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Biomedical subjects

R Stoohs

Publications and source records attributed to R Stoohs.

At least 19 recordsLinked to original sources
PubMed2001

Sleep-disordered breathing and hypotension.

We investigated the presence of low blood pressure (BP) in 4,409 subjects referred for overnight polysomnography. A low resting arterial BP (systolic BP < 105 mm Hg, diastolic BP < 65 mm Hg) was present in 101 subjects (2.3%). Low BP was more prevalent in subjects with upper airway resistance syndrome (UARS) (23%) than in subjects with obstructive sleep apnea syndrome (OSAS) (0.06%), parasomnia (0.7%), restless leg syndrome (0.9%), or psychological insomnia (0.9%). In order to investigate BP homeostasis, we conducted polysomnography followed by tilt-table testing on 15 subjects with orthostatic intolerance (OI) and UARS, five normotensive subjects with UARS, five subjects with insomnia and low BP, 15 subjects with OSAS, and 15 healthy control subjects. Fifteen subjects with UARS and OI and 15 healthy controls also underwent 24-h ambulatory BP monitoring. Subjects with OI and UARS had lower mean daytime systolic (119 +/- 28 mm Hg) and diastolic (75 +/- 18 mm Hg) BP than did control subjects (131 +/- 35 mm Hg and 86 +/- 19 mm Hg, respectively) (p < 0.05). During tilt-table testing, subjects with UARS and a history of OI had a greater decrease in systolic BP (27 +/- 3 mm Hg) than did control subjects (7.5 +/- 1.6 mm Hg), subjects with OSAS (6.8 +/- 1.2 mm Hg), normotensive subjects with UARS (7.2 +/- 0.84 mm Hg), or hypotensive insomniacs (7.4 +/- 1.1 mm Hg) (p < 0.01). We conclude that approximately one fifth of subjects with UARS have low BP and complain of OI. Tilt-table testing may be indicated to confirm orthostatic intolerance in subjects with UARS.

Adult↗
PubMed1997

Passive constriction of the upper airway during central apneas: fiberoptic and EMG investigations.

We studied five adult male patients with central sleep apnea syndrome (> 75% of the monitored events being central) during sleep using a fiberoptic scope and EMG monitoring of the superior and middle constrictors of the pharynx and the genioglossus and geniohyoid muscles. The fiberoptic investigation revealed a spontaneous decrease in the size of the airway during central apneas, without negative intrathoracic pressure or activation of the superior and middle pharyngeal constrictor muscles. We found a mean maximum decrease of 71 +/- 7% in the cross-sectional area of the airway and an absence of superior-middle pharyngeal constrictor EMG discharge. We did not observe any complete collapses of the airway.

Adult↗
PubMed1996

Determinants of sleepiness in automobile drivers.

Governmental agencies do not systematically investigate the presence of daytime sleepiness as a determinant of driving accidents. We surveyed automobile drivers traveling on summer vacations and driving long distances on a European highway. We evaluated their subjective daytime sleepiness while driving and any sleep deprivation just prior to departure. Five-hundred sixty-seven automobile drivers (mean age 37.7 +/- 11 years) were interviewed at a roadside rest-stop. Questions covered the sleep/wake schedule during the year, sleep habits, and the presence of symptoms frequently associated with sleep-disordered breathing. Sleep behavior just prior to departure was compared to the usual sleep schedule during the year. Fifty percent of the responders had a sleep restriction just prior to departure (mean -203 minutes) compared to usual total sleep time during the year; 10% had no nocturnal sleep prior to departure. Drivers younger than 30 years were significantly more acutely sleep deprived than other drivers. Economic migrants (subjects with low economic status) also experienced significant acute sleep restriction.

Accidents, Traffic↗
PubMed1996

Upper airway resistance syndrome, nocturnal blood pressure monitoring, and borderline hypertension.

