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Biomedical subjects

R Stoohs

Publications and source records attributed to R Stoohs.

36 records · Page 2Linked to original sources
PubMed1993

Cardiac failure and benzodiazepines.

Nine patients with stable cardiac failure and mean left ventricular ejection fraction of 30% were investigated. All had previously been prescribed a benzodiazepine hypnotic by their home physicians, but the medication had been discontinued for at least 1 month. Subjects were monitored under three conditions: 1) without any sleeping medication, 2) during nasal CPAP administration and 3) at two points during a month-long administration of the benzodiazepine that had initially been prescribed to them. Overall, the benzodiazepine hypnotic improved the sleep fragmentation noted in these patients by decreasing the arousal index from a mean of 18 +/- 6 per hour at baseline to a mean of 9 +/- 6.5 per hour after one month of benzodiazepine therapy. Total nocturnal sleep time was consequently improved [baseline mean nocturnal total sleep time: 313 +/- 27.3 minutes; benzodiazepine mean nocturnal total sleep time: 350 +/- 17.3 minutes (p < 0.0003)], as was sleep efficiency. However, the benzodiazepine hypnotic had no significant effect on central hypopneas or apneas [baseline mean respiratory disturbance index (RDI): 20.5 +/- 5.85 events/hour; mean RDI after 1 month of drug intake: 21.3 +/- 2.5 events/hour]. Nasal CPAP was also ineffective on the disordered breathing. In this group of subjects, respiration was even significantly worsened with nasal CPAP compared to baseline, as indicated by RDI (p < 0.0001), lowest SaO2 (p < 0.0001) and total nocturnal sleep time (p < 0.0001) measurements.

Benzodiazepines↗
PubMed1992

Cardiovascular changes associated with obstructive sleep apnea syndrome.

Five men free of lung or cardiovascular diseases and with severe obstructive sleep apnea participated in a study on the impact of sleep states on cardiovascular variables during sleep apneas. A total of 128 obstructive apneas [72 from stage 2 non-rapid-eye-movement (NREM) sleep and 56 from rapid-eye-movement (REM) sleep] were analyzed. Each apnea was comprised of an obstructive period (OP) followed by a hyperventilation period, which was normally associated with an arousal. Heart rate (HR), stroke volume (SV), cardiac output (CO) (determined with an electrical impedance system), radial artery blood pressures (BP), esophageal pressure nadir, and arterial O2 saturation during each OP and hyperventilation period were calculated for NREM and REM sleep. During stage 2 NREM sleep, the lowest HR always occurred during the first third of the OP, and the highest was always seen during the last third. In contrast, during REM sleep the lowest HR was always noted during the last third of the OP. There was an inverse correlation when the percentage of change in HR over the percentage of change in SV during an OP was considered. The HR and SV changes during NREM sleep allowed maintenance of a near-stable CO during OPs. During REM sleep, absence of a compensatory change in SV led to a significant drop in CO. Systolic, diastolic, and mean BP always increased during the studied OPs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

MESAM 4: an ambulatory device for the detection of patients at risk for obstructive sleep apnea syndrome (OSAS).

