Dynamic perfusion CT assessment of the blood-brain barrier permeability: first pass versus delayed acquisition.

BACKGROUND AND PURPOSE: The Patlak model has been applied to first-pass perfusion CT (PCT) data to extract information on blood-brain barrier permeability (BBBP) to predict hemorrhagic transformation in patients with acute stroke. However, the Patlak model was originally described for the delayed steady-state phase of contrast circulation. The goal of this study was to assess whether the first pass or the delayed phase of a contrast bolus injection better respects the assumptions of the Patlak model for the assessment of BBBP in patients with acute stroke by using PCT. MATERIALS AND METHODS: We retrospectively identified 125 consecutive patients (29 with acute hemispheric stroke and 96 without) who underwent a PCT study by using a prolonged acquisition time up to 3 minutes. The Patlak model was applied to calculate BBBP in ischemic and nonischemic brain tissue. Linear regression of the Patlak plot was performed separately for the first pass and for the delayed phase of the contrast bolus injection. Patlak linear regression models for the first pass and the delayed phase were compared in terms of their respective square root mean squared errors (square root MSE) and correlation coefficients (R) by using generalized estimating equations with robust variance estimation. RESULTS: BBBP values calculated from the first pass were significantly higher than those from the delayed phase, both in nonischemic brain tissue (2.81 mL x 100 g(-1) x min(-1) for the first pass versus 1.05 mL x 100 g(-1) x min(-1) for the delayed phase, P < .001) and in ischemic tissue (7.63 mL x 100 g(-1) x min(-1) for the first pass versus 1.31 mL x 100 g(-1) x min(-1) for the delayed phase, P < .001). Compared with regression models from the first pass, Patlak regression models obtained from the delayed data were of better quality, showing significantly lower square root MSE and higher R. CONCLUSION: Only the delayed phase of PCT acquisition respects the assumptions of linearity of the Patlak model in patients with and without stroke.

The search for cost-effective prevention of postoperative nausea and vomiting in the child undergoing reconstructive burn surgery: ondansetron versus dimenhydrinate.

Postoperative nausea and vomiting (PONV) is a common and unpleasant problem for children with burns who are undergoing reconstructive burn surgery. Ondansetron and dimenhydrinate have been found to be effective for the prevention of PONV in other patient populations, but they have not been directly compared in the pediatric population. A prospective, randomized, double-blind, placebo-controlled comparison of ondansetron and dimenhydrinate was performed. One hundred patients with a mean age of 11.8 years who were undergoing reconstructive burn surgery with general anesthesia were randomly assigned to receive either a placebo, 0.1 mg/kg of ondansetron, or 0.5 mg/kg of dimenhydrinate. The 3 groups were well matched for all demographic and procedural variables. The study drugs were given twice, first at the end of surgery and again 4 hours later, to ensure adequate blood levels during the 8-hour study period. Postoperatively, on the basis of the presence and amount of PONV experienced, all patients were assigned a PONV score by a blinded investigator. Statistically significant reductions in the incidence of PONV in the patients who received ondansetron or dimenhydrinate were found, as compared with the results of patients who received placebo. Postoperative vomiting was reduced from 61% in the placebo group to 29% and 40% in the ondansetron and dimenhydrinate groups, respectively, and PONV was similarly reduced from 69% to 47% and 40%, respectively. The differences between ondansetron and dimenhydrinate were not significant. The average cost to our pharmacy for the prescribed dose of ondansetron was $19.34; the cost for dimenhydrinate was $0.90. In this patient population, dimenhydrinate was as effective as ondansetron for the prevention of PONV and postoperative vomiting, and it was much less expensive.

Use of nonsterile gloves for routine noninvasive procedures in thermally injured patients.

A total of 26 boxes of gloves were analyzed to determine if using nonsterile gloves for routine noninvasive procedures was sufficient for thermally injured patients and if the risk of infection increased. All of the study boxes had some organism present on or in the used box; the most common type found was Staphylococcus aureus. Eleven of the 13 subjects (85%) had specific antibiotic-resistant strains of S. aureus present on cultures obtained from open wounds. Seven (64%) of these corresponded to the glove boxes assigned to that patient. The remaining four boxes of gloves had no S. aureus present. In all of the boxes of gloves that had positive S. aureus cultures, 100% of the resistant strains occurred after it was first cultured from the patient. As a result, nonsterile gloves can be used safely for routine non-invasive procedures in the thermally injured patient. It is imperative to avoid using a common box of gloves for two or more patients to prevent the transfer of organisms between patients.