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D Pond

Publications and source records attributed to D Pond.

12 recordsLinked to original sources
PubMed1992

Sleep disordered breathing and cognitive function in a retirement village population.

Sleep disordered breathing (SDB) may be associated with cognitive dysfunction in non-demented elderly people. A random sample of 96 retirement village residents were given both neuropsychological assessment and overnight sleep monitoring with a portable microprocessor based system (Vitalog PMS-8). Respiratory disturbance index (RDI) was calculated as the number of apnoeas and hypopnoeas per hour of sleep. RDI was not associated with 'memory', 'verbal', and 'motor' factors identified from the analysis of cognitive tests, but was associated with the 'cerebral efficiency' factor (R2 = 0.21, p less than 0.0001). Seventy-three subjects had repeat neuropsychological tests, median time to follow-up being 17 months. Baseline RDI did not predict changes in scores on the two factors identified from the second analysis. We conclude that mild to moderate disturbance of breathing during sleep is not associated with cognitive dysfunction in non-demented subjects.

Activities of Daily Living↗
PubMed1992

Sleep-disordered breathing in elderly people and subjective sleep-wake disturbance.

Sleep-disordered breathing and subjective reports of sleep-wake disturbances are both common in elderly people but previous studies investigating the relationship between the two have produced uncertain results. We hypothesized that there is no relationship between sleep-disordered breathing and subjective reports of sleep-wake disturbance. Ninety-three random-sampled retirement-village residents, mean age 77.6 years, were monitored overnight with a portable microprocessor-based system. The respiratory disturbance index (RDI) was used as a measure of sleep-disordered breathing. Subjects were interviewed regarding sleep-wake patterns and snoring history and the Mini Mental State Examination, Geriatric Depression Scale and Nelson Adult Reading Test were administered. The sleep-wake responses were entered into a principal components analysis. Two components, reflecting night-time and daytime disturbance, accounted for 34% of the variance. Multiple regression analyses were performed using RDI as a continuous dependent variable, and three predictor variables, night-time, and daytime disturbance and history of snoring. Together, these variables accounted for only 2% of the variance. We conclude there is no relationship between mild and moderate sleep-disordered breathing and subjective sleep-wake disturbance in this population.

Aged↗
PubMed1991

Night-to-night variability of disturbed breathing during sleep in an elderly community sample.

Night-to-night variability of breathing and oxygenation during sleep was examined with portable monitoring equipment in 30 residents of a retirement village. Subjects had a variety of health problems as might be expected in the elderly, but all were living independently in self-contained units. None had clinical features to suggest obstructive sleep apnea. Two pairs of consecutive nights were studied, separated by 4-6 months. Satisfactory recordings on all four nights were obtained in 15 subjects, and in these subjects variability of measurements was examined across nights 1-4 using the kappa (K) statistic. There was low but significant agreement in estimated total sleep time (K = 0.23, p less than 0.01) and estimated wakefulness after sleep onset (K = 0.18, p less than 0.05) as assessed with a wrist actigraph. Good agreement was found among measures of disturbed breathing during sleep whether expressed in terms of numbers of events [respiratory disturbance index (RDI), K = 0.62, p less than 0.0001], their duration (event minutes, K = 0.53, p less than 0.0001), or associated disturbance of oxygenation (% cumulative time less than 90% SaO2, K = 0.50, p less than 0.001, n = 9). Twenty-eight subjects had at least two nights' satisfactory recordings. Although some of these individuals showed considerable variation in RDI, this had little overall effect on classification of them into normal (RDI less than or equal to 15) and abnormal groups. The accuracy of the first night's recording in predicting classification derived from recording on three or four nights was 83%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Interrater reliability of computer-assisted scoring of breathing during sleep.

Twenty-six records of sleep and breathing obtained with a portable monitoring system from elderly subjects were scored by three raters with computer assistance to examine interrater reliability of scoring. Raters were a medical student, a nurse practitioner, and a family physician, all of whom had at least one month's experience with the equipment. Agreement among raters was measured with the unweighted kappa statistic. Significant agreement was observed for all variables, although agreement was better for variables describing breathing (range of kappa 0.71-0.87) than for those describing sleep (range of kappa 0.34-0.57). Complete agreement among the three raters on diagnostic classification occurred in 17 cases. In the remaining 9 cases, 2 raters agreed, whereas the third differed by not more than one category for type of disturbance (e.g., normal versus hypopnea, hypopnea versus apnea) or severity (e.g., mild versus moderate). There was only one disagreement among raters for the 9 subjects with severe respiratory disturbance. We conclude that interrater reliability of identifying and characterizing breathing disturbance during sleep as recorded by portable monitoring is high among trained raters using computer assistance.

Aged↗
PubMed1987

Evaluation of a microprocessor-based portable home monitoring system to measure breathing during sleep.

Study of the epidemiology of disturbances of breathing during sleep was hampered until recently by the need to conduct studies in the laboratory, with attendant inconvenience and limited sample sizes. We assessed the accuracy of a microprocessor-based portable monitoring system (Vitalog PMS-8, Vitalog Corp., CA) to detect and classify episodes of disturbed breathing during sleep in 14 patients with sleep apnea by simultaneously recording oxygenation and thoracoabdominal motion on the portable system and a polygraph. Each patient slept in the laboratory for 1 night. In two subjects, the portable system failed to record thoracoabdominal signals. In the remaining subjects, the portable system detected 78% of 2,340 episodes of disturbed breathing, but the recorded information was not sufficient to allow confident classification into central or obstructive events. The positive predictive value of disturbed breathing detected by the portable system was 64%, Respiratory disturbance indices (RDI) computed from the polygraph and portable records were correlated (r = 0.70; p less than 0.01), and all patients with sleep apnea were correctly diagnosed by the portable system. The portable system overestimated arterial oxygen saturation (SaO2) recorded by an ear oximeter (Biox IIA, Ohmeda, CO) but the error was less than 10% of the true value at SaO2 greater than 60%. Seven normal subjects were studied while awake to examine the accuracy of volume measurements made by the portable system and the system's ability to detect paradoxical thoracoabdominal motion of various degrees. Absolute measurement of tidal volume was inaccurate, but detection rate of paradoxical thoracoabdominal motion was excellent (97%). We conclude that the portable system is sufficiently sensitive to allow detection of patients with breathing disorders during sleep, but further developments are necessary before the system can be relied on for accurate classification of apneas and hypoventilation.

Adult↗