Deep Versus Moderate Neuromuscular Blockade During Laparoscopic Surgery: Meta-Analysis of Randomized Controlled Trials

1. Introduction

Minimally invasive surgery has progressively become the preferred approach for a wide spectrum of abdominal, gynecologic, urologic, hepatobiliary, colorectal, and bariatric procedures because of its association with reduced postoperative pain, shorter hospital length of stay, faster recovery, earlier mobilization, and improved quality of life compared with open surgery [1,2]. The worldwide expansion of laparoscopic and selected robot-assisted procedures has substantially increased interest in perioperative strategies capable of optimizing surgical exposure while minimizing perioperative burden [2].

The establishment of pneumoperitoneum through carbon dioxide insufflation is essential for laparoscopic surgery because it creates the operative workspace required for adequate visualization and surgical manipulation. However, increased intra-abdominal pressure (IAP), typically ranging from 12 to 15 mmHg, may induce important physiological alterations including decreased pulmonary compliance, increased airway pressures, reduced venous return, diaphragmatic irritation, and postoperative pain syndromes, particularly referred shoulder pain [3,4,5,6,7].

To reduce the physiological burden associated with elevated IAP, low-pressure pneumoperitoneum strategies have increasingly attracted attention. Previous studies demonstrated that lower insufflation pressures may reduce postoperative pain and improve postoperative comfort [8,9]. Nevertheless, low-pressure laparoscopy may compromise operative exposure and increase technical difficulty, particularly during complex minimally invasive procedures [10,11].

In this context, deep neuromuscular blockade has emerged as a potential strategy to facilitate lower pneumoperitoneum pressures while maintaining adequate surgical exposure. Moderate neuromuscular blockade is generally characterized by one to three train-of-four responses, whereas deep neuromuscular blockade is characterized by absence of train-of-four responses with maintenance guided by post-tetanic count stimulation [12].

Early randomized trials evaluating DNMB primarily focused on surgeon-rated operative conditions and demonstrated improvements in surgical workspace quality and surgeon satisfaction [13,14,15]. Subsequent studies expanded these findings across several minimally invasive procedures including bariatric surgery, colorectal surgery, gynecologic surgery, donor nephrectomy, and urologic surgery [14,15,16,17,18,19,20,21]. More recent studies additionally explored whether improved operative conditions may translate into clinically relevant postoperative benefits, particularly reduced postoperative pain and referred shoulder pain associated with lower pneumoperitoneum pressures. However, findings across studies remain heterogeneous.

Despite increasing interest in this topic, previous systematic reviews frequently included relatively small numbers of randomized trials or focused predominantly on surgical field quality outcomes alone [29]. Furthermore, additional randomized evidence evaluating low-pressure pneumoperitoneum strategies has emerged during recent years [23,24,25,26,27,28].

Therefore, we conducted an updated systematic review and meta-analysis of randomized controlled trials to evaluate whether deep neuromuscular blockade improves surgical workspace quality, facilitates lower intra-abdominal pressure strategies, and influences early postoperative pain outcomes during minimally invasive surgery [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

2. Methods

This systematic review and meta-analysis was conducted according to recommendations from the Cochrane Handbook for Systematic Reviews of Interventions and reported according to the PRISMA 2020 statement [30,31]. The review protocol was prospectively registered in PROSPERO before study selection and data extraction (CRD420261392976).

2.1. Eligibility Criteria

Eligibility criteria were established according to the Population, Intervention, Comparator, Outcomes, and Study Design (PICOS) framework.

Randomized controlled trials comparing deep or profound neuromuscular blockade versus moderate neuromuscular blockade in adults undergoing laparoscopic or selected robot-assisted abdominal or pelvic procedures were eligible.

Deep neuromuscular blockade was defined according to the original study definitions and generally corresponded to absence of train-of-four responses with maintenance guided by post-tetanic count monitoring. Moderate blockade was generally defined as one to three train-of-four responses.

Studies involving pediatric populations, observational designs, conference abstracts without full text, reviews, editorials, animal studies, duplicated populations, open procedures, or studies lacking extractable outcome data were excluded.

2.2. Outcomes

Primary outcomes were surgical workspace quality and intra-abdominal pressure requirements.

Secondary outcomes included postoperative pain at 24 h and referred shoulder pain.

