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Department of Anaesthesia and Pain Management, Wellington Hospital, Wellington, New Zealand
Address correspondence and reprint requests to C. P. Marsland, FRCPC, FANZCA, Department of Anesthesia, Wellington Hospital, Pvt Bag 7902, Wellington South, New Zealand. Address e-mail to colin.marsland{at}paradise.net.nz
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Abstract |
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= 0.62; P = 0.0001). Benchmark levels of clinical bronchoscopic performance can be anticipated from bench model performance without a clinical learning curve. DexterTM is a more effective model for learning endoscopic dexterity than the Choose the Hole model. Airway topicalization with lidocaine in a dose range consistent with published series (490–980 mg or 7.14–14.77 mg/kg) resulted in a frequent incidence of side effects. No major adverse events occurred. IMPLICATIONS: Endoscopic skills can be developed and measured on models with the expectation that good model performance will result in good clinical performance. Benchmark levels of endoscopic dexterity can be achieved clinically without a novice learning curve. DexterTM is a more effective model than "Choose the Hole" for learning endoscopic dexterity. Caution is warranted in the use of topical lidocaine in amounts approaching the upper limits of published dose ranges.
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Introduction |
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A "Choose the Hole" model, consisting of three wooden panels with labeled holes through which a bronchoscope is guided, has been validated (6). Residents who received both didactic teaching and supervised training on the model were endoscopically superior on anesthetized patients compared with residents who received only didactic teaching. A replica of the published model was made locally for the purposes of this study (Fig. 1).
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Methods |
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Initial endoscopic assessment was performed on all participants by using coded videotape of recorded video endoscopy (Olympus Evis Exera BF Type IT160 bronchoscope and tower) of an anatomical manikin (Scopin 11 Broncho-Boy; Coburger Lehrmittelanstalt, Coburg, Germany). All endoscopic attempts were unassisted, with intervention used only to ensure personal or equipment safety. This method and equipment were used for all subsequent performance measurements.
Quantitative assessment was performed by timing each endoscopic event from videotape. Endoscopic end-points included the vocal cords, carina, and upper lobes of the manikin’s bronchial tree, as marked by colored hat pins. Qualitative assessment of the recorded events was performed with a text-anchored Global Rating Scale (GRS). This was based on a previously validated scale for fiberoptic bronchoscope manipulation ability (6). A score of 3 was deemed to represent proficiency (6). The scale was modified by adding detail pertinent to quality endoscopy and appropriate for videotape scoring (Table 1). Both timing and GRS assessments were independently performed from videotape by two blinded observers (PDL and RS).
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Over 3 mo, subgroups of up to six participants from each group underwent a 2-wk self-directed training program on their allocated bench model. Each participant recorded the time they spent practicing, exclusive of setup time. The models and conventional fiberoptic bronchoscopes were continuously and exclusively available to the appropriate subgroups in separate closed rooms over the training period.
Immediately after training, performance measurements were repeated on the anatomical manikin. Within 48 h, each participant then performed 5 consecutive clinical bronchoscopies on other study participants. Participants took turns being bronchoscopic subjects; each subject was topicalized once and bronchoscoped five times.
Airway topicalizing and subject monitoring were performed or supervised by CPM. A 22-gauge IV line was placed in each subject, and 5 µg/kg of glycopyrrolate was given IV 10 to 20 min before airway topicalization. All subjects were fasted and were monitored continuously with standard monitoring. No IV sedation or analgesia was used.
Airway topicalization was performed with lidocaine and consisted of 2% viscous gargle, 2% aerosolized solution, and 10% spray. An initial bronchoscopic pass was performed by CPM with a "spray as you go" technique with 2% lidocaine solution. This allowed assessment and completion of topicalization. Each subject was then bronchoscoped from mouth to carina five times by study participants. If requested, 2% lidocaine was reapplied during bronchoscope withdrawal. Subjects were continuously assessed regarding safety, comfort, and desire to continue. Subject weight and total applied local anesthetic dose were recorded. Subjects remained clinically monitored for 15–45 min while videoscopes were cleaned and sterilized (SterisTM system) and while the next person was prepared. As the study progressed and side effects from lidocaine became apparent, attempts were made to reduce the total dose used in topicalization. Participants awaiting the clinical aspect of the study were informed as part of the consent process about the side effects being reported by colleagues. Timing and GRS assessments of clinical bronchoscopies were made from coded videotapes as previously described.
