title: Gravity line strategy may reduce risks of intraoperative injury during laparoscopic surgery.
abstract: BACKGROUND
  "Tilt" of surgical view was commonly shown on the monitor due to unintentional rotation of camera along its long axis by camera driver. Surgeons may be influenced on identification of anatomical structures by the tilt vision. We aimed to analyze the surgical records and videos of laparoscopic surgery, and to reveal the correlation between intraoperative complications and tilt view.
  
  
  METHODS
  A series of 425 consecutive patients who received laparoscopic low anterior resection and abdominoperineal resection were studied, and 398 surgery videos were reviewed. Still pictures showing intraoperative injury were selected. A method was established to measure tilt angle in the still pictures according to the reference line based on several anatomic landmarks. The patients were grouped with two methods according to different study purposes. Incidence of intraoperative complication and tilt angle were calculated, and statistical analysis was performed.
  
  
  RESULTS
  The incidence of intraoperative complications was 8.3%. Tilt of the surgical field at different degrees (<15°, 15°-30° and >30°) was found in a relatively high rate in these surgery videos (31.4%). Compared with controls, comparatively bigger tilt angles were found in all cases of complication group. It is interesting to note that intraoperative complications happened more often when the tilt angle was in the range of 15°-30° (72.7%) than >30° (18.2%). We also noted a high incidence of complication (72.7%), while tilt angle was over 15° (26%) in the first 100 cases; comparatively a steady declining low rate of complication occurrence (5-7%) and also tilt angle over 15° (9-11%) were noted in the later 298 cases.
  
  
  CONCLUSIONS
  Rotation of camera is common during laparoscopic procedures. The tilt view increased the risk of laparoscopic procedures. Tilt angle at 15-30° is the most dangerous rotation for laparoscopic surgeries. Therefore, we propose the "Gravity Line Strategy" principle as one of the basic operating criteria to correct the tilt angle.
authors.affiliation: Department of General Surgery, First Affiliated Hospital of Harbin Medical University, Harbin, Hei Long Jiang, China, zhuanlone@163.com.
authors.forename: Anlong
authors.initials: A
authors.lastname: Zhu
authors.forename: Chao
authors.initials: C
authors.lastname: Yuan
authors.forename: Daxun
authors.initials: D
authors.lastname: Piao
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.forename: Hongchi
authors.initials: H
authors.lastname: Jiang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D002681:China / Q000453:epidemiology; D004867:Equipment Design; D005260:Female; D006112:Gravitation; D006801:Humans; D015994:Incidence; D007431:Intraoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D010535:Laparoscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning / Q000592:standards*; D012002:Rectal Diseases / Q000601:surgery*; D012810:Sigmoid Diseases / Q000601:surgery*; D016896:Treatment Outcome; D020535:Video-Assisted Surgery / Q000295:instrumentation*; D055815:Young Adult
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