Pulmonary effects of thoracic epidural analgesia for cardiac valve replacement surgery

ABSTRACT

The study was performed on forty patients [ASA physical status II III] with symptomatic mitral valve disease underwent mitral valve replacement surgery. The patients where criteria were randomly allocated into two equal groups [20 patients each] 1- General anesthesia group [GA] ['control group]. 2- General anesthesia with thoracic epidural analgesia group [TEA group]. Anesthetic technique and management of cardiopulmonary bypass were standardized for all patients. Spirometric data [FVC, FEV1, FEV1/FVC% and PEFR,], and respiratory rate were measured at the night before surgery, after extubation by 1h, 12h, 24h, 48h, 72h and [6th postoperative day Arterial Blood Gases PaO2, PaCO2 and pH were measured after induction of GA by 15 min., after extubation by 48h, 72h and 6th postoperative day. Visual analogue scale [VAS] score for assessment of pain was measured after extubation by 1h, 6h, 12h, 18h, 24h, 48h, 72h and 6th postoperative day. Total dose of fentanyl analgesia was calculated in each group. There were some improvement in respiratory function [FVC, FEV 1 and PEFR.] started at the 3rd to the 6th post operative days.There were insignificant changes in FEV1/FVC all over the study period RR decreased significantly in the epidural group than control group in all readings. There was a significant decrease in VAS in TEA group than the control group throughout the study period. PaO 2 was significantly decreased in both groups at all readings. 1. Intensive Care Unit [ICU] stay There was insignificant difference between the two groups. 2. Time to first awake /hour was significantly decreased in thoracic epidural group than general anesthesia group [1.3 +/- 0.3 vercus 2.5 +/- 0.6]. 3. Time to extubation /hour was significantly decreased in thoracic epidural group than general anesthesia group [3.5 + 0.2 versus 7.3 +/- 0.3]. 4. Total postoperative fentanyl consumption in 1st 24h was a significant decrease in TEA than GA group [p<0. 00] [677.9 +/- 26 in TEA group versus 1203.4 +/- 44 in general anesthesia group] perioperative epidural infusion of 0.125% bupivacaine and fentanyl, started before induction of anesthesia in valve replacement surgery reduces the total requirements of intraoperative narcotics, without cm appreciable delay in extubation. There was slight improvement in pulmonary function, but not to expected values and far less than control reading indicating multifactorial bases of pulmonary dysfunction in cardiac surgery using CBP