Surgeons skills in measures evaluation

Habilidade dos cirurgiões na avaliação de medidas

a02v17n5

2 – PRELIMINARY NOTE

SURGEONS SKILLS IN MEASURES EVALUATION¹

Fernando Augusto Mardiros Herbella²

José Carlos Del Grande³

Herbella FAM, Del Grande JC. Surgenos skills in measures evaluation. Acta Cir Bras [serial online] 2002 Sept-Oct;17(5). Available from URL: http://www.scielo.br/acb.

ABSTRACT - BACKGROUND: Surgeons commonly estimate dimensions without the help of measuring instruments, a practice with importance to the right therapeutic choice, scientific purposes and legal matters. METHODS: 40 senior surgeons were asked to estimate measures of lines in cards (visual evaluation) and to draw lines with a chosen measure (motor evaluation). RESULTS: Visual evaluation is overestimated, and motor evaluation is underestimated.CONCLUSION: Measures evaluation without the help of instruments is prone to error.

KEY WORDS – Measurements. Metric system. Evaluation.

INTRODUCTION

It is a common practice among surgeons, specially in the operating room, to estimate dimensions without the help of measuring instruments. The knowledge of a measure as correct as possible and your inclusion in medical records has a strong importance to the right therapeutic choice, scientific purposes and even legal matters.

This paper has the intention to analyze the ability of surgeons to estimate correctly the metric measures and alert to the possibility of error when instruments are not used to help in the measurement.

METHODS

Forty senior surgeons (37 males, 3 females, mean age 41.2 ± 9.6, range 28 - 59 years), whose specialties are listed in Table 1, were participants of the trial. They were always interviewed in the operating room, just before scrubbing, i. e., in the same enviromental conditions they will be submitted in the operation (glasses, luminosity, etc).

In the first part of the experiment (experiment I – Figure 1), four numbers between 1 and 15 were randomically chosen, namely: 1, 5, 8 and 13. The participant surgeons received a white sheet of paper measuring 25 x 13 centimeters and they were asked to draw lines measuring in centimeters the numbers chosen. They were not aware of the following number until the previous line was drawn. When asked, the use of fingers as a parameter was allowed.

In the second part of the experiment (experiment II – Figure 2), enrolled surgeons were shown four white cards measuring 15 x 6 centimeters where lines were drawn measuring again four randomically chosen numbers between 1 and 15, namely: 6, 3, 7 and 9. Surgeons were then asked to identify the dimension of the line, in centimeters. Cards were presented in the same order as the numbers were chosen and they were not seen simultaneously. Once more, when asked, the use of fingers as a parameter was allowed.

Statistical tests used were confidence interval and linear regression.

RESULTS

Results concerning experiment I are disposed in table 2. Data show that participant surgeons drew lines smaller than asked (99% confidence interval), excluding 1 centimeter line. The difference between drawn line and theoretical value increases progressively with higher values.

Results concerning experiment II are disposed in table 3. Data show that estimation of cards measures is overestimated (99% confidence interval). The difference between theoretical value and estimated value increases progressively with higher numbers..

DISCUSSION

We could not find similar experiments in the literature to compare our results. However, we think we were able to show the imprecision of the evaluation of measures without the use of instruments.

Based on our results we noticed that motor evaluation (like the size of a skin incision or an esophageal myotomy, e. g.) is underestimated and visual evaluation (like estimating the size of a tumor or a safety margin, e. g.) is overestimated. We believe it is not necessary to repeat the importance of a correct measurement. A sterile ruler should always be available, or inexpensive acts like gauging every-day-use instruments like forceps must be done.

CONCLUSION

Measures evaluation without the help of instruments is prone to error.

N. B. There are no references found to be cited.

Herbella FAM, Del Grande JC. Habilidade dos cirurgiões na avaliação de medidas. Acta Cir Bras [serial online] 2002 Set-Out;17(5). Disponível em URL: http://www.scielo.br/acb.

RESUMO – INTRODUÇÃO: Cirurgiões comumente estimam dimensões sem a ajuda de instrumentos adequados, prática com implicâncias na terapêutica, trabalhos científicos e de ordem legal. MÉTODOS: No estudo apresentado foi solicitado a 40 cirurgiões estimar as medidas de linhas traçadas em cartões (avaliação visual) e traçar linhas com medidas pré-determinadas (avaliação motora). RESULTADOS: Mostraram que a avaliação visual é superestimada e a motora subestimada. CONCLUSÃO: A avaliação de medidas sem instrumental adequado é sujeita a erro.

DESCRITORES – Medições. Sistema métrico. Avaliação.

Conflito de interesse: nenhum

Fonte de financiamento: nenhuma

Address for correspondence:

Dr. Fernando A. M. Herbella

Rua Diogo de Faria, 1087/301

04037-003 São Paulo - SP

Phone/Fax: [phone] [e-mail]

Data do recebimento: 20/01/2002

Data da revisão: 17/02/2002

Data da aprovação: 08/03/2002

1. Institution Surgical Gastroenterology Department, Federal University - Escola Paulista de Medicina.

. Institution Surgical Gastroenterology Department, Federal University - Escola Paulista de Medicina. 2. MD. Fellow. 3. MD. Assistant Professor.

Publication Dates

• Publication in this collection
  03 Sept 2003
• Date of issue
  Sept 2002

History

• Reviewed
  17 Feb 2002
• Received
  20 Jan 2002
• Accepted
  08 Mar 2002