A randomised clinical trial to study postoperative abdominal and shoulder tip pain following low and standard pressure laparoscopic cholecystectomy

Abstract

Background

Laparoscopic cholecystectomy (LC) has become the gold standard for the management of symptomatic gallstone disease. The complications related to different pressure ranges of pneumoperitoneum have been studied widely with no definite conclusion till date. The current study was planned to determine the effect of standard versus low pressure laparoscopic cholecystectomy (LPLC) on postoperative abdominal and shoulder tip pain (STP).

Methods

The present randomised clinical trial included 84 patients divided into two groups: standard pressure laparoscopic cholecystectomy (SPLC) (13 mmHg) and LPLC (9 mmHg). The variables tested were abdominal pain at 3, 6, 12 and 24 h (by verbal rating scale), the incidence and intensity of STP, post-operative nausea and vomiting (PONV) and surgeon's comfort for the two techniques.

Results

The demographic characteristics of patients were similar in both groups. In LPP group, the postoperative abdominal pain at 6, 12 and 24 h was significantly less than SPLC; p = 0.02. Incidence of shoulder pain was significantly less in low pressure group (7.14%) compared with standard pressure (28.57%).

Conclusions

Low-pressure pneumoperitoneum (LPP) is safe and feasible surgery with reduced abdominal and STP.

Introduction

Worldwide biliary disorders constitute a major chunk of gastrointestinal diseases. Gallstones denote an important risk factor for gall bladder carcinoma (∼85% cases), thus has become a major cause of abdominal morbidity and mortality.^1,2 Almost 10% of population has gallstones, and cholecystectomy remains the most common surgical method for its treatment.³

In the year 1988, Dubois first introduced laparoscopic cholecystectomy (LC), a minimally invasive technique that was gradually improved in terms of better visualisation of surgical field with high magnification video systems that in turn has improved the patient's prognosis.^4,5 LC is accepted worldwide as a gold standard procedure and is associated with lower mortality, shorter hospitalisation, smaller incision, early return to daily activity and comparatively less postoperative pain.⁶ In laparoscopic surgeries, a creation of pneumoperitoneum is the requirement for providing clear surgical field and carbon dioxide (CO₂) is commonly used for pneumoperitoneum and is believed to be responsible for postoperative shoulder tip pain (STP).⁷ Other physiological effects such as changes in cardiovascular system, respiratory system and blood chemistry may also result either from increased intra-abdominal pressure or due to the effect of CO₂.⁸

Many factors affect the recovery of patients after an uncomplicated LC and the postoperative complications play a major role. Amongst the postoperative complications, STP is a significant one with an incidence rate of 30–50% while nausea, vomiting, postoperative ileus and postoperative fatigue being other complications reported.^8,9 The pressure employed in standard pressure LC for creating a pneumoperitoneum ranges between 12 and 14 mm Hg. However, there is an increasing trend to perform laparoscopic surgeries under low pressure pneumoperitoneum (LPP) using a pressure range of 7–10 mm Hg.¹

The rationale of using low pressure was to lower the complications due to pneumoperitoneum such as CO₂ embolism, vasovagal reflex, cardiac arrhythmia, hypercarbic acidosis.¹ LPP also reduces the haemodynamic changes due to insufflation as it has been observed that pain in the upper abdomen, lower abdomen, back or shoulders occurring after LC may occur due to CO₂ retention in the subdiaphragmatic space after laparoscopy for >24 h irritating the diaphragm and leading to referred shoulder and neck pain. Second, the rapid distension of the peritoneum in standard pressure laparoscopic cholecystectomy (SPLC) may result in overstretching of the diaphragmatic muscle fibres, tearing of blood vessels, traumatic traction of nerves and release of inflammatory mediators. The excitation of phrenic nerve may cause prolonged STP. Although the visceral pain post LC reduces first postoperative day onwards, the STP on the contrary being minor on first day increases and becomes significant on the following day.¹⁰ Most of the studies that have compared the effects of low pressure (7–9 mm Hg) and standard pressure (12–15 mm Hg) for LC have illustrated the feasibility of LPP with an advantage of reduction in postoperative pain.¹¹ However, despite the increasing trend till date, no national or international surgical groups have issued guidelines favouring the routine use of low pressure laparoscopic cholecystectomy (LPLC) preferring over SPLC.

