Effect of Patient Body Mass Index on Laparoscopic Surgical Ergonomics.

BACKGROUND: Minimally invasive surgery may introduce new ergonomic challenges for surgeons. Increased patient body mass index (BMI) may further add to this ergonomic stress. OBJECTIVES: The objective of this study was to quantify the ergonomic impact of patient BMI on surgeons during laparoscopic surgery. SETTING: University Hospital, USA. METHODS: This prospective cohort study analyzed five minimally invasive surgeons during 24 laparoscopic procedures. Each subject's muscle stress was assessed by recording surface electromyography (EMG) data from eight upper body muscle groups during laparoscopic procedures. EMG data was normalized against the maximal voluntary contraction (MVC) of each muscle measured before the start of surgery to create a percentage of the MVC value (%MVC). Subject workload was assessed through the NASA Task Load Index (NTLX). Statistical analysis was used to determine significance between surgeons operating on patients with or without obesity for %MVC and NTLX scores. RESULTS: There was no significant difference (p > 0.05) in both the average muscle activation of all eight muscle groups and NTLX scores during laparoscopic surgery in surgeons operating on patients with BMI > = 30 compared with patients with a BMI < 30. CONCLUSIONS: We detected no differences in ergonomic stress or workload for surgeons operating on patients with or without obesity. For surgeons, the laparoscopic approach may offer an additional advantage over open surgery in patients with obesity. This advantage may be due to an "equalizing effect" of laparoscopy-that surgical ergonomics are less affected by the BMI of the patient when using laparoscopic tools.

Ethical considerations in the use of Pernkopf's Atlas of Anatomy: A surgical case study.

The use of Eduard Pernkopf's anatomic atlas presents ethical challenges for modern surgery concerning the use of data resulting from abusive scientific work. In the 1980s and 1990s, historic investigations revealed that Pernkopf was an active National Socialist (Nazi) functionary at the University of Vienna and that among the bodies depicted in the atlas were those of Nazi victims. Since then, discussions persist concerning the ethicality of the continued use of the atlas, because some surgeons still rely on information from this anatomic resource for procedural planning. The ethical implications relevant to the use of this atlas in the care of surgical patients have not been discussed in detail. Based on a recapitulation of the main arguments from the historic controversy surrounding the use of Pernkopf's atlas, this study presents an actual patient case to illustrate some of the ethical considerations relevant to the decision of whether to use the atlas in surgery. This investigation aims to provide a historic and ethical framework for questions concerning the use of the Pernkopf atlas in the management of anatomically complex and difficult surgical cases, with special attention to implications for medical ethics drawn from Jewish law.

Ergonomic analysis of laparoscopic and robotic surgical task performance at various experience levels.

INTRODUCTION: Traditional laparoscopic surgery (TLS) has increasingly been associated with physical muscle strain for the operating surgeon. Robot-assisted laparoscopic surgery (RALS) may offer improved ergonomics. Ergonomics for the surgeon on these two platforms can be compared using surface electromyography (sEMG) to measure muscle activation, and the National Aeronautics and Space Administration Task Load Index (NTLX) survey to assess workload subjectively. METHODS: Subjects were recruited and divided into groups according to level of expertise in traditional laparoscopic (TLS) and robot-assisted laparoscopic surgery (RALS): novice, traditional laparoscopic surgeons (TL surgeons), robot-assisted laparoscopic surgeons (RAL surgeons). Each subject performed three fundamentals of laparoscopic surgery (FLS) tasks in randomized order while sEMG data were obtained from bilateral biceps, triceps, deltoid, and trapezius muscles. After completing all tasks, subjects completed the NTLX survey. sEMG data normalized to the maximum voluntary contraction of each muscle (MVC%), and NTLX data were compared with unpaired t tests and considered significant with a p ≤ 0.05. RESULTS: Muscle activation was higher during TLS compared to RALS in most muscle groups for novices except for the trapezius muscles. Muscle activation scores were also higher for TLS among the groups with more experience, but the differences were less significant. NTLX scores were higher for the TLS platform compared to the RALS platform for novices. DISCUSSION: TLS is associated with higher muscle activation in all muscle groups except for trapezius muscles, suggesting greater strain on the surgeon. Increased trapezius muscle activation on RALS has previously been documented and is likely due to the position of the eye piece. The differences seen in muscle activation diminish with increasing levels of expertise. Experience likely mitigates the ergonomic disadvantage of TLS. NTLX survey data suggest there are subjective benefits to RALS, namely in the perception of temporal demand. Further research to correlate NTLX data and sEMG measurements, and to investigate whether these metrics affect patient outcomes is warranted.

Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance.

BACKGROUND: Robotic platforms have the potential advantage of providing additional dexterity and precision to surgeons while performing complex laparoscopic tasks, especially for those in training. Few quantitative evaluations of surgical task performance comparing laparoscopic and robotic platforms among surgeons of varying experience levels have been done. We compared measures of quality and efficiency of Fundamentals of Laparoscopic Surgery task performance on these platforms in novices and experienced laparoscopic and robotic surgeons. METHODS: Fourteen novices, 12 expert laparoscopic surgeons (>100 laparoscopic procedures performed, no robotics experience), and five expert robotic surgeons (>25 robotic procedures performed) performed three Fundamentals of Laparoscopic Surgery tasks on both laparoscopic and robotic platforms: peg transfer (PT), pattern cutting (PC), and intracorporeal suturing. All tasks were repeated three times by each subject on each platform in a randomized order. Mean completion times and mean errors per trial (EPT) were calculated for each task on both platforms. Results were compared using Student's t-test (P < 0.05 considered statistically significant). RESULTS: Among novices, greater errors were noted during laparoscopic PC (Lap 2.21 versus Robot 0.88 EPT, P < 0.001). Among expert laparoscopists, greater errors were noted during laparoscopic PT compared with robotic (PT: Lap 0.14 versus Robot 0.00 EPT, P = 0.04). Among expert robotic surgeons, greater errors were noted during laparoscopic PC compared with robotic (Lap 0.80 versus Robot 0.13 EPT, P = 0.02). Among expert laparoscopists, task performance was slower on the robotic platform compared with laparoscopy. In comparisons of expert laparoscopists performing tasks on the laparoscopic platform and expert robotic surgeons performing tasks on the robotic platform, expert robotic surgeons demonstrated fewer errors during the PC task (P = 0.009). CONCLUSIONS: Robotic assistance provided a reduction in errors at all experience levels for some laparoscopic tasks, but no benefit in the speed of task performance. Robotic assistance may provide some benefit in precision of surgical task performance.

Which causes more ergonomic stress: Laparoscopic or open surgery?

BACKGROUND: There is increasing awareness of potential ergonomic challenges experienced by the laparoscopic surgeon. The purpose of this study is to quantify and compare the ergonomic stress experienced by a surgeon while performing open versus laparoscopic portions of a procedure. We hypothesize that a surgeon will experience greater ergonomic stress when performing laparoscopic surgery. METHODS: We designed a study to measure upper-body muscle activation during the laparoscopic and open portions of sigmoid colectomies in a single surgeon. A sample of five cases was recorded over a two-month time span. Each case contained significant portions of laparoscopic and open surgery. We obtained whole-case electromyography (EMG) tracings from bilateral biceps, triceps, deltoid, and trapezius muscles. After normalization to a maximum voltage of contraction (%MVC), these EMG tracings were used to calculate average muscle activation during the open and laparoscopic segments of each procedure. Paired Student's t test was used to compare the average muscle activation between the two groups (*p < 0.05 considered statistically significant). RESULTS: Significant reductions in mean muscle activation in laparoscopic compared to open procedures were noted for the left triceps (4.07 ± 0.44% open vs. 2.65 ± 0.54% lap, 35% reduction), left deltoid (2.43 ± 0.45% open vs. 1.32 ± 0.16% lap, 46% reduction), left trapezius (9.93 ± 0.1.95% open vs. 4.61 ± 0.67% lap, 54% reduction), right triceps (2.94 ± 0.62% open vs. 1.85 ± 0.28% lap, 37% reduction), and right trapezius (10.20 ± 2.12% open vs. 4.69 ± 1.18% lap, 54% reduction). CONCLUSIONS: Contrary to our hypothesis, the laparoscopic approach provided ergonomic benefit in several upper-body muscle groups compared to the open approach. This may be due to the greater reach of laparoscopic instruments and camera in the lower abdomen/pelvis. Patient body habitus may also have less of an effect in the laparoscopic compared to open approach. Future studies with multiple subjects and different types of procedures are planned to further investigate these findings.

Transfer and priming of surgical skills across minimally invasive surgical platforms.

