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Query: UMLS:C0020440 (hypercapnia)
 7,939 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The distribution of symptoms, physiologic responses, and upper airway structure in members of one family with three generations of subjects with sleep apnea (SA) is reported. Questionnaire data were obtained from ten family members (ages 7 to 66 years), overnight sleep studies were performed in nine subjects, and ventilatory responses to hyperoxic hypercapnia and to eucapnic hypoxia and cephalometry were obtained in five subjects. All ten family members reported habitual snoring or nighttime snorting/gasping; five of ten family members also reported excessive daytime sleepiness. All studied subjects except for a pregnant woman had greater than ten apneas/hypopneas per hour. Ventilatory responses to hypoxia were markedly reduced in all five subjects studied (less than or equal to 0.51 L/min/SaO2); hypercapnic responses were reduced in three of five subjects (less than or equal to 0.61 L/min/mm Hg CO2). No subject was morbidly obese (body mass index less than 29 kg/m2) or demonstrated retrognathia. The posterior airway space was reduced in three subjects, and the mandibular to hyoid distance was increased in four subjects. The two subjects with the longest soft palates and the most inferiorly displaced hyoids had the most severe sleep disorder. Sleep apnea was present, albeit less profound, in the one subject with normal anatomy who had an abnormal hypoxic ventilatory response. The distribution of these physiologic and anatomic measurements in this family provides further support for a genetic basis for SA, and suggests that the disorder may occur as a result of interactions between ventilatory control abnormalities and anatomic risk factors.
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PMID:A family study of sleep apnea. Anatomic and physiologic interactions. 239 35

Snoring (inspiratory noise related to narrowing of the upper airways) and obstructive sleep apnea (OSA) are two aspects of the same basic disorder: sleep-related narrowing of the upper airways. Patients with OSA have been heavy snorers for years and even decades. Lying supine induces snoring and mild OSA in heavy snorers due to hypotonia of pharyngeal dilator muscles, decreasing waking neural drive and recumbent position, which contribute to functional narrowing of the upper airways. Functional factors in obstruction during sleep include (a) respiratory instability prevalent in the male sex, (b) increased extensibility of the lax tissues surrounding the oro-pharynx and (c) deficient contraction of the pharyngeal dilator muscles during inspiration. These effects are worsened by sleep deprivation and fragmentation, alcohol intake and sedatives. Anatomical factors favoring narrowing of the upper airways in snorers and OSA patients are (a) abnormally narrow airways as well as (b) increased thickness and length of the velum palatinum in snorers and OSA patients, (c) tonsillar and adenoid hypertrophy, micro- and retrognathia, and nasal insufficiency, (d) obesity with fat infiltration of the soft tissues and in particular of the oropharynx, (e) relatively open mandibular angle, hypertrophy and thickness of the tongue, and lowered hyoid bone (as shown by MRI imaging). It is possible that many anatomical abnormalities may be the consequence of snoring and obstructive apnea. During NREM sleep the ineffective inspiratory efforts progressively increase with worsening hypoxia and hypercapnia. The upper airways become patent again when arousal induces phasic activation of the dilator pharyngeal muscles.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Pathogenic aspects of snoring and obstructive apnea syndrome. 318 70

Persons with alveolar hypoventilation have abnormal daytime arterial blood gases and abnormal responses to hypercapnia and hypoxia in the absence of any identifiable lung or neuromuscular disease. The underlying defect in the control of breathing has not, however, been confirmed. We studied a 6-yr-old girl who was admitted in respiratory failure after a long history of disturbed breathing awake and asleep, which had been diagnosed as primary alveolar hypoventilation, (PaCO2 = 120). After several days of endotracheal intubation and assisted ventilation, her condition improved and she was extubated. At this time her ventilatory response to hypoxia was absent (VE/SaO2:0.1 l/min/% at a CO2 of 45) and there was a right-shifted response to hypercapnia (VE/PaCO2:2.6 l/min/mmHg). As obstructive sleep apnea was suspected, nocturnal nasal continuous positive airway pressure (CPAP) was tried; however, it was not effective in maintaining arterial oxyhemoglobin saturation. Definite central apneas were observed during sleep both with and without nasal CPAP, and there was an absence of snoring. Her condition deteriorated, and there was a progressive increase in her awake arterial CO2 levels for a period of 4 wk. The IPPV with 5 cm H2O of PEEP was administered through a nose mask during sleep and this maintained both oxygen saturation and transcutaneous CO2 levels within the normal range. After 10 days of nocturnal assisted ventilation, the hypercapnic response returned to the normal position (VE/CO2:2.1 l/min/mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Treatment of alveolar hypoventilation in a six-year-old girl with intermittent positive pressure ventilation through a nose mask. 330 Apr 41

