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Biomedical subjects

George B Hanna

Publications and source records attributed to George B Hanna.

6 recordsLinked to original sources
PubMed2004

Optimal angle between instrument shaft and handle for laparoscopic bowel suturing.

OBJECTIVE: To determine the optimal angle between the handle and instrument shaft for endoscopic suturing. DESIGN: A rocker handle needle driver was used to investigate the 0 degrees, 40 degrees, and 80 degrees handle-to-shaft angles. The standard task entailed closure of a 50-mm enterotomy in a nonliving porcine small-bowel model. Fifty enterotomies were performed with each angle in a random sequence. SETTING: Research laboratory in the Surgical Skills Unit at Ninewells Hospital. PARTICIPANTS: Ten surgeons with previous experience in laparoscopic surgery. MAIN OUTCOME MEASURES: The execution time (in minutes), leakage pressure (in centimeters of water), and suture error placement score (deviations of the entry and exit points <3 mm or >5 mm from the enterotomy edge or between sutures). RESULTS: The 40 degrees handle-to-shaft angle had a higher mean (SD) leakage pressure of 43.8 (20.0) cm H2O compared with the 80 degrees and 0 degrees angles (31.1 [21.0] and 26.3 [19.0] cm H2O, respectively) (P<.001). In addition, the 40 degrees angle had a lower mean (SD) suture error placement score of 13.6 (7.6), compared with the 80 degrees and 0 degrees angles (19.4 [9.4] and 21.1 [8.5], respectively) (P<.001). No significant difference was found in the execution time between the different angles (P =.20). CONCLUSION: The best quality of laparoscopic bowel suturing, in terms of the accuracy of suture placement and the integrity of the suture line closure, was obtained with a 40 degrees handle-to-shaft angle.

Analysis of Variance↗
PubMed2004

Optimum shadow-casting illumination for endoscopic task performance.

HYPOTHESES: Task performance improves with the use of a balanced degree of shadow and illumination compared with no or maximum shadow contrast; and overhead shadow-casting illumination is better than side illumination. DESIGN: The standard task entailed touching target points on an undulating surface by using a surgical hook. Each run consisted of 13 target points in a random sequence. Five settings were investigated: no shadow; 22%, 42%, and 65% shadow contrast created by overhead illumination; and 22% shadow contrast produced by side illumination. Each surgeon completed 3 runs with each setting in a random order. SETTING: Research laboratory at the Surgical Skills Unit, Ninewells Hospital, Dundee, Scotland. PARTICIPANTS: Ten surgical trainees. MAIN OUTCOME MEASURES: Number of errors and execution time. RESULTS: Shadow contrast settings had fewer errors than shadowless imaging (P<.001). Work with overhead 22% shadow contrast had a lower error rate than side illumination (P<.001). With overhead illumination, 22% and 42% shadow contrast were accompanied by a lower error rate than maximum shadow contrast of 65% (P<.001 and P =.005, respectively). No significant difference was found in the execution time. CONCLUSION: Optimum endoscopic task performance is obtained with overhead shadow-casting illumination and a balanced degree of illumination and shadow contrast.

Analysis of Variance↗
PubMed2004

Abdominal wall lift versus positive-pressure capnoperitoneum for laparoscopic cholecystectomy: randomized controlled trial.

OBJECTIVE: To compare intraoperative cardiac function, postoperative cognitive recovery, and surgical performance of laparoscopic cholecystectomy with abdominal wall lift (AWL) versus positive-pressure capnoperitoneum (PPCpn). SUMMARY BACKGROUND DATA: AWL has been proposed as an alternative approach to PPCpn to avoid adverse cardio-respiratory changes. However, the workspace obtained with the AWL is less optimal than PPCpn and previous studies documenting delayed postoperative recovery of consciousness following PPCpn have not assessed mental alertness despite its importance. METHODS: Forty operations were randomized into AWL and PPCpn. A standard anesthetic protocol was followed. Cardiac indices were measured with an esophageal Doppler machine. An auditory vigilance test was used to measure alertness level following extubation. All operations were videotaped and human reliability assessment techniques were used to identify surgical errors. RESULTS: There was a significant reduction in cardiac output during the first 20 minutes following CO2 insufflation in the PPCpn group, whereas in the AWL group it did not exhibit any significant change. Patients in AWL arm had better vigilance scores at 90 and 180 minutes following extubation compared with the PPn group (P < 0.05). Significantly more surgical errors were observed during surgery with AWL than with PPCpn (7.1 +/- 1.1; versus 2.9 +/- 0.4; P = 0.001). CONCLUSIONS: The AWL approach avoids fall in cardiac output associated with PPCpn during laparoscopic surgery and is associated with a more rapid recovery of postoperative cognitive function compared with PPCpn. However, AWL increases the level of difficulty in the execution of the operation.

Abdominal Wall↗
PubMed2002

Shadow depth cues and endoscopic task performance.

HYPOTHESIS: A shadow-inducing laparoscopic system improves task performance. DESIGN: Experimental study was carried out using the Dundee Endoscopic Psychomotor Tester for objective assessment of task performance. The standard exercise consisted of passing a probe through 37 holes on the target plate in a random order. Shadow was induced by using separate ports for illumination and imaging of the target plate. Light direction-to-target (LDT) angles of 90 degrees, 75 degrees, and 60 degrees were investigated with each of the 90 degrees and 75 degrees optical axis-to-target view angles. SETTING: Research laboratory at the Surgical Skills Unit, Ninewells Hospital. PARTICIPANTS: Twenty medical students with no previous exposure to laparoscopic surgery. MAIN OUTCOME MEASURES: Success score, execution time, the force applied on the target, and angular deviations of the probe. RESULTS: With a 90 degrees optical axis-to-target angle, there was improvement in the success score using either 75 degrees or 60 degrees LDT angles compared with a 90 degrees LDT angle (P =.02, P =.01, respectively), but the execution time became longer (P =.008, P =.03, respectively). With a 75 degrees optical axis-to-target angle, there was improvement in the success score (P<.001), execution time (P<.001, P =.03, respectively), and horizontal and vertical deviations (P<.001) on using either 90 degrees or 60 degrees LDT angles compared with a 75 degrees LDT angle. CONCLUSION: Endoscopic task performance significantly improves with a system that provides illumination and shadows in the operative field.

Cues↗
PubMed2002

The performance of master surgeons on the Advanced Dundee Endoscopic Psychomotor Tester: contrast validity study.

HYPOTHESIS: The contrast validity of the Advanced Dundee Endoscopic Psychomotor Tester (ADEPT) was determined by comparing the performance of "master surgeons" with that of surgical trainees (also called junior surgeons) on the system. DESIGN: Twenty master surgeons and 20 junior surgeons were tested on the ADEPT system. The master surgeons, all of consultant grade, were recruited as established experts of national or international standing in laparoscopic surgery. The junior surgeons were participants of essential laparoscopic courses at the start of their higher surgical training. The ADEPT end points used in the study were instrument error, execution time, and task completion. An analysis of variance was used for the data analysis, with statistical significance set at.05. RESULTS: Master surgeons incurred a significantly lower instrument error rate than surgical trainees (P =.007), with no significant difference in execution time and the task completion score (P =.42 and P =.40, respectively). CONCLUSION: The ADEPT system has contrast validity because master surgeons completed the tasks more accurately without sacrificing execution time.

Adult↗