Haemodynamic Changes at Induction during Laryngeal Mask Airway Insertion: Comparison of Propofol Versus Lignocaine-Thiopentone Admixture

Abstract

To determine the haemodynamic changes at induction during laryngeal mask airway (LMA) insertion comparing propofol versus lignocaine-thiopentone admixture. In this comparative randomised study, patients of American Society of Anesthesiologists’ (ASA) class I and II with age range of 18-60 years scheduled for short elective surgeries were randomly assigned into two equal groups. Patients were premedicated with fentanyl 1ug.kg-1. Anaesthesia was induced with either 2.5mg.kg-1 propofol or a sequence of 2mg.kg-1 lignocaine and 5mg.kg-1 thiopental given by a trained assistance. Anaesthesia was maintained with 2% isoflurane and 100% oxygen. Haemodynamic variables [Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), Mean Arterial Pressure (MAP) and Heart Rate (HR)] were measured non-invasively in three periods; before drug administration, immediately after drug administration prior to insertion of LMA and finally after LMA insertion.In group A, the baseline heart rate (92.3±11) was compared to the post-induction heart rate (100.7±09) with p=0.765 and post-insertion heart rate (98.0±13) with p=0.767. Although, there was a rise in the heart rate from the baseline after induction and insertion of LMA, this was not statistically significant. Also, baseline SBP (120.7±09) was compared to the post-induction SBP (102.5±07) with p=0.001 and post-insertion SBP (102.59±07) with p=0.001. This was statistically significant. The baseline DBP (77.9±08) was compared to the post-induction DBP (67.0±12) with p=0.004 and post-insertion DBP (62.5±09) with p=0.001.This was statistically significant. The baseline MAP (92.6±01) was compared to the post-induction MAP (79.7±01) with p=0.008 and post-insertion MAP (76.2±07) with p=0.001. This was also statistically significant. In group B, the baseline heart rate (93.2±12) was compared to post-induction heart rate (99.2±11) with p=0.520 and post-insertion heart rate (94.8±12) with p=0.989. This was not statistically significant. The baseline SBP (120.7±13) was compared to the post-induction SBP (115.9±12) with p=0.139 and post-insertion SBP (117.5±13) with p=0.318. This was not statistically significant. The baseline DBP (80.6±14) was compared to the post-induction DBP (75.2±11) with p=0.636 and post-insertion DBP (76.6±13) with p=0.712. This was also not statistically significant. The baseline MAP (94.3±01) was compared to the post-induction MAP (87.5±01) with p=0.779 and post-insertion MAP (88.3±01) with p=0.882. This was not statistically significant. We concluded that propofol and lignocaine-thiopentone admixture exhibited similar haemodynamic profile in our study and therefore recommend that both drugs can be used for patients.