Abstract ID: A29

Abstract Title: INTERSCALENE BRACHIAL PLEXUS BLOCK WITH SPARING OF THE PHRENIC NERVE BY INTERSCALENE CATHETER

Poster Type: Either

ABSTRACT BODY

Introduction: Interscalene anesthesia is associated with a high incidence (up to100%) of phrenic nerve blockade and decrease in pulmonary function. Placement of an interscalene catheter would allow for a slow infusion of local anesthetic by decreasing the hydrostatic pressure and minimizing the rostral spread of the solution. The study will support the hypothesis that the incidence of diaphragm blockade will be less with injection of local anesthetic with a catheter technique.

Materials and Methods: In this investigation, ultrasonography was used to study the incidence of ipsilateral diaphragmatic paresis utilizing interscalene catheters. Thirty- two patients had a stimulating catheter placed in the interscalene sheath. The catheter was advanced with continual stimulation at less than 0.5 milliamps with positive motor response distal to the deltoid. All the patients had the head of the bed elevated 30 degrees and the local anesthetic was infused at 1cc per minute. Twelve patients had 30ml of 1.5% mepivicaine with added epinephrine and bicarbonate (Group I), nine patients had 15cc of the mepivicaine solution(GROUP II), and 11 patients had 15cc of 0.35% ropivicaine administered(Group III).

Results: Ipsilateral and contra lateral diaphragm excursion was measured pre and post block by a radiologist blinded by the volume and the anesthetic administered. The percentage of patients that lost more than 50% of diaphragm excursion was 50%, 67% and 27% for Groups I, II, and III, respectively. The difference between Groups I and III was statistically significant (Fisher exact test, p = 0.03).

Discussion: Adequate analgesia can be provided by interscalene catheter technique with sparing of the diaphragm. Additional studies are needed to determine if extended analgesia by interscalene catheter can be accomplished without phrenic nerve blockade.

Key Words: Diaphragm, Interscalene Catheter, Phrenic Nerve,Ultrasound

ATTACHED FILES

Reg Anesth Pain Med 2004; 29(2):A29