title: Low-pressure pneumoperitoneum versus standard pneumoperitoneum in laparoscopic cholecystectomy, a prospective randomized clinical trial.
abstract: BACKGROUND
  Post-laparoscopic pain syndrome is well recognized and characterized by abdominal and particularly shoulder tip pain; it occurs frequently following laparoscopic cholecystectomy. The etiology of post-laparoscopic pain can be classified into three aspects: visceral, incision, and shoulder. The origin of shoulder pain is only partly understood, but it is commonly assumed that the cause is overstretching of the diaphragmatic muscle fibers owing to a high rate of insufflations. This study aimed to compare the frequency and intensity of shoulder tip pain between low-pressure (7 mmHg) and standard-pressure (14 mmHg) in a prospective randomized clinical trial.
  
  
  METHODS
  One hundred and forty consecutive patients undergoing elective laparoscopic cholecystectomy were randomized prospectively to either high- or low-pressure pneumoperitoneum and blinded by research nurses who assessed the patients during the postoperative period. The statistical analysis included sex, mean age, weight, American Society of Anesthesiologists (ASA) grade, operative time, complication rate, duration of surgery, conversion rate, postoperative pain by using visual analogue scale, number of analgesic injections, incidence and severity of shoulder tip pain, and postoperative hospital stay. p < 0.05 was considered indicative of significance.
  
  
  RESULTS
  The characteristics of the patients were similar in the two groups except for the predominance of males in the standard-pressure group (controls). The procedure was successful in 68 of 70 patients in the low-pressure group compared with in 70 patients in the standard group. Operative time, number of analgesic injections, visual analogue score, and length of postoperative days were similar in both groups. Incidence of shoulder tip pain was higher in the standard-pressure group, but not statistically significantly so (27.9% versus 44.3%) (p = 0.100).
  
  
  CONCLUSIONS
  Low-pressure pneumoperitoneum tended to be better than standard-pressure pneumoperitoneum in terms of lower incidence of shoulder tip pain, but this difference did not reach statistical significance following elective laparoscopic cholecystectomy.
authors.affiliation: Department of Surgery, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. tsandhu@mail.med.cmu.ac.th
authors.forename: Trichak
authors.initials: T
authors.lastname: Sandhu
authors.forename: Sirikan
authors.initials: S
authors.lastname: Yamada
authors.forename: Veeravorn
authors.initials: V
authors.lastname: Ariyakachon
authors.forename: Thiraphat
authors.initials: T
authors.lastname: Chakrabandhu
authors.forename: Wilaiwan
authors.initials: W
authors.lastname: Chongruksut
authors.forename: Wasana
authors.initials: W
authors.lastname: Ko-iam
mesh_terms: D000328:Adult; D000368:Aged; D017081:Cholecystectomy, Laparoscopic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000209:etiology; D011028:Pneumoperitoneum, Artificial / Q000379:methods*; D011446:Prospective Studies; D020069:Shoulder Pain / Q000209:etiology