Carbon monoxide reduces near-infrared spectroscopy determined 'total' hemoglobin: a human volunteer study. (19th May 2017)

• Record Type: Journal Article
• Authors: Niemann, Mads J.; Sørensen, Henrik; Siebenmann, Christoph; Lundby, Carsten; Secher, Niels H.
• Is Part Of: Scandinavian journal of clinical & laboratory investigation. Volume 77:Number 4(2017)
• Page Start: 259
• Page End: 262
• Publication Date: 2017-05-19
• Subjects: Carbon monoxide -- carbon monoxide poisoning -- carboxyhemoglobin -- cerebral blood flow -- near-infrared spectroscopy -- oximetry -- transcranial Doppler ultrasonography; Clinical biochemistry -- Periodicals; Physiology, Pathological -- Periodicals; Physiology, Experimental -- Periodicals; Medicine -- Research -- Periodicals; Clinical medicine -- Periodicals; 616.0072
• DOI: 10.1080/00365513.2017.1299209
• Languages: English
• ISSNs: 0036-5513

Abstract

Abstract: Carbon monoxide (CO) increases middle cerebral artery mean flow velocity (MCAVmean ), but the effect of CO on the near-infrared spectroscopy (NIRS) determined cerebral oxygenation (Sc O2 ) is not detailed. In our study, 11 non-smoking subjects breathed 100% O2 through a closed circuit. A CO2 scrubber with CO (1.5 mL kg −1 ) was added to the circuit. Two NIRS systems (NIRO-200NX and INVOS-5100) assessed Sc O2 as the ratio of oxygenated to deoxygenated hemoglobin, while venous blood samples were analyzed for carboxyhemoglobin (COHb). After CO/O2 rebreathing COHb increased to 8.7% (IQR; 7.9–9.4; p = .004) vs. normoxia, but MCAVmean remained stable (55.6 cm s −1 ; 53.1–69.7) compared to inhalation of O2 (54.6 cm s −1 ; 48.4–62.9; p = .178) and normoxia (54.1 cm s −1 ; 44.5–66.9; p = .055). Also, INVOS-5100 determined Sc O2 increased during CO/O2 (74.4 ± 7.5%) and O2 inhalation (73.1 ± 7.2%) compared to normoxia (68.9 ± 6.9%; p < .001). In contrast, NIRO-200NX determined Sc O2 remained unchanged during CO/O2 and O2 inhalations but oxygenated and deoxygenated hemoglobin decreased (by 19.7 μM (median; IQR 2.8–34.8; p = .016) and 37.3 μM (30.8–46.6; p = .004), respectively) during inhalation of CO/O2 compared to inhalation of O2 . Therefore, NIRO-200NX determined 'total' hemoglobin (sum of O2 Hb and HHb) decreased (by 62.1 μM; 44.5–78.2; p = .001). In conclusion, exposure to CO did not increase MCAVmean, and neither NIRO-200NX nor INVOS-5100 detected a change in Sc O2 when CO was added to inhalation of oxygen. Unaffected Sc O2 after exposure to CO reflected a similar decrease in oxygenated and deoxygenated hemoglobin suggesting that detection of exposure to CO by NIRS should focus on 'total' hemoglobin rather than on Sc O2 .