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Br J Anaesth. 2015 May;114(5):812-7. doi: 10.1093/bja/aeu484. Epub 2015 Jan 20.

Non-invasive blood haemoglobin and plethysmographic variability index during brachial plexus block.

Author information

1
Department of Anaesthesia, Faculty of Health Sciences, Linköping University, Linköping 585 85, Sweden christian.bergek@lio.se.
2
Department of Anaesthesia, Faculty of Health Sciences, Linköping University, Linköping 585 85, Sweden.
3
Department of Anaesthesia, Faculty of Health Sciences, Linköping University, Linköping 585 85, Sweden Research Unit, Södertälje Hospital, Södertälje, Sweden.

Abstract

BACKGROUND:

Plethysmographic measurement of haemoglobin concentration ([Formula: see text]), pleth variability index (PVI), and perfusion index (PI) with the Radical-7 apparatus is growing in popularity. Previous studies have indicated that [Formula: see text] has poor precision, particularly when PI is low. We wanted to study the effects of a sympathetic block on these measurements.

METHODS:

Twenty patients underwent hand surgery under brachial plexus block with one Radical-7 applied to each arm. Measurements were taken up to 20 min after the block had been initiated. Venous blood samples were also drawn from the non-blocked arm.

RESULTS:

During the last 10 min of the study, [Formula: see text] had increased by 8.6%. The PVI decreased by 54%, and PI increased by 188% in the blocked arm (median values). All these changes were statistically significant. In the non-blocked arm, these parameters did not change significantly.

CONCLUSIONS:

Brachial plexus block significantly altered [Formula: see text], PVI, and PI, which indicates that regional nervous control of the arm greatly affects plethysmographic measurements obtained by the Radical-7. After the brachial plexus block, [Formula: see text] increased and PVI decreased.

KEYWORDS:

haemoglobinometry; nerve blockade; perfusion; photoplethysmography; vasodilation

PMID:
25603961
DOI:
10.1093/bja/aeu484
[Indexed for MEDLINE]
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