Hampson Neil B
Center for Hyperbaric Medicine, Virginia Mason Medical Center, Seattle, Washington.
Undersea Hyperb Med. 2018 Mar-Apr;45(2):165-171.
One of carbon monoxide's several mechanisms of toxicity is binding with circulating hemoglobin to form carboxyhemoglobin, resulting in a functional anemia. While patients with carbon monoxide poisoning are often said to be "cherry-red," such discoloration is rarely seen. Carboxyhemoglobin levels cannot be measured with conventional pulse oximetry, can be approximated with pulse CO-oximetry, and are most accurately measured with a laboratory CO-oximeter. Carboxyhemoglobin levels are quite stable and can be accurately measured on a transported blood sample. For clinical purposes, arterial and venous carboxyhemoglobin levels can be considered to be equivalent. Carboxyhemoglobin levels are typically lower than 2% in non-smokers and lower than 5% in smokers. A level over 9% is almost always due to exogenous carbon monoxide exposure, even among smokers. Conversely, a low level does not exclude significant exposure under certain circumstances. As carboxyhemoglobin levels of poisoned patients do not correlate with symptoms or outcome, their greatest utility is a marker of exposure.
一氧化碳的多种毒性机制之一是与循环中的血红蛋白结合形成碳氧血红蛋白，从而导致功能性贫血。虽然一氧化碳中毒患者常被说成是“樱桃红”，但这种变色很少见。碳氧血红蛋白水平无法用传统脉搏血氧饱和度测定法测量，可用脉搏碳氧血氧饱和度测定法大致估算，最准确的测量方法是使用实验室碳氧血红蛋白测定仪。碳氧血红蛋白水平相当稳定，在转运的血样上也能准确测量。出于临床目的，动脉血和静脉血中的碳氧血红蛋白水平可视为等同。非吸烟者的碳氧血红蛋白水平通常低于2%，吸烟者低于5%。即使在吸烟者中，超过9%的水平几乎总是由于外源性一氧化碳暴露所致。相反，在某些情况下，低水平并不能排除大量暴露。由于中毒患者的碳氧血红蛋白水平与症状或预后无关，其最大作用是作为暴露的标志物。