On completion of the clinical component, participants in each subgroup received a questionnaire. They were asked to mark on visual analog scales (VAS) their experience of being topicalized and bronchoscoped, their assessment of their allocated model, how frequently they would practice on it if the model were readily available, and whether they thought this form of training should become a permanent feature in our department. In an unstructured section of the questionnaire, participants were asked to describe their own experiences of the study and any side effects they experienced.
Parametric data were compared between groups by using an unpaired Student’s t-test and within groups by using a paired Student’s t-test; Bonferroni’s correction for multiple tests was applied. Nonparametric data were compared by using Wilcoxon’s signed rank test (paired) and the Mann-Whitney U-test (unpaired). Correlations were performed by using the Spearman rank test. GRS scores over the five clinical bronchoscopies were compared by using analysis of variance. All statistical analysis was performed with StatView 5.0 (SAS Institute, Cary, NC).
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Results |
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During their allocated 2-wk training period, participants in the DexterTM group spent more time practicing on their model than those in the Choose the Hole group (median time [range]: 152 min [70–510 min] versus 75 min [17–281 min]; P < 0.01; Mann-Whitney U-test). The DexterTM group rated model training as more interesting, as more useful in terms of developing dexterity, and as resulting in more improvement in bronchoscopy skills than the Choose the Hole group (Table 2). Participants were asked to indicate on a scale of fixed time intervals from "weekly" to "never" how often they would practice on their allocated model. Eighty-nine percent (16 of 18) of subjects in the DexterTM group and 43% (9 of 21) of subjects in the Choose the Hole group indicated that they would practice at least 3 times monthly (P = 0.002; 
2 test). None of the DexterTM group but 33% (7 of 21) of the Choose the Hole group indicated that they would never practice.
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= –0.76; P < 0.0001) and on the anatomical manikin after training ( = –0.75; P < 0.0001). There was a significant positive correlation between posttraining performance on the anatomical model and on clinical subjects ( = 0.62; P = 0.0001), as assessed by individual mean GRS scores (Fig. 3). The mean [SD] clinical GRS score was significantly higher than the manikin GRS score (2.8 [0.5] versus 2.4 [0.7], respectively; P < 0.0001). There was no significant difference in the findings of the study if either rater were excluded from data analysis.
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The median (range) dose of lidocaine was 720 mg (490–980 mg). The median (range) dosage was 9.6 mg/kg (7.14–14.77 mg/kg). The 3 participants who could not be topicalized received lidocaine 10.24, 12.28, and 14.77 mg/kg.
The questionnaire response rate was 100%. The subjective experience of topicalization and bronchoscopy was assessed with a VAS from 0 ("terrible") to 10 ("enjoyable"), with a score of 5 anchored to "tolerable." The median (range) score in response to the question "How would you describe the experience of being topicalized?" was 5.0 (0–7.2). The median (range) score in response to the question "How would you describe the experience of being bronchoscoped?" was 5.2 (1.0–9.3). When asked "Do you think that this sort of training should become a permanent feature in the department?" participants were strongly in favor, with a median (range) VAS (0 "definitely not" to 10 "definitely") score of 9.4 (4.0–10.0).
Ninety-two percent (36 of 39) of subjects reported some side effect from lidocaine topicalization in the unstructured component of the questionnaire (Table 4). The three subjects who did not experience any side effects received 9.46, 10.24, and 10.46 mg/kg.
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Apart from occasional minor mucosal abrasions, no airway trauma was observed on video endoscopy. There were no clinically significant episodes of hypoxemia or electrocardiogram abnormalities, and there was no cardiovascular instability. No major adverse events occurred.
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Discussion |
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The clinical performance of both groups on awake subjects, as measured by time, compares favorably to published studies on anesthetized patients (6–9). However, although time taken to achieve a set endoscopic task is an important measure of performance, it may give a limited indication of the quality of that performance. GRS and checklists have been shown to be valid and reliable tools for evaluating surgical proficiency and skill transfer (6,10). Our observation was that the GRS provided a discerning measurement of performance quality and skill development, with implications for patient safety and comfort.
There was a significant correlation between endoscopic performance on an anatomical manikins and performance on awake human subjects as measured by GRS scoring. Although endoscopic skill transfer from a bench model to the clinical environment has been previously implied (5,6), this is the first time that the correlation has been demonstrated.
