Assessment of changes in lactate concentration with intravascular microdialysis during high-risk cardiac surgery using the trend interchangeability method.

Background: Blood lactate is a strong predictor of mortality, and repeated blood lactate assays are recommended during surgery in high-risk patients. We hypothesized that the use of intravascular microdialysis incorporated in a central venous catheter would be interchangeable with the reference blood gas technique to monitor changes in blood lactate. Methods: Microdialysis and central venous blood lactate measurements were recorded simultaneously in high-risk cardiac surgical patients. The correlation between absolute values was determined by linear regression, and the Bland-Altman test for repeated measurements was used to compare bias, precision, and limits of agreement. Changes in lactate measurements were evaluated with a four-quadrant plot and trend interchangeability method (TIM). Results: In the 23 patients analysed, the central venous catheter was used as part of standard care, with no complications. The correlation coefficient for absolute values ( n =104) was 0.96 ( P <0.0001). The bias, precision, and limits of agreement were -0.19, 0.51, and -1.20 to 0.82 mmol litre -1 , respectively. The concordance rate for changes in blood lactate measurements ( n =80) was 94% with the four-quadrant plot. In contrast, the TIM showed that 23 (29) changes in lactate measurements were not interpretable, and among the remaining 57 (71) interpretable changes, 18 (32) were interchangeable, 8 (14) were in the grey zone, and 31 (54) were not interchangeable. Conclusions: Microdialysis with a central venous catheter appears to provide reliable absolute blood lactate values. Although changes in blood lactate measurements showed an excellent concordance rate, changes between the two methods were poorly interchangeable with the TIM. Clinical trial registration: NCT02296593.

Economic burden of moderate to severe plaque psoriasis in Canada.

BACKGROUND: Psoriasis is a chronic debilitating disease affecting approximately one million Canadians. The objective of this study is to estimate the economic burden in $CDN (2008) of moderate to severe plaque psoriasis among Canadian adults. METHODS: Using a cross-sectional design, direct resource use, costs, lost productivity, and quality of life were obtained for 90 subjects diagnosed with psoriasis in three dermatology clinics in British Columbia, Ontario, and Québec. An Excel-based economic model was developed to project the annual cost of psoriasis, from the societal perspective. RESULTS: The estimated mean annual cost of psoriasis was $7999/subject (95% CI: $3563-$12,434) with direct costs accounting for 57%. Mean lost productivity costs, which accounted for 43% of the mean annual costs of psoriasis, were $3442/subject (95% CI: $1293-$5590). CONCLUSION: Projecting the mean costs per patient to the afflicted population yields an estimated total annual cost of $1.7 billion (95% CI: $0.8-$2.6 billion) attributable to moderate to severe psoriasis in Canada. Understanding the interplay between direct costs, lost productivity, and quality of life is critical for accurately identifying and evaluating effective treatments for this disease.

Assessment of an uncalibrated pressure waveform device's ability to track cardiac output changes due to norepinephrine dose adjustments in patients with septic shock: a comparison with Doppler echocardiography.

OBJECTIVES: The FloTrac Vigileo (FTV) estimates cardiac output (CO) on the basis of an uncalibrated arterial pressure waveform. To assess the ability of the third-generation of FTV (v.3.02) to track changes in CO following norepinephrine dose adjustment in patients with septic shock, we performed a comparative study using Doppler echocardiography (DE). STUDY DESIGN: Prospective observational study. PATIENTS: We prospectively included 20 mechanically ventilated patients receiving norepinephrine and monitored with the FTV. Five minutes after each change in norepinephrine dose (decided by the attending physician), CO was measured simultaneously with the FTV (CO(FTV)) and DE (CO(DE)). The changes in CO were compared. ROC curves were built to assess the ability of FTV to detect significant changes in CO(DE) of at least 15%. RESULTS: Ninety pairs of CO variations measurements were made. The intertechnique correlation coefficient for changes in CO of at least 15% was r=0.59; P=0.0009. The AUC of a ROC curve built to test the FTV's ability to detect a CO(DE) increase of 15% or more was 0.783 (±0.083) (P=0.005). A CO(FTV) threshold value of 15% had a sensitivity of 54% (25-81) and a specificity of 87% (77-94). For a CO(DE) decrease of 15% or more, the ROC curve had an AUC of 0.616 (±0.075) (P=0.12) and a CO(FTV) threshold value of 13% yielded a sensitivity of 53% (27-79) and a specificity of 72% (60-82). CONCLUSIONS: The FTV was unable to accurately track changes in CO following norepinephrine dose adjustments in critically ill patients with septic shock.

