A prospective study to assess the association of body mass index and contamination of urinalysis samples.

BACKGROUND: There is a commonly held belief that overweight women are more likely to offer contaminated urine samples (UAs) in the emergency department (ED) than women with normal body mass index (BMI). However, there is a paucity of research evaluating this potential concern. OBJECTIVE: We hypothesized that patients with higher BMI would be more likely to provide contaminated urine samples than women with low BMI. METHODS: This was a prospective, observational, cohort study evaluating consenting, adult, women that provided a clean catch, mid-stream sample at an inner-city ED. UAs were ordered at the discretion of the caring physician, cultures based on standardized parameters. The primary outcome parameter was the presence of UA contamination as defined by our microbiology lab. Demographic/historical data and BMI were recorded on a structured data sheet. Categorical data were analyzed by chi-square; continuous data by t-tests. Multivariable logistic regression was performed to control for confounding. RESULTS: There were 350 patients in the study group; 22% overweight, 35% obese, 17% morbidly obese, mean BMI 31. 5, and 60% provided contaminated specimens. The mean BMIs of the subjects with contaminated vs. uncontaminated UAs were significantly different (32.7 ±â€¯10.2 vs 29.7 ±â€¯8.8, p < 0.01). Within our multiple variable logistic regression model, obese and morbidly obese patients were more likely to provide contaminated UAs, while there were no significant associations for contamination with other variables except for hypertension (OR = 1.85, p = 0.02). CONCLUSION: Obesity was significantly associated with contamination of clean catch mid-stream samples in our population.

The Influence of Cervical Collar Immobilization on Optic Nerve Sheath Diameter.

BACKGROUND: Prior research has revealed that cervical collars elevate intracranial pressure (ICP) in patients with traumatic brain injury. Two recent small studies evaluated the change in optic sheath nerve diameter (ONSD) measured by ultrasound as a proxy for ICP following cervical collar placement in healthy volunteers. OBJECTIVE: We sought to validate the finding that ONSD measured by ultrasound increases after cervical collar placement within an independent data set. METHODS: This was a prospective, crossover study involving volunteers. Participants were randomized to either have the ONSD measured first without a cervical collar or initially with a cervical collar. Two sonographers performed independent ONSD diameter measurements. Continuous data were analyzed by matched-paired t-tests. Alpha was set at 0.05. The primary outcome parameter was the overall mean difference between ONSD measurements with the cervical collar on and off. Multiple linear regression was performed to examine the relationship between variables and the primary outcome parameter. RESULTS: There were 30 participants enrolled in the study. Overall mean ONSD for participants without the collar was 0.365 ± 0.071 cm and with the collar was 0.392 ± 0.081 cm. The mean change in ONSD for participants with and without the collar was 0.026 ± 0.064 cm (95% confidence interval of difference: 0.015-0.038; P < 0.001). Multiple regression analysis did not identify any variables associated with the variation in ONSD observed for collar versus noncollar. CONCLUSIONS: We confirmed that ONSD does vary by a measurable amount with placement of a rigid cervical collar on healthy volunteers when assessed by ultrasound.