A validation study was performed on the MESAM 4, a digital recording device developed to monitor oxygen saturation, heart rate (HR), snoring, and body position in order to screen subjects for obstructive sleep apnea syndrome (OSAS). MESAM 4 recordings were scored with the computer-based automatic scoring system provided with the equipment. Nocturnal polysomnography (PSG) and MESAM 4 recordings were run simultaneously on 56 subjects presenting with any type of sleep complaint, including those secondary to OSAS. Patients were assigned to one room by hospital administration and were monitored consecutively. The polygraphic equipment and MESAM 4 equipment were placed on the subjects by separate teams. Records of PSG and MESAM 4 were analyzed in double-blind fashion. With the MESAM 4 computerized analysis, three indices based on SaO2 (ODI), on heart rate (HVI), and on snoring (ISI) were obtained, and the number of abnormal respiratory events occurring during the time selected for analysis (TAT) were determined. Polysomnographic records were scored by 30-s epochs following the American Sleep Disorders Association standards for sleep states and stages and for sleep-related events, including sleep apneas, hypopneas, and periodic leg movements. Following independent scoring, 26 subjects were identified with OSAS by PSG, while MESAM 4 identified 25 subjects with OSAS using oxygen algorithm; all had a respiratory disturbance index greater than or equal to 10 with PSG. Results of each polysomnogram and each MESAM 4 analysis were compared. With the polysomnogram used as a standard, the degree of error for each variable with the MESAM 4 was calculated. Specificity and sensitivity of the most accurate index of the MESAM 4, the ODI, were 97 percent and 92 percent, respectively. The other two indices, HVI and ISI, were less accurate: specificity and sensitivity were 32 percent and 58 percent for HVI and 27 percent and 96 percent for ISI. Nevertheless, a combination of all three indices (ODI, HVI, ISI) would have prevented the two false-positive cases we observed. The results of this validation study show that MESAM 4 can be helpful to general practitioners, clinicians, and epidemiologists as a low-cost screening device for subjects with OSAS and habitual snoring.

Female↗
PubMed1992

From apnea of infancy to obstructive sleep apnea syndrome in the young child.

Obstructive sleep apnea syndrome (OSAS) and heavy snoring during sleep, without sleep apnea, has been well described in children and adults. We report a case series of 25 full-term infants, prospectively obtained from a database of nearly 700 "apparent life-threatening event" (ALTE) cases, who presented between 3 weeks and 4 1/2 months of age an ALTE and who progressively developed more florid symptomatology and polygraphic findings. All of them were classified as OSAS patients by five years of age. These index cases are compared with two other ALTE infant groups followed in parallel during the first year of life but whose symptoms were short-lived. The index cases presented more frequently a positive family history of OSAS and an early report of snoring or noisy breathing during sleep. Usage of an esophageal balloon to monitor esophageal pressure (Pes) and usage of nasal continuous positive airway pressure (CPAP) as a test may help in the early recognition of these infants, who appear to make more effort to breathe during sleep, based on the indirect evidence of Pes measurements. It is suggested that anatomic features, including a small posterior airway space leading to an abnormal degree of upper airway resistance, may be the cause of the symptoms presented by these infants. Considering the parental anxiety generated by persistence of symptoms after the first year of life in ALTE infants, recognition of this subgroup is important.

Apnea↗
PubMed1992

From obstructive sleep apnea syndrome to upper airway resistance syndrome: consistency of daytime sleepiness.

Some patients with excessive daytime sleepiness who do not present the features of obstructive sleep apnea syndrome (OSAS) present a sleep fragmentation due to transient alpha EEG arousals lasting between three and 14 seconds. These transient EEG arousals are related to an abnormal amount of breathing effort, indicated by peak inspiratory esophageal pressure (Pes) nadir. In the studied population, these increased efforts were associated with snoring. Usage of nasal CPAP, titrated on Pes nadir values, for several weeks eliminated subjective daytime sleepiness and improved Multiple Sleep Latency Test scores from baseline evaluations. Patients suspected of CNS hypersomnia should be asked about continuous snoring, and their clinical evaluation should include a good review of maxillo-mandibular and upper airway anatomy.

Airway Obstruction↗
PubMed1992

Sleep-related obstructive and nonobstructive apneas and neurologic disorders.

