91), P = 0.86], pneumonia [OR 1.15; CI (0.22, 6.09), P = 0.87], SSI [OR 0.69; CI (0.19, 2.47), P = 0.57], overall post-operative complications [OR 0.82; CI (0.52, 1.30), P = 0.40], Clavien-Dindo grade ≥ 3 [OR 1.27; CI (0.59, 2.77), P = 0.54], and length of hospital stay [OR -0.68; CI (-1.61, 0.24), P = 0.15].

CONCLUSION

Low intraabdominal pressure is safe and feasible approach to laparoscopic colorectal resection surgery with non-inferior outcomes to standard or high pressures. More robust and well-powered RCTs are needed to consolidate the potential benefits of low over high pressure intra-abdominal surgery.

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.

Abdominal compartment syndrome in critically ill patients

Intra-abdominal hypertension can have severe consequences, including abdominal compartment syndrome, which can contribute to multi-organ failure. An increase in intra-abdominal hypertension is influenced by factors such as diminished abdominal wall compliance, increased intraluminal content, and certain systemic conditions. Regular measurement of intra-abdominal pressure is essential, and particular attention must be paid to patient positioning. Nonsurgical treatments, such as decompression of intraluminal content using a nasogastric tube, percutaneous drainage, and fluid balance optimization, play crucial roles. Additionally, point-of-care ultrasonography aids in the diagnosis and treatment of intra-abdominal hypertension. Emphasizing the importance of regular measurements, timely decompressive laparotomy is a definitive, but complex, treatment option. Balancing the urgency of surgical intervention against potential postoperative complications is challenging.

3D printed cannulas for use in laparoscopic surgery in feline patients: A cadaveric study and case series

OBJECTIVE

To evaluate custom 3D printed laparoscopic cannulas (3DPC) in a feline cadaveric abdominal surgery model and report their use in two live feline subjects.

STUDY DESIGN

Experimental cadaver study, live subject case series.

ANIMALS

Ten feline cadavers; two feline subjects.

METHODS

Custom 3DPCs were initially modeled in a PLA filament material and then created in an autoclavable dental resin for use in live patients. The surgery time, number of surgical collisions and cannula complications were recorded during cadaver procedures before and after use of 3DPCs. Cannula complications were recorded during live procedures and patients were followed to suture removal to record any incisional complications.

RESULTS

There was a significant reduction in mean surgical time (125.6 vs. 95.2 min, p = 0.03), mean number of instrument collisions (6.8 vs. 2.6, p = 0.03), and mean number of cannula complications (10 vs. 2.2, p = 0.03) with the use of only 3DPCs during the procedure. During the live procedures the use of the 3DPCs was successful and no postoperative complications occurred at the incision sites.

CONCLUSION

The use of customized 3DPCs may improve surgical dexterity and decrease complications in advanced procedures and was not associated with any clinical complications in two cats. The use of 3DPCs in veterinary medicine may allow for wider practice of laparoscopic techniques in small animals.

MRI measurement of the effects of moderate and deep neuromuscular blockade on the abdominal working space during laparoscopic surgery, a clinical study

BACKGROUND

Conflicting data exist regarding the effects of deep neuromuscular blockade (NMB) on abdominal dimensions during laparoscopic procedures. We performed a clinical study to establish the influence of moderate and deep neuromuscular blockade (NMB) on the abdominal working space, measured by Magnetic Resonance Imaging (MRI), during laparoscopic donor nephrectomy with standard pressure (12 mmHg) pneumoperitoneum under sevoflurane anaesthesia.

METHODS

Ten patients were intraoperatively scanned three times in the lateral decubitus position, with pneumoperitoneum maintained by a mobile insufflator. The first scan without NMB (T1) was followed by scans with moderate (T2) and deep NMB (T3). The skin-sacral promontory (S-SP) distance was measured, and 3D pneumoperitoneum volumes were reconstructed.

RESULTS

The mean difference in the S-SP distance was -0.32 cm between T2 and T3 (95% CI -1.06 - 0.42 cm; p = 0.344) and + 2.1 cm between T1 and T2 (95% CI 0.81 - 3.39 cm; p = 0.006). The mean differences in pneumoperitoneum volume were 166 mL between T2 and T3 (95% CI, 5 - 327 mL; p = 0.044) and 108 mL between T1 and T2 (95% CI, -273 - 488 mL; p = 0.525). The pneumoperitoneum volume showed high inter-individual variability and no increase in three patients with a high volume at T1.