Upper airway resistance syndrome (UARS) is a sleep-disordered breathing syndrome characterized by complaints of daytime fatigue and/or sleepiness, increased upper airway resistance during sleep, frequent transient arousals, and no significant hypoxemia. Of a population of 110 subjects (58 men) diagnosed as having UARS, we investigated acute systolic and diastolic BP changes seen during sleep in two different samples. First, six patients from the original subject pool were found to have untreated chronic borderline high BP, and were subjected to 48 h of continuous ambulatory BP monitoring before treatment and another 48 h of BP monitoring 1 month after the start of nasal-continuous positive airway pressure (N-CPAP) treatment. Five of six subjects used their equipment on a regular basis and had their chronic borderline high BP completely controlled. No change in BP values was seen in the last subject, who discontinued N-CPAP after 3 days. A second protocol investigated seven normotensive subjects drawn from the initial subject pool. Continuous radial artery BP recording was performed during nocturnal sleep with simultaneous polygraphic recording of sleep/wake variables and respiration. BP changes were studied during periods of increased respiratory efforts and at the time of alpha EEG arousals. Increases in systolic and diastolic BP were noted during the breaths with the greatest inspiratory efforts without significant hypoxemia. A further increase in BP was noted in association with arousals. Three of these subjects also underwent echocardiography during sleep, which demonstrated a leftward shift of the interventricular septum with pulsus paradoxus in association with peak end-inspiratory esophageal pressure more negative than -35 cm H2O. Our study indicates that, in the absence of classic apneas, hypopneas, and repetitive significant drops in oxygen saturation (below 90%), repetitive increases in BP can occur as a result of increased airway resistance during sleep. It also shows that, in some patients with both UARS and borderline high BP, high BP can be controlled with treatment of UARS. We conclude that abnormal upper airway resistance during sleep, often associated with snoring, can play a role in the development of hypertension.

Adult↗
PubMed1996

Should everyone be monitored for upper-airway resistance and how?

Preliminary data indicate that the use of a morphometric model, an expert system with standardized questions, and an evaluation of snoring can be effective tools for diagnosing upper-airway sleep-disordered breathing (UASDB) in many cases. This eliminates the need for many sleep recordings.

Airway Obstruction↗
PubMed1995

Upper airway sleep-disordered breathing in women.

OBJECTIVE: To investigate the various clinical presentations of sleep-disordered breathing in women. DESIGN: A retrospective case-control study. SETTING: A sleep disorders clinic. PATIENTS: 334 women, aged 18 years and older, seen between 1988 and 1993, who were diagnosed with upper airway sleep-disordered breathing. Controls were 60 women with insomnia and 100 men with sleep-disordered breathing. MEASUREMENTS: Clinical, anatomic, and polygraphic information. RESULTS: The mean lag time (+/- SD) in women between the appearance of symptoms and a positive diagnosis was 9.7 +/- 3.1 years; among participants 30 to 60 years of age, the duration of untreated symptoms differed (P < 0.001) between women and men. Sleep-disordered breathing was blamed for divorce or social isolation by 40% of the case patients. Abnormal maxillomandibular features were noted in 45% of the women with disordered breathing. Dysmenorrhea and amenorrhea (which disappeared after treatment with nasal continuous positive airway pressure) were reported in 43% of premenopausal women compared with 13% of persons in the control group of women with insomnia. Thirty-eight women (11.4%) with upper airway sleep-disordered breathing had a respiratory disturbance index of less than 5 and were significantly younger, had a smaller neck circumference, and had a lower body mass index than women with a respiratory disturbance index of 5 or more. CONCLUSION: Physicians should revise their understanding of upper airway sleep-disordered breathing so that they notice women with certain craniofacial features, a low body mass index, a small neck circumference, and a respiratory disturbance index of less than 5. These revisions may enable more rapid diagnosis and treatment of women with sleep-disordered breathing.

Adolescent↗
PubMed1995

Arousal, increased respiratory efforts, blood pressure and obstructive sleep apnoea.

The roles of hypoxaemia, of mechanical changes related to partial or complete airway obstruction and of arousals during sleep in the haemodynamic and heart rate changes seen in association with sleep-disordered breathing have been questioned. Several experiments have been performed by these authors to investigate the role of arousals and mechanical changes in the blood pressure changes associated with sleep disordered breathing. Investigation of the role of arousals. Two different populations were used in this study; one of normal, young volunteers without sleep-disordered breathing monitored at baseline (normal sleep) who were submitted to auditory stimulation during sleep, causing sleep fragmentation, and another of obstructive sleep apnoeic patients who were monitored at baseline and after nasal CPAP treatment. Before treatment and after one month of treatment while still being treated with nasal CPAP, these subjects were submitted to the same auditory stimulation and sleep fragmentation as normal controls. The studied variables were systolic and diastolic blood pressure and heart rate. In normal controls, auditory induced arousals lead to an increase in diastolic as well as systolic blood pressure. The increase was related to the type of arousal but was also noted with K complexes to a lesser degree. In OSAS patients under treatment with nasal CPAP, similar increases were noted with auditory stimulation. Compared to baseline hypoxaemia and hyperventilation periods, however, the haemodynamic increase was, at its highest, only one-third of the mean pressure monitored during the baseline, end-of-apnoea hyperventilation period with EEG arousals. Investigation of the role of nasal CPAP on blood pressure (BP) while patients had no hypoxaemia (SaO2>92%) but still showed increased respiratory efforts indicated a persistence of higher systolic and diastolic pressures than when nasal CPAP completely eliminated increased efforts. Possible long-term impact of arousals and mechanical changes. A last study was performed on patients with upper airway resistance syndrome (UARS). Out of 112 patients, 6 were identified using the World Health Organization (WHO) protocol and ambulatory monitoring as having borderline high BP (140-160//90-98). Subjects were calibrated with nasal CPAP and were asked to use their equipment on a nightly basis. The CPAP machines were equipped with counters that could accurately measure the number of hours that the device was used. Patients were their own controls and were re-monitored one month later. Four subjects used their nasal CPAP at least 6 nights per week and more than 5 hours per night. One patient used his CPAP approximately 3 nights per week and more than 4 hours per night. One patient used his CPAP a total of 3 nights in the whole month. Blood pressure was unchanged in the patient who failed to use his CPAP, but was normalized in the 5 others, as were nocturnal recordings.