Snoring usually is trivial and unimportant, but it can turn into a social or medical problem. Obesity, hypertension and heart disease are more frequent among snorers than among nonsnorers, and especially snorers with hypersomnia during the day are at risk. Hypersomnia in association with snoring usually signifies obstructive sleep apnea. Increased resistance in the upper airways, together with negative inspiratory pharyngeal pressure and muscular hypotonia during deep non-REM and REM sleep, lead to collapse of the pharynx, hypoxia and hypercapnia. Only after arousal from sleep does muscle tone return, pharyngeal obstruction reopen and airflow resume. Since this process can occur 300 or 400 times a night, repetitive alveolar hypoventilation leads to pulmonary-arterial hypertension and cor pulmonale, and the repetitive sympathetic activations can cause systemic hypertension or serious cardiac arrhythmias. The countless arousals deprive the sufferer of deep non-REM and REM sleep and their consequence is sleep fragmentation. The symptoms are excessive daytime sleepiness, intellectual deterioration and personality and behavioral changes. Oronasomaxillofacial, endocrine and neuromuscular anomalies and diseases predispose to sleep apnea, and alcohol or CNS-depressant drugs can favour its occurrence. Diagnosis is made by nighttime oxymetry, and if this is abnormal, by polysomnography. After polysomnography it is possible to distinguish between obstructive and nonobstructive sleep apnea, and the decisions for an adequate treatment can be made.
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PMID:[Dangerous snoring. Sleep-apnea syndrome]. 331 92

The development of important respiratory disorders and significant hypertension in association with increasing body weight is not widely recognized. Altered respiratory function results from a combination of mechanical impedance to breathing exerted by thoracic and abdominal fat and a ventilation-perfusion mismatch. Sleep-disordered breathing with periods of hypoventilation, with or without apnoeic episodes, may commonly occur in patients with extreme obesity. Nocturnal hypercapnia and hypoxia in such patients may lead to a decrease in ventilatory drive, abnormal central respiratory control and possibly, in time, the development of the obese-hypoventilation syndrome. Respiratory abnormalities should be suspected in obese patients with a history of restlessness at night, loud snoring and daytime somnolence. Treatment is substantial weight reduction, but short-term measures include the use of compressed air via nasal cannulae for obstructive apnoea, and drugs which alter sleep pattern or stimulate respiration. The alterations in endocrine function, which accompany weight gain, may contribute to an increase in blood pressure and there appears to be a relationship between plasma insulin and catecholamine concentrations, fat cell size and the development of hypertension. The confirmation of a raised blood pressure requires that readings be taken with an adequately sized arm-cuff. In many instances endocrine function becomes normal with weight loss, and there is a corresponding decrease in blood pressure. The ideal management for an obese hypertensive patient is the combination of a suitable calorie-restricted diet with a programme of physical exercise.
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PMID:Clinical complications of obesity. 639 58

Twenty-two infants and children were found to have clinically significant obstructive sleep apnea. A history suggesting complete or partial airway obstruction during sleep was obtained on all patients, and physical examination of the sleeping patient revealed snoring, retractions, or OSA in 21 patients. Nevertheless, the mean delay in referral for 20 patients first seen after the neonatal period was 23 +15 (+ SD) months. Sixteen of 22 patients (73%) developed serious sequelae: cor pulmonale in 12 (55%), failure to thrive in six (27%), permanent neurologic damage in two (9%), and behavioral disturbances, hypersomnolence, or developmental delays in five (23%). Clinical and radiologic evaluations revealed anatomic abnormalities which narrowed the upper airway in 21 patients; enlarged tonsils and/or adenoids in 14, micrognathia in three,generalized facial abnormalities in three, and cleft palate repair/tonsillar hypertrophy in one. In five patients, upper airway fluoroscopy was performed and was helpful in establishing the site and mechanism of obstruction. Polygraphic monitoring was utilized to quantify the frequency and duration of OSA. Prolonged partial airway obstruction during sleep resulted in significant hypercarbia in 11 patients and hypoxemia in five. Twenty patients improved after surgery which relieved or bypassed the pharyngeal airway obstruction; two cases are pending. Increased awareness of OSA and examination of the sleeping patient should result in earlier treatment and less morbidity for infants and children with OSA.
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PMID:Obstructive sleep apnea in infants and children. 705 14

