Brief ReportNoninvasive pulse CO-oximetry expedites evaluation and management of patients with carbon monoxide poisoning
Introduction
Basic principles of toxicology include identification and quantification of the poison involved, clearance of the toxin from the body, and administration of antidotes, all as rapidly as possible. In the case of carbon monoxide (CO) poisoning, the toxin is CO, clearance is accelerated by the administration of oxygen, and a subset of the most severely poisoned patients are treated with hyperbaric oxygen [1].
Diagnosis of CO poisoning typically includes presentation with a history compatible with exposure, symptoms typical of the syndrome, and demonstration of an elevated blood carboxyhemoglobin (COHb) level [1]. Historically, COHb levels have been measured on arterial or venous blood samples using a laboratory CO-oximeter. This has required that the patient or his/her blood sample be transported to a hospital with laboratory CO-oximetry capability. In one region of the country, it was demonstrated that even within the past decade, only one-half of acute care hospitals had laboratory CO-oximetry capability [2], likely due to the expense of the instrumentation. Additional delay arises when it is determined that hyperbaric oxygen therapy is appropriate for the patient, and transfer to yet another medical center with hyperbaric capability must be coordinated and accomplished.
The RAD-57 (Masimo Corp) is a handheld, noninvasive pulse CO-oximeter, capable of measuring COHb at the scene of discovery by transilluminating the fingertip with multiple wavelengths of near-infrared light [3]. Since it was introduced to the market in 2005, it has been adopted and used by many first-responder units such as paramedics and firefighters. No one, however, has demonstrated that the use of the device has reduced the time to measurement of a COHb level or the time to hyperbaric oxygen treatment of CO poisoning. This study examines those variables in a large population of patients referred for hyperbaric oxygen treatment of CO poisoning across the United States, comparing the timing of diagnosis and treatment in those with initial COHb measurement by hospital laboratory CO-oximetry vs those initially evaluated with pulse CO-oximetry.
Section snippets
Materials and methods
From August 2008 to October 2011, the Undersea and Hyperbaric Medical Society maintained an online system for surveillance of cases of CO poisoning treated with hyperbaric oxygen. When a patient was treated in a facility enrolled in this voluntary program, facility staff logged on to a secure Web site and entered nonidentifiable demographic and epidemiologic data about the exposure. The system was been financially supported by and operated in conjunction with the Centers for Disease Control and
Results
For the 105 patients evaluated by pulse CO-oximetry, it was possible to obtain a match for 5 of 5 characteristics from the group of patients evaluated by laboratory CO-oximetry in 95 instances. The remaining 10 patients matched with a laboratory CO-oximetry patient in 4 of 5 characteristics. In 8 cases, race/ethnicity was the mismatch. In 2 cases, age was the mismatch because it was outside the range of ±1 year. Data for baseline characteristics for the 2 groups are shown in Table 1. Patients
Discussion
When the RAD-57 pulse CO-oximeter was introduced in 2005, it appeared to offer 2 potential opportunities [8]. First, it could be used as a screening tool to detect unsuspected cases of significant CO poisoning [9]. Mass screening at sites of potential CO exposure, screening of workers at increased risk for occupational CO exposure (eg firefighters), and screening of individuals presenting with nonspecific symptoms of illness were all seen as potential applications that might yield results in
Conclusions
In summary, this is the first study that suggests that early application of pulse CO-oximetry technology in the CO-poisoned patient may result in earlier diagnosis and more rapid initiation of definitive therapy. The significance in clinical outcome from the amount of time saved is unknown. Nonetheless, it seems reasonable to consider further study of this simple and inexpensive technology for its potential benefit and to hope that even more time delay to treatment can be saved through
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