Determination of Induction Time in Adult Patients with Valvular Heart Disease

Abstract

Objective: Intravenous anaesthetics induce loss of consciousness in one arm-brain circulation time. As the circulatory transit time in patients with mitral stenosis (MS) and aortic stenosis (AS) is increased, the delivery of anaesthetics to the brain may be prolonged and consequently the onset of hypnosis. This study aimed to compare the induction time in patients with and without valvular heart disease (VHD). Design: Prospective, single-center, open-label analytical study. Setting: It was conducted in adult patients undergoing elective cardiac surgery. Participants: The patients (n = 144) were segregated into three groups; Group 1 - Stenotic VHD (MS, AS), Group 2 - Regurgitant VHD (Mitral Regurgitation, Aortic Regurgitation), and Group 3 – Control (coronary artery disease). Method: General anaesthesia was induced with intravenous thiopental 4mg kg−1 bolus over 20s. The time to induction was noted as loss of eyelash reflex. Bispectral Index (BIS) values were recorded over 2 min. Statistical analysis was performed using SPSS software version 25.0. A p value < 0.05 was considered significant. Main results: Patients in Group 1 (n = 48) had significantly prolonged induction time (99.6 ± 12.9s; p < 0.001) compared to the other two groups (n = 48 each) (68.5 ± 9.6s in Group 2 and 70.4 ± 11.8s in Group 3). Time required for BIS to fall below 60 was significantly longer in Group 1 (139.4 ± 24.6s; p < 0.001) compared to Group 2 (90.4 ± 6.3s) and Group 3 (92.1 ± 12s). Conclusion: The induction time was prolonged in patients with stenotic VHD compared to patients with regurgitant VHD or those without VHD.

Keywords

• Bispectral index
• Hypnosis
• Anaesthesia Induction
• Intravenous anaesthetics
• Valvular heart disease