The present study was conducted to further augment the benefits of LPLC by comparing the level of post LC abdominal pain, STP and post-operative nausea and vomiting (PONV) in patients undergoing LPLC and SPLC and also to evaluate the feasibility of adopting LPLC as a routine procedure by assessing the surgeon's comfort to perform surgery under LPP.

Materials and methods

Study type and duration

The present prospective randomised clinical trial was conducted from February 2019–September 2020 after due approval from institutional research and ethics committee and registered with clinical trials registry of India. A written informed consent was taken from all patients/participants for inclusion in the study.

Study place and population

The study was conducted in a tertiary care teaching hospital in Pune, India on patients undergoing LC who met the inclusion and exclusion criteria of the study (Consort Diagram).

Sample size calculation

The sample size to test the two different types of procedures SPLC and LPLC was calculated based on the prevalence of two important study variables i.e. post-operative shoulder tip pain and abdominal pain. To test the difference in abdominal pain, the sample size was calculated as 29 for each group after taking 5% α error and 80% power of the study.¹² Similarly, for shoulder pain, the sample size after calculation came out to be 42 for each group using the formula H_0: μ1 = μ2 and H_1: μ1≠μ2; μ1 = 0.92 (SD 3.19) and μ2 = 5.72 (SD = 8.59) with mean verbal analogue scale score and (H_0: π1 = π2 and H_1: π1≠π2; π1 = 8% and π2 = 32%) with frequency of incidence.⁷ Taking into consideration the sample size for the two variables, the total sample size was calculated as 42 for each group, making it to the total of 84 patients in the study.

Inclusion criteria and exclusion criteria

Inclusion criteria—Patients of either sex undergoing laparoscopic cholecystectomy.

• i.Aged between 20 and 70 years.

Exclusion criteria

• i.Empyema of gall bladder,
• ii.Common bile duct stones,
• iii.Previous history of extensive upper abdominal surgery,
• iv.Pregnant females and patients with body mass index (BMI) >30 and <19,
• v.American Society of Anaesthesiologists (ASA) grade III to V.

Methodology

Eighty-four patients were assigned to the study groups using random number tables and were equally divided between the two study groups (n-42). For LC, the standard four-port method, the same surgical protocol and general anaesthesia were applied in both the groups except for the gas pressure used to create pneumoperitoneum. The pneumoperitoneum with PaCO₂ of 13 and 9 mmHg was used in the SPLC and LPLC, respectively. The instillation of local anaesthetic agent at the gall bladder bed was not performed in the study patients.

Abdominal pain at the site of surgery, STP, level of nausea and vomiting were evaluated in both groups based on the verbal rating scale (VRS) at 1, 3, 6, 12 and 24 h after the surgery. The pain scores calculated were as: no pain-0, moderate pain-1, medium pain (need one dose of sedative)-2, severe pain-3 and intractable pain-4. For nausea and vomiting, the VRS scores were calculated as: no nausea and vomiting-0, slight nausea and vomiting-1, need for anti-nausea drug-2 and intractable vomiting-3. The surgeon's ease to perform surgery under two different pressure ranges of pneumoperitoneum (low versus standard) and their experiences were measured on Likert's scale with scores (1-bad, 2-poor, 3-fair, 4-good and 5-very good experience). The incidence of bile spillage was taken as an indirect indicator of the surgeon's comfort to perform LPLC and SPLC.

The information about socio-demographic details along with complete medical and surgical history of the patient were collected and analysed.

Statistical analysis

The quantitative and qualitative data collected from the patients were analysed using paired ‘t’ test and chi square test, respectively. The ‘p’ value of <0.05 was taken as a statistically significant difference for a given variable among the two groups. All data were analysed using IBM SPSS statistics for Windows, version 20.0 (IBM Corp., Armonk, N.Y., USA).

Results

A total of 87 patients meeting the inclusion criteria were enrolled but three of them were excluded as they did not give consent for participation. So, a total of 84 patients with 42 patients placed in each group (SPLC and LPLC) were finally included in the study (Consort diagram, Fig. 1).

Fig. 1.