Daytime breathing problems caused by neurologic lesions always worsen during sleep, and in certain cases abnormal breathing patterns are only seen during sleep or specific sleep states. The first clinical manifestation of maltase deficiency, myopathy, or myotonic dystrophy is often a sleep-related complaint, such as unexplained waking from sleep (insomnia) or daytime somnolence. Thus, systematic investigation during sleep of disorders impairing the loop involved in breathing is strongly encouraged. Lesions may involve sensory receptors, sensory pathways, brainstem-controlling neurons, upper motor neurons, descending motor pathways, lower motor neurons, motor nerves, neuromuscular junctions, or respiratory muscles. Most of these lesions lead to a decrease in or absence of inspiratory efforts (diaphragmatic apnea or hypopnea) during sleep. These events differ from the classic obstructive sleep apnea syndrome and the recently described upper airway resistance syndrome, which usually involve mild or significant anatomic abnormalities of the upper airway and craniofacial region. The treatment of abnormal breathing during sleep has been improved by the development of nasal ventilation methods: continuous positive airway pressure, intermittent positive pressure, and volume ventilation. These therapeutic approaches can prevent tracheostomy and diaphragmatic pacing and are more efficacious than drug treatments. Long-term compliance is generally much better in breathing disorders secondary to neurologic impairments than in cases of mild to moderate obstructive sleep apnea.

Humans↗
PubMed1991

Snoring during NREM sleep: respiratory timing, esophageal pressure and EEG arousal.

Eight men who were regular heavy snorers were monitored while awake and during nocturnal sleep. All subjects were known to be free of lung disease, obstructive sleep apnea syndrome, and oxygen drops during sleep. For each subject, two snoring periods of 3-31 min with a mean of 12.7 min were randomly selected for comparison with periods of normal, non-snoring NREM sleep breathing. A mean of 150 respiratory cycles per period were analyzed. For each respiratory cycle, respiratory inductive plethysmography and measurements of peak flow, laryngeal sounds, and esophageal pressure (Pes) were used to calculate breathing frequency (bf), inspiratory time (Ti), expiratory time (Te), total respiratory cycle length (Ttot), and Pes at its nadir. During NREM sleep silent breathing, the Ti/Te ratio was analogous to that already measured in normal subjects. With the onset of snoring, an immediate increase in Ti, Te, and Pes nadir were noted. Mean peak Pes nadir increased 120 +/- 37%, and mean Ttot increased by 18%. Through the duration of the snoring period, a further increase in Ti (mean = 10.4 +/- 3.4%) and a decrease in Te were noted, with a mean change in Ti/Ttot of 12 +/- 3.1%. The shape of the esophageal pressure wave during expiration shifted from its normal dynamics. The percentage of Te decreased by a mean of -9.8 +/- 2.3% (P less than 0.0001), and the rise time in Pes increased a mean of 37%. When Pes nadir was the most negative, a mean peak flow decrease of 43 +/- 13.6% from baseline was observed. Tidal volume had decreased by a mean of 22% and minute ventilation by a mean of 21% at the end of the snoring period. Separate investigation of each subject indicates that the evolutions of Ti, Te and Pes during snoring were not the same for all subjects. At least two different groups of snorers exist; these groups may be differentiated by the evolution of Pes over time during snoring. Modifications in the 'braking' role of inspiratory muscles during expiration may explain the changes in the Pes wave dynamics snoring which lead to repetitive EEG arousals, termination of snoring periods, and some sleep fragmentation.

Adult↗
PubMed1991

Changes in the QT interval during obstructive sleep apnea.

Abnormalities of ventricular repolarization are associated with life-threatening ventricular arrhythmias. The effects of obstructive sleep apnea on the QT interval were evaluated in 12 male patients with obstructive sleep apnea syndrome (OSAS) who had no evidence of underlying cardiac, pulmonary or central nervous system disease. Seventy episodes of OSAS during nonrapid eye movement (NREM) sleep were randomly selected for analysis of RR and QT intervals. Differences in the QT interval, corrected QT interval (QTc) and RR interval just before the onset of apnea, at the end of apnea and during the postapnea hyperventilation period were compared. As expected, the RR interval prolonged considerably during OSAS (1,499 +/- 128 msec) compared to quiet sleep (1,019 +/- 131 msec, p less than 0.002) and decreased during the postapnea hyperventilation period (969 +/- 152 msec, p less than 0.002). The QT interval was prolonged at the onset of apnea (482 +/- 34 msec) compared to the active awake state (421 +/- 10 msec, p less than 0.01). Further prolongation of the QT interval was observed during OSAS (528 +/- 64 msec, p less than 0.002). The QT interval shortened abruptly during the postapnea hyperventilation period (435 +/- 34 msec, p less than 0.002). The QTc was also prolonged during the onset of apnea (482 +/- 34 msec) and shortened significantly during apnea (435 +/- 34 msec, p less than 0.002) and during the postapnea hyperventilation period (423 +/- 39 msec). Significant variations of the RR interval, QT and QTc intervals were not observed during episodes of NREM sleep after initiation of effective therapy in six patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Arousal↗
PubMed1991