Journal Article↗
PubMed1995

The effect of electrical stimulation on obstructive sleep apnea syndrome.

Patients with severe obstructive sleep apnea polygraphically documented underwent electrical stimulation treatment trials. Submental and intraoral stimulations were applied during waking and during nocturnal sleep. The stimulation was applied using a custom-designed neuromuscular electrical stimulator (EdenTec Corp) providing symmetric biphasic constant voltage pulses. Pulse duration of each phase was set to 80 microseconds based on a subjective evaluation of pulse durations from 80 to 300 microseconds to minimize sensation while generating equivalent motor responses. Pulse repetition rate was set to 50 pulses per second. Cephalometric radiographs and endoscopies were obtained with and without stimulations during waking. Most commonly, stimulations induced alpha EEG arousals. Submental subcutaneous stimulation induced good contractions of platysmal muscles but had no impact on the upper airway. Intraoral stimulation induced clear tongue muscle movements but with change of shape of the upper airway and posterior movements of the tongue. Each time a breakage of apnea was noted, it was associated with a time-linked alpha EEG arousal. The results obtained by us and others do not, at this time, give convincing support for the use of electrical stimulation using submental surface or intraoral electrodes as a viable approach for effective control of obstructive sleep apnea syndrome symptoms.

Electric Stimulation Therapy↗
PubMed1995

Familial aggregates in obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) was diagnosed in157 subjects based on clinical symptoms, physical evaluation, cephalometric x-ray films, and polysomnography. These index cases identified 844 living first-degree relatives. Mailings were sent to 792 (94%). The mailing consisted of two identical questionnaires, one for the family member of the index case and one to be given to a friend (not a relative) of approximately the same age. In response, we received 531 (63%) questionnaires from relatives and 198 (25%) questionnaires from age-matched nonrelated friends, which were used as a control group. A more extensive investigation was performed on first-degree relatives of the index group living in the San Francisco Bay Area or vicinity. Two hundred seventy-nine relatives (100%) were identified. One hundred sixty-six subjects (59%) as well as 69 age-matched friends (ie, 41% of the 166 relatives and 25% of the potential total group) agreed to participate in further studies. These subjects had interviews, clinical investigations, and nonattended ambulatory monitoring. Cephalometric x-ray films could be obtained on only 22 of 166 participating relatives and 6 of 69 friends. Body mass index was not a differentiating measure between relatives and friends. Odds ratios (ORs) were calculated from the questionnaiare data. The report of tiredness, fatigue, and sleepiness did not distinguish family members from friends. The OR, however, progressively increases when there is a positive history of near nightly loud snoring (OR = 1.78; 95% confidence interval [CI] 1.25-2.54) or a positive history of daytime sleepiness in conjunction with near nightly loud snoring (OR = 3.11; 95% CI = 1.94-4.99). The investigation in the Bay Area indicated that, when first-degree relatives were compared with friends, the complaint of daytime tiredness, sleepiness, or both with the presence of a high and narrow(ogival) hard palate sharply differentiated between friends and relatives (OR = 10.9, 95, CI = 5.31-22.5). An Epworth Sleepiness Scale score of 9 or greater with the presence of another symptom associated with OSAS, and a respiratory disturbance index greater than 5 (number of apneas and hypopneas per hour of sleep > 5) gave an OR of 45.6 (95% CI = 18.8-11.0). Disproportionate craniofacial anatomy was common in familial groups with OSAS. Craniofacial familial features can be a strong indicator of risk for the development of OSAS.