BACKGROUND: Robot-assisted laparoscopic surgery (RALS) uses 3-dimensional visualization and wristed instruments that provide more degrees of freedom than rigid traditional laparoscopic (TLS) instrumentation. These features have been touted to improve accuracy and efficiency during surgical task performance. Little is known, however, about the transferability of skills between the two platforms or whether task performance on one platform primes surgeons for task performance on the other. METHODS: Twenty-six subjects naïve to RALS were recruited to perform three Fundamentals of Laparoscopic Surgery tasks on both TLS and RALS platforms: peg transfer, pattern cutting (PC), and intracorporeal suturing. All tasks were performed within Fundamentals of Laparoscopic Surgery testing parameters and repeated three times by each subject on each platform. Platform and task order were randomized. Errors in task performance were defined as drops in the peg transfer task, faults 5 mm or more from the defined pattern during PC, and faults greater than 1 mm in suture placement from the defined points in intracorporeal suturing. Mean completion times and mean errors per trial (EPT) were calculated for each task on both platforms. Results were compared between those who performed TLS first (LF) and those who performed RALS first (RF) using unpaired Student's t-test (P < 0.05 considered statistically significant). RESULTS: No statistically significant differences in task completion time were noted between the LF and RF groups. RF subjects had fewer errors during robotic PC than LF subjects (1.02 EPT versus 1.86 EPT, respectively; P = 0.02). No other differences in task quality were noted. CONCLUSIONS: In surgeon's naïve to RALS, there is no evidence that skills acquired on RALS or TLS platforms are transferable to the other platform or that performing tasks on one platform primes a subject for task performance on the other. Performing TLS PC may have had a negative impact on subsequent RALS PC performance. These findings suggest that distinct programs for skills acquisition are necessary for both the TLS and RALS platforms.

Ergonomic analysis of primary and assistant surgical roles.

BACKGROUND: Laparoscopic surgery is associated with a high degree of ergonomic stress. However, the stress associated with surgical assisting is not known. In this study, we compare the ergonomic stress associated with primary and assistant surgical roles during laparoscopic surgery. We hypothesize that higher ergonomic stress will be detected in the primary operating surgeon when compared with the surgical assistant. METHODS: One right-hand dominant attending surgeon performed 698 min of laparoscopic surgery over 13 procedures (222 min primary and 476 min assisting), whereas electromyography data were collected from bilateral biceps, triceps, deltoids, and trapezius muscles. Data were analyzed in 1-min segments. Average muscle activation as quantified by maximal voluntary contraction (%MVC) was calculated for each muscle group during primary surgery and assisting. We compared mean %MVC values with unpaired t-tests. RESULTS: Activation of right (R) biceps and triceps muscle groups is significantly elevated while operating when compared with assisting (R biceps primary: 5.47 ± 0.21 %MVC, assistant: 3.93 ± 0.11, P < 0.001; R triceps primary: 6.53 ± 0.33 %MVC, assistant: 5.48 ± 0.18, P = 0.002). Mean activation of the left trapezius muscle group is elevated during assisting (primary: 4.33 ± 0.26 %MVC, assistant: 5.70 ± 0.40, P = 0.024). No significance difference was noted in the other muscle groups (R deltoid, R trapezius, left [L] biceps, L triceps, and L deltoid). CONCLUSIONS: We used surface electromyography to quantify ergonomic differences between operating and assisting. Surgical assisting was associated with similar and occasionally higher levels of muscle activation compared with primary operating. These findings suggest that surgical assistants face significant ergonomic stress, just as operating surgeons do. Steps must be taken to recognize and mitigate this stress in both operating surgeons and assistants.

Expanded Polytetrafluoroethylene for Chordal Replacement: Preventing Knot Failure.

