Systemic Lidocaine Versus Nalbuphine for Post-Operative Analgesia in Bariatric Patients in ICU

The use of bariatric surgery in the treatment for severe obesity has several benefits in terms of sustainable weight loss, improvements or resolution of several metabolic comorbidities as well as improved life expectancy. These benefits in combination with the continuously decreasing rates of complications have led the way to a significant rise in the demand for bariatric surgical procedures worldwide. Also it has been proved to be cost effective cure for the patients themselves as its prognosis is good and long lived than medical therapy.1-3

For post-surgical pain, classical systemics including morphine and fentanyl remain the therapeutic mainstay. Obese patients, however, are prone to opioid-associated side effects, particularly post-operative nausea and vomiting (PONV), and respiratory depression. Further, obstructive sleep apnea is common in morbidly obese patients, which predisposes them even to respiratory depression.4-5

The use of non-opioid drugs and adjuvants can minimise opioid related side effects and are highly desirable in morbidly obese patients undergoing surgical procedures. Intravenous lidocaine has been used as a part of multimodal approach for postoperative analgesia in various surgeries including laparoscopic procedure. It has analgesic, anti-inflammatory and anti-hyperalgesic properties. This is done through inhibition of Na+ channels, N-methylaspartic acid (NMDA), and G-protein-coupled receptors. The concerns for LA toxicity has been raised with continuous intravenous lidocaine infusion.6-7

The use of nalbuphine on bariatric surgery is promising: less side effects, less addiction and equianalgesic to morphine. These are important features of an opioid especially for certain populations, like those that are at higher risk for developing respiratory depression. Also, like other mixed agonists-antagonists, nalbuphine has a ceiling effect. It was observed that increasing doses of nalbuphine produces increasing intensity of analgesia only up to a point; beyond that point, further increases in dose do not result in increased intensity of analgesia, which is bounded for excruciating pain but safer for opioid side effects on risky populations and an improvement on post-operative care due to its qualities instead of morphine.8-9

A study conducted in India on pain control in bariatric surgeries compared lidocaine and nalbuphine reported mean time of first rescue analgesia 35.89±33.83 and 4.11±11.87 respectively and mean postoperative consumption of fentanyl as 218.93±138.04 with lidocaine and 138.04±198.28 nalbuphine respectively.10 It has been reported in literature that both intravenous lidocaine and nalbuphine are effective for postoperative analgesia after bariatric surgery and had been compared with placebo or some other strategies.6-9 However the level of evidence comparing in randomised controlled trial, the efficacy of intravenous lidocaine versus nalbuphine in bariatric surgery in our local set up of Pakistan remains scarce in literature as well as in routine practise.

The purpose of this study is to compare the effects of systemic lidocaine and nalbuphine for post-operative analgesia in obese patients undergoing laparoscopic bariatric surgeries under general anaesthesia. Findings from this study may be used to inform clinical practise guidelines and help choose the best analgesic regimen for obese patients undergoing laparoscopic bariatric surgeries. If the results of the trial demonstrating non-inferiority or superiority of systemic lidocaine or nalbuphine compared to fentanyl in terms of pain control and opioid consumption is shown, this could lead to a change in analgesic practises to safer and more effective approaches, thus leading to improved postoperative outcomes and patient satisfaction in this vulnerable population.

After approval by the Hospital Ethical Committee, this was a randomised controlled trial which was carried out at the Anaesthesia Unit of Shalamar Hospital, Lahore, over a period of six months from January 9th, 2025, to July 8th, 2025. One hundred and ten patients who met the inclusion and exclusion criteria were recruited into the study using non-probability consecutive sampling. The patients were divided into two equal groups. 55 patients were in each group. A 95% confidence level and 80% power of the study were used to determine the sample size, based on the mean postoperative consumption of fentanyl of 218.93 ± 138.04 µg in the lidocaine group and 138.04 ± 198.28 µg in the nalbuphine group in previous studies.10

Patients of both gender and between 18 to 60 years of age under ASA class II or III and BMI greater than 35 kg/m2 undergoing laparoscopic bariatric surgeries under general anaesthesia were included in the study. Patients who were hemodynamically unstable (systolic blood pressure < 90 mmHg, mean blood pressure < 60 mmHg, or heart rate < 55 beats/min), had a history of liver or renal disease or cerebrovascular accident, or were pregnant or lactating were excluded.