CONSORT diagram of patient selection in the Randomized Clinical Trial (RCT) and division into the two groups.

Out of 84 patients, 21 were males and 63 females and the mean age in SPLC group and LPLC group was 37.27 ± 13.22 and 36.23 ± 12.89 years, respectively. The mean age and sex ratio of patients in the two groups were comparable (p = 0.78 and 0.61; Table 1). The mean operative time revealed no statistically significant difference with 58.23 ± 7.19 and 59.89 ± 8.23 min taken for SPLC and LPLC, respectively, (p = 0.61).

Table 1.

Baseline characteristics of the two groups.

Characteristics	Group 1 (SPLC)	Group 2 (LPLC)	P value
Mean Age ± SD (in years)	37.27 ± 13.22	36.23 ± 12.89	0.78
Gender			0.61
Male	11	10
Female	31	32
Co-Morbidities			>0.05
DM	11	12
HTN	08	07
COPD	02	02
ASA grade			>0.05
ASA 1	32	31
ASA 2	10	11
Mean BMI ± SD (in kg/m2)	24.42 ± 4.03	23.83 ± 3.92	>0.05

P value- <0.05- statistically significant; >0.05 – statistically not significant.

The VRS scores calculated for post LC abdominal pain in both the groups showed a significant pain reduction in LPLC group at 3, 6, 12 and 24 h of surgery (p < 0.05) when compared to SPLC group. The incidence of STP in LPLC group was significantly less (p = 0.031) i.e. 7.14% (3/42) compared to SPLC group 28.57% (12/42), though the pain scores did not show any significant difference (Table 2).

Table 2.

Comparison of outcome variables in the two groups.

		SPLC	LPLC	P value
Postoperative Abdominal pain (VRS) Mean ± SD
1 h		2.05 ± 0.73	1.83 ± 0.61	0.41
3 h		1.69 ± 0.52	1.52 ± 0.5	0.03
6 h		1.55 ± 0.5	1.36 ± 0.48	0.02
12 h		1.62 ± 0.49	1.14 ± 0.35	0.007
24 h		1.14 ± 0.56	0.83 ± 0.37	0.01
Postoperative Shoulder pain
Incidence		12/42	3/42	0.031
Intensity (Pain score) Mean ± SD
1 h		1.83 ± 0.39	1.67 ± 0.57	>0.05
3 h		1.42 ± 0.51	1.33 ± 0.57
6 h		0.92 ± 0.51	0.67 ± 0.58
12 h		0.58 ± 0.51	0.67 ± 0.58
24 h		0.25 ± 0.45	0.33 ± 0.58
Postoperative Nausea and vomiting (PONV)
	VRS Scale	SPLC (n = 42 patients)	LPLC (n = 42 patients)
1 h	0	19	21	0.54
	1	18	19
	2	4	3
	3	1	0
3 h	0	25	31	0.047
	1	13	8
	2	3	3
	3	1	0
6 h	0	29	36	0.031
	1	10	5
	2	3	1
	3	1	0
12 h	0	33	39	0.024
	1	8	3
	2	1	0
	3	0	0
Intraoperative bile spillage		SPLC	LPLC
Incidence (%)		8/42 (19.06%)	11/42 (26.19%)	0.027
Surgeon's Comfort		SPLC	LPLC
Likert's score (Mean ± SD)		3.548 ± 1.095	3.476 ± 1.139	0.768

P value- <0.05- statistically significant; >0.05 – statistically not significant.

The incidence of PONV too was found to be significantly less in LPLC than SPLC when observed at 3, 6, 12 h of surgery (p < 0.05) (Table 2). The qualitative verbal assessment of surgeon's comfort measured on Likert's scale showed no difference in the difficulty level observed by the operating surgeon's for the two techniques (p = 0.768) (Table 2). But on the other hand, the incidence of intraoperative bile spillage was found to be significantly more among LPLC (11/42) group than SPLC group (08/42); p = 0.027.