Adolescent↗
PubMed1994

Sleep fragmentation in normals: a model for sleepiness associated with upper airway resistance syndrome.

Eight young adults underwent 1 night of auditory sleep fragmentation followed by four naps of the multiple sleep latency test and performance testing the next day. A latin-square design was used to compare results with baseline. Efforts were made to eliminate effects of learning on repeated performance tests. A mean of 303 arousals, lasting a mean of 11 seconds, disrupted nocturnal sleep. This sleep fragmentation was induced to mimic as closely as possible the nocturnal sleep disruption seen in subjects with upper airway resistance syndrome. There was a significant disruption of nocturnal sleep architecture with a significant overall decrease in slow-wave sleep (SWS) and a significant but more moderate decrease in rapid eye movement (REM) sleep during the fragmented night. The most interesting finding related to analysis by thirds of the night, which indicated an important increase over time in arousal threshold during SWS followed by REM sleep. This threshold increase was associated with a parallel increase in dB(A) levels needed to induce an arousal. Stages 1 and 2 nonrapid eye movement (NREM) sleep were less affected by the stimulation, but the amount of stage 1 NREM sleep decreased from the beginning to the end of the night, again indicating an increase in pressure to sleep. Following 1 night of sleep fragmentation, subjects had significantly shorter sleep latencies on the multiple sleep latency test for naps 2, 3 and 4. There was a significant relationship between percent nocturnal SWS and mean sleep latencies. The selected performance tests were not affected by 1 night of sleep fragmentation, despite the obvious sleepiness.

Adult↗
PubMed1993

Aging, respiratory efforts during sleep, and pulsus paradoxus.

Forty patients with either obstructive sleep apnea syndrome or a clinical complaint of daytime sleepiness with measured nocturnal increase in upper airway resistance and snoring were investigated during sleep for the presence of pulsus paradoxus, which is defined as a decrease in systolic blood pressure (SBP) of at least 10 mmHg during inspiration. Two thirds of the subjects presented pulsus paradoxus. Age, lowest oxygen saturation (SaO2), and negative inspiratory esophageal pressure nadir (an index of inspiratory effort) were the only studied variables which could statistically dissociate patients presenting pulsus paradoxus. We then divided the patient population into three different subgroups of equal number based upon the degree of decrease in SBP (i.e., > 20 mmHg, < 20 but > 10 mmHg, and < 10 mmHg). In this second analysis, age was the only significant variable that separated the three groups. Lowest SaO2 could not be used to statistically separate subjects with mild to moderate pulsus paradoxus from those without it; and negative inspiratory esophageal pressure measurements could only significantly identify subjects with severe pulsus paradoxus (i.e., > 20 mmHg) from those without any pulsus paradoxus. The variable which correlated best with age was negative inspiratory esophageal pressure nadir (R = 0.83). Our interpretation is that as age increased, negative inspiratory esophageal pressure became less negative, due to the known impact of aging on muscles, and pulsus paradoxus was no longer observed.

Adult↗
PubMed1993

Does snoring intensity predict flow limitation or respiratory effort during sleep?

We tested whether snoring sound intensity could be an accurate predictor of the degree of respiratory effort or the decrease of inspiratory volume during partially obstructed breathing in sleep. Six snorers were investigated with nocturnal polygraphic monitoring including measurement of esophageal pressure (Pes), airflow (pneumotachometer and face mask, indicating tidal volume [VT]), and snoring sound intensity (SSI) measured in decibels. SSI was a poor predictor of flow limitation during snoring. Considerable between- and within-subject variance did not allow establishment of models for the interdependence between VT and SSI. The increase in peak-negative inspiratory efforts was better predicted by SSI. Individual multiple correlation analyses of Pes on SSI indicated a positive interdependence in all subjects. Calculation of ecological correlations with subject means of Pes and SSI was performed. SSI significantly predicted the level of peak-negative inspiratory effort during obstructed, noisy breathing for a given subject. Monitoring of snoring sound intensity may be a useful indicator identifying subjects performing high peak negative inspiratory efforts with obstructed, noisy breathing during sleep.

Analysis of Variance↗
PubMed1993

Upper airway resistance in infants at risk for sudden infant death syndrome.

