Does patient’s position count during Endoscopic Retrograde Cholangio-pancreatography? Left lateral decubitus versus prone position

Objective: To compare the efficacy and safety of left lateral decubitus versus prone position during endoscopic retrograde cholangio-pancreaticography (ERCP). Methods: This prospective single-centre cohort study was carried out at Pak Emirates Military Hospital from January to June 2021. Patients requiring ERCP were subsequently allotted LL or PP group randomly (unequal randomization) except patients with recent abdominal surgery, in-dwelling catheters, raised intra-abdominal pressure, cervical spine abnormalities and limb contractures. Qualitative data was analysed using frequencies and chi square statistics whereas, quantitative data was analysed using mean±SD and student T or Mann Whitney U-test. Results: A total of 114 patients were enrolled according to the inclusion criteria with 62(54%) males and majority of the patients (42%) belonging to the age group 31-45 years. The most common ERCP indication was choledocholithiasis (36%). Technical success was achieved in 109(96%) patients with no statistically significant difference between the two groups. The total time of procedure, time for deep cannulation, time for acquiring therapeutic goal and ERCP complexity level were all similar between the two groups. The rate of inadvertent PD cannulation and PEP were relatively higher for the PP group but were statistically non-significant through univariate and logistic regression analyses and the only outcome measure that showed significance was multiple cannulations in the PP group. Conclusion: The study concludes that LL is non-inferior to PP and both positions have comparable outcomes with non-significant differences in terms of technical success rate, complications (specifically PEP), total procedure time, time required for deep cannulation and attainment of goal, ERCP complexity level and inadvertent PD cannulation.


INTRODUCTION
Although a widely used pancreatico-biliary procedure world-wide, endoscopic retrograde cholangio-pancreaticography (ERCP) is nevertheless associated with considerable complications and mortality in the absence of due regard to the quality indicators. 1 Large volumes of research is available on the risk factors for complications (intra and post ERCP procedures) that can be narrowed down to two most relevant components, endoscopist's expertise and the ease of cannulation. 2raditionally, ERCP has been performed in the prone position (PP) and has been linked to greater facilitation of deep biliary cannulation and superiority of fluoroscopic images of the pancreatico-biliary tree. 3Left lateral decubitus position (LL), on the other hand, is preferred by the anaesthetists and is considered relatively comfortable for the patients with limited cervical mobility, morbid obesity, abdominal distension, recent abdominal surgery

Does patient's position count during Endoscopic
Retrograde Cholangio-pancreatography? Left lateral decubitus versus prone position and raised intra-abdominal pressure, limb contractures and pregnancy. 4Some of the setbacks quoted in the literature regarding LL are poor opacification of the proximal biliary tree, scope torsion and the need of the endoscopist to look away from the monitors during cannulation. 3,4Supine position (SP), however, is rarely tried in the endoscopy suite due to its potential risk of cardiopulmonary collapse and a relatively low technical success rate. 5 thorough literature review revealed that efficacy and safety of ERCP in PP versus SP has been reported in randomized controlled trials but there is a paucity of research regarding LL position.No such study was found locally by using multiple search engines like PakMediNet, Google Scholar and PubMed.This prospective study was designed to compare the efficacy and safety of prone versus left lateral decubitus position during ERCP in terms of technical success rate, time during cannulation and goal attainment, inadvertent PD cannulation and complications.

METHODS
This study was designed as a prospective singlecentre cohort study carried out at Pak Emirates Military Hospital, Rawalpindi from January 2021 to June 2021 after obtaining ethical committee review (EC/406/2022, dated January 2021) and patients' consent.Inclusion and Exclusion Criteria: All patients, age 15 years and above with indication for ERCP and consenting to the study were enrolled.Exclusion criteria included active shock and hemodynamic instability, coagulopathy, severe cardio-pulmonary disease and pregnancy.The patients underwent unequal allocation randomization to either of the two groups; prone (PP) or left lateral (LL).The exceptions to randomization were patients with morbid obesity, tense ascites, recent abdominal surgery, in-dwelling catheters, raised intra-abdominal pressure, cervical spine abnormalities and limb contractures. 6hese were assigned LL group to prevent discomfort and obvious complications.
The study was performed in a dedicated tertiary care advance GI procedure suite by two high volume Consultant Endoscopists with 95% success rate of biliary cannulation and 400 ERCPs per year.Sedation with intravenous midazolam (0.05-0.1 mg/kg) and propofol (0.5-1 mg/kg) was provided to all patients.All patients were provided with oxygen at 2L/minutes through nasal cannula and were continuously monitored for BP, pulse, oxygen saturation, ECG and level of sedation.A strict cannulation protocol of a total of five cannulation attempts with no more than two inadvertent PD cannulations was followed.If deep cannulation was not achieved through this standard method, double guidewire and/or pancreatic stent assisted procedure, use of early Needle Knife Sphincterotomy (NKS), NKS as a last resort or TPS and/or combined sphincterotomy were tried according to the indication of the procedure and the local anatomy.Both the operators used the same technique for deep cannulation and the demographics, extensive cannulation data, laboratory and outcome measures were noted for every patient.All patients received pre-procedure rectal indomethacin, were observed for 6 hours post-ERCP and those with significant abdominal pain were retained for 24 hours. 7Definitions: Cannulation attempt was defined as a continuous contact between the papilla and the sphincterotome for at least five seconds. 7Resorting to NKS after a total of five attempts at cannulation with standard method was defined as early NKS.In some of the cases, NKS was tried earlier at the endoscopist's discretion considering the local anatomy.Difficult biliary cannulation was defined as more than five attempts at papillary cannulation, more than five minutes spent to cannulate after papilla was clearly visualized or more than one inadvertent PD cannulation. 8echnical success was defined as free and deep instrumentation of the biliary tree. 7Total time of the procedure was defined as the time from initial intubation to the procedure termination. 9Pancreatitis was defined as abdominal pain and more than three times rise in serum amylase levels 24 hours post-procedure.Cholangitis was defined as fever of >38ºC with abdominal pain for more than 24 hours. 10Perforation was defined as the presence of free air or contrast leakage seen radiogarphically. 9ERCP complexity level was defined using the classification provided by Cotton PB.