Discussion

LC has become the surgery of choice to treat gallstones replacing the open cholecystectomy. The laparoscopic surgery gives the benefit of faster patient recovery, short hospital stays but may sometimes lead to bowel or vascular injuries particularly during the access of surgical instruments which is unlikely in open cholecystectomy.¹³ CO₂; the most preferred gas for pneumoperitoneum creation usually evokes local and systemic effects due to high diffusibility, quick absorption and excretion. The routinely used pressure for creating pneumoperitoneum ranges from 12 mm Hg to 14 mm Hg and have been found to be associated with postoperative complications either by raising intraabdominal pressure or due to the effects of gas used for pneumoperitoneum. Such complications usually hamper early patient recovery, thus to minimise the impact of pneumoperitoneum, the trend to perform LPLC is on the rise.¹

Female, fertile, fat, fair and forty are 5 F's of predisposition for gallstones.¹⁴ In the present study, the mean age of the patients in SPLC group and LPLC group was 37.27 ± 13.22 and 36.23 ± 12.89 years, respectively, with statistically insignificant difference (p = 0.78). Similar mean ages of patients were observed in studies by Mahajan et al and Chok et al. while a higher mean age of patients was observed in a study by Joshipura et al.^8,9,15 In the current study, there were 63 females as against 21 males (p = 0.61) and the gender ratio (M:F) of the two groups were comparable 11:31 in SPLC and 10:32 in LPLC group. Many Indian and global studies have observed similar female predominance among their patient groups^9,16,17 while a study by Joshipura et al., revealed gender ratio tilted towards males among patients admitted for LC.⁸ A smaller number of study patients recruited for the study could be the reason for this male skewed ratio.

The time taken for surgery is dependent on many factors and adequate visualisation of the site of surgery is an important one. The pneumoperitoneum pressure is directly proportional to the surgical site view. More the pressure used for pneumoperitoneum, more would be the visual clarity of the surgical field.¹² In the current study, the surgery duration (measured from time of incision to closure) in SPLC and LPLC group was 58.23 ± 7.19 and 59.89 ± 8.23 min, respectively. Despite the mean surgery time in LPLC group to be little more than SPLC, the difference was statistically insignificant (p = 0.61). Many other studies have reported similar observations with more operative time taken for LPLC than SPLC but without any statistical significance (p values > 0.05).20, 21, 22 However, a meta-analytical review by Hua et al. observed a significantly greater time taken for LPLC than SPLC (weighted mean difference = 2.07; p < 0.001).²⁰ Contrary to other studies, Joshipura et al. found a higher operative time for SPLC than LPLC though statistically insignificant (p > 0.05).⁸

The pneumoperitoneum required in laparoscopic surgery frequently results in painful complications caused by diaphragmatic stretching, chemical irritation of peritoneum by carbonic acids from CO₂ and activation of sympathetic system due to hypercarbia leading to the amplification of local tissue inflammatory response and splanchnic mucosal ischaemia.²³

Post LC pain is multifactorial in origin, being affected by patient demographics, nature of underlying disease, surgical factors, anaesthetic technique and postoperative care. It may be incisional pain, STP and/or upper abdominal pain. The surgical factors affecting the pain include the type of gas, temperature and the pressure used for pneumoperitoneum. It also depends on the residual gas volume.⁹ Comparing the effect of low and standard pressure pneumoperitoneum on the post LC abdominal pain, we observed that the mean VRS scores showed a significant reduction in the pain intensity in LPLC group than SPLC group when observed at 3, 6 and 24 h after surgery (p < 0.05). Mahajan et al. too observed significantly decreased pain intensity among patients who underwent LPLC up till 48 h after surgery than SPLC group patients while the mean scores approached zero till the maximum observation post-surgery period in LPLC patient group.⁹

Pain in the shoulder is an unpleasant experience for patients after laparoscopic surgeries. The diaphragmatic stretching resulting from pneumoperitoneum causes the right shoulder pain because of phrenic nerve irritation.²³ Therefore, removing the residual gas dioxide after the completion of surgery have been associated with the decreased incidence along with reduced severity of shoulder tip pain.²¹