CONCLUSIONS

During laparoscopic surgery in the lateral decubitus position with standard pressure under sevoflurane anaesthesia, deep NMB did not increase the S-SP distance compared to moderate NMB. Moderate NMB increased the S-SP distance by a mean of 2.1 cm (15.2%) compared with no NMB. The mean pneumoperitoneum volume increased slightly from moderate to deep NMB, with high inter-individual variability.

TRIAL REGISTRATION

Clinicaltrials.gov ID: NCT03287388.

Low intra-abdominal pressure in laparoscopic surgery: a systematic review and meta-analysis

BACKGROUND

Guidelines do not provide clear recommendations with regard to the use of low intra-abdominal pressure (IAP) during laparoscopic surgery. The aim of this meta-analysis is to assess the influence of low versus standard IAP during laparoscopic surgery on the key-outcomes in perioperative medicine as defined by the StEP-COMPAC consensus group.

MATERIALS AND METHODS

We searched the Cochrane Library, PubMed, and EMBASE for randomized controlled trials comparing low IAP (<10 mmHg) with standard IAP (10 mmHg or higher) during laparoscopic surgery without time, language, or blinding restrictions. According to the PRISMA guidelines, two review authors independently identified trials and extracted data. Risk ratio (RR), and mean difference (MD), with 95% CIs were calculated using random-effects models with RevMan5. Main outcomes were based on StEP-COMPAC recommendations, and included postoperative complications, postoperative pain, postoperative nausea and vomiting (PONV) scores, and length of hospital stay.

RESULTS

Eighty-five studies in a wide range of laparoscopic procedures (7349 patients) were included in this meta-analysis. The available evidence indicates that the use of low IAP (<10 mmHg) leads to a lower incidence of mild (Clavien-Dindo grade 1-2) postoperative complications (RR=0.68, 95% CI: 0.53-0.86), lower pain scores (MD=-0.68, 95% CI: -0.82 to 0.54) and PONV incidence (RR=0.67, 95% CI: 0.51-0.88), and a reduced length of hospital stay (MD=-0.29, 95% CI: -0.46 to 0.11). Low IAP did not increase the risk of intraoperative complications (RR=1.15, 95% CI: 0.77-1.73).

CONCLUSIONS

Given the established safety and the reduced incidence of mild postoperative complications, lower pain scores, reduced incidence of PONV, and shorter length of stay, the available evidence supports a moderate to strong recommendation (1a level of evidence) in favor of low IAP during laparoscopic surgery.

Optimising working space for laparoscopic pyeloplasty in infants: Preliminary observations with the SGPGI Protocol

AIMS

This study aimed to test the efficacy of SGPGI protocol to minimise bowel distension and optimise working space for laparoscopic pyeloplasty in infants.

METHODOLOGY

All infants who underwent laparoscopic pyeloplasty for unilateral pelvi-ureteric junction obstruction (PUJO) between January 2017 and March 2020 were included in the study. The patient cohort was divided into two groups: Group A and B. Group A included patients who underwent routine pre-operative preparation. Group B included patients wherein the SGPGI protocol was used. The key features of the protocol were fasting for 8 h, enemas, inserting a nasogastric tube in the pre-operative period and decompressing the colon on the operation table. Demographic features, pre-operative, intraoperative and post-operative parameters were compared between the two groups.

RESULTS

A total of 26 infants with unilateral PUJO underwent laparoscopic pyeloplasty during the study period. Group A included 12 patients and Group B included 14 patients. Both the groups were similar in age, weight and sex distribution. The median surgeon's rating score for suturing conditions was 2 for Group A and 5 for Group B patients (P > 0.05). The operating time was significantly longer in Group A (196 ± 21 min) as compared to Group B (114 ± 18 min) (P < 0.05). In Group A, intra-abdominal pressure (IAP) varied between 9 and 14 mmHg (median 12 mmHg), while in Group B, IAP varied between 6 and 9 mmHg (median 8 mmHg) (P < 0.05). In Group A, in 2/12 cases (16.7%), conversion to an open procedure was necessary because of inadequate working space owing to gross intestinal distension. Two patients in Group A also had intraoperative injuries to adjacent structures due to poor working space.

