Reply: Elevated SpCO is Most Commonly from an Exogenous Source of Carbon Monoxide

Abstract

We thank Dr. Hampson for his comments in his letter to the editor. Although in the overwhelming majority of cases that present to the emergency department, the elevated carboxyhemoglobin (COHb) is a result of exogenous carbon monoxide (tobacco or otherwise), our title did not specify the source of carbon monoxide toxicity. In our cohort, the patients with elevated SpCO, which was confirmed with COHb measurements, all had exposure to CO (carbon monoxide). There were no cases of hemolysis or other endogenous sources of CO in this group. As Dr. Hampson points out, the differential diagnosis of elevated COHb or SpCO levels should include endogenous as well as exposure to exogenous sources of CO. It also should be pointed out there is no established and verified index of actual toxicity from CO. It is well known that there are delayed manifestations of CO toxicity in addition to acute signs and symptoms from CO exposure; therefore, any study that evaluates population screening for COHb will suffer from lack of an objective definition of CO toxicity. Non-Invasive Pulse CO-oximetery: What is Measured?Journal of Emergency MedicineVol. 37Issue 3PreviewI read with interest the article by Suner and colleagues describing use of a non-invasive pulse CO-oximeter for rapid screening for “CO (carbon monoxide) toxicity” in a high-volume, urban emergency department (1). I commend the authors for the size of their clinical trial but contend that the study was actually using the SpCO measured by the device to screen for elevated carboxyhemoglobin (COHb) levels. Although this may be an issue of semantics, it should be clarified that the device does not measure any index of actual toxicity from CO. Full-Text PDF Sensitivity of Screening Tests and Other QuestionsJournal of Emergency MedicineVol. 37Issue 3PreviewWe were quite interested to read the results reported by Dr. Suner et al. regarding their use of a non-invasive carboxyhemoglobin detector (RAD-57, Masimo Corp., Irvine, CA), given that our experience with the device was very different from theirs (1). Full-Text PDF SpCO Screening at Triage Continues to Identify Occult CO ToxicityJournal of Emergency MedicineVol. 37Issue 3PreviewWe read with concern the letter by Doctors O'Malley and Chudnofsky. The calculation of sensitivity and specificity in our manuscript is accurate. We clearly indicated that this calculation was based upon patients with paired COHb and SpCO measurements and that this constituted a small portion of the study population. The aim of this study was not to assess the accuracy of this device compared to blood COHb measurements, which was the subject of earlier studies. We discuss the implementation of a screening program using this device to capture occult cases of CO toxicity, which we suspected were in the population at large. Full-Text PDF