Measuring the cardiac output in acute emergency admissions: use of the non-invasive ultrasonic cardiac output monitor (USCOM) with determination of the learning curve and inter-rater reliability

Luke E Hodgson; Richard Venn; Lui G Forni; Theophilus L Samuels; Howard G Wakeling

doi:10.1177/1751143715619186

Measuring the cardiac output in acute emergency admissions: use of the non-invasive ultrasonic cardiac output monitor (USCOM) with determination of the learning curve and inter-rater reliability

J Intensive Care Soc. 2016 May;17(2):122-128. doi: 10.1177/1751143715619186. Epub 2015 Dec 10.

Authors

Luke E Hodgson^{1

2}, Richard Venn¹, Lui G Forni³, Theophilus L Samuels³, Howard G Wakeling¹

Affiliations

¹ Anaesthetics & Intensive Care Department, Western Sussex Hospitals NHS Foundation Trust, Worthing Hospital, Worthing, UK.
² Primary Care and Population Sciences, University of Southampton, Southampton General Hospital, Southampton, Hampshire, UK.
³ Intensive Care Department, The Royal Surrey County Hospital NHS Foundation Trust, Guildford, Surrey, UK.

Abstract

Traditionally, assessment of the cardiac output has been limited to theatre or the intensive care unit. However, non-invasive cardiac output estimation is now readily available, and its application may have wider benefit in the emergency setting. The non-invasive ultrasonic cardiac output monitor (USCOM) was investigated to determine its learning curve and inter-rater reliability. Four trainee operators each performed stroke volume measurements on 25 volunteers, compared to an experienced operator pre- and post-passive leg raise. Inter-rater reliability was then assessed on 24 acute emergency in-patients. Mean percentage difference in stroke volume decreased from 19% (95% confidence intervals 14-23) across volunteers 1-5, to 6% (4-8) for the last 5 volunteers scanned. Consequently, on acute emergency in-patients, excellent inter-rater reliability (Lin's concordance correlation coefficient (ρ_c) 0.96 (0.92-0.98)) and agreement of a change ≥10% in stroke volume following passive leg raise on 23/24 cases were found. Following a training period of less than 5 h, USCOM stroke volume measurements demonstrated excellent inter-rater reliability.

Keywords: Measurement techniques; cardiac output; equipment; ultrasound machines.