During sleep, none of 9 subjects with chronic obstructive pulmonary disease (COPD) were apneic. Despite ventilation, acute arterial oxygen desaturation of 11% or more occurred in 6 of them. The other 3 were nondesaturators (i.e., 3% or less desaturation) during sleep. The desaturation that occurred in the 6 subjects with COPD was associated with episodes of (1) esophageal pressure or abdominal respiratory movement that acutely decreased in amplitude during rapid-eye-movement (REM) sleep, or (2) esophageal pressure or abdominal respiratory movement that acutely increased in amplitude in association with snoring during non-REM and REM sleep. During daytime wakefulness, ventilatory responses to hypoxia and hypercapnia were markedly less in the 6 desaturators compared with the 3 nondesaturators and 5 healthy control subjects. The decreased ventilatory responses in the 6 desaturators appeared to result from both impaired respiratory mechanical effectiveness and impaired respiratory center responsiveness to chemoreceptor stimulation. We suggest that subjects with COPD with these respiratory impairments are predisposed to develop severe nonapneic oxygen desaturation during the added respiratory impairment of REM sleep or of what appears to be sleep-related partial upper airway obstruction.
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PMID:Determinants of oxygen desaturation in the course of ventilation during sleep in chronic obstructive pulmonary disease. 745 58

Respiratory disorders during sleep were studied in 42 patients with Duchenne muscular dystrophy (DMD) (mean age 18.4 years). Chest and abdominal movement, nasal airflow, snoring sounds, eye movement, and oxygen saturation were monitored during sleep. Three patterns of disorders were found: obstructive apnea, central apnea, and paradoxical respiration without upper airway obstruction (non-obstructive paradoxical respiration). Of these three patterns, obstructive apnea was the most common. Hypertrophy of the tongue and collapsibility of the upper airway seemed to be responsible for the obstructive apnea in these patients. The relationships between PaCO2 while breathing room air and the various indices of respiratory disorders were studied. The index of central apnea differed significantly between patients in whom PaCO2 was less than 50 Torr (early disease, n = 22) and those in whom PaCO2 was greater than or equal to 50 Torr (advanced disease, n = 20), but the indices of obstructive apnea and non-obstructive paradoxical respiration did not differ between those two groups. In conclusion, sleep disorders were common in patients with DMD, and the most common was obstructive apnea. In the patients with advanced DMD, blood gas analysis showed hypercapnia, and the index of central sleep apnea was high, probably because of respiratory muscle weakness or abnormalities in the respiratory center.
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PMID:[Respiratory disorders during sleep in Duchenne muscular dystrophy]. 747 61

Persons with sleep apnea syndromes experience 10 or more episodes per hour of sleep during which airflow ceases for more than 10 seconds. Sleep apnea syndromes are classified as obstructive, central or mixed: obstructive when the respiratory muscles continue to contract but airflow is not obtained, central when respiratory effort is not present, and mixed when elements of both obstructive and central apnea are present. Approximately 4 percent of adult men and 2 percent of adult women are believed to have these conditions. In addition to having symptoms such as snoring, headaches, depression, decreased libido and fatigue, patients with sleep apnea are at risk for a range of severe complications secondary to recurrent hypoxia and hypercapnia during sleep. Diagnosis may require an overnight polysomnogram in addition to the history, a physical examination and a laboratory assessment. Less cumbersome diagnostic modalities are being developed. Treatment options include weight reduction, change in sleeping position, avoidance of sedatives, use of continuous positive airway pressure and surgical treatment.
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PMID:Adult sleep apnea syndromes. 765 25

The two broad categories of sleep apnea syndrome are associated with obstructive or mixed events on the one hand, and central events on the other. The pathogenesis of both seems to involve periodic reduction in respiratory drive, although obstructive apneas may also involve an anatomic abnormality of the upper airway. Patients with obstructive sleep apnea syndrome most commonly exhibit resuscitative snoring and daytime sleepiness. Snoring is generally less prominent in the central sleep apnea syndromes; those with daytime hypercapnia generally complain of daytime sleepiness, whereas those without hypercapnia complain of disturbed sleep. The overnight polysomnogram is the preferred method of diagnosing both disorders.
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PMID:Sleep apnea syndromes: overview and diagnostic approach. 802 35


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