Abstract:
Methods of sensory testing in neuraxial anesthesia may supposedly account for different results in reporting the extent of the block. To determine whether the caudad to cephalad versus the cephalad to caudad direction as well as the side of testing, left versus right, may affect the assessment of sensory block after subarachnoid anesthesia, two groups of patients undergoing transurethral surgery were studied. One group, 44 patients were tested for the influence of direction of block determination and another group 50 patients for the influence of side. Subarachnoid anesthesia was performed with 100 mg of 5% hyperbaric lidocaine using a 25 Whitacre needle with its opening consistently pointing cranially and the patient in the sitting position. To assess the sensory block four lines were drawn bilaterally along the posterior, middle, and anterior axillary lines and a line 5 cm medial to the anterior axillary line. A pressure palpator was moved along each of the four lines and patients were asked to answer if they detected a stimulus, with "yes/no". In the 44 patients assessment of sensory block was performed from caudad to cephalad direction on one side and viceversa on the other. In the other 50 patients the extent of the block was compared between the right and left side. In 44 patients, the level of sensory block determined 20, 25 and 30 minutes after the subarachnoid anesthesia in a cephalad to caudad direction was found at the T11 dermatome at each time point and did not differ when compared to the levels determined following the caudad to cephalad direction. In the second study in a different group of 50 patients, the level of sensory block 20, 25 and 30 minutes after the subarachnoid injection was found at the T11 dermatome on the right side at each time point and did not differ from the level determined on the left side. We conclude that the level of sensory block after subarachnoid anesthesia with lidocaine is independent of the direction of testing and the side the assessment is performed using the pressure palpator.
Fassoulaki, Zotou, Pourgiezi, Siafaka, Hogan, , , , (2003). Direction and side used to determine the extent of sensory block after subarachnoid anesthesia do not influence the level of the block. Acta anaesthesiologica Belgica, 2003 ;54(1):33-6. https://www.ncbi.nlm.nih.gov/pubmed/12703344