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A comparison of the monitors INVOS 3100 and NIRO 500 in detecting changes in cerebral oxygenation
Author(s) -
Grubhofer G.,
Tonninger W.,
Keznickl P.,
Skyllouriotis P.,
Ehrlich M.,
Hiesmayr M.,
Lassnigg A.
Publication year - 1999
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.1999.430417.x
Subject(s) - hypocapnia , hyperventilation , medicine , oxygenation , cardiology , anesthesia , hypoxia (environmental) , oxygen , respiratory system , hypercapnia , chemistry , organic chemistry
Background: Measurements of cerebral haemoglobin oxygenation of 2 near‐infrared spectroscopy devices (INVOS 3100 and NIRO 500) were compared during and after hypocapnia. Methods: Fifteen awake, healthy volunteers, who hyperventilated to obtain end‐tidal CO 2 (EtCO 2 ) values of approximately 20 mmHg, were studied. During hyperventilation and 8 min thereafter, EtCO 2 , INVOS 3100 (RSO 2 =regional cerebral oxygenation) and NIRO 500 recordings (HbO 2 =oxyhaemoglobin, Hb=deoxyhaemoglobin, Hb‐diff=HbO 2 –Hb, CtO 2 =oxidised cytochrome oxidase aa3) were analysed. Results: Hyperventilation induced a significant decline in EtCO 2 from 30.5 to 14.7 mmHg ( P <0.001) and RSO 2 from 67.1% to 62.7% ( P =0.025). At hypocapnia, only Hb (+1.61±0.48 μmol/L; P <0.001) and Hb‐diff (−3.01±2.0 μmol/L; P <0.001) indicated a decline in cerebral haemoglobin oxygenation. Within 8 min after hyperventilation, both EtCO 2 and RSO 2 normalised to values insignificantly different from baseline. In contrast, Hb and Hb‐diff remained significantly different (Hb: +2.52±1.28 μmol/l; P <0.001, Hb‐diff: −4.31±4.0 μmol/L; P <0.001). A correlation with EtCO 2 was found for RSO 2 (R=0.35; P <0.001) and CtO 2 (R=0.42; P <0.001). All volunteers were continuously awake and none presented clinical symptoms of cerebral hypoxia. Conclusion: Changes in cerebral haemoglobin oxygenation state were reflected more accurately by INVOS 3100 than NIRO 500. The cause may be the different technology of the monitors, since INVOS 3100 eliminates the contribution of extracranial oxygenation.