Hazel Knight

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We studied the periodicities of ventilation in elderly subjects using digital comb filtering. Two groups of subjects were studied, those with and without sleep apnea. Measurements were made in wakefulness, stage 1-2 sleep, and where possible in stage 3-4 sleep. For each of the digital filters we calculated the average power of the oscillatory output. To(More)
Although previous studies have shown that patients with obstructive sleep apnea have a higher automobile crash rate than normal subjects, objective measurements of driving performance in patients with sleep apnea have not been reported. Therefore, we compared the driving performance of subjects with untreated, severe sleep apnea to that of control subjects(More)
The effect of phasic eye movement activity on ventilation during rapid-eye-movement (REM) sleep was studied in seven healthy young adults by use of the respiratory inductive plethysmograph. Mean ventilation (VE) and ventilatory components during REM sleep were not significantly different from that seen in either stages 1-2 or 3-4 sleep. The percent of rib(More)
The generally accepted polysomnographic criteria for diagnosis of sleep apnea is exceeded by elderly subjects with such frequency that the validity of its application to this age group has been questioned. We studied a group of elderly volunteers with nocturnal polysomnography and partitioned them into 2 groups based upon an apnea index of greater than or(More)
OBJECTIVE To test specific standards set in the newly established cleft lip and palate service in three regions of the U.K. The standards relate to record collection and outcomes. DESIGN Retrospective analysis. PATIENTS Records of 31 children, 5 years of age, who were born in 1997 with complete unilateral clefts of lip and palate and were treated by(More)
BACKGROUND AND STUDY AIMS Independent verification of colonoscopy completion is important for quality assurance. Cecal photographs aimed at showing key landmarks, including the ileocecal valve (ICV) and appendiceal orifice are the currently recommended standard, but are often perceived as unreliable. Images of the terminal ileum demonstrating villi may(More)
The relationship among diaphragm length (LD), the width of the zone of apposition (WZapp), and transverse chest diameter (Drc) was developed from model equations and statistical analysis. We present a theoretical model of diaphragm motion that predicts that the decrease in WZapp during inspiration is the result not only of shortening of the diaphragm muscle(More)
Diaphragmatic volume displacement (Vdi) is calculated from two models using measurements obtained from anteroposterior fluoroscopic images of supine anesthetized dogs. In model 1, diaphragmatic descent was treated as if it were a "piston in a cylinder." In contrast, model 2 incorporated thoracic configuration as well as inspiratory changes in rib cage(More)
We investigated the relationship between the volumes displaced by the diaphragm and the abdominal wall during spontaneous breathing in supine anesthetized dogs. Diaphragmatic volume displacement (Vdi) was calculated from measurements taken from anteroposterior fluoroscopic images employing a previously described geometric model. The volume displacement of(More)
We tested the hypothesis that dynamic shortening of the costal diaphragm can be accurately estimated from measurements of the radiographic width of the zone of apposition (WZapp) by studying seven supine anesthetized dogs. Both muscle fiber length, represented by the distance between implanted radiopaque markers, and WZapp were measured from digitized(More)