Biomedical subjects

Michael S W Lee

Publications and source records attributed to Michael S W Lee.

5 recordsLinked to original sources

PubMed2004

Human error identification: an analysis of myringotomy and ventilation tube insertion.

OBJECTIVES: To use a human reliability assessment tool to identify commonly occurring errors during myringotomy and ventilation tube (VT) insertion and to quantify the likelihood of error occurrence. METHODS: Error-free task analysis for myringotomy and VT insertion was defined at the outset. Fifty-five consecutive myringotomy and VT insertion procedures were videotaped. The operator was either the senior author (S.S.M.H.) or a trainee in the specialist registrar or senior house officer grade. Three assessors (M.-L.M., M.S.W.L, and S.S.M.H.) blinded to operator identity independently evaluated each procedure. Interobserver agreement was calculated (kappa values). RESULTS: Twelve potential error types were identified. A total of 87 errors were observed in 55 procedures. In 53% of procedures (n = 29) multiple errors were identified. Seven percent of procedures (n = 4) were error free. The 4 most frequent errors identified were (1) failure to perform a unidirectional myringotomy incision (n = 37; 43%); (2) multiple attempts to place VT (n = 14; 16%); (3) multiple attempts to complete the myringotomy (n = 11; 13%); and (4) magnification setting too high (n = 11; 13%). The human error probability was 0.13. Interobserver agreement as expressed by kappa statistics was high. CONCLUSIONS: Human error identification in this most common of otologic procedures is crucial to future error avoidance. Eliminating the 2 most common errors in this model will halve the human error probability. Extending the role of error analysis to error-based teaching as an educational tool has potential.

Clinical Competence↗

PubMed2004

Post-tonsillectomy hemorrhage: cold versus hot dissection.

OBJECTIVE: The aim of our study was to assess the rate of reactionary and secondary posttonsillectomy hemorrhage using "cold" dissection and bipolar diathermy and to determine whether there was any difference in the postoperative hemorrhage rate between the 2 methods. METHODS: This was a prospective study of all patients undergoing tonsillectomy between November 8, 1999 and November 7, 2000 in a tertiary medical centre. The data collected included patient identity, age, gender, date of surgery, method of operation, and complications (if any). The timing of reactionary or secondary posttonsillectomy hemorrhage and the treatment were recorded. We hypothesized no difference in posttonsillectomy hemorrhage rates using the 2 methods. Chi2 test was used for statistical analysis. RESULTS: A total of 349 patients underwent tonsillectomy in the period (134 males, 215 females, mean age was 16.7 years). Of these, 337 were bilateral procedures, 145 patients had tonsillectomy using cold dissection, and 192 patients had bipolar diathermy. Reactionary hemorrhage occurred in 1 patient (0.3%) and 31 patients (9.2%) developed secondary hemorrhage. The hemorrhage rates using cold dissection (n = 8) and bipolar diathermy (n = 24) were 5.5% and 12.5%, respectively ( P < 0.05). CONCLUSIONS: The primary and secondary posttonsillectomy hemorrhage rates were 0.3 and 9.2%, respectively. Tonsillectomy using bipolar diathermy has a statistically significant higher secondary hemorrhage rate than using cold dissection (12.5% vs. 5.5%, P < 0.05).

Adolescent↗

PubMed2003

Post-tonsillectomy haemorrhage: reusable and disposable instruments compared.

The aim of this study was to determine if the introduction of disposable instruments for tonsillectomy resulted in a significant change in post-tonsillectomy haemorrhage rates. This is a prospective comparative study of haemorrhage rates for cold dissection (CD) tonsillectomy in adults using reusable instruments during 1999-2000 ( n=83) and disposable instruments between August and December 2001 ( n=111). Haemorrhage rates in children with reusable instruments ( n=156) and disposable instruments ( n=115) were also compared. Confidence intervals were established for the differences between study groups along with exact levels of significance. No difference was found in the overall reactionary haemorrhage rate [ P=0.32, Diff 0.9% (95% CI; -3.2 to +0.4)] or secondary haemorrhage rate [ P=1.00, Diff 3.4% (95% CI; -0.09 to +0.01)] between reusable and disposable instruments. The introduction of disposable instruments has not produced a statistically significant increase in post-tonsillectomy haemorrhage rates in our centre.

Adolescent↗

PubMed2003

Effect of disposable instruments on paediatric post-tonsillectomy haemorrhage rates.

BACKGROUND: A government directive aiming to minimise the theoretical risk of acquiring variant Creutzfeld-Jacob disease from reusable instruments lead to tonsillectomy with disposable instruments becoming standard practice in the UK during 2001. A perceived increase in post-tonsillectomy haemorrhage followed soon after implementation of the directive. OBJECTIVE: To determine if the introduction of disposable instruments is associated with a statistically significant change in post-tonsillectomy haemorrhage rates in children. METHODS: A prospective audit of paediatric tonsillectomy with reusable instruments (n=156) had been undertaken (November 1999-November 2000). All children undergoing tonsillectomy with disposable instruments (n=115) were also studied prospectively (August 2001-December 2001) allowing the reactionary and secondary post-tonsillectomy haemorrhage rates for the two study periods to be compared. We hypothesised no difference in haemorrhage rates between reusable and disposable instruments. Statistical significance was calculated using Fisher's exact test and confidence intervals were established for the differences between study groups. RESULTS: Cold dissection was undertaken in 62 children with reusable instruments and in 76 children with disposable instruments with secondary haemorrhage rates of 3.2% (n=2) and 2.6% (n=2), respectively. Bipolar diathermy dissection was undertaken in 94 children with reusable instruments and in 39 children with disposable instruments with respective secondary haemorrhage rates of 6.4% (n=6) and 12.8% (n=5). No reactionary haemorrhages occurred with reusable or disposable instruments. No difference was found in the overall secondary haemorrhage rate between reusable and disposable instruments (P=0.93, difference 1.0% (95% CI; -7.4 to +4.6)). CONCLUSIONS: The introduction of disposable instruments has not produced a statistically significant increase in paediatric post-tonsillectomy haemorrhage rates in our centre.

Child↗

PubMedDate not supplied

A randomized control trial of surgical task performance in frontal recess surgery: zero degree versus angled telescopes.

The use of angled telescopes in frontal recess surgery has the theoretical advantage of improved visualization in areas characterized by reduced access such as the frontal recess. However, their use also is accompanied by the disadvantage of increased visuospatial distortion. To examine the surgical error and task performance of angled telescopes when compared with the use of the 0 degree telescope in frontal recess surgery, we carried out a surgical controlled trial on a cadaveric specimen. Ten surgeons performed randomly predetermined surgical tasks on both sides of the frontal recess. The surgical tasks were divided into three components (passing, grasping, and withdrawing) for analysis. Our study revealed significant difficulty passing instruments with the highly angled 70 degrees telescope as implied by the increased passing time ratio (p = 0.000). This was associated with significant risk of passing instruments blindly (p = 0.011), resulting in significant surgical error of hits to the middle turbinate (p = 0.005). This study also showed that use of less-angled telescopes (30 and 45 degrees) in frontal recess surgery does not appear to be associated with these risks.

Cadaver↗