CONCLUSIONS

Optimal working space is critical to the performance of advanced laparoscopic surgery like pyeloplasty in infants. SGPGI protocol significantly improves working space, which permits a faster and safer surgery with a lower intra-abdominal working pressure. This protocol is simple, safe and easy to replicate at most centres in our country.

Low-pressure versus standard pressure laparoscopic colorectal surgery (PAROS trial): a phase III randomized controlled trial

TRIAL DESIGN

This is a phase III, double-blind, randomized, controlled trial.

METHODS

In this trial, patients with laparoscopic colectomy were assigned to either low pressure (LP: 7 mmHg) or standard pressure (SP: 12 mmHg) at a ratio of 1 : 1. The aim of this trial was to assess the impact of low-pressure pneumoperitoneum during laparoscopic colectomy on postoperative recovery. The primary endpoint was the duration of hospital stay. The main secondary endpoints were postoperative pain, consumption of analgesics and postoperative morbidity.

RESULTS

Some 138 patients were enrolled, of whom 11 were excluded and 127 were analysed: 62 with LP and 65 with SP. Duration of hospital stay (3 versus 4 days; P = 0.010), visual analog scale (0.5 versus 2.0; P = 0.008) and analgesic consumption (level II: 73 versus 88 per cent; P = 0.032; level III: 10 versus 23 per cent; P = 0.042) were lower with LP. Morbidity was not significantly different between the two groups (10 versus 17 per cent; P = 0.231).

CONCLUSION

Using low-pressure pneumoperitoneum in laparoscopic colonic resection improves postoperative recovery, shortening the duration of hospitalization and decreasing postoperative pain and analgesic consumption. This suggests that low pressure should become the standard of care for laparoscopic colectomy.

TRIAL REGISTRATION

NCT03813797.

Neuromuscular Blocking Agents and Rapid Sequence Induction for Laparoscopic Pyloromyotomy: Impact on Time to Extubation and Perioperative Complications

INTRODUCTION

 Infants with hypertrophic pyloric stenosis have gastric outlet obstruction, indicating a pyloromyotomy. To prevent aspiration, a rapid sequence induction (RSI) of anesthesia used to be preferred. However, due to concerns about the side-effects of this technique in infants, a modified RSI with gentle mask ventilation is nowadays mostly used. This research investigates if induction with succinylcholine (classic RSI), cisatracurium (modified RSI), or no neuromuscular blocking agent (NMBA) influences time until extubation and incidence of complications in infants undergoing laparoscopic pyloromyotomy.

MATERIALS AND METHODS

 A retrospective chart review was performed, observing infants undergoing laparoscopic pyloromyotomy in Erasmus Medical Centre-Sophia Children's Hospital, Rotterdam, from January 2007 until July 2015. Baseline preoperative data, anesthesia and operation details, time to extubation, and reported complications were gathered. Inclusion criteria were maintenance of anesthesia with sevoflurane and a registered extubation time. Exclusion criteria were the use of combinations of NMBAs, repyloromyotomy, and conversion to laparotomy.

RESULTS

 A total of 168 patients were included, of which 21 received succinylcholine, 107 cisatracurium, and 40 no NMBA. Mean duration of surgery was 29 minutes in all three groups; mean duration of anesthesia was 89, 82, and 77 minutes; mean time to extubation was 26, 25, and 23 minutes, respectively, without statistically significant difference. Complications were evenly distributed, no aspiration occurred.

CONCLUSION

 The use of succinylcholine, cisatracurium, or no NMBA at induction of anesthesia in infants undergoing laparoscopic pyloromyotomy had no statistically significant effect on time until extubation and complication rates. A modified RSI seems to be safe and effective in these cases.

Effect of an individualized versus standard pneumoperitoneum pressure strategy on postoperative recovery: a randomized clinical trial in laparoscopic colorectal surgery

Background

It remains uncertain whether individualization of pneumoperitoneum pressures during laparoscopic surgery improves postoperative recovery. This study compared an individualized pneumoperitoneum pressure (IPP) strategy with a standard pneumoperitoneum pressure (SPP) strategy with respect to postoperative recovery after laparoscopic colorectal surgery.

