Biomedical subjects
Publications and source records attributed to M E Maddens.
1. A dayroom program focused intensively on functional needs and was implemented for confused geriatric inpatients who otherwise might have been restrained or required sitters. 2. There were fewer complications from hospitalization documented for dayroom patients. 3. There was an increase in family satisfaction regarding the nursing care provided for patients in the alternative environment.
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The elderly are at increased risk for syncope not only because of physiologic changes due to aging but also because they have a higher incidence of chronic illness and use a greater number of medications that may cause orthostatic hypotension. Although evaluation should emphasize cardiovascular and neurologic components, the cause may remain elusive in as many as 50% of patients.
A decrease in cardiac parasympathetic tone is a recognized finding in patients with ischemic heart disease, sudden cardiac death and heart failure, correlating closely with disease severity and overall survival. To study the clinical potential of vagomimetic intervention, the effect of transdermal scopolamine on fluctuations in heart rate was studied in 32 healthy adult subjects using both time-domain (mean RR interval, standard deviation of the mean RR interval, mean of the differences between consecutive RR intervals) and frequency-domain measures (spectrum analysis of 128 consecutive RR intervals) of heart rate variability. After an exposure of 24 hours, transdermal scopolamine resulted in a significant increase in all indexes tested. The increase was most pronounced in the 0.25-Hz respiratory peak of the RR interval power spectrum, compatible with a strong vagomimetic mode of action of transdermal scopolamine. Results indicate that transdermal scopolamine may have potential merit as a selective vagotonic agent in certain patients with myocardial infarction, heart failure or ventricular arrhythmias.
Decreased heart rate (HR) variability has been shown to be an independent predictor of poor outcome after acute myocardial infarction. Presumably, both reduced parasympathetic activity and increased sympathetic activity contribute to this observed HR variability response. To elucidate the physiologic contributions of the sympathetic and parasympathetic nervous systems to HR variability, the effect of passive head-up tilt (+70 degrees) was investigated on 4 indexes of HR variability in 17 healthy subjects. The standard deviation of the mean of 512 consecutive RR intervals, a traditional marker of HR variability and a purported index of cardiac parasympathetic neural tone, was compared with the mean difference of 512 consecutive RR intervals, with the maximal expiratory RR interval to minimal inspiratory RR interval ratio (respiratory RR ratio) and with the low- and high-frequency components of the power spectrum of 512 consecutive RR intervals. Passive tilt produced a nonsignificant decrease in the standard deviation of RR intervals. There was, however, a highly significant decrease in the mean difference of consecutive RR intervals and the high-frequency component of the RR-interval spectrum. Both the respiratory RR ratio and the low-frequency component of the RR-interval spectrum increased with tilt. It was concluded that the mean difference of consecutive RR intervals and the high-frequency component of the RR-interval spectrum are potentially superior indexes of "pure" parasympathetic neural tone and may be preferable for future use in cardiovascular studies of autonomic dysfunction.