Carbon monoxide reduces near-infrared spectroscopy determined 'total' hemoglobin: a human volunteer study

TY - JOUR

T1 - Carbon monoxide reduces near-infrared spectroscopy determined 'total' hemoglobin

T2 - a human volunteer study

AU - Niemann, Mads J

AU - Sørensen, Henrik

AU - Siebenmann, Christoph

AU - Lundby, Carsten

AU - Secher, Niels H

PY - 2017/5/19

Y1 - 2017/5/19

N2 - 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 (ScO2) 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 ScO2 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 ScO2 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 ScO2 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 O2Hb 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 ScO2 when CO was added to inhalation of oxygen. Unaffected ScO2 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 ScO2.

AB - 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 (ScO2) 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 ScO2 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 ScO2 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 ScO2 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 O2Hb 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 ScO2 when CO was added to inhalation of oxygen. Unaffected ScO2 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 ScO2.

KW - Adult

KW - Carbon Monoxide/analysis

KW - Female

KW - Hemoglobins/analysis

KW - Humans

KW - Male

KW - Middle Cerebral Artery/diagnostic imaging

KW - Spectroscopy, Near-Infrared/methods

KW - Ultrasonography, Doppler, Transcranial

U2 - 10.1080/00365513.2017.1299209

DO - 10.1080/00365513.2017.1299209

M3 - Journal article

C2 - 28281372

SN - 0085-591X

VL - 77

SP - 259

EP - 262

JO - Scandinavian Journal of Clinical and Laboratory Investigation

JF - Scandinavian Journal of Clinical and Laboratory Investigation

IS - 4

ER -