Predicting the difficult neuraxial block: A prospective study

Anticipated technical difficulty is one factor that can influence the anest hesiologist's decision to perform neuraxial (spinal or epidural) blockade. Problems during the procedure may be associated with patient dissatisfactio n, neurologic sequelae, or hematoma. We designed this study of 595 neuraxia l blocks to determine whether any patient characteristics would be useful i n predicting a difficult neuraxial block. Before the procedure, the followi ng data were noted: demographic data, body habitus (normal, thin, muscular, obese), spinal landmarks (good = easily palpable spinous processes, poor = difficult to palpate spinous processes, none = unable to positively identi fy spinous processes), and spinal anatomy (assessed by inspection and exami nation as normal or deformed). We noted the technique, approach, needle typ e, needle gauge, etc. We also recorded whether the procedure was completed at the first (first-level success) or second spinal level and the total num ber of new skin punctures (attempts) necessary to complete the procedure. O f all the factors considered, the quality of landmarks best correlated with technical difficulty as measured by both first level success and number of attempts. Abnormal spinal anatomy correlated with difficulty as measured b y number of attempts. Body habitus also correlated with difficulty, but onl y as measured by number of attempts. There was no association between eithe r measure of difficulty and any of the following: age, sex, spinal versus e pidural, approach, needle type, needle gauge, or training level of the prov ider. Thoracic epidurals were less difficult than lumbar epidurals by both measures of difficulty. We conclude that body habitus does not seem to be t he best predictor of technical difficulty. An examination of the patient's back for the quality of landmarks and obvious anatomical deformity better p redicts the ease or difficulty of neuraxial block. Other factors seem to ha ve Little or no influence on the difficulty of neuraxial block procedures. Implications: We studied a number of factors, including equipment, techniqu e, and patient characteristics, that may indicate the ease or difficulty of performing neuraxial (spinal and epidural) blocks. Of these factors, only patient characteristics had significant predictive value. We found that an examination of the patient's back for the quality of landmarks and obvious anatomical deformity better predicts the ease or difficulty of neuraxial bl ock than does body habitus.