Norepinephrine and cardiovascular responses to maximal exercise in Parkinson's disease on and off medication

The aim of this experiment is to understand how Parkinson's disease (PD) medication affects the autonomic responses of individuals during an acute exercise stress test. Fourteen people with PD and fifteen healthy individuals age‐matched between 50 and 80 years performed a modified Bruce protocol. Subjects with PD performed the test once off medication (PD‐off) and then 1 week later on medication (PD‐on). Heart rate (HR), blood pressure (BP), VO₂, and norepinephrine (NE) levels were taken at rest and at peak exercise. At peak exercise HR, BP, and NE values for the PD‐on and PD‐off group were all significantly lower than healthy controls, regardless of whether subjects were on their medication. Autonomic abnormalities during exercise in this population appear to be disease manifested and not impactedby medications used to treat PD. We can assume, both on and off medication, this population will show markedly lower BP, HR, and NE responses. © 2009 Movement Disorder Society     

Modeling a Predictive Energy Equation Specific for Maintenance Hemodialysis

Background: Hypermetabolism is theorized in patients diagnosed with chronic kidney disease who are receiving maintenance hemodialysis (MHD). We aimed to distinguish key disease‐specific determinants of resting energy expenditure to create a predictive energy equation that more precisely establishes energy needs with the intent of preventing protein‐energy wasting. Materials and Methods: For this 3‐year multisite cross‐sectional study (N = 116), eligible participants were diagnosed with chronic kidney disease and were receiving MHD for at least 3 months. Predictors for the model included weight, sex, age, C‐reactive protein (CRP), glycosylated hemoglobin, and serum creatinine. The outcome variable was measured resting energy expenditure (mREE). Regression modeling was used to generate predictive formulas and Bland‐Altman analyses to evaluate accuracy. Results: The majority were male (60.3%), black (81.0%), and non‐Hispanic (76.7%), and 23% were ≥65 years old. After screening for multicollinearity, the best predictive model of mREE (R² = 0.67) included weight, age, sex, and CRP. Two alternative models with acceptable predictability (R² = 0.66) were derived with glycosylated hemoglobin or serum creatinine. Based on Bland‐Altman analyses, the maintenance hemodialysis equation that included CRP had the best precision, with the highest proportion of participants’ predicted energy expenditure classified as accurate (61.2%) and with the lowest number of individuals with underestimation or overestimation. Conclusions: This study confirms disease‐specific factors as key determinants of mREE in patients on MHD and provides a preliminary predictive energy equation. Further prospective research is necessary to test the reliability and validity of this equation across diverse populations of patients who are receiving MHD.     

Abbreviated Steady State Intervals for Measuring Resting Energy Expenditure in Patients on Maintenance Hemodialysis

Background: Indirect calorimetry requires a steady state (SS) protocol to determine measured resting energy expenditure (mREE). Achieving stringent criteria for an SS interval may be difficult for patients on maintenance hemodialysis (MHD), as they may become uncomfortable because of the test itself or their health status. The study aim was to explore if a shortened SS interval was within acceptable limits for bias and precision. Materials and Methods: For this cross‐sectional secondary analysis, adults (N = 125) who received MHD thrice weekly were enrolled. The indirect calorimetry test was performed for a length of total time ≤30 consecutive minutes. SS was evaluated in accordance with intervals of 10, 5, 4, 3, and 2 minutes. The mREE at the 10‐minute SS was compared with the mREE at 5, 4, 3, and 2 minutes, via t tests and Bland‐Altman analysis, to determine degree of bias and level of agreement. The a priori alpha level was set at ≤0.5. Results: The sample was primarily male, African American, and non‐Hispanic, with a mean ± SD age of 55.4 ± 12.2 years, who reported being on MHD for an average of 62.4 ± 74.3 months. None of the mREE measures were significantly different from that of the 10‐minute SS interval. Seventy‐two percent of the participants were able to achieve SS at the 10‐minute interval, 83.2% at 5 minutes, 87.2% at 4 minutes, and 89.6% for both 3 and 2 minutes. Conclusion: For patients on MHD, an abbreviated SS interval of <10 minutes (eg, 5 minutes) yielded valid mREE measurements.