A comparison of carbon monoxide levels during the use of a multi-fuel camp stove.

OBJECTIVE: The use of camp stoves in an enclosed or poorly ventilated space is clearly not recommended due to the risk of carbon monoxide (CO) poisoning. Instances may arise, however, when use for a limited time is necessary. We sought to find differences in CO levels between various fuels used to power a commercially available camp stove. METHODS: A comparison was made between unleaded gasoline, kerosene, and white gas (Coleman fuel). The stove, fuels, and CO detector were all purchased from local retailers. A 0.4-m3 space was constructed with a cardboard box. Three trials were performed using each fuel in which water was heated over the stove for 5 minutes. Measurement of the CO level within the box was taken every 30 seconds. RESULTS: Kerosene created CO levels of 714 (SD = 113.5) parts per million (ppm) at 2 1/2 minutes but was out of the measurable range of >999 ppm within 4 minutes on each of its trials. White gas burned the cleanest, with an average of 212 ppm (SD = 27.8) at 2 1/2 minutes and 348 ppm (SD = 76.0) at 5 minutes. Unleaded gasoline created 305 ppm (SD = 27.1) at 2 1/2 minutes and 464 ppm (SD = 31.6) at 5 minutes. CONCLUSION: All of the fuels created a high level of CO in a short period of time. White gas burned the cleanest and would be preferred to unleaded gasoline or kerosene in the event that the unvented use of a camp stove was necessary.

Serum creatine kinase is an unreliable predictor of ectopic pregnancy.

OBJECTIVE: To compare serum creatine kinase (CK) values in patients with ectopic pregnancy vs patients with threatened miscarriage or normal pregnancy. METHODS: An observational case-control study was performed at an urban teaching hospital. Pregnant women with a quantitative beta-hCG obtained for suspicion of ectopic pregnancy were evaluated. Excluded were cases with recent trauma, i.m. injections, surgery, or history of heart, liver, or muscle disease. The serum beta-hCG and CK values were recorded and compared between groups with 1-way ANOVA and Tukey's multiple comparison procedure at the overall 0.05 level. RESULTS: The 15 ectopic, 28 threatened miscarriage, and 21 normal pregnancy cases were of similar gestational ages (p = 0.2), ranging from 3 to 12 weeks. Although the CK values for ectopic pregnancy (88.8 +/- 33.6 IU/L) exceeded those for threatened miscarriage (65.9 +/- 59.0 IU/L) and normal pregnancy (56.0 +/- 38.1 U/L) (p = 0.02), there was significant overlap between groups. CK values were at or above a cutoff of 74 IU/L in 80% (95% confidence interval: 52-96%) of ectopic pregnancies, 25% (11-45%) of threatened miscarriages, and 14% (3-36%) of normal pregnancies. CONCLUSIONS: Although the ectopic pregnancy population is characterized by a higher mean CK than are patients with threatened miscarriage or a normal pregnancy, a significant overlap in CK values makes use of this serum marker unreliable for detecting ectopic pregnancy.

Delayed tension pneumothorax complicating central venous catheterization and positive pressure ventilation.

Pneumothorax is the most common complication after central venous catheterization. The diagnosis of pneumothorax may be delayed for hours or days, in some instances because of minimal clinical symptoms or radiographic signs on initial evaluation, or in other instances because of late presentation precipitated by positive pressure ventilation. A case is presented in which a patient developed a tension pneumothorax while under general anesthesia 10 days after central venous line placement. A review of the literature suggests that delayed pneumothorax has an incidence of approximately 0.4% of all central venous access attempts, is much more common after subclavian than internal jugular approaches, especially in difficult or multiple attempts, is asymptomatic in 22%, and results in tension pneumothorax in 22%. End-expiratory upright chest radiographs, the optimal radiographic technique for detection of small pneumothoraces, were obtained in only 19% of reviewed cases. Supine views, the least sensitive radiographic technique, should be carefully reviewed for evidence of basilar hyperlucency, a deep sulcus sign, or a double diaphragm sign. In patients unable to tolerate the upright position, supine views should be supplemented with lateral decubitus, oblique, or cross-table lateral views. Emergency physicians should be aware of the possibility of delayed pneumothorax, as well as optimal radiographic technique for demonstration of small pneumothoraces, and subtle radiographic findings in supine or semirecumbent patients.