Studies of access for minimally invasive surgery

Ainslie, William George (2003) Studies of access for minimally invasive surgery. MD thesis, University of Glasgow.

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Introduction: The advantages of laparoscopic cholecystectomy over open cholecystectomy are now well established. Nevertheless, small changes in technique and careful attention to detail can result in further improvements in clinical outcome. The aim of this thesis was to apply this concept to studies of the trocar and cannula system used to gain access to the peritoneum. Methods and Results: Patients were randomised to conventional laparoscopic cholecystectomy (CLC) or micropuncture laparoscopic cholecystectomy (MPLC, three 3.3mm, one 10mm cannulae). The duration of each operative stage and the procedure were recorded. Interleukin-6, adrenocorticotropic hormone (ACTH) and vasopressin were sampled for 24 hours. Pain scores and analgesic consumption were recorded for one week. Pulmonary function and quality of life (EQ-5D) were monitored for four weeks. Forty patients participated. Groups were comparable for age, duration of symptoms and indications for surgery. Total operative time was similar but the time to clip the cystic duct after cholangiography was significantly longer for MPLC. Significantly fewer patients required postoperative parenteral opiates in the MPLC group but oral analgesic consumption was similar in both groups. Median pain scores were lower at all time points for MPLC but this was not statistically significant. There were no significant differences in interleukin-6, ACTH or vasopressin responses, pulmonary function or EQ-5D scores. The purpose of the second study was to compare the maximum depth of penetration of the peritoneal cavity by the tips of pyramidal, sharp conical and blunt conical trocars. Sections of abdominal wall from pigs were stretched across a jig so that the skin and peritoneal surfaces could be visualised. Each trocar was inserted ten times by hand and then with a mechanical device. The findings were similar for trocar s inserted by hand or the mechanical device. In the third study, the incidence and characteristics of injury sustained by the bowel, when impinged by pyramidal, sharp conical and blunt conical trocars were compared. Rates of deflection were also recorded. Pyramidal trocars caused stellate penetrating injuries and the sharp conical trocars, small round puncture wounds. The bowel did not deflect upon contact with either the pyramidal or the sharp conical trocar. The blunt conical trocars however, was more likely to cause deflection, never breached the serosa and only created a small round "dimple." These differences were all statistically significant. Conclusions: Diameter of trocar Cholecystectomy using smaller trocars, cannulae and instruments is widely applicable to elective cholecystectomy in a westernised population. Although the change from a 10mm to a 3mm laparoscope increased the time to clip and divide the cystic duct and artery, this had no impact on the overall time of the procedure. Despite a reduction in the consumption of parenteral analgesia among the patients in the micropuncture group, there was no corresponding reduction in pain scores. Overall, this study found no evidence that fine calibre instruments conferred any obvious major clinical benefits to the patients. Profile of the trocar Pyramidal trocars encroach less into the abdominal cavity during the process of insertion, but will injure bowel or aorta upon contact. Sharp conical trocars depress the abdominal wall to a greater extent before they facilitate entry of the cannula and will injure bowel or aorta upon contact. Blunt conical trocars require to be inserted to the same depth as sharp conical trocars but are unlikely to traumatise bowel. They can deflect aorta and are less likely to cause injury than trocars with a sharp tip. It is not clear whether the risk of injury fi om a pyramidal trocar that facilitates entry of the cannula with less depression of the abdominal wall is safer than a blunt conical trocar' that encroaches further into the abdomen but is less likely to cause injury should it contact bowel or aorta. However, it can be deduced that blunt conical trocars are unlikely to cause injury if bowel is inadvertently contacted during open or closed access. Trocars with a sharp tip should probably be avoided. (Abstract shortened by ProQuest.).

Item Type: Thesis (MD)
Qualification Level: Doctoral
Keywords: Surgery.
Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
Supervisor's Name: McMahon, Prof. M.J. and O'Dwyer, Prof. P.J.
Date of Award: 2003
Depositing User: Enlighten Team
Unique ID: glathesis:2003-71035
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 09 May 2019 14:28
Last Modified: 01 Jun 2021 10:51
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