Comparison of two spatially resolved NIRS oxygenation indices.
We compared the percentage haemoglobin oxygenation indices from two near infrared spectrophotometers (NIRS) to determine whether the devices reported similar changes in response to induced changes in oxygenation.


METHODS
24 healthy juvenile swine undergoing cardiac bypass surgery had INVOS 5100 and NIRO-300 sensors applied to the brow. Induced events included circulatory arrest, altered blood flow rate, core cooling, and re-warming.


RESULTS
The average data collection was 4 hours 36 minutes and had an r = 0.82 mean correlation between the INVOS and NIRO. The total resting baseline collection from all trials (8,590 pairs) had a correlation of r = 0.62. The average relationship between the INVOS and NIRO was non-linear: an INVOS regional oxygen saturation index (rSO2) of 0% was equivalent to a NIRO tissue oxygenation index (TOI) of 36.2%; values were equal at 56.8%; and an (rSO2) of 100% was equivalent to a TOI 85.9%. There was good or excellent agreement (r > 0.5) between the (rSO2) and TOI patterns of change during induced events in 96% of trials. The INVOS and NIRO were most closely correlated when an attenuation filter was used to obtain identical emitter/detector separations.


CONCLUSIONS
There was close agreement between the INVOS 5100 and NIRO-300 in response to major physiological change, although absolute values of (rSO2) and TOI were not identical. There was less agreement during baseline measurements or minimal physiologic change.
Gagnon
Roy E
RE
Department of Pediatrics, Children's & Women's Health Centre, University of British Columbia, Vancouver, Canada. roy.gagnon@telus.net
Macnab
Andrew J
AJ
Gagnon
Faith A
FA
Blackstock
Derek
D
LeBlanc
Jacques G
JG
D000818:Animals; D002560:Cerebrovascular Circulation; D001026:Coronary Artery Bypass; D006324:Heart Arrest, Induced; D007036:Hypothermia, Induced; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D010108:Oxyhemoglobins / Q000032:analysis*; D019265:Spectroscopy, Near-Infrared / Q000295:instrumentation*; D013552:Swine; D013997:Time Factors
D010108:Oxyhemoglobins