Cusum analysis is a useful tool to assess resident proficiency at insertion of labour epidurals

Can J Anaesth. 2003 Aug-Sep;50(7):694-8. doi: 10.1007/BF03018712.


Purpose: Cumulative sum (cusum) analysis is a statistical and graphical tool that examines trends for sequential events over time. It has been used to determine proficiency in technical procedures. We used cusum to determine the number of labour epidural attempts necessary for proficiency in our training program.

Methods: Residents unfamiliar with epidural anesthesia kept a log of their labour epidural successes and failures during a six-month hospital rotation. Failure was defined as a dural puncture or relinquishing the procedure to staff. Cusum analysis was performed using an acceptable failure rate of 10%. Residents were deemed competent when their graph remained below the calculated cusum boundary.

Results: Eleven anesthesia residents were recruited. The number of epidural attempts over six months ranged from 75 to 128. Ten residents attained competency by cusum between one and 85 attempts. One resident failed to achieve competency by cusum after 75 attempts.

Conclusion: After a period of training, residents are expected to perform the skill of labour epidural insertion independently. This study illustrates that some residents may need as many as 75 attempts to ensure proficiency. Training programs could use cusum to track the progress of their residents' technical skills in order to guarantee an adequate experience.

MeSH terms

  • Anesthesia, Epidural
  • Anesthesiology / education*
  • Canada
  • Clinical Competence*
  • Competency-Based Education / statistics & numerical data*
  • Data Interpretation, Statistical
  • Humans
  • Internship and Residency*