Surgical conditions were evaluated using validated operative condition scales including the Leiden Surgical Rating Scale (L-SRS), Surgical Rating Scale (SRS), or equivalent instruments.

2.3. Data Sources and Search Strategy

A comprehensive electronic literature search was performed in PubMed/MEDLINE, EMBASE, Cochrane CENTRAL, Scopus, Web of Science, and LILACS from database inception through May 2026.

Search terms included combinations of: "deep neuromuscular blockade", "profound neuromuscular blockade", "moderate neuromuscular blockade", "laparoscopy", "robotic surgery", "pneumoperitoneum", "low-pressure laparoscopy", "low intra-abdominal pressure", "surgical conditions", and "randomized controlled trial".

2.4. Study Selection

Two reviewers independently screened titles, abstracts, and full texts using standardized eligibility criteria. Disagreements were resolved through consensus. Screening and study selection were performed using the Rayyan web application [32].

2.5. Data Extraction and Risk of Bias Assessment

Two reviewers independently extracted study characteristics, surgical procedures, sample size, anesthetic protocols, neuromuscular blockade definitions, pneumoperitoneum strategies, and outcomes.

Risk of bias was evaluated using the revised Cochrane Risk of Bias tool for randomized trials (RoB 2) [33].

2.6. Certainty of Evidence

Certainty of evidence was evaluated using the GRADE framework for surgical workspace quality, intra-abdominal pressure requirements, postoperative pain at 24 h, and referred shoulder pain [34–38].

2.7. Data Synthesis and Statistical Analysis

Meta-analyses were performed using random-effects models because clinical and methodological heterogeneity across surgical procedures, pneumoperitoneum strategies, perioperative protocols, and outcome assessment methods was anticipated. Continuous outcomes were pooled using mean differences (MDs) or standardized mean differences (SMDs) according to the measurement scales used across studies. Seventeen randomized controlled trials were included in the qualitative synthesis. Quantitative meta-analyses were performed only for outcomes reported with sufficient methodological comparability, including surgical workspace quality, intra-abdominal pressure, postoperative pain at 24 hours, and referred shoulder pain. Quantitative synthesis was restricted to outcomes reported by at least two studies with comparable definitions, assessment time points, and extractable numerical data. Outcomes reported inconsistently or with insufficient quantitative information were summarized narratively. Statistical heterogeneity was assessed using Cochran’s Q test and the I² statistic. All analyses were conducted using Review Manager (RevMan), version 5.4 [39].

3. Results

3.1. Search Results

The electronic search identified studies evaluating deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB) during minimally invasive surgery. After removal of duplicates and screening of titles, abstracts, and full texts, 17 randomized controlled trials fulfilled the eligibility criteria and were included in the qualitative synthesis [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Because outcome reporting varied considerably across studies, not all trials contributed to every pooled quantitative analysis. Quantitative meta-analyses were therefore performed only for outcomes with sufficient methodological comparability and available extractable data.

Figure 1. PRISMA flowchart.

Figure 1. PRISMA flowchart.

3.2. Characteristics of the Included Studies

The 17 included randomized controlled trials evaluated adult patients undergoing laparoscopic abdominal, gynecologic, urologic, colorectal, bariatric, hepatobiliary, donor nephrectomy, and laparoendoscopic single-site procedures [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Most studies compared DNMB, generally maintained using post-tetanic count guidance, with MNMB, typically maintained at one to three train-of-four responses [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

The most frequently reported outcomes were surgical field quality, postoperative pain, referred shoulder pain, recovery or extubation time, and quality of recovery. Surgical conditions were primarily assessed using the Leiden Surgical Rating Scale (L-SRS), Surgical Rating Scale (SRS), or equivalent surgeon-reported operative field instruments [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Quantitative neuromuscular monitoring and sugammadex-based reversal strategies were increasingly incorporated in contemporary trials [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

Detailed characteristics of the included trials are presented in Table 1.

Table 1. Study characteristics related to population and perioperative setting.