The STP incidence was observed to be lesser in LPLC group (7.14%) than SPLC (28.57%) (p = 0.031) in our study. Although the pain was less intense in LPLC than SPLC patients, the difference was found to be statistically insignificant. Yasir et al. have reported a similar incidence of shoulder pain with 10% incidence in LPLC while 28% in SPLC group was observed. Also, the pain scores were observed to be significantly less among patients with LPLC, especially at 4 h of surgery.¹⁹ The average pain score in a study by Barczynski et al. was 6.18 lower after LPLC procedure than SPLC with the statistically significant difference in the scores amounting to 22.2% (p < 0.005).²² Although statistically insignificant, both the occurrence and the pain severity scores measured on verbal analogue scale were found to be less in LPLC than SPLC patients in the study by Sandhu et al.¹⁸

In a study by Kandil et al., the authors while studying the effect of different pressure ranges used for pneumoperitoneum have observed the correlation of high-pressure ranges with the increased shoulder pain intensities. Apart from pressure pneumoperitoneum, other associated factors for increased shoulder pain occurrences are lengthy surgeries, the use of surgical drains and female gender.²⁴

PONV, a frequently reported complication in post LC patients, is very stressful occasionally more than the stress of surgery. An important mechanism of postoperative PONV is the high intracranial pressure due to raised intra-abdominal pressure impairing the venous drainage.²⁵ The occurrence of visceral ischaemia due to CO₂ used for pneumoperitoneum is another cause for PONV.²⁶ Administration of high concentration oxygen, intravenous (IV) fluids and sympathomimetic agents reduces PONV.²⁷ We, during our study, used the intraoperative oxygen, IV fluids and sympathomimetic agents as per the routine protocol and were not specifically directed against the complication of PONV. Keeping the variables matched among both the groups, it was observed that LPLC group reported significantly lesser complaints of PONV at 3, 6 and 12 h of surgery than SPLC group. Mandal et al. in their study observed that in SPLC 31.25% and in LPLC 9.38% of participants experienced post-operative nausea and found the difference to be statistically significant (p = 0.02).²⁸ Similarly, Ghosh et al. observed significantly higher PONV in SPLC versus LPLC at 2 h after surgery.¹ While a double blind trial by Nasajiyan et al. observed statistically insignificant difference in the frequencies of PONV during 0–4, 4–8, 8–12, 12–24 h after the surgery between patients with SPLC and LPLC.²⁷

An important but less studied factor for a successful surgery is the intraoperative surgeon's comfort. To date, not many studies have assessed the surgeon's comfort to perform surgeries under low pressure. On a whole, low pressure is expected to result in inadequate pneumoperitoneum, inadequate operative field, technique difficulty and subsequently increasing the risk of intraoperative complication and possible life-threatened situation.²⁹

To assess the technical difficulty to perform LC under low pressure, the surgery conversion rate of LPLC to SPLC and is an indirect indicator for surgeon's discomfort. As per 2014 cochrane review, 90% of surgeries performed under LPP were completed successfully while 2015 and 2016 reviews have found low pressures to be associated with worse visualisation of the surgical field and higher conversion rates.³⁰ Joshipura et al. observed differences in favour of the higher pressure group in parameters such as operative comfort (vision), space for dissection, and vision while using suction but the differences were not statistically significant.⁸ We in our study too observed an insignificant difference during qualitative assessment of surgeon's comfort to perform surgery under low pressure versus standard pressure with zero conversion rate to SPLC/open LC from LPLC. But the incidence of intraoperative bile spillage was found to be slightly more in LPLC group which could possibly be related to compromised surgical field. On the contrary, in a study by Ghosh et al., the intraoperative complication of bile spillage occurred in 20.3% patients in SPLC group compared to 18.6% in LPLC group.¹ Hence, low pressure surgery cannot be labelled as the sole reason for intraoperative complication after LC and patient related factors along with surgeon's experience play an important role. Therefore, as per our experience, it can be conferred that LPLC can be conveniently performed as a routine surgery in patients to avoid pressure-related post LC complications.

Conclusion

Laparoscopic cholecystectomy (LC) using LPP at 9 mm of Hg pressure is safe and feasible in the hands of experienced surgeon. Intra-operative complications, operative field visualisation, operative difficulties and duration of surgery are not affected by low-pressure pneumoperitoneum. Moreover, LPP confers advantage of decreased consumption of intra-operative CO₂, less postoperative abdominal and shoulder tip pain due to pneumoperitoneum, PONV and promotes early per oral feeding, thus reducing the hospital stay.

Disclosure of competing interest

The authors have none to declare.