Evaluating Approaches for the Diagnosis of Hemodialysis Catheter-Related Bloodstream Infections.

BACKGROUND AND OBJECTIVES: Guideline-recommended diagnostic criteria for hemodialysis (HD) catheter-related bloodstream infections (CRBSIs) are based on data from indwelling central catheters in patients not on HD and non-HD situations, and upon which peripheral vein cultures are the gold standard. We aimed to examine the validity of these criteria in patients on HD. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: Adult patients on in-center HD using catheters were prospectively followed from 2011 to 2014 at a large academic-based HD facility (Toronto, Canada). When a CRBSI was suspected, blood culture sets were obtained from four sites (peripheral vein, both catheter hubs, and HD circuit) to determine the guideline-recommended differential time to positivity (DTTP). DTTP criteria were met when catheter hub cultures turned positive ≥120 minutes before peripheral vein cultures. The sensitivity, specificity, and accuracy were first calculated using peripheral vein cultures as the gold standard and then these same calculations were repeated with additional information, including exit site/catheter tip and HD circuit cultures, as the true gold standard. The feasibility of obtaining peripheral vein cultures was determined. RESULTS: Of 178 suspected CRBSIs, 100 had peripheral vein blood cultures. Using the true gold standard, sensitivity, specificity, and accuracy of blood culture results were highest in samples from the HD circuit (93.5%, 100%, and 95%, respectively). The guideline recommended combination of peripheral vein and arterial hub blood cultures was the least sensitive, specific, and accurate (91.7%, 93.1%, and 92.7%, respectively). The diagnostic criteria using measured DTTP were met in less than one third of events. CONCLUSIONS: In patients on HD, blood culture results are the most sensitive, specific, and accurate for diagnosing CRBSIs when taken from the HD circuit and the venous catheter hub, and blood culture results are the least sensitive, specific, and accurate in any combination with peripheral vein cultures. The DTTP does not increase diagnostic accuracy, reducing the necessity for venipuncture and its potential vein damage. Future guidelines should consider the applicability of criterion on specific patient populations and tailor them accordingly.

Why substitute decision makers provide or decline consent for ICU research studies: a questionnaire study.

PURPOSE: Consent for research participation in the intensive care unit (ICU) is often obtained from a substitute decision maker (SDM). In this study we explored SDMs' reasons for declining or providing consent for research studies for critically ill adult family members. METHODS: Two questionnaires were developed, one directed at SDMs who agreed to have their relative participate in a research study (AGREE group), and another for SDMs who declined participation (DECLINE group). The questionnaires explored SDMs' opinions about research in general, timing of research approach, the informed consent process, and reasons for agreeing or declining participation. RESULTS: Ninety-six SDMs completed the questionnaire (68 AGREE, 27 DECLINE). There were no differences between AGREE and DECLINE groups with respect to SDM demographics, perceived severity of illness of the patient, or the research study approach. The most common reasons for providing consent were potential for research to help others (91%), research is important for medical progress (88%), and trust in the medical team (87%). The most common reasons for declining consent were SDM was too anxious to consider research (67%), fear that patient would receive experimental treatment (37%), and concern about risks of the study (33%). CONCLUSIONS: SDMs who agree to have a relative participate in an ICU research study are motivated by the potential benefit to the patient and altruism. SDMs who decline research participation, while not generally opposed to research, are fearful of study-related harm or discomfort for the patient, and are too anxious to consider a research study at that time.

Oral tolvaptan is safe and effective in chronic hyponatremia.

Vasopressin antagonists increase the serum sodium concentration in patients who have euvolemia and hypervolemia with hyponatremia in the short term (145 mmol/L) led to discontinuation in one patient. Mean serum sodium increased from 130.8 mmol/L at baseline to >135 mmol/L throughout the observation period (P < 0.001 versus baseline at most points). Responses were comparable between patients with euvolemia and those with heart failure but more modest in patients with cirrhosis. In conclusion, prolonged administration of tolvaptan maintains an increased serum sodium with an acceptable margin of safety.