Andrew Maturen

Predictors of Occult Carbon Monoxide Poisoning in Patients with Headache and Dizziness

Headache and dizziness occur at carboxyhemoglobin levels of greater than 10%. We studied 89 patients with headache or dizziness for evidence of carbon monoxide exposure. The mean carboxyhemoglobin level was 2.87%. Number of cigarettes smoked per day (r = 0.471; p less than 0.00002), use of gas kitchen stoves for heating purposes (r = 0.252, p less than 0.02), problems with the home heating system (r = 0.278, p less than 0.01), and cohabitants with concurrent headache or dizziness (r = 0.427, p less than 0.01) correlated with carboxyhemoglobin levels. Multiple regression analysis identified number of cigarettes smoked daily, use of stoves for heat, and concurrently symptomatic cohabitants as significant predictors of carboxyhemoglobin level (F = 13.939 [3, 85]; p less than 0.01). Obtaining carboxyhemoglobin levels from patients who used stoves for heat or had similarly affected cohabitants identified 4 of 4 patients with levels greater than 10% (sensitivity, 100%) and excluded 47 of 85 patients with lower levels (specificity, 55.3%). The 4 patients with carboxyhemoglobin levels in excess of 10% may represent occult carbon monoxide poisoning in this population.

Occult carbon monoxide poisoning: Validation of a prediction model

Headache and dizziness are early symptoms of carbon monoxide poisoning, occurring at carboxyhemoglobin levels of greater than 10 percent. Previously, it was shown that among patients presenting to an emergency department during the winter with headache or dizziness, an algorithm for obtaining carboxyhemoglobin levels on patients who used gas stoves for heating purposes or who had similarly affected cohabitants correctly identified all patients with carboxyhemoglobin levels greater than 10 percent. To test the validity of this retrospectively derived rule, 65 patients were studied who were unaware of any carbon monoxide exposure and who presented during the winter of 1986-1987 with headache or dizziness. The algorithm correctly identified three of four patients with carboxyhemoglobin levels greater than 10 percent (sensitivity = 75 percent) and correctly excluded 45 of 61 patients with lower levels (specificity = 74 percent). The presence of symptomatic cohabitants alone was an equally sensitive (75 percent) but more specific (90 percent) marker for elevated carboxyhemoglobin levels. When data from the two cohorts were combined, stepwise multiple regression identified number of cigarettes smoked daily (F = 8.66) and concurrently symptomatic cohabitants (F = 34.71) as significant predictors of the carboxyhemoglobin level. It is concluded that a retrospectively derived rule correctly identified most cases of occult carbon monoxide poisoning when applied prospectively, and that the presence of similarly affected cohabitants was the most reliable marker for a carbon monoxide-mediated illness.

Occult carbon monoxide poisoning in patients with neurologic illness

To investigate occult carbon monoxide poisoning in patients with neurologic illness, we prospectively studied 168 patients who presented to the emergency department between December 1987 and February 1988 with neurologic symptoms for evidence of carbon monoxide exposure. Patients with known carbon monoxide poisoning were excluded. The mean carboxyhemoglobin level was 3.1 percent; there were no significant differences in carboxyhemoglobin between categories of neurologic illness (F(5,162) = 1.35; p less than 0.25). Five patients (3 percent) had a carboxyhemoglobin greater than 10 percent, with levels ranging from 11.7 percent to 29.5 percent. After controlling for the effects of active and passive exposure to cigarette smoke, problems with the home heating system (odds ratio 9.6; p less than 0.03) and the presence of cohabitants with concurrent headache or dizziness (odds ratio 21.6; p less than 0.0001) were associated with an increased risk of a carboxyhemoglobin greater than 10 percent. A rule for obtaining carboxyhemoglobin tests only on patients who used gas stoves for heat or who had symptomatic cohabitants would have correctly identified all patients with carboxyhemoglobins greater than 10 percent, correctly excluded 77 percent of patients with lower levels, and eliminated the need for testing in 75 percent of cases. We conclude that unrecognized carbon monoxide poisoning occurs in a small but important fraction of patients with wintertime neurologic illness and can be identified by a characteristic risk factor profile.