Study	Surgery	N (DNMB/MNMB)	Pneumoperitoneum	Anesthesia	Main assessed outcome
Martini 2014	Retroperitoneal laparoscopic urologic surgery	12/12	Standard pressure	Balanced anesthesia	Surgical conditions
Dubois 2014	Laparoscopic hysterectomy	51/51	13 mmHg	Desflurane anesthesia	Surgical field quality
Staehr-Rye 2014	Laparoscopic cholecystectomy	24/24	Low pressure (8 mmHg)	TIVA	Surgical workspace conditions
Yoo 2015	Robotic radical prostatectomy	19/19	Standard pressure	Propofol/remifentanil	Intraocular pressure
Torensma 2016	Bariatric surgery	50/50	Standard pressure	Balanced anesthesia	Surgical conditions and postoperative pain
Kim 2016	Laparoscopic colorectal surgery	30/31	Adjusted low pressure	Balanced anesthesia	Intra-abdominal pressure and postoperative pain
Rosenberg 2017	Laparoscopic cholecystectomy	60/60	Low vs standard pressure	Balanced anesthesia	Surgeon satisfaction and surgical conditions
Baete 2017	Bariatric surgery	25/25	Low pressure	Balanced anesthesia	Respiratory mechanics and surgical conditions
Madsen 2017	Laparoscopic hysterectomy	55/55	8 vs 12 mmHg	Balanced anesthesia	Shoulder pain and abdominal contractions
Koo 2018	Laparoscopic colorectal surgery	32/32	Standard pressure	Balanced anesthesia	Intraoperative surgical conditions
Bruintjes 2019	Laparoscopic donor nephrectomy	48/48	Low pressure	Balanced anesthesia	Quality of recovery (QoR-40)
Honing 2021	Laparoscopic renal surgery	49/49	12 mmHg	Sevoflurane anesthesia	Surgical conditions
Kathopoulis 2022	Gynecologic laparoscopic surgery	73/71	Standard pressure	Balanced anesthesia	Surgical conditions and postoperative pain
Yang 2024	Laparoscopic sleeve gastrectomy	40/40	Standard pressure	Balanced anesthesia	Quality of recovery (QoR-15)
Esa 2024	Gynecologic laparoscopy	35/35	Low pressure (8 mmHg)	Balanced anesthesia	Surgical conditions and postoperative pain
Morisson 2024	Laparoscopic colorectal surgery	45/48	Adjusted pressure	Desflurane/remifentanil	Remifentanil requirement and surgical conditions
Alotaibi 2024	Laparoscopic sleeve gastrectomy	29/28	Standard pressure	Balanced anesthesia	Postoperative pain and recovery
Meletti 2025	Laparoscopic cholecystectomy	31/31	Low vs standard pressure	Balanced anesthesia	QoR-40 and postoperative pain
Shen 2026	LESS total hysterectomy	121/122	Standard pressure	Intravenous anesthesia	Surgical conditions and postoperative pain

Table 1. Study characteristics related to population and perioperative setting.

Study	Surgery	N (DNMB/MNMB)	Pneumoperitoneum	Anesthesia	Main assessed outcome
Martini 2014	Retroperitoneal laparoscopic urologic surgery	12/12	Standard pressure	Balanced anesthesia	Surgical conditions
Dubois 2014	Laparoscopic hysterectomy	51/51	13 mmHg	Desflurane anesthesia	Surgical field quality
Staehr-Rye 2014	Laparoscopic cholecystectomy	24/24	Low pressure (8 mmHg)	TIVA	Surgical workspace conditions
Yoo 2015	Robotic radical prostatectomy	19/19	Standard pressure	Propofol/remifentanil	Intraocular pressure
Torensma 2016	Bariatric surgery	50/50	Standard pressure	Balanced anesthesia	Surgical conditions and postoperative pain
Kim 2016	Laparoscopic colorectal surgery	30/31	Adjusted low pressure	Balanced anesthesia	Intra-abdominal pressure and postoperative pain
Rosenberg 2017	Laparoscopic cholecystectomy	60/60	Low vs standard pressure	Balanced anesthesia	Surgeon satisfaction and surgical conditions
Baete 2017	Bariatric surgery	25/25	Low pressure	Balanced anesthesia	Respiratory mechanics and surgical conditions
Madsen 2017	Laparoscopic hysterectomy	55/55	8 vs 12 mmHg	Balanced anesthesia	Shoulder pain and abdominal contractions
Koo 2018	Laparoscopic colorectal surgery	32/32	Standard pressure	Balanced anesthesia	Intraoperative surgical conditions
Bruintjes 2019	Laparoscopic donor nephrectomy	48/48	Low pressure	Balanced anesthesia	Quality of recovery (QoR-40)
Honing 2021	Laparoscopic renal surgery	49/49	12 mmHg	Sevoflurane anesthesia	Surgical conditions
Kathopoulis 2022	Gynecologic laparoscopic surgery	73/71	Standard pressure	Balanced anesthesia	Surgical conditions and postoperative pain
Yang 2024	Laparoscopic sleeve gastrectomy	40/40	Standard pressure	Balanced anesthesia	Quality of recovery (QoR-15)
Esa 2024	Gynecologic laparoscopy	35/35	Low pressure (8 mmHg)	Balanced anesthesia	Surgical conditions and postoperative pain
Morisson 2024	Laparoscopic colorectal surgery	45/48	Adjusted pressure	Desflurane/remifentanil	Remifentanil requirement and surgical conditions
Alotaibi 2024	Laparoscopic sleeve gastrectomy	29/28	Standard pressure	Balanced anesthesia	Postoperative pain and recovery
Meletti 2025	Laparoscopic cholecystectomy	31/31	Low vs standard pressure	Balanced anesthesia	QoR-40 and postoperative pain
Shen 2026	LESS total hysterectomy	121/122	Standard pressure	Intravenous anesthesia	Surgical conditions and postoperative pain

