At 1 year a novel reflex arc with stimulation of the appropriate dermatome was seen in the majority of subjects. Improvements in voiding and bowel function were noted. Lower extremity weakness was mostly self-limited, except in 1 subject with a persistent foot drop. More patients and longer followup are needed to assess the risk/benefit ratio of this novel procedure.
BACKGROUND: Frailty is a geriatric syndrome thought to identify the most vulnerable older adults, and morbidity and mortality has been reported to be higher for frail patients after cardiac surgery compared to nonfrail patients. However, the cognitive consequences of frailty after cardiac surgery have not been well described. In this study, we examined the hypothesis that baseline frailty would be associated with postoperative delirium and cognitive change at 1 and 12 months after cardiac surgery. METHODS: This study was nested in 2 trials, each of which was conducted by the same research team with identical measurement of exposures and outcomes. Before surgery, patients were assessed with the validated “Fried” frailty scale, which evaluates 5 domains (shrinking, weakness, exhaustion, low physical activity, and slowed walking speed) and classifies patients as nonfrail, prefrail, and frail. The primary outcome was postoperative delirium during hospitalization, which was assessed using the Confusion Assessment Method, Confusion Assessment Method for the Intensive Care Unit, and validated chart review. Neuropsychological testing was a secondary outcome and was generally performed within 2 weeks of surgery and then 4–6 weeks and 1 year after surgery, and the outcome of interest was change in composite Z-score of the test battery. Associations were analyzed using logistic and linear regression models, with adjustment for variables considered a priori (age, gender, race, education, and logistic European System for Cardiac Operative Risk Evaluation). Multiple imputation was used to account for missing data at the 12-month follow-up. RESULTS: Data were available from 133 patients with baseline frailty assessments. Compared to nonfrail patients (13% delirium incidence), the incidence of delirium was higher in prefrail (48% delirium incidence; risk difference, 35%; 95% CI, 10%–51%) and frail patients (48% delirium incidence; risk difference, 35%; 95% CI, 7%–53%). In both univariable and multivariable models, the odds of delirium were significantly higher for prefrail (adjusted odds ratio, 6.43; 95% CI, 1.31–31.64; P = .02) and frail patients (adjusted odds ratio, 6.31; 95% CI, 1.18–33.74; P = .03) compared to nonfrail patients. The adjusted decline in composite cognitive Z-score was greater from baseline to 1 month only in frail patients compared to nonfrail patients. By 1 year after surgery, there were no differences in the association of baseline frailty with change in cognition. CONCLUSIONS: Compared to nonfrail patients, both prefrail and frail patients were at higher risk for the primary outcome of delirium after cardiac surgery. Frail patients were also at higher risk for the secondary outcome of greater decline in cognition from baseline to 1 month, but not baseline to 1 year, after surgery.
Monitoring cerebral autoregulation (CA) may help identify the lower limit of autoregulation (LLA) in individual patients. Mean arterial blood pressure (MAP) below LLA appears to be a risk factor for postoperative acute kidney injury (AKI). CA can be monitored in real-time using correlation approaches. However, the precise thresholds for different CA indexes that identify the LLA are unknown. We identified thresholds for intact autoregulation in patients during cardiopulmonary bypass surgery and examined the relevance of these thresholds to postoperative AKI.
Design: A single-center retrospective analysisSetting: Tertiary academic medical center Patients. Data from 59 patients was used to determine precise CA thresholds for identification of the LLA. These thresholds were validated in a larger cohort of 226 patients.
Methods and Main Results:Invasive MAP, cerebral blood flow velocities (CBFV), regional cortical oxygen saturation and total hemoglobin were recorded simultaneously. Three CA indices were calculated, including mean flow index (Mx), cerebral oximetry index (COx), and hemoglobin volume index (HVx). CA curves for the three indices were plotted, and thresholds for each index were used to generate threshold-and index-specific LLAs. A reference LLA could be identified in 59 patients by plotting CBFV against MAP to generate gold standard Lassen curves. The LLAs defined at each threshold were compared with the gold standard LLA determined from Lassen curves. The results identified the following thresholds: Mx (0.45), COx (0.35), and HVx (0.3). We then calculated the product of magnitude and duration of MAP < LLA in a larger cohort of 226 patients. When using the LLAs identified by the optimal thresholds above, MAP
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