After obtaining written informed consent from each patient, demographic data such as age, gender, weight, height, BMI and ASA class were recorded. Randomization by using random number table was performed to assign patients into 2 groups: Group A (systemic lidocaine) and Group B (nalbuphine). Standard preoperative preparations were performed and all patients were monitored with standard hospital monitoring equipment. Anaesthesia was carried out according to standard protocol as accepted by the hospital. Approximately 90 seconds prior to the estimated tracheal intubation time, the patients in Group A received intravenous infusion of lidocaine at a dose of 1.5 mg/kg as bolus over 10 min, followed by continuous infusion of 1.5 mg/kg/h, which was turned off at the time of removal of laparoscopic ports at the end of surgery. Patients in Group B received ultrasound guided bilateral transversus abdominis plane (TAP) block by subcostal approach using nalbuphine at a dose of 0.1 mg kg-1 bolus each side under ultrasound guided using Sonosite S nerve machine after induction of anaesthesia.

Intraoperatively, patients were treated to maintain hemodynamic stability and normothermia. At the end of the surgery, patients were extubated for alert, warm, awake and comfortable, once adequate reversal of the neuromuscular block was complete. The time of extubation was documented. An analgesia pump containing fentanyl (20 ug/dose, lockout interval of 15 minutes, maximum dose 60 ug/dose/hour) had been attached and managed by the ICU nursing staff. After extubation, patients were continuously monitored and when a patient first complained of pain, the staff nurse evaluated the pain on a Likert scale, from 0 to 10 (0 = no pain, 10 = worst pain). When the pain score was greater than 5, rescue analgesia was given. The time from extubation to the first rescue analgesia was recorded as time to first rescue analgesia.

Postoperatively, patients were evaluated for pain every hour for 24 hours by the staff nurse. Whenever the pain score was greater than 5, fentanyl was titrated in increments of 20 ug, a max of 60 ug per hour. The cumulative amount of fentanyl used in 24 hours after surgery was collected. All the relevant information

Table-1: Comparison of distribution of different variables between groups

Table-2: Comparison of mean time to first rescue analgesia and total fentanyl consumption between groups

Table-3: Stratification of mean time to first rescue analgesia between groups with respect to different variables

Table-4: Stratification of mean total fentanyl consumption between groups with respect to different variables

The present study compared efficacy of systemic lidocaine and nalbuphine for postoperative analgesia in obese patients who underwent laparoscopic bariatric surgery. Our results showed the mean time to first rescue analgesia was much longer in the systemic lidocaine group (33.99 ± 24.96 min) than in the nalbuphine group (10.24 ± 5.75 min), total fentanyl consumption in the postoperative period in the lidocaine group was slightly higher than that in the nalbuphine group (222.77 ± 137.90 ug vs. 188.82 ± 176.01 ug; p = 0.043). These findings are consistent with recent publications describing the benefits of intravenous lidocaine on improving pain relief and prolonging analgesic pain relief in the early postoperative period in bariatric patients.

Yurttas et al. (2023) found that systemic lidocaine decreased the intensity of postoperative pain and delayed the first opioid request in their meta-analysis after bariatric surgeries in line with our results.11 Also, a meta-analysis by Hung et al. (2022) showed that intraoperative intravenous lidocaine significantly increased the time to the first rescue analgesia and the quality of postoperative recovery in obese patients.12 Duarte-Medrano et al. (2024) also confirmed that lidocaine infusion during bariatric surgery reduced the early postoperative pain and opioid demand without major adverse effects.13

In contrast, Plass et al. (2021) found no significant decrease in opioid consumption with intraoperative lidocaine but did find improved recovery profiles.14 Our finding of slightly increased fentanyl consumption with lidocaine is consistent with this and suggests that although lidocaine prolongs initial analgesia, its overall opioid-sparing effect may depend on dosing and infusion duration.