Table 2. Study characteristics related to neuromuscular blockade strategy and perioperative outcomes.

Study	DNMB Definition	MNMB Definition	Neuromuscular Monitoring	Reversal Strategy	Main Findings
Martini 2014	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex vs neostigmine	Improved surgical conditions with DNMB
Dubois 2014	TOF <1	TOF recovery/spontaneous	TOF	Neostigmine	Reduced unacceptable surgical conditions with DNMB
Staehr-Rye 2014	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved low-pressure surgical workspace
Yoo 2015	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Lower intraocular pressure fluctuations
Torensma 2016	PTC 2–3	TOF 1–2	TOF/PTC	Sugammadex	Better surgical conditions and lower postoperative pain
Kim 2016	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Lower intra-abdominal pressure and less postoperative pain
Rosenberg 2017	PTC 1–2	TOF ratio 10%	TOF/PTC	Sugammadex	Improved surgeon satisfaction under DNMB
Baete 2017	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved respiratory mechanics and surgical exposure
Madsen 2017	Deep continuous block	Single-bolus/standard block	TOF/PTC	Sugammadex	Reduced abdominal contractions and insufflator alarms
Koo 2018	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex vs neostigmine	Reduced IAP alarms and spontaneous breathing recovery
Bruintjes 2019	PTC 1–3	TOF 1–3	TOF/PTC	Sugammadex	Improved postoperative recovery and lower pain in as-treated analysis
Honing 2021	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	No improvement in surgical conditions during sevoflurane anesthesia
Kathopoulis 2022	PTC 0–1	TOF 0–1	TOF/PTC	Sugammadex	Lower postoperative pain without major surgical field differences
Yang 2024	PTC 1–3	TOF 1–3	TOF/PTC	Sugammadex	Better QoR-15 scores and improved surgical conditions
Esa 2024	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Better surgical space quality with lower insufflation pressure
Morisson 2024	PTC 1–2	TOF 1–3	TOF/PTC + NOL	Sugammadex	Reduced remifentanil requirement and lower IAP
Alotaibi 2024	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	No major differences in postoperative recovery outcomes
Meletti 2025	Deep blockade	Moderate blockade	TOF/PTC	Sugammadex	Better surgical field quality without QoR-40 improvement
Shen 2026	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved surgical conditions and lower postoperative pain

Table 2. Study characteristics related to neuromuscular blockade strategy and perioperative outcomes.

