Identification of the Sensory Level Block to Cold During Epidural Analgesia for Labor: A Cohort Study to Determine the Influence of the Direction of Testing (Anesthetized Area to Non-anesthetized Area Versus Non-anesthetized to Anesthetized Area)

Assessment of the upper sensory block level during neuraxial analgesia for labor and delivery is an essential component of clinical management and patient safety. A variety of methods have been used for testing the sensory block such as cold, light touch, sharp touch or prick and transcutaneous electrical stimulation. In addition to the diversity of methods, the endpoints used by investigators have also been variable, considering total or partial responses as endpoints. Not surprisingly, a variable sensory block level could be identified as a result of the different methods and types of question asked by the examiner. Another complicating factor is the lack of standardization of the direction of the testing as it relates to anesthetized and non-anesthetized areas. This lack of standardization may result in a difference of several dermatomes in the level that two different assessors might record for the same patient. Considering a clinical research scenario, it may be difficult to replicate results and implement clinical practices. The objective of this study is to determine the degree of agreement between two methods of assessing the sensory block level to cold in women receiving epidural analgesia for labor (anesthetized to non-anesthetized segments versus non-anesthetized to anesthetized segments).