Volume 17 Supplement 3

Seventh International Symposium on Intensive Care and Emergency Medicine for Latin America

Open Access

Effects of rapid repetition of a vascular occlusion test on near-infrared spectroscopy-derived variables in healthy subjects and in critically ill patients

  • DO Cortes1,
  • F Puflea1,
  • K Donadello1,
  • D de Backer1,
  • J-L Vincent1 and
  • J Creteur1
Critical Care201317(Suppl 3):P2

https://doi.org/10.1186/cc12618

Published: 19 June 2013

Introduction

Transient ischemia modifies cellular metabolism and microvascular physiology in order to limit damage from future hypoxic episodes, a phenomenon called preconditioning. Near-infrared spectroscopy (NIRS) is a non-invasive technique that, when coupled to a vascular occlusion test (VOT), provides an indirect measurement of muscle oxygen consumption (VO2) and microvascular reactivity. We hypothesized that: rapid repetition of a VOT may alter VOT-induced NIRS-derived variables and these changes could reflect preconditioning; and these alterations would be different in healthy volunteers and critically ill patients.

Methods

Continuous non-invasive measurements of thenar tissue oxygen saturation (StO2) were performed using NIRS technology (InSpectra 650; Hutchinson, USA). VOTs were performed by inflating a cuff to 50 mmHg above the systolic pressure for 3 minutes. In a group of healthy volunteers, the VOT was repeated after 5 minutes on day 1, after 15 minutes on day 2 and after 30 minutes on day 3. In a group of critically ill patients, the VOT was repeated after 5 minutes. For each VOT, we calculated the StO2 desaturation slope (DescSlope), StO2 resaturation slope (AscSlope) and the NIRS VO2 as the DescSlope×mean total hemoglobin index over the occlusion time. All statistical analyses were performed using SPSS 19.0 (IBM, USA).

Results

Twenty-one healthy volunteers (age 29 ± 6 years, heart rate 71 ± 6 bpm, mean arterial pressure 82 ± 6 mmHg) and 18 critically ill patients (age 59 ± 14 years, APACHE II score 21 ± 9, norepinephrine use in 10/18, ICU mortality 22%) were included. In the healthy volunteers, repetition of the VOT was associated with a decrease in the DescSlope and in NIRS VO2. This effect was not observed in the critically ill patients (Tables 1 and 2).
Table 1

Effects of a repeat VOT on VOT-induced NIRS-derived variables in healthy volunteers

Interval

Variable

First

Second

P value

5 minutes

AscSlope

4.2 (3.4 to 4.9)

4 (3.3 to 5)

0.298

 

DescSlope

12 (9.2 to 14.5)

9.8 (8.3 to 10.8)

>0.001

 

NIRS VO2

151 (132 to 171)

131 (118 to 146)

0.001

15 minutes

AscSlope

4 (3.2 to 5.2)

4.1 (3.4 to 5)

0.676

 

DescSlope

10.3 (9.6 to 11.3)

9.4 (8.3 to 10.2)

0.003

 

NIRS VO2

153 (141 to 165)

141 (120 to 146)

0.005

30 minutes

AscSlope

4.2 (3.6 to 5.3)

3.4 (3.1 to 4.8)

0.006

 

DescSlope

10.9 (9.5 to 12.6)

9.4 (7.4 to 10.4)

>0.001

 

NIRS VO2

157 (122 to 171)

132 (112 to 152)

>0.001

Table 2

Effects of a repeat VOT on VOT-induced NIRS-derived variables in critically ill patients

Interval

Variable

First

Second

P value

5 minutes

AscSlope

3.6 (2.7 to 4)

3.4 (2.8 to 4.6)

0.065

 

DescSlope

10 (8.4 to 11.6)

10.5 (8 to 11.8)

0.774

 

NIRS VO2

103 (74 to 156)

108 (73 to 140)

0.442

Conclusion

Rapid repetition of a VOT alters VOT-induced NIRS-derived variables in healthy volunteers but not in critically ill patients. If these alterations reflect preconditioning, our results suggest that this phenomenon may be altered in critically ill patients.

Authors’ Affiliations

(1)
Erasme Hospital, Universite Libre de Bruxelles

Copyright

© Cortes et al; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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