Volume 13 Supplement 1

29th International Symposium on Intensive Care and Emergency Medicine

Open Access

Adaptability of muscle tissue oxygenation to repeated vascular occlusion

  • SJ Thomson1,
  • N Al-Subaie1,
  • M Hamilton1,
  • ML Cowan1,
  • S Musa1,
  • RM Grounds1 and
  • TM Rahman1
Critical Care200913(Suppl 1):P241

https://doi.org/10.1186/cc7405

Published: 13 March 2009

Introduction

Dynamic testing of muscle tissue oxygenation (StO2) with near-infrared spectroscopy and vascular occlusion (VOT) is a developing area of research in critical care. VOT is often performed multiple times during analysis. We report the impact of repeated VOT on StO2 parameters.

Methods

Twenty-five healthy subjects were studied with the InSpectra 650 monitor and a 15 mm probe. VOT was set at systolic blood pressure + 50 mmHg for 3 minutes in triplicate. Each VOT was separated by a 5-minute rest period. StO2 data are reported for baseline%, downslope (DS) and upslope (US)%/min, overshoot%, area over the ischaemic curve (AOC Isch) and area under the recovery curve (AUC Rec)%/min and recovery time (Rec Time) in minutes. Data were compared by ANOVA.

Results

See Table 1.
Table 1

Population StO2 means (± SD) for consecutive VOT and significance

StO2 curve parameter

Baseline (%)

Total drop (%)

DS (%/min)

US (%/min)

AOC Isch (%/min)

Overshoot (%)

AUC Rec (%/min)

Rec Time (min)

VOT 1

78.7 (± 4.2)

33.4 (± 7)

-11.2 (± 2.5)

213 (± 55.8)

-53 (± 11.5)

15 (± 3.8)

18.9 (± 6.6)

2.4 (± 0.4)

VOT 2

78.3 (± 4.2)

29.8 (± 6.2)

-10 (± 2.3)

240 (± 58.8)

-48.2 (± 10.7)

14.9 (± 3.7)

21.7 (± 7.5)

2.6 (± 0.4)

VOT 3

77.9 (± 4)

28.2 (± 5.5)

-9.4 (± 1.8)

220 (± 45.3)

-44.5 (± 8.7)

15.3 (± 3.5)

23.4 (± 7.3)

2.6 (± 0.5)

P value

0.79

0.01

0.02

0.19

0.02

0.92

0.09

0.09

Conclusion

It is important to understand the impact of serial VOT. We have observed sequential change in rates of StO2 decline during ischaemia (reduced DS gradients, total drop and AOC Isch). Although the overshoot was unchanged, the AUC Rec and Rec time demonstrated increases approaching significance. These patterns imply a preconditioned adaptation to repeated VOT and an exaggerated hyperaemic response. Further studies are required to determine acceptable rest periods between VOTs to ameliorate these changes.

Authors’ Affiliations

(1)
St George's Hospital NHS Trust

Copyright

© Thomson et al; licensee BioMed Central Ltd. 2009

This article is published under license to BioMed Central Ltd.

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