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Changes in thenar eminence tissue oxygen saturation measured using near-infrared spectroscopy suggest ischaemic preconditioning in a repeated arterial occlusion forearm ischaemia model
Critical Care volume 12, Article number: P70 (2008)
Ischaemic preconditioning (IP) describes the process whereby a tissue exposed to brief sublethal periods of ischaemia becomes protected from longer lethal episodes of ischaemia. One mechanism by which skeletal muscle may effect protection from ischaemic insult is to reduce the resting rate of oxygen consumption (VO2) following a preconditioning stimulus. Tissue oxygen saturation (StO2) reflects the dynamic balance between oxygen supply and utilisation. We hypothesised that using near-infrared spectroscopy to measure thenar eminence StO2 repeated arterial occlusion of the upper arm would induce an IP effect.
The study was approved by the UCL Research Ethics Committee and written consent was obtained from 20 healthy volunteers. StO2 was measured using the InSpectra Tissue Spectrometer (Model 325; Hutchinson Technology Inc., USA). The tissue spectrometer probe was attached to the left thenar eminence and a blood pressure cuff was placed around the left upper arm. The repeated arterial occlusion forearm ischaemia model (RAOFIM) consisted of resting measurements and then a cycle of four cuff inflations (200 mmHg, 3 min) and four deflations (5 min). Finally the cuff was inflated for 3 minutes on the right upper arm while the StO2 was measured from the right thenar eminence. Paired t tests were used to compare rates of oxygen desaturation; P < 0.05 was considered statistically significant.
There was a fall in thenar eminence StO2 during all arterial occlusions. The rate of decline of StO2 was significantly reduced during the fourth inflation (0.160%/s) as compared with the first in the left arm (0.213%/s), P < 0.001. There was an increase in the rate of StO2 decline in the right arm (0.268%/s) when compared with the first left occlusion (P < 0.001).
The data from this pilot study demonstrate that, following preconditioning using a RAOFIM, the rate of oxygen desaturation in resting skeletal muscle during subsequent arterial occlusion manoeuvres is reduced. This could be explained by a fall in resting muscle VO2 as a result of the preceding short ischaemic stimuli and therefore represents evidence of IP in skeletal muscle. These data do not provide evidence to support a remote IP effect in the contralateral arm.
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Sen, A., Martin, D., Grocott, M. et al. Changes in thenar eminence tissue oxygen saturation measured using near-infrared spectroscopy suggest ischaemic preconditioning in a repeated arterial occlusion forearm ischaemia model. Crit Care 12, P70 (2008). https://doi.org/10.1186/cc6291
- Arterial Occlusion
- Oxygen Desaturation
- Blood Pressure Cuff
- Cuff Inflation
- Thenar Eminence