Selection and Receipt of Kidney Replacement in Critically Ill Older Patients with AKI.

BACKGROUND AND OBJECTIVES: Older patients in the intensive care unit are at greater risk of AKI; however, use of kidney replacement therapy in this population is poorly characterized. We describe the triggers and outcomes associated with kidney replacement therapy in older patients with AKI in the intensive care unit. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Our study was a prospective cohort study in 16 Canadian hospitals from September 2013 to November 2015. Patients were ≥65 years old, were critically ill, and had severe AKI; exclusion criteria were urgent kidney replacement therapy for a toxin and ESKD. We recorded triggers for kidney replacement therapy (primary exposure), reasons for not receiving kidney replacement therapy, 90-day mortality (primary outcome), and kidney recovery. RESULTS: Of 499 patients, mean (SD) age was 75 (7) years old, Charlson comorbidity score was 3.0 (2.3), and median (interquartile range) Clinical Frailty Scale score was 4 (3-5). Most were receiving mechanical ventilation (64%; n=319) and vasoactive support (63%; n=314). Clinicians were willing to offer kidney replacement therapy to 361 (72%) patients, and 229 (46%) received kidney replacement therapy. Main triggers for kidney replacement therapy were oligoanuria, fluid overload, and acidemia, whereas main reasons for not receiving therapy were anticipated recovery (67%; n=181) and therapy not consistent with patient preferences for care (24%; n=66). Ninety-day mortality was similar in patients who did and did not receive kidney replacement therapy (50% versus 51%; adjusted hazard ratio, 0.78; 95% confidence interval, 0.58 to 1.06); however, decisions to offer kidney replacement therapy varied significantly by patient mix, acuity, and perceived benefit. There were no differences in health-related quality of life or rehospitalization among survivors. CONCLUSIONS: Most older, critically ill patients with severe AKI were perceived as candidates for kidney replacement therapy, and approximately one half received therapy. Both willingness to offer kidney replacement therapy and reasons for not starting showed heterogeneity due to a range in patient-specific factors and clinician perceptions of benefit.

Assessment of functional capacity before major non-cardiac surgery: an international, prospective cohort study.

BACKGROUND: Functional capacity is an important component of risk assessment for major surgery. Doctors' clinical subjective assessment of patients' functional capacity has uncertain accuracy. We did a study to compare preoperative subjective assessment with alternative markers of fitness (cardiopulmonary exercise testing [CPET], scores on the Duke Activity Status Index [DASI] questionnaire, and serum N-terminal pro-B-type natriuretic peptide [NT pro-BNP] concentrations) for predicting death or complications after major elective non-cardiac surgery. METHODS: We did a multicentre, international, prospective cohort study at 25 hospitals: five in Canada, seven in the UK, ten in Australia, and three in New Zealand. We recruited adults aged at least 40 years who were scheduled for major non-cardiac surgery and deemed to have one or more risk factors for cardiac complications (eg, a history of heart failure, stroke, or diabetes) or coronary artery disease. Functional capacity was subjectively assessed in units of metabolic equivalents of tasks by the responsible anaesthesiologists in the preoperative assessment clinic, graded as poor (<4), moderate (4-10), or good (>10). All participants also completed the DASI questionnaire, underwent CPET to measure peak oxygen consumption, and had blood tests for measurement of NT pro-BNP concentrations. After surgery, patients had daily electrocardiograms and blood tests to measure troponin and creatinine concentrations until the third postoperative day or hospital discharge. The primary outcome was death or myocardial infarction within 30 days after surgery, assessed in all participants who underwent both CPET and surgery. Prognostic accuracy was assessed using logistic regression, receiver-operating-characteristic curves, and net risk reclassification. FINDINGS: Between March 1, 2013, and March 25, 2016, we included 1401 patients in the study. 28 (2%) of 1401 patients died or had a myocardial infarction within 30 days of surgery. Subjective assessment had 19·2% sensitivity (95% CI 14·2-25) and 94·7% specificity (93·2-95·9) for identifying the inability to attain four metabolic equivalents during CPET. Only DASI scores were associated with predicting the primary outcome (adjusted odds ratio 0·96, 95% CI 0·83-0·99; p=0·03). INTERPRETATION: Subjectively assessed functional capacity should not be used for preoperative risk evaluation. Clinicians could instead consider a measure such as DASI for cardiac risk assessment. FUNDING: Canadian Institutes of Health Research, Heart and Stroke Foundation of Canada, Ontario Ministry of Health and Long-Term Care, Ontario Ministry of Research, Innovation and Science, UK National Institute of Academic Anaesthesia, UK Clinical Research Collaboration, Australian and New Zealand College of Anaesthetists, and Monash University.

Reorienting in virtual 3D environments: do adult humans use principal axes, medial axes or local geometry?

Studies have shown that animals, including humans, use the geometric properties of environments to orient. It has been proposed that orientation is accomplished primarily by encoding the principal axes (i.e., global geometry) of an environment. However, recent research has shown that animals use local information such as wall length and corner angles as well as local shape parameters (i.e., medial axes) to orient. The goal of the current study was to determine whether adult humans reorient according to global geometry based on principal axes or whether reliance is on local geometry such as wall length and sense information or medial axes. Using a virtual environment task, participants were trained to select a response box located at one of two geometrically identical corners within a featureless rectangular-shaped environment. Participants were subsequently tested in a transformed L-shaped environment that allowed for a dissociation of strategies based on principal axes, medial axes and local geometry. Results showed that participants relied primarily on a medial axes strategy to reorient in the L-shaped test environment. Importantly, the search behaviour of participants could not be explained by a principal axes-based strategy.