Study	DNMB Definition	MNMB Definition	Neuromuscular Monitoring	Reversal Strategy	Main Findings
Martini 2014	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex vs neostigmine	Improved surgical conditions with DNMB
Dubois 2014	TOF <1	TOF recovery/spontaneous	TOF	Neostigmine	Reduced unacceptable surgical conditions with DNMB
Staehr-Rye 2014	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved low-pressure surgical workspace
Yoo 2015	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Lower intraocular pressure fluctuations
Torensma 2016	PTC 2–3	TOF 1–2	TOF/PTC	Sugammadex	Better surgical conditions and lower postoperative pain
Kim 2016	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Lower intra-abdominal pressure and less postoperative pain
Rosenberg 2017	PTC 1–2	TOF ratio 10%	TOF/PTC	Sugammadex	Improved surgeon satisfaction under DNMB
Baete 2017	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved respiratory mechanics and surgical exposure
Madsen 2017	Deep continuous block	Single-bolus/standard block	TOF/PTC	Sugammadex	Reduced abdominal contractions and insufflator alarms
Koo 2018	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex vs neostigmine	Reduced IAP alarms and spontaneous breathing recovery
Bruintjes 2019	PTC 1–3	TOF 1–3	TOF/PTC	Sugammadex	Improved postoperative recovery and lower pain in as-treated analysis
Honing 2021	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	No improvement in surgical conditions during sevoflurane anesthesia
Kathopoulis 2022	PTC 0–1	TOF 0–1	TOF/PTC	Sugammadex	Lower postoperative pain without major surgical field differences
Yang 2024	PTC 1–3	TOF 1–3	TOF/PTC	Sugammadex	Better QoR-15 scores and improved surgical conditions
Esa 2024	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Better surgical space quality with lower insufflation pressure
Morisson 2024	PTC 1–2	TOF 1–3	TOF/PTC + NOL	Sugammadex	Reduced remifentanil requirement and lower IAP
Alotaibi 2024	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	No major differences in postoperative recovery outcomes
Meletti 2025	Deep blockade	Moderate blockade	TOF/PTC	Sugammadex	Better surgical field quality without QoR-40 improvement
Shen 2026	PTC 1–2	TOF 1–2	TOF/PTC	Sugammadex	Improved surgical conditions and lower postoperative pain

3.3. Risk of Bias in Individual Studies

Risk of bias was assessed using the revised Cochrane Risk of Bias tool for randomized trials. Overall, most studies demonstrated low risk of bias or some concerns across evaluated domains. The principal methodological concerns involved allocation concealment, blinding of personnel or surgeons, selective reporting of secondary perioperative outcomes, and incomplete standardization of perioperative protocols [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

Earlier randomized trials more frequently demonstrated limitations regarding allocation concealment and blinding methodology, whereas more recent studies generally incorporated quantitative neuromuscular monitoring, standardized anesthetic protocols, and structured postoperative recovery assessment [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

3.4. Effectiveness of Interventions

3.4.1. Statistically Significant Resultsi

i.

Surgical field quality

Randomized controlled trials evaluating surgical field quality generally suggested improved operative conditions with deep neuromuscular blockade (DNMB) compared with moderate neuromuscular blockade (MNMB) across different laparoscopic and robotic procedures, including bariatric, gynecologic, colorectal, donor nephrectomy, and other minimally invasive surgeries [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Individual study findings varied, with some studies demonstrating moderate-to-large effects whereas others showed minimal or no differences between groups.

Figure 2. Risk of bias assessment according to the revised Cochrane Risk of Bias tool (RoB 2).

Figure 2. Risk of bias assessment according to the revised Cochrane Risk of Bias tool (RoB 2).

Quantitative synthesis demonstrated that DNMB was associated with significantly improved surgeon-rated surgical conditions compared with MNMB (SMD 0.49, 95% CI 0.17–0.80; P = 0.002). The magnitude of effect was small-to-moderate, favoring DNMB. However, substantial heterogeneity was observed across studies (I² = 71%), likely reflecting differences in surgical populations, operative techniques, and the scoring systems used to assess surgical conditions.

Figure 3. Meta-analysis on surgical field quality comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

Figure 3. Meta-analysis on surgical field quality comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

ii.

Intra-abdominal pressure

Randomized controlled trials evaluating intra-abdominal pressure generally suggested that deep neuromuscular blockade (DNMB) allowed the use of lower pneumoperitoneum pressures while maintaining adequate surgical conditions compared with moderate neuromuscular blockade (MNMB) across different minimally invasive procedures [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. This finding supports the hypothesis that deeper neuromuscular relaxation may improve abdominal wall compliance and optimize the surgical workspace.

Quantitative synthesis demonstrated that DNMB was associated with significantly lower intra-abdominal pressure requirements compared with MNMB (MD −1.69, 95% CI −2.72 to −0.67; P = 0.001). Substantial heterogeneity was observed across studies (I² = 90%), likely reflecting differences in surgical procedures, pressure adjustment protocols, and perioperative management strategies. Despite the high heterogeneity, all included studies demonstrated a consistent direction of effect favoring DNMB.

Figure 4. Meta-analysis on intra-abdominal pressure comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

Figure 4. Meta-analysis on intra-abdominal pressure comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

iii.