Clinical performance was usually better than bench performance (Fig. 3). GRS benchmarks could be set on models with the expectation that clinical performance would usually be at least as good. It may be less expensive and more efficient to achieve benchmark endoscopic dexterity by spending 2–4 hours on an appropriate model than performing 18–45 clinical endoscopies (8). In this way, the clinical learning curve as it relates to basic endoscopic skills could be dispensed with. Advanced airway skills for which clinical exposure and experience in the operating room are essential could then be developed without the distraction of an endoscopic dexterity learning curve.
Our study population reflected the "real-world" target population for endoscopic dexterity training within a single anesthesia department. The matching of participants on the basis of measured psychomotor performance allowed us to minimize the effect of individual variation in experience and ability. The inclusion of a control group that did not undergo model training was rejected on ethical grounds. Clinical learning curves have been previously demonstrated (8). Fiberoptic intubation of anesthetized patients by untrained novices with a mean time to intubation exceeding five minutes has been reported (11). It was considered unethical to have an untrained group performing clinical endoscopy on awake subjects.
The use of airway course participants as subjects for clinical bronchoscopy has been previously described (12). Two clinical series report the administration of topical lidocaine for bronchoscopy in sedated patients in dose ranges of 5.5–16 mg/kg (13) and 4.3–14.3 mg/kg (14) without signs or symptoms of toxicity. Corresponding mean peak plasma concentrations of lidocaine were 2.9 and 1.29 µg/mL, respectively. Peak plasma concentrations of 6.5 and 9.5 µg/mL were measured in 2 patients in the first series without reported toxicity.
We report a frequent incidence of subjective side effects and three cases of objective signs of early lidocaine toxicity in a nonsedated study population consisting mostly of anesthesiologists. Performance of sequential lidocaine assays and formal psychometric testing would have strengthened the value of these observations, but the extent of side effects was unanticipated. The total dose range used in this study was consistent with the series described above (13,14). Neither of these series reported side effects attributable to topically administered lidocaine. This may have been due to effects of coadministered drugs or to a delayed onset of symptoms. A reported death of a healthy 19-year-old research volunteer who received an estimated 1200 mg of lidocaine in the course of bronchoscopy demonstrates the dangers of excessive lidocaine doses and delayed toxicity (15).
A maximum topical lidocaine dose of 8.2 mg/kg, based on the mean dose reported by Langmack et al. (14), has been recommended by the British Thoracic Society (16). However, as many as half of the patients in the reference study required doses of lidocaine larger than the subsequent recommendation to achieve adequate topicalization. This highlights the difficulty in recommending a maximum lidocaine dose in the face of marked patient variation. It may be possible to refine our topicalization procedure and develop a smaller-dose technique that is effective for endoscopy via the oral route and that is acceptable to nonsedated volunteers.
In conclusion, it is clearly beneficial to achieve proficiency in a technical skill before performing that skill on a patient. We have shown that DexterTM is a more effective model than Choose the Hole and that benchmark levels of endoscopic dexterity can be attained without subjecting patients to novice learning curves. The significant correlation between model performance and clinical performance suggests a mechanism for determining when trainees are ready for the clinical environment.
The experience of performing clinical bronchoscopy and in turn being topicalized and bronchoscoped was both well tolerated and highly valued by participants in this study. However, the frequent incidence of lidocaine-related side effects in a group of volunteers undergoing an educational process was of concern. For subsequent courses in our institution, we will incorporate our findings into the informed consent, refine the topicalization procedure to use less lidocaine, and provide at least three hours of supervision after bronchoscopy.
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Acknowledgments |
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The authors are grateful to Olympus New Zealand for loan of video-endoscopy equipment used in this study.
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Footnotes |
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References |
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This article has been cited by other articles:
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  N. M. Woodall, R. J. Harwood, and G. L. Barker Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending a training course Br. J. Anaesth., June 1, 2008; 100(6): 850 - 855. [Abstract] [Full Text] [PDF]
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 M. P. Eason Simulation Devices in Cardiothoracic and Vascular Anesthesia Seminars in Cardiothoracic and Vascular Anesthesia, December 1, 2005; 9(4): 309 - 323. [Abstract] [PDF]
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K. A. Williams, G. L. Barker, R. J. Harwood, and N. M. Woodall Combined nebulization and spray-as-you-go topical local anaesthesia of the airway Br. J. Anaesth., October 1, 2005; 95(4): 549 - 553. [Abstract] [Full Text] [PDF]
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 N. M. Woodall, R. J. Harwood, and G. L. Barker Lidocaine Toxicity in Volunteer Subjects Undergoing Awake Fiberoptic Intubation Anesth. Analg., August 1, 2005; 101(2): 607 - 607. [Full Text] [PDF]
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