Leftward shift of the interventricular septum and pulsus paradoxus in obstructive sleep apnea syndrome.

Echocardiograms were taken from the parasternal long axis view during nocturnal sleep in ten patients diagnosed with OSAS. A table designed to support the echocardiographic probe prevented significant sleep disturbances during monitoring and allowed continuous data collection with and without nasal CPAP administration. In five of ten patients, there was before CPAP treatment a diastolic LSIVS during NREM sleep, inducing a flattening of the left ventricle. Arterial blood pressure recordings showed pulsus paradoxus when LSIVS was occurring. Nasal CPAP led to normal, unobstructed breathing, significant decrease in Pes nadir and disappearance of LSIVS and pulsus paradoxus. Increase in left ventricular afterload and increase in total peripheral resistance could lead to hypertrophy and hypertension in some OSAS patients. The presence of pulsus paradoxus in OSAS indicates a marked increase in Pes nadir, and its disappearance with nasal CPAP may be one of the signs of effective treatment of OSAS.

Adult↗
PubMed1991

Snoring (I). Daytime sleepiness in regular heavy snorers.

Fifteen men, mean (means) age 44 years, were investigated. Their means body mass index was 21.9 kg/m2, and all of them had a respiratory disturbance index below 5 and had good nocturnal oxygen saturation. The subjects were monitored several nights both with and without the following devices: a tight-fitting facial mask, a pneumotachometer, and an esophageal balloon. They were also monitored with and without nasal continuous positive airway pressure. The Multiple Sleep Latency Test was administered after three of the experimental nights (after the baseline nights and after the second nasal CPAP night). Determination of short EEG arousals during nocturnal sleep, which lasted 2 to 10 s, was performed. The relationship between short EEG arousals, the esophageal pressure nadir, and airflow decrease was investigated. We also determined the relationship between clinical reporting of decrease in daytime alertness and MSLT results, and the relationship between MSLT results and the frequency of EEG arousals. The monitoring indicated that heavy snorers may present significant increase in Pes nadir with abrupt decrease in flow leading to EEG arousals. The frequency at which EEG arousals occur has an impact on MSLT scores. Nasal CPAP improves MSLT scores and eliminates these respiration-related EEG arousals. Some heavy snorers without obstructive sleep apnea syndrome may be at risk of having a decrease in daytime alertness.

Adult↗
PubMed1990

Chronic snoring and obstructive sleep apnea syndrome in children.

Increased upper airway resistance during sleep may lead to heavy snoring and/or obstructive sleep apnea in infants and children. Clinical symptoms will be seen with increased upper airway resistance during sleep, even without obstructive sleep apnea or significant oxygen saturation drop. It may be responsible for apparent life threatening events (ALTE). Mild cranio-facial morphometric changes are often associated with increased upper airway resistance during sleep, and there is a continuous interaction between airway patency during sleep and maxillo-mandibular growth. Nasal CPAP can be as much a diagnostic tool as a treatment procedure. Orthodontic and surgical approaches may also be combined in the treatment of this significant health problem.

Airway Obstruction↗
PubMed1990

Obstructive sleep apnea syndrome or abnormal upper airway resistance during sleep?