An assessment of Hyalella azteca burrowing activity under laboratory sediment toxicity testing conditions.

Burrowing of the freshwater amphipod Hyalella azteca was evaluated under laboratory conditions similar to those recommended for standard sediment toxicity testing in Canada (EPS 1/RM/33; Environment Canada, 1997) and the United States (EPA/600/R-99/064; US EPA, 2000). Sediment type, time of day (light versus dark), size of animal, and the presence or absence of food were varied to assess their effects on burrowing activity. Hyalella azteca were found to burrow rapidly in fine, organic-rich sediments, but were slower to burrow in a sandy sediment. There was no increase in the number of animals occupying the sediment surface of a fine, organic-rich sediment after 4h of darkness compared to the previous 4h of light. Over a 9- to 10-d duration, a higher percentage of animals occupied the surface of the sandy sediment. The addition of food promoted burrowing in sandy sediment, as did using smaller animals. Overall, longer-duration tests involving older animals and coarse sediments may require formal observation to confirm burrowing and ensure adequate sediment exposure. The addition of food during a test may promote the burrowing of larger animals in coarse sediments, but may not be necessary in field-collected sediments that are not excessively sandy.

Lymph node assessment in melanoma.

The surgical management of lymph nodes continues to be important in melanoma since effective systemic therapies are not available. Controversy exists around the significance of the early detection and management of microscopically positive lymph nodes detected by sentinel lymph node biopsy and this is the subject of current surgical clinical trials. Complete lymphadenectomy is recommended for lymph node metastases. The importance of proper surgical technique is discussed.

Thyroid scintigraphy in the assessment of the solitary thyroid nodule: differences in practice patterns between family physicians and specialists.

OBJECTIVE: It has been shown that there is considerable variation in the diagnosis and management of the thyroid nodule. The purpose of this study was to investigate the differences in the practice of family physicians and specialists in ordering thyroid scans in the initial workup of patients with thyroid nodules. DESIGN: Retrospective electronic and paper-based chart review. SETTING: University Health Network, Toronto. PARTICIPANTS: All patients who underwent thyroidectomy over a 2-year period. INTERVENTIONS: An audit of their preoperative diagnostic tests was performed, and the specialties of the ordering physicians were identified. RESULTS: One hundred ninety-four patients were assessed. Sixty-three patients (32.5%) were investigated exclusively by their family physician, 63 (32.5%) were investigated exclusively by a specialist, and 68 (35%) were investigated by both. Family physicians ordered thyroid scans in 51% of patients, whereas specialists ordered scans in 29% of patients (p<.001). The medical specialists ordered 36 scans (33.6%) in 107 patients, whereas the surgical specialists ordered 2 (8.3%) scans in 24 patients (p<.001). CONCLUSION: Despite the limited role for thyroid scans in the initial workup of a solitary thyroid nodule, they are still frequently ordered, particularly by family physicians. We recommend publication of Canadian evidence-based guidelines for the management of thyroid nodules, similar to existing American guidelines, which could help reduce the amount of unnecessary testing.

Cost-minimization analysis of darbepoetin alfa versus epoetin alfa in the hospital setting.

PURPOSE: The cost of darbepoetin alfa versus that of epoetin alfa in a hospital setting was studied. METHODS: The study was an observational, retrospective review of the hospitalwide use of darbepoetin and epoetin during hospital admissions beginning in the period from January 2003 through April 2003. After the identification from daily charge reports of patients who used at least one of the study drugs during an admission, charts were requested for review. Drug product costs were determined from hospital purchasing information. Material and labor costs were combined to estimate drug administration costs. Total costs were calculated as the sum of drug product costs and administration costs. RESULTS: A total of 429 epoetin records and 80 darbepoetin records were included. The two cohorts were similar with respect to demographic characteristics. With respect to costs, the only significant difference between cohorts was in daily administration costs, which were lower for patients receiving darbepoetin. Sensitivity analysis found lower costs for darbepoetin only after the dose-conversion ratio (DCR) was increased to above 256.74 units:1 microg. The overall DCR based on the median daily dose of each drug was 244.90 units:1 microg. CONCLUSION: A cost-minimization study in a hospital showed no cost difference between treatment with epoetin and darbepoetin.