Regarding nalbuphine, studies have focused on its k-opioid receptor mediated analgesic and opioid-sparing properties. It has been shown that Lee et al. (2023) found extended release nalbuphine had a significant effect on reduction of postoperative pain scores and rescue opioid requirements after laparoscopic bariatric surgery.15 Similarly, Liu et al. (2021) described the use of long acting dinalbuphine sebacate had a prolonged effect on postoperative analgesia when combined with regional blocks.16 Our study's lower fentanyl requirement in the nalbuphine group supports these findings, confirming nalbuphine's role as an effective opioid sparing adjuvant.

Comparative studies have additionally highlighted nalbuphine's efficacy in multimodal protocols. Nasr et al. (2022) reported lower postoperative pain and opioid consumption of nalbuphine compared to fentanyl in laparoscopic bariatric surgery, and Mahdy et al. reported lower nalbuphine consumption in opioid-free anaesthesia regimens.17-18 Likewise, Mansour et al. (2024) reported lower nalbuphine consumption in enhanced recovery technology for sleeve gastrectomy.19

The present findings, therefore, support the evidence that both agents, systemic lidocaine and nalbuphine, improve postoperative pain control, by different mechanisms. Lidocaine's primary mechanism is through sodium channel blockade and central sensitization inhibition, and nalbuphine's primary mechanism is k-receptor agonist with an effective analgesia and ceiling effect on respiratory depression.20-21

Future studies are needed to focus on enhancing lidocaine dosing strategies and assessing lidocaine and nalbuphine combinations for improved analgesic effect with less opiate consumption. Larger multicenter trials could investigate pharmacogenomic variability, as well as long-term outcomes among obese patients.

This study was limited in that its design was a single centre study with a relatively small sample size and did not include long-term evaluation of pain or recovery. Additionally, the brief observation time (24 hours) may not be sufficient to describe the analgesic effects beyond the early postoperative period.

Systemic lidocaine had significantly longer postoperative analgesia than nalbuphine but at the cost of a slightly increased opioid use. Both agents were effective and well-tolerated in bariatric ICU patients for control of pain.

1.      Gerber P, Anderin C, Gustafsson UO, Thorell A. Impact of age on obesity-related comorbidity after gastric bypass: a cohort study from the Scandinavian Obesity Surgery Registry (SOReg). Ann Surg. 2022;276(6):798-804.

2.      Angrisani L, Santonicola A, Iovino P, Ramos A, Shikora S, Kow L. Bariatric surgery survey 2018: similarities and disparities among the 5 IFSO chapters. Obesity Surg. 202131(5):1937-48.

3.      Abbas K, Gul F, Kazmi SNH. Implications of bariatric surgery and recommendations for Pakistan. Ann Med Surg (Lond). 2022;78:103799.

4.      Chen YY, Boden KA, Schreiber K. The role of regional anaesthesia and multimodal analgesia in the prevention of chronic postoperative pain: a narrative review. Anaesthesia. 2021;76:8-17.

5.      Pardue B, Thomas A, Buckley J, Suggs WJ. An opioid-sparing protocol improves recovery time and reduces opioid use after laparoscopic sleeve gastrectomy. Obesity Surg. 2020;30(12):4919-25.

6.      Sun J, Wang S, Wang J, Gao X, Wang G. Effect of Intravenous Infusion of Lidocaine Compared with Ultrasound-Guided Transverse Abdominal Plane Block on the Quality of Postoperative Recovery in Patients Undergoing Laparoscopic Bariatric Surgery. Drug Des Devel Ther. 2022;16:739-748.

7.      Barbosa EC, Ortegal GH, Aguirre JM, Costa PR, Ferreira LN, Moreira LF, et al. Effects of intravenous lidocaine on quality of recovery after laparoscopic bariatric surgery: a systematic review and meta-analysis of randomized controlled trials. Obesity Surg. 2024;34(7):2663-9.

8.      De Oliveira AR, Conter FS, Martinelli ES, Weston AC. Nalbuphine Use for Postoperative Pain in Bariatric Surgery: Case Series and Rationale. Eur J Med Health Sci. 2020;2(6):150-5.