Methods

This was a multicentre RCT. The IPP strategy comprised modified patient positioning, deep neuromuscular blockade, and abdominal wall prestretching targeting the lowest intra-abdominal pressure (IAP) that maintained acceptable workspace. The SPP strategy comprised patient positioning according to the surgeon's preference, moderate neuromuscular blockade and a fixed IAP of 12 mmHg. The primary endpoint was physiological postoperative recovery, assessed by means of the Postoperative Quality of Recovery Scale. Secondary endpoints included recovery in other domains and overall recovery, the occurrence of intraoperative and postoperative complications, duration of hospital stay, and plasma markers of inflammation up to postoperative day 3.

Results

Of 166 patients, 85 received an IPP strategy and 81 an SPP strategy. The IPP strategy was associated with a higher probability of physiological recovery (odds ratio (OR) 2·77, 95 per cent c.i. 1·19 to 6·40, P = 0·017; risk ratio (RR) 1·82, 1·79 to 1·87, P = 0·049). The IPP strategy was also associated with a higher probability of emotional (P = 0·013) and overall (P = 0·011) recovery. Intraoperative adverse events were less frequent with the IPP strategy (P &lt; 0·001) and the plasma neutrophil–lymphocyte ratio was lower (P = 0·029). Other endpoints were not affected.

Conclusion

In this cohort of patients undergoing laparoscopic colorectal surgery, an IPP strategy was associated with faster recovery, fewer intraoperative complications and less inflammation than an SPP strategy. Registration number: NCT02773173 (http://www.clinicaltrials.gov).

Effects of intra-abdominal pressure on laparoscopic working space in domestic rabbits (Oryctolagus cuniculus)

OBJECTIVE

To assess the effects of 3 intra-abdominal pressures (IAPs) on pneumoperitoneal (laparoscopic working space) volume in domestic rabbits (Oryctolagus cuniculus).

ANIMALS

6 female New Zealand White rabbits.

PROCEDURES

A Latin-square design was used to randomly allocate sequences of 3 IAPs (4, 8, and 12 mm Hg) to each rabbit in a crossover study. Rabbits were anesthetized, subumbilical cannulae were placed, and CT scans were performed to obtain baseline measurements. Each IAP was achieved with CO₂ insufflation and maintained for ≥ 15 minutes; CT scans were performed with rabbits in dorsal, left lateral oblique, and right lateral oblique recumbency. The abdomen was desufflated for 5 minutes between treatments (the 3 IAPs). Pneumoperitoneal volumes were calculated from CT measurements with 3-D medical imaging software. Mixed linear regression models evaluated effects of IAP, rabbit position, and treatment order on working space volume.

RESULTS

Mean working space volume at an IAP of 8 mm Hg was significantly greater (a 19% increase) than that at 4 mm Hg, and was significantly greater (a 6.9% increase) at 12 mm Hg than that at 8 mm Hg. Treatment order, but not rabbit position, also had a significant effect on working space. Minor adverse effects reported in other species were observed in some rabbits.

CONCLUSIONS AND CLINICAL RELEVANCE

A nonlinear increase in abdominal working space was observed with increasing IAP. Depending on the type of procedure and visual access requirements, IAPs > 8 mm Hg may not provide a clinically important benefit for laparoscopy in rabbits.

Abdominal wall elasticity of children during pneumoperitoneum

OBJECTIVE

Laparoscopic surgery in children is often hampered by limited working space. This is partially compensated by stretching the child's abdominal wall. The volume of space that can be gained and changes to abdominal wall elasticity with respect to age are unknown. In the current research, we studied the extent of abdominal wall elasticity while establishing pneumoperitoneum in children.

METHODS

One hundred and sixty three children less than 18 years of age, undergoing elective laparoscopic surgery were recruited for the study. After induction of general anesthesia with a standardized muscle relaxant dose, a length of 5 cm was marked above, below and lateral to the umbilicus. The length of the marking was measured under increasing intraabdominal pressure (IAP of 0, 4, 6, 8, 10, 12 mmHg). The measurements were repeated to assess the effect of prestretching. The patients were divided into two groups: infants (less than one year of age) and older children (more than one year of age).

