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The pulse oximeter as a non-invasive measure of cardiovascular response to lower body negative pressure

The pulse oximeter as a non-invasive measure of cardiovascular response to lower body negative pressure
The pulse oximeter as a non-invasive measure of cardiovascular response to lower body negative pressure
Objectives: Current assessment of early haemorrhagic shock relies on non-specific and relatively unreliable parameters such as change in blood pressure and heart rate. The aim of this study was to evaluate the use of the pulse oximeter waveform (POW) as a non-invasive measure of early changes in the cardiovascular system. This was achieved by the simulation of graded hypovolaemia using lower body negative pressure (LBNP).
Method: LBNP of up to –40 mmHg was used to simulate a reduction in circulating blood volume of up to 15% in 12 healthy male volunteers in the supine position. A pulse oximeter probe was attached to the left index finger. Cardiovascular parameters were continuously monitored using a PropaqTM monitor and defined safety end point criteria were applied. The POW was recorded using MicroMedicalTM pulse oximeter software and the traces analysed spectrally and non-spectrally on a customized MatlabTM programme.
Results: A rise in heart rate of 20 beats/min and a rise in diastolic blood pressure occurred at –40 mmHg. The amplitude of the POW did not change significantly but the ratio of peak to notch height changed significantly (p<0.05) at LBNP levels of –10 mmHg and –20mmHg. Frequency domain analysis showed a mean increase in frequency (p<0.02) at –30 mmHg and –40 mmHg LBNP. Change in spectral power in the low frequency range analysed (0.01-0.1Hz) was not significant.
Conclusions: The pulse oximeter has been shown to be a sensitive indicator of POW response to early hypovolaemic stress. LBNP produced haemodynamic changes and sympathetic activation simulating a mild hypovolaemic state. However, its use as a model for studying changes in POW due to wave reflection may be complicated by the introduction of complex vascular responses originating from the lower body.
A8
Ewe, C.
db016346-36d3-45df-83be-580694cf1ec7
Parker, K.
fcd57d73-5582-42d7-8abc-ae701955bcd4
White, P.
2dd2477b-5aa9-42e2-9d19-0806d994eaba
Henry, J.A.
8216cd92-998f-42d5-8d5f-a41cec8f4897
Ewe, C.
db016346-36d3-45df-83be-580694cf1ec7
Parker, K.
fcd57d73-5582-42d7-8abc-ae701955bcd4
White, P.
2dd2477b-5aa9-42e2-9d19-0806d994eaba
Henry, J.A.
8216cd92-998f-42d5-8d5f-a41cec8f4897

Ewe, C., Parker, K., White, P. and Henry, J.A. (2001) The pulse oximeter as a non-invasive measure of cardiovascular response to lower body negative pressure. Scientific Meeting of the Faculty of Accident and Emergency Medicine. 01 Jan 2001. A8 .

Record type: Conference or Workshop Item (Paper)

Abstract

Objectives: Current assessment of early haemorrhagic shock relies on non-specific and relatively unreliable parameters such as change in blood pressure and heart rate. The aim of this study was to evaluate the use of the pulse oximeter waveform (POW) as a non-invasive measure of early changes in the cardiovascular system. This was achieved by the simulation of graded hypovolaemia using lower body negative pressure (LBNP).
Method: LBNP of up to –40 mmHg was used to simulate a reduction in circulating blood volume of up to 15% in 12 healthy male volunteers in the supine position. A pulse oximeter probe was attached to the left index finger. Cardiovascular parameters were continuously monitored using a PropaqTM monitor and defined safety end point criteria were applied. The POW was recorded using MicroMedicalTM pulse oximeter software and the traces analysed spectrally and non-spectrally on a customized MatlabTM programme.
Results: A rise in heart rate of 20 beats/min and a rise in diastolic blood pressure occurred at –40 mmHg. The amplitude of the POW did not change significantly but the ratio of peak to notch height changed significantly (p<0.05) at LBNP levels of –10 mmHg and –20mmHg. Frequency domain analysis showed a mean increase in frequency (p<0.02) at –30 mmHg and –40 mmHg LBNP. Change in spectral power in the low frequency range analysed (0.01-0.1Hz) was not significant.
Conclusions: The pulse oximeter has been shown to be a sensitive indicator of POW response to early hypovolaemic stress. LBNP produced haemodynamic changes and sympathetic activation simulating a mild hypovolaemic state. However, its use as a model for studying changes in POW due to wave reflection may be complicated by the introduction of complex vascular responses originating from the lower body.

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More information

Published date: 2001
Venue - Dates: Scientific Meeting of the Faculty of Accident and Emergency Medicine, 2001-01-01 - 2001-01-01

Identifiers

Local EPrints ID: 10870
URI: http://eprints.soton.ac.uk/id/eprint/10870
PURE UUID: dbe69092-da0d-4e34-b010-40cd42d8817f
ORCID for P. White: ORCID iD orcid.org/0000-0002-4787-8713

Catalogue record

Date deposited: 05 Feb 2007
Last modified: 11 Jul 2024 01:33

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Contributors

Author: C. Ewe
Author: K. Parker
Author: P. White ORCID iD
Author: J.A. Henry

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