Investigating the ability of non-invasive measures of cardiac output to detect a reduction in blood volume resulting from venesection in spontaneously breathing subjects

Benjamin Mothibe Bussmann; William Hulme; Andrew Tang; Tim Harris

doi:10.1186/s13049-018-0571-5

Investigating the ability of non-invasive measures of cardiac output to detect a reduction in blood volume resulting from venesection in spontaneously breathing subjects

Scand J Trauma Resusc Emerg Med. 2018 Dec 4;26(1):104. doi: 10.1186/s13049-018-0571-5.

Authors

Benjamin Mothibe Bussmann¹, William Hulme², Andrew Tang³, Tim Harris^{4

5}

Affiliations

¹ Emergency Department, Royal London Hospital, Barts Health NHS Trust, London, UK. Bussmann.benjamin@gmail.com.
² Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
³ Department of anaesthesia at Norfolk and Norwich University Hospital, Colney Lane, Norwich, UK.
⁴ Emergency Department, Royal London Hospital, Barts Health NHS Trust, London, UK.
⁵ Queen Mary University of London, London, UK.

Abstract

Background: Monitoring cardiac output (CO) in shocked patients provides key etiological information and can be used to guide fluid resuscitation to improve patient outcomes. Previously this relied on invasive monitoring, restricting its use in the Emergency Department (ED) setting. The development of non-invasive devices (such as LiDCOrapid^v2 with CNAP™ and USCOM 1A), and ultrasound based measurements (Transthoracic echocardiography, inferior vena cava collapsibility index (IVCCI), carotid artery blood flow (CABF) and carotid artery corrected flow time (FTc)) enables stroke volume (SV) and CO to be measured non-invasively in the ED. We investigated the ability of these techniques to detect a change in CO resulting from a 500 ml reduction in circulating blood volume (CBV) following venesection in spontaneously breathing subjects. Additionally, we investigated if using incentive spirometry to standardise inspiratory effort improved the accuracy of IVC based measurements in spontaneously breathing subjects.

Methods: We recorded blood pressure, heart rate, IVCCI, CABF, FTc, transthoracic echocardiographic (TTE) SV and CO, USCOM 1A SV and CO, LIDCOrapidv2 SV, CO, Stroke volume variation (SVV) and pulse pressure variation (PPV) in 40 subjects immediately before and after venesection. The Log-Odds and coefficient of variation of the difference between pre- and post-venesection values for each technique were used to compare their ability to consistently detect CO changes resulting from a reduction in CBV resulting from venesection.

Results: TTE consistently detected a reduction in CO associated with venesection with an average decrease in measured CO of 0.86 L/min (95% CI 0.61 to 1.12) across subjects. None of the other investigated techniques changed in a consistent manner following venesection. The use of incentive spirometry improved the consistency with which IVC ultrasound was able to detect a reduction in CBV.

Conclusions: In a population of spontaneously breathing patients, TTE is able to consistency detect a reduction in CO associated with venesection.

Keywords: CNAP; Cardiac output; Carotid blood flow; Circulating blood volume; Flow time; Inferior vena cava collapsibility index; LiDCO; Stroke volume; USCOM; Venesection.

Publication types

Comparative Study
Observational Study

MeSH terms

Adult
Aged
Blood Pressure / physiology
Blood Volume / physiology*
Cardiac Output / physiology*
Diagnostic Techniques, Cardiovascular* / instrumentation
Echocardiography
Female
Hemochromatosis / therapy*
Hemodynamics
Humans
Male
Middle Aged
Phlebotomy / methods*
Polycythemia / therapy*
Respiration
Spirometry
Stroke Volume / physiology
Vena Cava, Inferior / diagnostic imaging
Vena Cava, Inferior / physiology