RESULTS

Depending on the age and axes of the measurements, a child's abdomen stretches up to 17% on average, with induction of pneumoperitoneum. The percentage of stretch tapers off as the IAP approaches peak pressure. As children become older, the longitudinal abdominal wall elasticity decreases, but the transverse abdominal wall elasticity increases. Regardless of age, prestretching results in a statistically significant increase in the elasticity over the transverse and lower sagittal abdominal wall.

CONCLUSION

A child's abdominal wall has considerable expandability. The characteristics of elasticity change depending on the axis and age. Prestretching can improve intraabdominal working space. This knowledge is helpful in port position design for minimally invasive surgery in children.

LEVEL OF EVIDENCE

Level II.

Change in irrigation flow through a flexible ureteroscope with various devices in the working channel: Comparison between an automatic irrigation pump and gravity-based irrigation

OBJECTIVES

To evaluate the change in the irrigation flow with various instruments in the working channel of a flexible ureteroscope by two automatic irrigation pumps and gravity-based irrigation in an ex vivo setting.

METHODS

We used two automatic irrigation pumps: the Endoflow II and the UROMAT Endoscopic Automatic System for Irrigation and gravity-based irrigation. A flexible ureteroscope was connected to an irrigation tube with a working channel. The other side of the irrigation tube was attached to each automatic irrigation pump, which was connected with a 2-L saline bag or to a 2-L saline bag directly in case of gravity pressure. The flow volume from the working channel was measured three times for 30 s at various irrigation pressure settings, both when the working channel was unoccupied and occupied with various instruments.

RESULTS

The irrigation flow steadily increased as the irrigation pressure in the automatic irrigation pumps increased and the saline position in gravity became higher (P < 0.05). However, the flow decreased as the size of the instrument in the working channel increased (P < 0.05). The efficiency of irrigation flow in gravity-based irrigation under the same pressure is significantly lower than one of two automatic irrigation pumps (P < 0.05). However, there was no significant difference in the efficiency of the irrigation flow between the Endoflow II and UROMAT Endoscopic Automatic System for Irrigation. The irrigation pressure setting needed to change to maintain adequate irrigation flow when using various working tools.

CONCLUSIONS

The efficiency of irrigation flow in gravity-based irrigation is significantly lower than one of two automatic irrigation pumps. The irrigation flow decreases as the size of the instrument in the working channel increases.

Conversion Rate in Pediatric Robotic-Assisted Surgery: Looking for the Culprit

Introduction: Robotic-assisted surgery (RAS) is increasingly used in adulthood but its application in pediatric population is limited. We report our initial experience in pediatric RAS, focusing on conversions to analyze their causes. Methods: All pediatric patients who underwent RAS between June 2015 and April 2019 were included, analyzing demographics, comorbidities, previous surgery, and intraoperative surgical and anesthetic parameters. A three-arms robotic technique was used in all cases. Additional laparoscopic ports were added, when needed. The surgical team did not change during the program, whereas the anesthesiology team varied. Results: Thirty-nine patients (23 females, 16 males; mean age ± SD = 9.33 ± 4.73 years [range = 1-16]; mean weight ± SD = 35.2 ± 20.0 kg [range = 9-85]) underwent 40 different procedures (18 gastrointestinal, 15 urogynecological, 5 oncological, and 2 miscellaneous). Three procedures (7.5%) were converted to open surgery for inadequate working space (two marked bowel distension and one insufficient hepatic retraction). Converted patients were of significant lower age (mean ± standard error of mean [SEM] = 2.97 ± 1.03 versus 9.83 ± 0.77 years, P = .01) and lower weight (mean ± SEM = 11.83 ± 1.74 versus 35.47 ± 3.16 kg, P = .03). The two groups did not differ statistically for duration of facial mask ventilation before intubation (mean ± SEM = converted 10.67 ± 2.33 versus completed 10.31 ± 0.91 minutes), neuromuscular block dosage (rocuronium; mean ± SEM = converted 0.46 ± 0.06 mg/kg versus completed 0.62 ± 0.03 mg/kg) and in the type of bowel preparation (mechanical and/or pharmacological). Discussion: Conversion rate in initial pediatric RAS program is acceptable. In children, the need for conversion is mainly because of inadequate working space, particularly in smaller children, but it seems not to be influenced by measurable anesthetic factors or different regimen for bowel preparation.