To investigate the relationship between sudden infant death syndrome and upper airway obstruction, we studied 14 term infants at a mean age of 11 weeks who had been identified as being at risk for sudden infant death syndrome on the basis of clinical and family histories and polygraphic monitoring. Respiratory efforts during sleep were investigated by esophageal pressure monitoring (all 14 infants) and by monitoring of flow with a pneumotachometer (6 infants). During apparently normal sleep, increased respiratory efforts were shown by intermittent increases in the magnitude of the negativity of esophageal pressure. Mild changes in tidal volume occurred occasionally, always at the lowest monitored esophageal pressure of a breath sequence. These tidal volume decreases had no impact on oxygen saturation but led to a short arousal and decreased respiratory efforts, followed by a return to normal breathing. Occasionally the abnormal increase in upper airway resistance did not lead to an immediate arousal but instead to a short obstructive apnea that was then followed by an arousal. This investigation indicates the importance of arousal mechanisms in maintaining normal breathing during sleep. Any disruption of the arousal mechanisms during sleep (including sleep fragmentation caused by repetitive arousals) may place these infants with increased upper airway resistance at risk for obstructive apnea during sleep.

Airway Resistance↗
PubMed1993

Daytime somnolence: therapeutic approaches.

Excessive daytime somnolence is a major neurological problem involving about 4% of the general population. Its treatment is based on accurate etiological dissection. Sleep-disordered breathing is a major cause of EDS. Stimulant medication is helpful in many other instances.

Disorders of Excessive Somnolence↗
PubMed1993

Excessive daytime somnolence in women with abnormal respiratory efforts during sleep.

An abnormal level of respiratory efforts, indicated by significant increase in peak negative esophageal pressure (Pes), can be associated with daytime somnolence in snoring pre-menopausal women. No drop in oxygen saturation (SaO2) or visual evidence of transient electroencephalographic (EEG) arousals can be found at repeat polysomnography. Nasal continuous positive airway pressure (CPAP) titrated on Pes measurements eliminates somnolence.

Adult↗
PubMed1993

Obstructed breathing in children during sleep monitored by echocardiography.

Six 3 to 14-year-old boys with snoring and obstructive sleep apnea syndrome were monitored polygraphically during sleep with and without nasal continuous positive airway pressure with simultaneous recording of esophageal pressure (Pes) and M-mode and two-dimensional echocardiograms. Continuous non-invasive blood pressure monitoring was performed in two older children. Three of the six children demonstrated a diastolic leftward shift of the interventricular septum related to the negativity of Pes. Progressively more negative Pes correlated significantly with an increase in right ventricular internal end-diastolic dimension and a decrease in left ventricular internal end-diastolic dimension, with at times left ventricular "collapse". One of the subjects with blood pressure monitoring demonstrated pulsus paradoxus with leftward shift of the interventricular septum. Nasal continuous positive airway pressure normalized all changes. Pulsus paradoxus and leftward shift of the interventricular septum are related to the mechanical changes associated with heavy snoring during sleep, regardless of the amount of oxygen desaturation.

Adolescent↗
PubMed1993

A cause of excessive daytime sleepiness. The upper airway resistance syndrome.

Subjects with isolated complaints of chronic daytime sleepiness are usually classified as "idiopathic hypersomniacs" and treated symptomatically. A group of these subjects was investigated during nocturnal sleep and daytime naps. In a subgroup of them, sleep was fragmented by very short alpha EEG arousals throughout the sleeping period. These short arousals are usually ignored in sleep analyses, but their impact is significant (in the 15 subjects identified with the syndrome, the mean sleep latency in multiple sleep latency tests was 5.1 +/- 1 min). These arousals are directly related to an abnormal increase in respiratory efforts during sleep (the mean peak inspiratory esophageal pressure measured in our subjects in the respiratory cycle just preceding a transient arousal was -33 +/- 7 cm H2O). Typically, an arousal occurs within one to three breaths of flow limitation associated with abrupt but limited reduction in tidal volume (ie, abnormal increase in upper airway resistance during sleep). The arousal restores normal breathing. Snoring was noted in association with these transient arousals in 10 of the 15 subjects; however, snoring was neither sufficient nor necessary for the identification of the clinical syndrome. Both sexes were equally represented in the affected group. All studied subjects had upper airway anatomy that was mildly abnormal. Nasal continuous positive airway pressure, used as an experimental tool, eliminated the daytime sleepiness (multiple sleep latency mean score = 13.5 min), the transient arousals (mean alpha EEG arousal index decreased from 31.3 +/- 12.4 to 8 +/- 2 per hour of sleep), and the abnormal upper airway resistance. Chronic daytime sleepiness is a major cause of social, economic, and medical impairment. Recognition of this syndrome and its cause is important, as specific treatments can be developed to eliminate the problem.

Adult↗