Unilateral spinal anaesthesia - comparison between the hypobaric vs. the hyperbaric technique

Oana D. Predescu, Mihaela Logeanu, Camelia Călin, F. Constandache
Departamentul de Anestezie Terapie Intensivă, Spitalul Clinic Universitar de Urgenţă, Bucureşti

Abstract

Background and objectives.Unilateral spinal anesthesia is an efficient anesthetic technique characterized by good hemodynamic stability. The slow injection (0.05mL/min) of a relatively small dose of an anesthetic solution into the subarachnoid space through a pencil-point needle and the maintainance of the patients lateral decubitus position for 15 minutes, are necessary in obtaining a unilateral spinal block. The aim of this study was to determine whether there are differences in the spinal block obtained with the administration of a hypobaric vs. hyperbaric anesthetic solution.

Method. This was a prospective study of 129 patients undergoing orthopedic lower limb procedures or unilateral lower abdomen surgery; 67 patients received a mean of 8 mg (7.697 ± 1.588) hyperbaric Bupivacaine 0.5% and 59 patients received a mean of 8 mg hypobaric Bupivacaine (7.862±0.999). Injection of the local anesthetic was in the L2-L3 interspace with the patient in the lateral decubitus position, maintaining the surgical site upwards with the hypobaric solution and downside with the hyperbaric solution for 15 minutes post injection. The spinal block was tested with the pinprick test and modified Bromage scale.

Results. There were no statistical differences between the unilateral spinal block obtained with the hypobaric and hyperbaric Bupivacaine (P < 0.001). Patients in both groups were stable hemodynamically. None of the patients had postoperative urinary retention. Orthopaedic patients receiving hypobaric Bupivacaine were more satisfied with the position during the anesthetic procedure.

Conclusions. This study shows that a good unilateral spinal anaesthesia may be obtained with either hypobaric or hyperbaric Bupivacaine. Unilateral spinal anesthesia being a relatively short anaesthetic procedure, easily performed, conferring a good hemodynamic stability and limiting the polypharmacy associated with the general anaesthetic, may be a good option for one day surgery. The hypobaric technique is preferred in elderly patients requiring lower limb orthopedic surgery.

Key words: unilateral spinal anesthesia, hypobaric bupivacaine, hyperbaric bupivacaine

Rahianestezia unilaterală – comparaţie între tehnica hipo- şi hiperbară

Jurnalul Român de Anestezie Terapie intensivă 2006 Vol.13 Nr.2, 103-109