Abdominal Compliance and Laparoscopy: A Review

Background and Objectives

Creating and maintaining a pneumoperitoneum to perform laparoscopy is governed by gas laws and the limiting physical constraints of the abdomen.

Methods

A review of how gas, biomechanical and physical properties affect the abdomen and a systematic structured Medline and PubMed search was conducted to identify relevant studies related to the topic.

Results

Abdominal compliance is a measure of ease of abdominal expansion and is determined by the elasticity of the abdominal wall and diaphragm. It is the change in intra-abdominal volume per change in intra-abdominal pressure. Caution should be exercised with pressures exceeding 12 millimeters mercury since this is defined as intra-abdominal hypertension.

Conclusions

Abdominal compliance has its limits, is unique for each patient and pressure-volume curves cannot be easily predicted. Using the lowest possible pressure to accomplish the surgical task without compromising surgical outcome is the desired goal. The clinical importance is caution and knowing there is a point where more pressure does not increase working space and only increases pressure.

An individualised versus a conventional pneumoperitoneum pressure strategy during colorectal laparoscopic surgery: rationale and study protocol for a multicentre randomised clinical study

Background

A recent study shows that a multifaceted strategy using an individualised intra-abdominal pressure titration strategy during colorectal laparoscopic surgery results in an acceptable workspace at low intra-abdominal pressure in most patients. The multifaceted strategy, focused on lower to individualised intra-abdominal pressures, includes prestretching the abdominal wall during initial insufflation, deep neuromuscular blockade, low tidal volume ventilation settings and a modified lithotomy position. The study presented here tests the hypothesis that this strategy improves outcomes of patients scheduled for colorectal laparoscopic surgery.

Methods

The Individualized Pneumoperitoneum Pressure in Colorectal Laparoscopic Surgery versus Standard Therapy (IPPCollapse-II) study is a multicentre, two-arm, parallel-group, single-blinded randomised 1:1 clinical study that runs in four academic hospitals in Spain. Patients scheduled for colorectal laparoscopic surgery with American Society of Anesthesiologists classification I to III who are aged > 18 years and are without cognitive deficits are randomised to an individualised pneumoperitoneum pressure strategy (the intervention group) or to a conventional pneumoperitoneum pressure strategy (the control group). The primary outcome is recovery assessed with the Post-operative Quality of Recovery Scale (PQRS) at postoperative day 1. Secondary outcomes include PQRS score in the post anaesthesia care unit and at postoperative day 3, postoperative complications until postoperative day 28, hospital length of stay and process-related outcomes.

Discussion

The IPPCollapse-II study will be the first randomised clinical study that assesses the impact of an individualised pneumoperitoneum pressure strategy focused on working with the lowest intra-abdominal pressure during colorectal laparoscopic surgery on relevant patient-centred outcomes. The results of this large study, to be disseminated through conference presentations and publications in international peer-reviewed journals, are of ultimate importance for optimising the care and safety of laparoscopic abdominal surgery. Selection of patient-reported outcomes as the primary outcome of this study facilitates the translation into clinical practice. Access to source data will be made available through anonymised datasets upon request and after agreement of the Steering Committee of the IPPCollapse-II study.

Trial registration

ClinicalTrials.gov, NCT02773173. Registered on 16 May 2016. EudraCT, 2016-001693-15. Registered on 8 August 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3255-1) contains supplementary material, which is available to authorized users.

A multifaceted individualized pneumoperitoneum strategy for laparoscopic colorectal surgery: a multicenter observational feasibility study

BACKGROUND

While guidelines for laparoscopic abdominal surgery advise using the lowest possible intra-abdominal pressure, commonly a standard pressure is used. We evaluated the feasibility of a predefined multifaceted individualized pneumoperitoneum strategy aiming at the lowest possible intra-abdominal pressure during laparoscopic colorectal surgery.