Screening hospital admissions from the emergency department for occult carbon monoxide poisoning

Because cases of unrecognized carbon monoxide (CO) poisoning have been described among patients admitted to the hospital with other diagnoses, screening hospital admissions with carboxyhemoglobin testing has the potential for preventing morbidity among patients as well as among their cohabitants. Carboxyhemoglobin levels were obtained on 753 patients admitted to the hospital from the emergency department over a 3-month period during the winter. Patients in whom CO poisoning was diagnosed in the emergency department prior to admission were excluded. The mean carboxyhemoglobin level was 2.52% +/- 1.85%; there was no significant difference in mean carboxyhemoglobin among patients with medical, surgical, neurological, and psychiatric admission diagnoses (F = 1.17; df = 3,746; P = .32). Two patients (0.3%; 95% confidence limits, 0.04% to 1.1%) from the entire admission cohort, and one of 20 patients (5%; 95% confidence limits, 0.3% to 26.9%) admitted with seizures, had carboxyhemoglobin levels greater than 10%. The carboxyhemoglobin levels of the two patients were only marginally elevated, with levels of 10.9% and 11.3%. The cost of the carboxyhemoglobin screening program was

DETECTION OF ANTICARDIOLIPIN ANTIBODY IN PATIENTS WITH COCAINE ABUSE

2.26 per patient result, or approximately

Use of beta-hydroxybutyric acid levels in the emergency department.

2,100 over a 3-month winter heating season. A program for screening emergency department admissions with carboxyhemoglobin testing, although feasible in terms of cost, detected few cases of unrecognized CO poisoning.

Digoxin‐Like Immunoreactive Substance in Renal Transplant Patients

Anticardiolipin antibody, an immunoglobulin that binds negatively charged phospholipids, is considered to be an in vitro inhibitor of clot-based coagulation procedures. We adapted an enzyme immunoassay using stationary cardiolipin antigen to compare anticardiolipin antibody activity in the plasma of 44 cocaine abusers with its activity in the serum of 72 blood donors and a sample of 203 random specimens from healthy volunteers. Activity of 20 of the 44 abusers and 43 of 203 random specimens exceeded the donor control reference range. Patients using intravenous cocaine were more likely to have elevated activity than those who inhaled (P less than 0.05). Of 7 patients who had seizures or thromboembolic disorders, 5 were anticardiolipin antibody positive. Enzyme immunoassay may have predictive value for ischemic disease in cocaine abusers.

Multicenter Clinical and Analytical Evaluation of the AxSYM Troponin-I Immunoassay to Assist in the Diagnosis of Myocardial Infarction

UNLABELLED The impact of a new test on the market, the beta-hydroxybutyric acid (BOH) assay, on clinical decision-making in the emergency department (ED) has not been well studied. In this retrospective analysis, we studied the potential benefit of this new test in the ED decision-making process in diabetic patients. BOH levels were measured on all patients who had glucose and acetone levels ordered by the emergency physician during a 3-month period in the ED of a university tertiary referral center. Two groups were analyzed: group 1 was acetone-positive and BOH-positive (n = 13); group 2 was acetone-negative BOH-positive (n = 31). There was no difference between the two groups in terms of gender (p = 0.55) or age (p = 0. 47). The length of stay (p = 0.97) and number of complications (p = 0.89) were also similar between the two groups. CONCLUSION This study suggests that in those diabetic patients with a negative acetone test and a positive BOH test, the addition of the positive result on the BOH test may provide additional prognostic information for predicting hospital length of stay and number of in-hospital complications.

Toxidrome recognition to improve efficiency of emergency urine drug screens

Digoxin‐like immunoreactive substance (DLIS) has been detected in several patient populations that were not receiving digoxin, including those patients with end‐stage renal disease. The structure and physiologic significance of this compound are unknown, and the fate of DLIS after renal transplantation has not been studied. The authors prospectively evaluated 163 patients (not receiving digoxin) before and after transplantation for the presence of DLIS. Three different assays were used: radioimmunoassay (RIA), affinity mediated immunoassay (ACA), and fluorescence polarization immunoassay (TDX I). Depending on the assay method used, 11% (RIA), 6% (ACA), and 9% (TDX) of patients had detectable DLIS pretransplant. Using all 3 assays, a total of 34 patients (21%) were found to have DLIS. The mean serum digoxin concentration was 0.41 ± 0.13 ng/mL (range: 0.2–1.2 ng/mL) and DLIS was detectable by > 1 assay method in seven patients. DLIS persisted longer in patients who had delayed allograft function (13.7 ± 7 days) than in those who did not (3 ± 1.9 days), P <.05. In summary, detection of DLIS in renal transplant recipients appears to be an infrequent occurrence when using a single digoxin assay method. When detected, the concentration of DLIS is often below the usual therapeutic range for digoxin and disappears once allograft function is established. The authors conclude that the presence of DLIS is unlikely to be clinically significant in the renal transplant population.