This single‑center, prospective, randomized, double‑blind parallel‑group trial compared low‑pressure pneumoperitoneum (8 mmHg) with a standard pressure of 14 mmHg in elective laparoscopic cholecystectomy (LC). The prespecified primary objective was to test whether low pressure would reduce postoperative pain at 6 hours measured by the Visual Analogue Scale (VAS). Secondary objectives included VAS at 12 and 24 hours, analgesic consumption, postoperative nausea and vomiting (PONV), operative time, conversion rate, length of stay, and 30‑day morbidity. The trial was conducted at Charles Nicolle University Hospital, Tunis, and registered on ClinicalTrials.gov (NCT06685250).
Consecutive adult patients scheduled for elective LC were screened between November 12, 2024 and December 31, 2025. Inclusion criteria were age ≥ 18 years, ASA I or II, and uncomplicated symptomatic gallbladder lithiasis. Key exclusions included choledocholithiasis, prior major upper abdominal surgery, ascites or carcinomatosis, and neurological disorders affecting pain perception.
Randomization used balanced permuted blocks and allocation was concealed in sequentially numbered opaque envelopes opened in the operating room after induction of anesthesia. Patients and postoperative outcome assessors were blinded; operating surgeons were not blinded for safety reasons and to allow immediate pressure adjustments if visualization or cardiopulmonary status required it.
All procedures used the standard four‑trocar technique in most cases. Pneumoperitoneum pressure was set to the assigned value (8 mmHg or 14 mmHg) after insufflation. Surgeons were permitted to adjust pressure if visualization was compromised or cardiopulmonary instability developed; such adjustments were documented as protocol deviations. At the end of surgery, residual CO2 was evacuated.
The primary endpoint was the VAS pain score at 6 hours postoperatively (0–10 scale). Median VAS at 6 hours for the entire cohort was reported and compared between groups. The prespecified between‑group comparison of VAS at 6 hours constituted the main efficacy analysis and was analyzed on an intention‑to‑treat basis.
Secondary measures included VAS at 12 and 24 hours; PONV score (0–3); number of analgesic doses (paracetamol, tramadol, nefopam) during the first 24 hours; total operative time; conversions; length of hospital stay; and 30‑day postoperative morbidity. Analgesic consumption was recorded as total paracetamol doses per patient over 24 hours and compared between groups.
Sample size calculations targeted a 1.0‑point difference on the VAS at 6 hours, based on literature means and an assumed SD, with two‑sided alpha 0.05 and 90% power. The planned enrollment accounted for anticipated losses. Analyses were performed on an intention‑to‑treat basis. Continuous variables were tested with t‑tests or Mann‑Whitney U tests as appropriate; categorical variables used chi‑square or Fisher exact tests. Repeated VAS measurements were analyzed with a linear mixed‑effects model including treatment, time (6, 12, 24 h), and treatment‑by‑time interaction.
Of 317 patients who underwent LC during the study period, 160 met eligibility and consented to randomization (80 assigned to 8 mmHg and 80 to 14 mmHg). Baseline characteristics were balanced: mean age 51.5 ± 15.3 years, majority female (M/F ratio 0.27), mean BMI 30.1 ± 4.5 kg/m2, and ASA I in 59.4% of patients. Procedures were performed or supervised by senior surgeons in 44.4% and by residents under supervision in 55.6%.
Two intervention failures occurred in the standard‑pressure (14 mmHg) group due to intraoperative hypercapnia prompting pressure reduction; these were recorded as protocol deviations. No conversions to open laparotomy or major morbidities were reported.
Median VAS at 6 hours did not differ significantly between the low‑pressure and standard‑pressure groups (reported medians 3 vs. 4; p = 0.221). Site‑specific assessments, including referred shoulder pain, showed no significant intergroup differences.
A linear mixed‑effects model found VAS scores decreased significantly over time across the cohort (p < 0.001), but there was no significant overall treatment effect of pneumoperitoneum pressure (F = 2.550, p = 0.112) and no significant treatment‑by‑time interaction (F = 0.272, p = 0.762). This indicates similar postoperative pain trajectories over the first 24 hours for 8 mmHg and 14 mmHg groups.
Operative time was similar between groups (mean ≈ 59 minutes; 59.9 ± 27.5 vs. 58.2 ± 22.4 minutes; p = 0.880). No conversions to laparotomy occurred. PONV affected 58 patients (36.3%) across the cohort.
Analgesic use differed: mean number of paracetamol doses in the first 24 hours was significantly lower in the low‑pressure group (1.04 ± 0.906) than in the standard‑pressure group (1.35 ± 0.873; p = 0.014). Overall, 34 patients (21.25%) received no analgesics; paracetamol was used in 123 patients (76.9%), tramadol in 22 (13.8%), and nefopam in 3 (1.9%). A two‑drug combination was used in 23 patients (14.4%). The authors note that analgesic consumption data were recorded only as total paracetamol doses per 24 hours, not at discrete time points.
In this randomized trial of elective, uncomplicated LC in ASA I–II adults, operating at 8 mmHg was feasible and did not prolong operative time. The primary outcome—median VAS at 6 hours—was not significantly reduced by low‑pressure pneumoperitoneum. Longitudinal pain analysis confirmed declining pain over time with no detectable treatment effect.
A statistically significant reduction in 24‑hour paracetamol consumption was observed with low pressure, suggesting a possible clinical benefit in analgesic requirements. The authors caution that this was a secondary outcome without adjustment for multiple comparisons and should be interpreted carefully.
Limitations include single‑center conduct, exclusion of acute/severe cholecystitis, a population at generally low perioperative risk, and lack of surgeon blinding. The sample size, while adequate for the prespecified primary outcome, limits inference about rare safety events; the authors call for larger studies to confirm safety equivalence for uncommon complications.
Low‑pressure pneumoperitoneum at 8 mmHg is feasible for elective laparoscopic cholecystectomy and does not extend operative time. It did not produce a statistically significant reduction in VAS pain at 6 hours postoperatively compared with 14 mmHg, although paracetamol consumption during the first 24 hours was lower in the low‑pressure group. Further larger trials are needed to confirm safety and to evaluate whether reduced analgesic needs are reproducible and clinically meaningful.