Postoperative pain

Several randomized controlled trials demonstrated lower postoperative pain scores with DNMB compared with MNMB during the early postoperative period and within the first 24 postoperative hours [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Beneficial effects were more frequently observed in studies incorporating low-pressure pneumoperitoneum strategies and recovery-oriented perioperative pathways. However, some studies reported neutral findings regarding postoperative pain outcomes.

Quantitative synthesis demonstrated significantly lower postoperative pain scores with DNMB compared with MNMB (SMD −1.19, 95% CI −1.88 to −0.51; P = 0.0006). Substantial heterogeneity was observed across studies (I² = 89.9%), likely reflecting differences in surgical procedures, perioperative analgesic protocols, pneumoperitoneum strategies, and outcome assessment methods.

Figure 5. Meta-analysis on postoperative pain at 24 hours comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

Figure 5. Meta-analysis on postoperative pain at 24 hours comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

iv.

Referred shoulder pain

Referred shoulder pain was evaluated in selected randomized controlled trials and generally favored DNMB over MNMB [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. The observed effects appeared particularly associated with low-pressure pneumoperitoneum strategies and improved abdominal wall compliance during minimally invasive surgery.

Quantitative synthesis demonstrated significantly lower referred shoulder pain scores with DNMB compared with MNMB (MD −0.30, 95% CI −0.52 to −0.07; P = 0.0096). No statistical heterogeneity was observed across studies (I² = 0%), suggesting a consistent direction of effect among the included trials.

Figure 6. Meta-analysis on referred shoulder pain comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

Figure 6. Meta-analysis on referred shoulder pain comparing deep neuromuscular blockade (DNMB) versus moderate neuromuscular blockade (MNMB).

3.5. Certainty of Evidence

Evidence for surgical workspace quality was rated as moderate certainty because randomized trials consistently favored DNMB despite substantial heterogeneity across surgical procedures and operative scales [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Evidence for intra-abdominal pressure was also rated as moderate certainty because, although heterogeneity was present, the direction of effect was consistent across studies [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Evidence for postoperative pain at 24 hours was rated as low certainty because of substantial heterogeneity and imprecision across studies [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Evidence for referred shoulder pain was rated as moderate certainty because findings were consistent across included trials, although certainty was limited by the relatively small number of available studies [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,34–38].

Outcome	No. of studies	Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias	Certainty of evidence
Surgical workspace quality	6	Not serious	Serious	Not serious	Not serious	Undetected	⨁⨁⨁◯ Moderate
Intra-abdominal pressure	3	Not serious	Serious	Not serious	Not serious	Undetected	⨁⨁⨁◯ Moderate
Postoperative pain at 24 h	4	Not serious	Serious	Not serious	Serious	Undetected	⨁⨁◯◯ Low
Referred shoulder pain	2	Not serious	Not serious	Not serious	Serious	Undetected	⨁⨁⨁◯ Moderate

4. Discussion

4.1. Main Findings

The present systematic review and meta-analysis evaluated the perioperative effects of deep neuromuscular blockade (DNMB) compared with moderate neuromuscular blockade (MNMB) during minimally invasive surgery. The principal finding was that DNMB improved surgeon-rated surgical field quality and facilitated the use of lower intra-abdominal pressure strategies across laparoscopic and selected robot-assisted procedures [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

These findings support the concept that profound neuromuscular relaxation improves abdominal wall compliance and facilitates operative exposure under reduced pneumoperitoneum pressures [3,4,5,8,9,10]. This mechanism is clinically relevant because lower insufflation pressures may reduce peritoneal stretch and diaphragmatic irritation, which represent plausible contributors to postoperative abdominal discomfort and referred shoulder pain [5,6,7,8,9].

Consistent with this physiological rationale, pooled analyses also demonstrated reductions in postoperative pain at 24 hours and referred shoulder pain [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. However, postoperative outcomes should be interpreted more cautiously than surgical workspace outcomes because pain assessment methods, perioperative analgesic protocols, surgical procedures, and pneumoperitoneum strategies differed across studies. Therefore, although the pooled direction of effect favored DNMB, the magnitude and generalizability of postoperative benefits remain less certain.

Overall, the principal clinical value of DNMB appears to reside in optimization of operative workspace and facilitation of low-pressure pneumoperitoneum strategies rather than broad claims of universally improved postoperative recovery.

