Assessment of Haemodynamic Response to Induction of General Anaesthesia in Healthy Adult Patients Undergoing Elective Orthopaedic Surgery by Using a Continuous Non-invasive Cardiovascular Monitoring

Continuous cardiovascular monitoring as part of management of high-risk surgical patients is widely practiced, however the role of continuous monitoring as part of routine management in low-risk surgical patients is unclear. Our aim was to investigate haemodynamic and Bispectral Index (BIS) changes in healthy patients undergoing surgery following induction of anaesthesia with propofol using a continuous non-invasive blood pressure device (LiDCO rapid™). We sought to obtain detailed monitoring of cardiovascular parameters from the pre-induction stage.

This prospective, observational single-centre study was conducted at a London teaching hospital between June-November 2014. Patients aged between 18-45 years, American Society of Anesthesiologists grade I-II undergoing elective lower-limb arthroscopic procedures were included. Variables including heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), cardiac output (CO), systemic vascular resistance (SVR) and BIS were recorded continuously prior to induction and up to 3-minutes after.

The following relative haemodynamic changes were noted between baseline and 1-minute post-induction with propofol: CO +15.2%, HR +10.1%, SVR -22.9% and MAP -10.1% (p<0.001 for each parameter). There was a mean change of: HR -10.1%, CO -14% and MAP -18.0%(p<0.001 for each parameter) between baseline and 3-minutes post-induction. Median change of BIS was -61.7% (p<0.001) between baseline and 3-minutes post-induction. Significant, positive correlations were noted between MAP and BIS at 30-seconds (r=0.60, p<0.001) and 1-minute post-induction (r=0.61, p<0.001).

Our study shows that healthy patients undergoing continuous minimally invasive orthopaedic surgery experience significant haemodynamic and BIS changes following induction of anaesthesia. Our findings highlight the importance of baseline cardiovascular and BIS monitoring as part of routine perioperative management.