Obstructive sleep apnea syndrome is well known by now, but, at both extremes of age, increased upper airway resistance may lead to clinical symptoms without complete apnea. Abnormal craniofacial features appear to be responsible for the very early appearance during childhood of increased upper airway resistance. In adults, snoring, often related to partial upper airway obstruction located in the pharynx, may be associated with changes in respiratory timing and intermittent arousal. Many treatments are currently available to deal with obstructive sleep apnea syndrome. It is important to recognize the location(s) of the upper airway obstruction before considering treatment and to evaluate the associated risk factors. Early recognition of factors involved in increased upper airway resistance may allow prevention, a more efficacious approach than treatment of an already developed syndrome.

Airway Resistance↗
PubMed1990

Obstructive sleep apnea syndrome in children.

Partial or complete repetitive obstructions of the upper airway during sleep give rise to clinical symptoms associated with heavy, chronic snoring. The number of obstructive sleep apneas during the night may be less important than the repetitive inspiratory increases in upper airway resistance, even if these are associated only with a partial airway collapse. Oxygen saturation may not be severely affected by partial occlusion during nocturnal recording, although clinical symptoms may occur. Esophageal pressure measurements and breathing frequency during sleep are key features in the polygraphic evaluation of prepubertal children. Tonsillectomy and adenoidectomy may be helpful in treating children with small upper airway during sleep. The marked interaction between upper airway adequacy and craniofacial morphology make it critical to evaluate the impact of partial or complete airway occlusion during sleep on facial prognathism. Nasal continuous positive airway pressure is a safe treatment for persistent, partial or complete upper airway occlusion during sleep, but it does not address the mandibular deficiency often seen in symptomatic children. Orthodontic evaluation and treatment may make maxillomandibular surgery unnecessary during the pubertal years.

Child↗
PubMed1990

Investigations of an automatic screening device (MESAM) for obstructive sleep apnoea.

A digital recording device developed to monitor heart rate (HR) and breathing sounds (snoring), and used to screen subjects for obstructive sleep apnoea syndrome (OSAS), was investigated. This device is called the MESAM and is currently commercially available in some western European countries. The computer-based automatic scoring systems provided with the equipment and a hand-scoring technique developed at Stanford and requiring 10-15 min to perform, were used. Polysomnography and MESAM recordings were performed simultaneously on two groups of 25 sleep disorder patients (each with respiratory disturbance index greater than or less than 10). Patients were randomly monitored and records were analysed by two teams blind to the initial clinical impression, to the events which occurred during the recordings, and to each other's findings. Specificity and sensitivity were calculated for each of the MESAM scoring techniques considered, with polysomnography being selected as the recording standard, With "automatic HR scoring" specificity was 12%, sensitivity 92%; with "automatic breathing sounds (snoring)" scoring, specificity was 8% and sensitivity 96%; with "hand-scoring" specificity was 72% and sensitivity 92%. If the three scoring techniques were combined, all patients with a respiratory disturbance index (RD) greater than 10 were recognized as having OSAS.

Electronics, Medical↗
PubMed1989

Attenuation of augmented ventilatory response to hypoxia in essential hypertension in the course of aging.

36 patients with essential hypertension and 15 of their adult descendants were investigated and compared with age-matched control groups of 33 and 15 healthy subjects, respectively. The ventilatory response to oxygen breathing and to progressive normo- und isocapnic hypoxia were studied. The reduction of ventilation during hyperoxia was significantly greater in all hypertensive patients. An augmented ventilatory response to hypoxia was found in 20- to 40-year-old patients whereas the older patients (41-60 years) were not different from the age-matched control subjects. Our results indicate that the augmented hypoxic sensitivity in early hypertension, as found also in the young adult descendants with family background of hypertension, is attenuated with age, similar to the normotensive subjects.

Adult↗
PubMed1989

Central alveolar hypoventilation and sleep. Treatment by intermittent positive-pressure ventilation through nasal mask in an adult.

Idiopathic central alveolar hypoventilation, uncommonly seen in middle-aged adults, has often been treated by tracheostomy and assisted ventilation during sleep or by implantation of a diaphragmatic pacemaker with or without tracheostomy. We report the successful treatment of a middle-aged man by the easy application of intermittent positive-pressure ventilation through a nose mask.

Humans↗