Absolute lymphocyte count as a predictor of CD4 count.

STUDY OBJECTIVE: To determine whether the absolute lymphocyte count (ALC) (white blood count x lymphocyte percentage) can be used to predict a low CD4 count. METHODS: We conducted a retrospective data analysis of consecutive CD4 count analyses performed between January 1, 1995, through December 1, 1995, at an urban university teaching hospital. Results of consecutive CD4 counts and simultaneously measured ALCs were analyzed from samples obtained in inpatient, clinic, and emergency department settings. The ability of ALC to predict a CD4 count less than 200 cells/mm3 was analyzed by calculating sensitivities, specificities, predictive values, and likelihood ratios for a range of ALC values. RESULTS: Among the 807 samples, 322 results (40%) had a CD4 count less than 200 cells/mm3. The ALC and CD4 count were correlated (r=.69, P<.0001). An ALC less than 1,000 cells/mm3 predicted CD4 counts less than 200 cells/mm3 with a sensitivity of .67 (95% confidence interval .62 to .72), specificity of .96 (.94 to .98), positive predictive value of .91 (.87 to .95), and a negative predictive value of .81 (.78 to .84). An ALC less than 2,000 cells/mm3 predicted CD4 counts less than 200 cells/mm3 with a sensitivity of .97 (.95 to .99), specificity of .41 (.37 to .45), positive predictive value of .52 (.48 to .56), and negative predictive value of .95 (.92 to .98). CONCLUSION: A reliable relationship exists between ALC and CD4 count. In a similar population, an ALC less than 1,000 cells/mm3 is predictive of a CD4 count less than 200 cells/mm3, and an ALC greater than or equal to 2,000 cells/mm3 is predictive of a CD4 count greater than or equal to 200 cells/mm3. Physicians may find these criteria useful in identifying patients with increased risk of opportunistic infection.

Focal intracranial infections.

Focal intracranial infections are relatively rare, but the consequences of a missed or delayed diagnosis are significant. The clinician is urged to consider these diagnoses in patients with headaches or focal neurologic examinations, particularly in the setting of known or suspected otorhinologic disease. For diagnosis, gadolinium-enhanced MR imaging or MR imaging with angiography are the procedures of choice; CT is far less sensitive and specific. Lumbar puncture is contraindicated in most of these infections. Management of suspected elevation of intracranial pressure and broad empiric antibiotic therapy should be instituted emergently. Early involvement of surgical services is recommended.

Chest pain associated with cocaine: an assessment of prevalence in suburban and urban emergency departments.

STUDY OBJECTIVE: Chest pain and myocardial infarction following the use of cocaine have been well documented. We assessed the prevalence of cocaine use in patients who presented to the emergency department with chest pain of possibly ischemic origin. DESIGN: During times of research assistant availability, consecutive adults with the chief complaint of chest pain unexplained by trauma or radiographic abnormality were questioned about cocaine use in the preceding week. Urine was tested for the presence of cocaine or cocaine metabolites with a highly accurate bedside urine test kit (specificity, 100%; sensitivity 98%). Anonymous unlinked data-collection methods were used. Therefore we could not determine whether the patients who used cocaine had sustained myocardial infarctions. SETTING: One suburban and three urban EDs. RESULTS: We enrolled 359 patients with a mean age of 51 years, 8% of whom sustained myocardial infarctions. Sixty patients (17%) had cocaine or cocaine metabolites in urine. The likelihood of testing positive for cocaine varied by age group: 18 to 30 years, 29%; 31 to 40 years, 48%; 41 to 50 years, 18%; 51 to 60 years, 3%; 61 years or older, 0% (P < .0001). Of the 60 patients who tested positive for cocaine, only 43 (72%) admitted recent use. CONCLUSION: Many ED patients with chest pain have recently used cocaine. Because the recent use of cocaine is not uncommon in patients with chest pain up to 60 years old, such patients should be questioned about cocaine use. When treatment or disposition may be altered, consideration should be given to objective assessment of cocaine use because patient self-report does not appear reliable.

Is circadian variation in asthma severity relevant in the emergency department?

STUDY OBJECTIVE: Asthmatic patients have marked circadian variation in disease severity, with bronchospasm far worse between midnight and 8 AM than at other times of day. In this study we sought to determine whether circadian variation in asthma severity is clinically relevant for purposes of emergency management. DESIGN: Prospective, observational cohort study. SETTING: The emergency department of a large urban university hospital. PARTICIPANTS: Asthmatic patients 16 years and older who presented with the complaint of asthma exacerbation. RESULTS: Peak expiratory flow rate (PEFR), respiratory rate, and objective and subjective assessments of dyspnea severity were determined at the time of each patient's presentation to the ED and at the time of disposition decision. Time of symptom onset, duration of symptoms, response to therapy, and final disposition were recorded. Nocturnal presentation and onset were defined as arrival in the ED or onset of symptoms between midnight and 8 AM. We enrolled 188 asthmatic patients in the study; 52 (28%) presented nocturnally. Comparison of asthmatic patients who presented nocturnally and those who presented at other times revealed no differences in initial or final PEFR or respiratory rate, change in PEFR, subjective or objective dyspnea, or rate of hospitalization, although nocturnal patients did have a significantly shorter ED treatment time. Analysis by time of symptom onset also revealed no differences between nocturnally and nonnocturnally presenting subjects in disease severity or outcome, with the exception that those with nocturnal symptom onset had less subjective dyspnea than other asthmatic patients. Repeat analysis with different "nocturnal" time periods did not alter the results. CONCLUSION: In our study group, asthmatic patients who presented nocturnally to the ED did not differ from other asthmatic patients in disease severity and therefore do not appear to represent a unique population for purposes of ED management or disposition decisions.

Zigadenus poisoning.

Significant toxicity can result from ingestion of certain species of the Zigadenus plant, an herb occasionally confused with nontoxic wild onions. A 50-year-old man inadvertently ingested Z paniculatus and presented to the emergency department with profound gastrointestinal toxicity, hypotension, and bradycardia. The pathophysiology and management of Zigadenus poisoning are reviewed. Emergency physicians, particularly in rural areas, should be aware of the morbidity caused by ingestion of some Zigadenus species.