RESULTS
A total of 114 patients were enrolled according to the inclusion criteria with 62(54%) males and majority of the patients (42%) belonging to the age group 31-45 years.The patients who were assigned PP were relatively young with less comorbidities and a lower ASA grade (Table-I), as already explained in the methods section.The most common ERCP indication was choledocholithiasis (36%) followed by benign CBD strictures (20%), stent replacement (13%) and hilar malignant strictures (8.6%) (Fig. 1).
Technical success was achieved in 109(96%) patients with no statistically significant difference between the two groups through different methods used for deep biliary cannulation (Table-III).Three patients, however, had to be shifted from LL to PP for deep cannulation, two of which failed and had to be referred for percutaneous trans-hepatic biliary drainage (PTBD).The total time of procedure, localization of papilla, time for deep cannulation, time for acquiring therapeutic goal (except for using standard cannulation method, which was shorter for PP) and ERCP complexity level were all similar between the two groups.
The rate of inadvertent PD cannulation and PEP were relatively higher for the PP group but were not statistically significant through univariate and logistic regression analyses (Table-II, III).Mortality was zero for both the groups with meticulous monitoring of those patients that did develop complications.Using univariate and logistic regression analyses, the only outcome measure that showed significance was multiple cannulations in the PP group (Table-III).

DISCUSSION
Large volumes of research are being carried out regarding safety and efficacy of ERCP as advance GI procedures are becoming available in secondary and tertiary care facilities.There is a paucity of literature regarding the effects of position on the outcomes of ERCP in terms of operator and patient perspective. 13ata from the last decade shows a few small singlecentre studies comparing prone to supine position, with no significant differences in success rate but greater procedural difficulty. 14As discussed earlier, PP is not ideal in pregnant patients, patients with rheumatological conditions and situations where there is a high intraabdominal pressure.
LL position can be safely used in these cases and is theoretically safer, convenient and acceptable to the operators as well as the anaesthetists. 13The only drawback of LL position is the inferior opacification of the biliary tree and difficulty in finding the ampullary location. 13owever, a recent RCT showed that LL is non-inferior to PP in terms of technical and clinical success rates, complication rate but showed a higher PD cannulation incident. 15ur study showed an equal technical and clinical success rate for both the groups (96%).The failure rate was also non-significant between the groups.Similar studies comparing patient position during ERCP concluded a technical success rate of 70 -90% for SP, 90 -100% for PP and 90 -96% for LL. 16,17The total time of procedure, time for deep cannulation and time for acquiring therapeutic goal were all similar between the two groups for our study, showing non-inferiority of LL in comparison to PP.This is in contrast to a pioneer study by Park et al which reported a relatively longer cannulation time for the PP group. 9he only difference seen in our study was a longer procedure time to attain therapeutic goal in LL group for standard cannulation.The probable reason for this difference is the fact that more complex procedures were done in LL rather than PP cohort.However, the risk of inadvertent PD cannulation (which is an indirect marker for a difficult cannulation 13 ) was lower and insignificant between the groups in contrast to a recent RCT. 15 The rate of complications for our study was also comparable to the international data and there was nonsignificant difference for occurrence of complications between the two groups.All the patients were treated conservatively as in-patient and only one patient with PEP required EUS guided cystgastrostomy.This suggests that LL does not increase the risk of complications (specifically PEP) although this position entails fluoroscopic challenge due to overlapping ducts. 13L position is preferred by some endoscopists especially while performing ERCP in non-intubated patients and without the help of anesthesiologist. 180][21] However, a higher radiation exposure in LL advocates carrying out large multi-centre studies. 12Limitations: It includes a single-centre setup, nonmatched sample, unequal allocation randomization and the lack of data regarding degree of duct opacification in the two positions.The strengths of the study include removal of operator bias, presence of C-arm fluoroscope, extensive data collection and meticulous follow up of patients who developed complications.

CONCLUSION
The study concludes that PP and LL positions have comparable outcomes with non-significant differences in terms of technical success rate, complications (specifically PEP), total procedure time, time required for deep cannulation and attainment of goal, ERCP complexity level and inadvertent PD cannulation.Multi-centre randomized control trials are however required locally to establish the efficacy, safety and non-inferiority of both LL and PP positions for ERCP.
Disclaimer: One of the authors is a member of the IRB for the same hospital.

Table - I
: Demographics of the study cohort (n=114).

Table -
II: Outcome of ERCP in the study population (n (%) or mean±SD).