METHODS

Multicenter prospective study in patients scheduled for laparoscopic colorectal surgery. The strategy consisted of ventilation with low tidal volume, a modified lithotomy position, deep neuromuscular blockade, pre-stretching of the abdominal wall, and individualized intra-abdominal pressure titration; the effect was blindly evaluated by the surgeon. The primary endpoint was the proportion of surgical procedures completed at each individualized intra-abdominal pressure level. Secondary endpoints were the respiratory system driving pressure, and the estimated volume of insufflated CO₂ gas needed to perform the surgical procedure.

RESULTS

Ninety-two patients were enrolled in the study. Fourteen cases were converted to open surgery for reasons not related to the strategy. The intervention was feasible in all patients and well-accepted by all surgeons. In 61 out of 78 patients (78%), surgery was performed and completed at the lowest possible IAP, 8 mmHg. In 17 patients, IAP was raised up to 12 mmHg. The relationship between IAP and driving pressure was almost linear. The mean estimated intra-abdominal CO₂ volume at which surgery was performed was 3.2 L.

CONCLUSION

A multifaceted individualized pneumoperitoneum strategy during laparoscopic colorectal surgery was feasible and resulted in an adequate working space in most patients at lower intra-abdominal pressure and lower respiratory driving pressure. ClinicalTrials.gov (Trial Identifier: NCT03000465).

Influence of body weight and body conformation on the pressure-volume curve during capnoperitoneum in dogs

OBJECTIVE To evaluate the pressure-volume relationship during capnoperitoneum in dogs and effects of body weight and body conformation. ANIMALS 86 dogs scheduled for routine laparoscopy. PROCEDURES Dogs were allocated into 3 groups on the basis of body weight. Body measurements, body condition score, and body conformation indices were calculated. Carbon dioxide was insufflated into the abdomen with a syringe, and pressure was measured at the laparoscopic cannula. Volume and pressure data were processed, and the yield point, defined by use of a cutoff volume (COV) and cutoff pressure (COP), was calculated. RESULTS 20 dogs were excluded because of recording errors, air leakage attributable to surgical flaws, or trocar defects. For the remaining 66 dogs, the pressure-volume curve was linear-like until the yield point was reached, and then it became visibly exponential. Mean ± SD COP was 5.99 ± 0.805 mm Hg. No correlation was detected between yield point, body variables, or body weight. Mean COV was 1,196.2 ± 697.9 mL (65.15 ± 20.83 mL of CO₂/kg), and COV was correlated significantly with body weight and one of the body condition indices but not with other variables. CONCLUSION AND CLINICAL RELEVANCE In this study, there was a similar COP for all dogs of all sizes. In addition, results suggested that increasing the abdominal pressure after the yield point was reached did not contribute to a substantial increase in working space in the abdomen. No correlation was found between yield point, body variables, and body weight.

Design of Virtual Fixtures for Robotic Cholecystectomy

BACKGROUND AND OBJECTIVE

With the ongoing developments in robotic surgery, the associated adverse events need to be carefully evaluated. Virtual fixtures (VFs), a safety design feature against unintended motion during robotic surgery, have been proposed, but the methodology for designing VFs remains experimental. In this study, we propose a novel methodology for designing VFs for robotic cholecystectomy.

MATERIALS AND METHODS

Laparoscopic cholecystectomy (LC) was performed in 24 patients with cholecystitis. Active working space (AWS), the distance between instrument heads (DBIH), motion speed of bilateral hands, and instrument heads were calculated and analyzed.

RESULTS

DBIH was 14.78 ± 6.94 cm. Diameter of right and left AWS was 15.81 ± 3.69 cm and 15.33 ± 1.52 cm, respectively. DBIH was found to significantly correlate with the surgeon's experience. Bilateral AWS was found to be significantly associated with body circumference at Murphy's point level. However, no association was observed between bilateral AWS and surgeon's experience.

CONCLUSIONS

A novel methodology to build VFs for designing VFs for robotic cholecystectomy is established. Surgeon's experience appears to play an important role in determining the DBIH during robotic laparoscopic cholecystectomy, but does not affect bilateral AWS.