PURPOSE: Expanded polytetrafluoroethylene suture is commonly used for chordal replacement in mitral valve repair, but due to material characteristics, knots can unravel. Our aim was to determine the knot security, including how many throws are necessary to prevent knot failure, with Gore-Tex (W.L. Gore and Associates, Elkton, MD) and the newly available Chord-X (On-X Life Technologies Inc, Austin, TX). DESCRIPTION: Knots were evaluated for maximal load based on: number of throws (6, 8, 10, and 12), tension to secure each throw (10%, 50%, and 85%) and suture type (Gore-Tex CV-5 and Chord-X 3-0). A physiologic force of 2 N was used for comparison. EVALUATION: We evaluated 240 knots. For all knots, the mean load to failure was 11.1 ± 5.8 N. Failure occurred due to unraveling in 141 knots (59%) at 7.1 ± 4.1 N and to breaking in 99 (41%) at 16.7 ± 2.0 N (p < 0.01). Gore-Tex failed at higher loads (12.6 ± 6.0 N vs 9.5 ± 5.2 N, p < 0.01); however, an equivalent number, 6 Gore-Tex and 6 Chord-X, unraveled at 2 N, all with fewer than 10 throws. CONCLUSIONS: Expanded polytetrafluoroethylene has adequate strength to prevent breakage; however, a risk of knot unraveling at physiologic conditions exists when fewer than 10 throws are performed.

Evaluation of a novel cryoablation system: in vitro testing of heat capacity and freezing temperatures.

OBJECTIVE: Cryoablation has been used to ablate cardiac tissue for decades and has been shown to be able to replace incisions in the surgical treatment of atrial fibrillation. This in vitro study evaluates the performance of a novel cryoprobe and compares it with existing commercially available devices. METHODS: A new malleable 10-cm aluminum cryoprobe was compared with a rigid 3.5-cm copper linear probe using in vitro testing to evaluate performances under different thermal loads and with different tissue thicknesses. Radial dimensions of ice formation were measured in each water bath by a high-precision laser 2 minutes after the onset of cooling. Probe-surface temperatures were recorded by thermocouples. Tissue temperature was measured at depths of 4 mm and 5 mm from the probe-tissue interface. Time to reach a tissue temperature of -20°C was recorded. RESULTS: Ice formation increased significantly with lower water-bath temperatures (P < 0.001). Width and depth of ice formation were significantly less for the rigid linear probe (P < 0.012 and P < 0.001, respectively). There was no difference between the probes in the maximal negative temperature reached under different thermal loads or at different tissue depths. The malleable probe achieved significantly lower temperatures at the proximal compared with the distal end (-61.7°C vs -55.0°C, respectively; P < 0.001). A tissue temperature of -20°C was reached earlier at 4 mm than at 5 mm (P < 0.001) and was achieved significantly faster with the 3011 Maze Linear probe (P < 0.021). CONCLUSIONS: The new malleable probe achieved rapid freezing to clinically relevant levels in up to 5-mm-thick tissue. Both probes maintained their performance under a wide range of thermal loads.

Evaluation of a novel cryoablation system: in vivo testing in a chronic porcine model.

OBJECTIVE: Cryoablation is commonly used at present in the surgical treatment of atrial fibrillation (AF). However, there have been few studies examining the efficacy of the commonly used ablation devices. This report compares the efficacy of two cryoprobes in creating transmural endocardial lesions on the beating heart in a porcine model for chronic AF. METHODS: In six Hanford miniature swine, the right atrial appendage and the inferior vena cava were isolated using a bipolar radiofrequency clamp to create areas of known conduction block. A connecting ablation line was performed endocardially via a purse string with the novel malleable 10-cm Cryo1 probe for 2 minutes at -40°C. Additional ablation lines were created with the Cryo1 and the 3.5-cm 3011 Maze Linear probe on the right and the left atrial wall. Epicardial activation mapping was performed before and immediately after ablation as well as 14 days postoperatively. Histologic examination was performed 14 days postoperatively. RESULTS: Transmural lesions were confirmed in 83/84 cross-sections (99%) for the Cryo1 probe and in 40/41 cross-sections (98%) for the 3011 Maze Linear probe. There was no difference between the devices in lesion width (mean ± SD, Cryo1, 10.7 ± 3.5 mm; 3011, 10.0 ± 3.9 mm; P = 0.31), lesion depth (Cryo1, 4.5 ± 1.7 mm; 3011, 4.6 ± 1.5 mm; P = 0.74), or atrial wall thickness (Cryo1, 4.5 ± 1.8 mm; 3011, 4.7 ± 1.7 mm; P = 0.74). There was a conduction delay across the right atrial ablation line (20 ± 2 milliseconds vs 51 ± 8 milliseconds, P < 0.001) that remained unchanged at 14 days (51 ± 8 milliseconds vs 52 ± 10 milliseconds, P = 0.88). CONCLUSIONS: The Cryo1 probe created transmural lesions on the beating heart, resulting in sustained conduction delay. Both probes had a similar performance in lesion geometry in this chronic animal model.