An evaluation of carboxyhemoglobin spot tests.

A number of spot tests for carboxyhemoglobin are described in the emergency medicine literature. Four of these tests were evaluated for specificity, sensitivity, ease of performance, and ease of interpretation. Second- and third-year emergency medicine residents were given samples of blood and asked to perform each of four spot tests on the samples. They were told that the samples may or may not contain carboxyhemoglobin. The reagents and instructions were available, but no technical assistance was given. The residents were asked to record the results of the tests and to answer a questionnaire. The test results were analyzed by linear regression and within-run precision. The available spot tests found in the literature were unable to determine accurately clinically significant levels of carboxyhemoglobin. The evaluators believed that the tests required a minimum of technical expertise and were easy to perform and interpret. None of the evaluators had any prior experience with carboxyhemoglobin spot tests.