The neglected role of abdominal compliance in organ-organ interactions

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Abdominal compliance: A bench-to-bedside review

Abdominal compliance (AC) is an important determinant and predictor of available workspace during laparoscopic surgery. Furthermore, critically ill patients with a reduced AC are at an increased risk of developing intra-abdominal hypertension and abdominal compartment syndrome, both of which are associated with high morbidity and mortality. Despite this, AC is a concept that has been neglected in the past.AC is defined as a measure of the ease of abdominal expansion, expressed as a change in intra-abdominal volume (IAV) per change in intra-abdominal pressure (IAP):AC = ΔIAV / ΔIAPAC is a dynamic variable dependent on baseline IAV and IAP as well as abdominal reshaping and stretching capacity. Whereas AC itself can only rarely be measured, it always needs to be considered an important component of IAP. Patients with decreased AC are prone to fulminant development of abdominal compartment syndrome when concomitant risk factors for intra-abdominal hypertension are present.This review aims to clarify the pressure-volume relationship within the abdominal cavity. It highlights how different conditions and pathologies can affect AC and which management strategies could be applied to avoid serious consequences of decreased AC.We have pooled all available human data to calculate AC values in patients acutely and chronically exposed to intra-abdominal hypertension and demonstrated an exponential abdominal pressure-volume relationship. Most importantly, patients with high level of IAP have a reduced AC. In these patients, only small reduction in IAV can significantly increase AC and reduce IAPs.A greater knowledge on AC may help in selecting a better surgical approach and in reducing complications related to intra-abdominal hypertension.

Optimizing working space in laparoscopy: CT measurement of the influence of small body size in a porcine model

INTRODUCTION

In our continuing research into the determinants of laparoscopic working space, the influence of small body size was investigated.

METHODS

In eight 6-kg pigs, the effects of intraabdominal CO2 pneumoperitoneum pressure (IAP), prestretching of the abdominal wall, and neuromuscular blockade (NMB) on laparoscopic working space volume and distances were studied. Computed tomography was used to measure working space during two stepwise abdominal insufflation-runs up to an IAP of 15mm Hg. Results were compared with data from earlier experiments in 20-kg pigs.

RESULTS

Cardiorespiratory parameters were stable up to an IAP of 8-10mm Hg. In 6-kg pigs working-space dimensions were five times smaller than in 20-kg pigs. Working-space volume, anteroposterior (AP) diameter and symphysis-diaphragm distance increased linearly up to an IAP of 8mm Hg. Above 8mm Hg, compliance decreased. Eighty percent of the total volume (618ml) and of AP diameter (3cm) at 15mm Hg had been achieved at an IAP of 10mm Hg. Prestretching by a first insufflation resulted in a statistically significant increase in working space volume and in AP diameter during the second insufflation. This effect was significantly larger than in 20-kg pigs. Neuromuscular blockade did not have a significant effect on working-space.

CONCLUSIONS

Working space in growing individuals is very limited. Eighty percent of the working space created by an IAP of 15mm Hg was already achieved at 10mm Hg, while cardiorespiratory side effects at an IAP of 8-10mm Hg seem acceptable. Prestretching of the abdominal wall significantly increased working space, even more so than in 20-kg pigs. As in 20-kg pigs, NMB had no significant effect on laparoscopic working space. Prestretching of the abdominal wall is a promising cheap, safe and easy strategy to increase laparoscopic working space, lessening the need for prolonged high-pressure pneumoperitoneum.

Optimizing working space in laparoscopy: CT-measurement of the effect of neuromuscular blockade and its reversal in a porcine model

OBJECTIVE

The objective of this paper was to determine the effect of neuromuscular blockade (NMB) on working space in a porcine laparoscopy model.

BACKGROUND

Conflicting results on the effect of NMB on laparoscopic working space are found in literature. Almost all studies are limited by absence of objective assessment of working space or use surrogate outcomes.

METHODS

In a standardized porcine laparoscopy model, laparoscopic working-space dimensions with and without NMB were investigated in 16 animals using computed tomography at intra-abdominal pressures of 0, 5, 10, and 15 mmHg during multiple runs of abdominal insufflation.

RESULTS

No statistically significant effect of NMB on abdominal dimensions and laparoscopic working-space volume was found during CO2 pneumoperitoneum. In contrast, the effect of pre-stretching of the abdominal wall by a previous abdominal insufflation was found to be significant.

CONCLUSIONS

This experimental study confirms the results from several clinical studies that NMB does not influence laparoscopic working space. Studies dealing with working space during laparoscopy should take note of pre-stretching bias.