4.2. Strengths and Limitations

The principal strength of this review is its focused quantitative synthesis of randomized controlled trials evaluating clinically relevant intraoperative and early postoperative outcomes. Quantitative analyses were intentionally restricted to outcomes with sufficient methodological comparability, including surgical field quality, intra-abdominal pressure, postoperative pain at 24 hours, and referred shoulder pain.

Several limitations should also be considered. Considerable clinical heterogeneity was present across studies regarding surgical procedures, pneumoperitoneum protocols, neuromuscular blockade targets, reversal strategies, operative rating systems, and perioperative analgesic regimens [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Additionally, some outcomes required standardized mean differences because of variability in measurement scales. Consequently, the results should be interpreted primarily as evidence supporting a consistent direction of effect rather than as precise estimates universally applicable to all minimally invasive procedures.

4.3. Certainty of Evidence

The certainty of evidence for surgical field quality and intra-abdominal pressure was rated as moderate because findings consistently favored DNMB despite heterogeneity across procedures and perioperative protocols [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,34–38]. Evidence for postoperative pain at 24 hours was rated as low certainty because substantial heterogeneity and imprecision were present across studies [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,34–38]. Evidence for referred shoulder pain was rated as moderate certainty because findings were consistent across trials, although the number of available studies remained limited [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,34–38].

Overall, the certainty profile suggests stronger support for intraoperative benefits related to surgical workspace optimization than for broader postoperative recovery outcomes.

4.4. Clinical Implications

DNMB should primarily be considered a strategy for optimization of surgical workspace and facilitation of low-pressure pneumoperitoneum. Its most defensible role appears to be in procedures where operative exposure may become technically challenging or where lower insufflation pressures are clinically desirable [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

Potential postoperative analgesic benefits, particularly reductions in referred shoulder pain, may be most relevant when DNMB is integrated into low-pressure pneumoperitoneum strategies [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Current evidence does not support broad conclusions that DNMB universally improves overall postoperative recovery.To facilitate interpretation of the principal findings and their potential physiological relationships, a conceptual synthesis integrating the proposed mechanisms and pooled outcomes is presented in Figure 7.

Figure 7. suggests that the principal effect of DNMB may be mediated through improved abdominal wall compliance, allowing maintenance of adequate surgical exposure at lower pneumoperitoneum pressures. Reduced intra-abdominal pressure may subsequently decrease peritoneal stretch and diaphragmatic irritation, which represent plausible mechanisms contributing to lower postoperative pain and reduced referred shoulder pain. Importantly, although postoperative outcomes favored DNMB, the certainty profile suggests that these benefits should be interpreted as secondary consequences of improved intraoperative conditions rather than as direct universal effects on postoperative recovery.

Figure 7. suggests that the principal effect of DNMB may be mediated through improved abdominal wall compliance, allowing maintenance of adequate surgical exposure at lower pneumoperitoneum pressures. Reduced intra-abdominal pressure may subsequently decrease peritoneal stretch and diaphragmatic irritation, which represent plausible mechanisms contributing to lower postoperative pain and reduced referred shoulder pain. Importantly, although postoperative outcomes favored DNMB, the certainty profile suggests that these benefits should be interpreted as secondary consequences of improved intraoperative conditions rather than as direct universal effects on postoperative recovery.

4.5. Future Research

Future randomized trials should seek greater standardization of surgical field assessment scales, pneumoperitoneum pressure protocols, neuromuscular blockade targets, analgesic pathways, and postoperative outcome measurements. The most relevant remaining question may not be whether DNMB improves surgical exposure, but rather which specific procedures and patient populations derive clinically meaningful postoperative benefit.

5. Conclusion

Current randomized evidence suggests that deep neuromuscular blockade improves surgical field quality during minimally invasive surgery and facilitates lower intra-abdominal pressure strategies compared with moderate neuromuscular blockade [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29].

DNMB may additionally reduce postoperative pain at 24 hours and referred shoulder pain, particularly when combined with low-pressure pneumoperitoneum pathways [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. However, postoperative outcomes demonstrated greater heterogeneity and lower certainty than intraoperative outcomes and therefore should be interpreted cautiously.

The most defensible clinical role of DNMB appears to be optimization of surgical workspace and support of low-pressure pneumoperitoneum rather than broad improvement of all postoperative recovery outcomes.