9.      Liu X, Hu J, Hu X, Li R, Li Y, Wong G, et al. Preemptive intravenous nalbuphine for the treatment of post-operative visceral pain: a multicenter, double-blind, placebo-controlled, randomized clinical trial. Pain Therapy. 2021;10(2):1155-69.

10.   Gupta C, Valecha UK, Singh SP, Varshney M. Systemic lidocaine versus ultrasound-guided transversus abdominis plane block for postoperative analgesia: A comparative randomised study in bariatric surgical patients. Indian J Anaesth. 2020;64(1):31-36.

11.   Yurttas T, Djurdjevic M, Schnider TW, Filipovic M. Analgesic efficacy of systemic lidocaine using lean body mass based dosing regime versus placebo in bariatric surgery: a prospective, randomised, double-blind, placebo-controlled, single-centre study. Br J Anaesthesia. 2023;131(1):122-9.

12.   Hung KC, Chang YJ, Chen IW, Chang YP, Chiu SF, Sun CK. Efficacy of intraoperative intravenous lidocaine for postoperative analgesia following bariatric surgery: a meta-analysis of randomized controlled studies. Surg Obesity Related Dis. 2022;18(1):135-47.

13.   Duarte-Medrano G, Nuño-Lámbarri N, Dominguez-Franco A, Lopez-Rodriguez Y, Minutti-Palacios M, Palacios-Chavarria A, et al. Perioperative intravenous lidocaine infusion for postsurgical pain management in bariatric surgery patients. J Anesthesia Analgesia Critical Care. 2024;4(1):73-7.

14.   Plass F, Nicolle C, Zamparini M, Al Issa G, Fiant AL, Le Roux Y, et al. Effect of intra‐operative intravenous lidocaine on opioid consumption after bariatric surgery: a prospective, randomised, blinded, placebo‐controlled study. Anaesthesia. 2021;76(2):189-98.

15.   Lee YE, Wang SY, Chen JH, Chen CY, Shiue YL, Soong TC, et al. Efficacy and safety of parenteral injection of an extended release κ-receptor opioid sebacoyl dinalbuphine ester for acute and chronic pain after laparoscopic bariatric surgery: a randomized, placebo-controlled, double-blind trial. Obesity Surg. 2023;33(4):1192-201.

16.   Liu SY, Ho YH, Wong CS. Multimodal analgesia with long-acting dinalbuphine sebacate plus transversus abdominis plane block for perioperative pain management in bariatric surgery: a case report. Front Pharmacol. 2021;12:683782.

17.   Nasr YM, Waly SH, Mokhtar WE. Intraperitoneal bupivacaine with dexamethasone versus bupivacaine alone for pain relief after laparoscopic bariatric surgeries: A randomized controlled trial. Egyptian J Hospital Med. 2022;88(1):3185-91.

18.   Mahdy EW, Mohammed EA, Abdelwahab ZM. Comparative Study between Opioid-Free Anesthesia and Opioid-Based Anesthesia in Obese Patients Undergoing Abdominal Laparoscopic Surgery? Effective and Safe Analgesia Challenge: A Randomized Double Blinded Study. Egyptian J Hospital Med. 2024;97(1):4261-7.

19.   Mansour HS, Megalla SA, Abdelzaher TA, Abdelwahab AT, Sewefy AM, Hetta HM. The Impact of Enhanced Recovery Protocols Regarding Postoperative Nausea and Vomiting Following Sleeve Gastrectomy under Triple Prophylaxis: A Controlled Randomized Study. Open Anesthesia J. 2024;18(1):150-5.

20.   Mieszczański P, Kołacz M, Trzebicki J. Opioid-free anesthesia in bariatric surgery: is it the one and only? A comprehensive review of the current literature. InHealthcare 2024;12(11):1094-8.

21.   Kamal NA, El-Aasar NM, El-Dorgham LT, Ahmed AF. Dexmedetomidine versus ketamine infusion for reducing intra and post-operative opioid consumption in obese patients Undergoing Abdominal Surgeries. Zagazig Univ Med J. 2024;30(4):1381-92.