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Query: UMLS:C0037315 (sleep apnea)
 8,000 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Before heart rate variability can be used as an investigational tool in the clinical setting, its reproducibility must be known. We studied heart rate variability four times during 44 weeks in 15 hypertensive patients with sleep apnoea syndrome. Time and frequency domain analytical approaches were used during the spontaneous and controlled breathing tests, orthostatic manoeuvre and the cold pressor test. Alterations in resting heart rate were taken into account using the coefficient of component variance. In general, the response of heart rate variability was abnormal and variability was reduced in the hypertensive patients with sleep apnoea syndrome compared with reference data. Time domain measures of heart rate variability demonstrated generally better reproducibility over four recordings than frequency domain measures in these hypertensive patients with sleep apnoea syndrome. On the other hand, the reproducibility of frequency domain measures depended on the specific conditions: during orthostatic manoeuvre and cold pressor test the best reproducibility was found using normalized units. In the reference data set, there were no significant differences between the two heart rate variability recordings during any of the autonomic nervous function tests. In this follow-up study we found that simple procedures such as the controlled breathing test show good reproducibility. More complex tests such as the orthostatic manoeuvre require special attention in order to obtain acceptable reproducibility of heart rate variability measurements. Quantitatively minor changes in the variability indices when the overall variability is reduced exert major effects on the results. Therefore we suggest that reproducibility data obtained in healthy volunteers are not valid for the interpretation of data in patients with damaged cardiovascular autonomic control.
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PMID:Reproducibility of abnormal heart rate variability indices: the case of hypertensive sleep apnoea syndrome. 1036 17

The development of polio vaccines 50 yr ago essentially halted childhood polio epidemics in the industrialized world. During the past quarter century, a constellation of delayed neuromuscular symptoms, called postpolio syndrome, became recognized among the aging polio survivors. The prevalence of postpolio syndrome in the U.S. population is estimated to be in the hundreds of thousands. The most common symptoms are fatigue, pain, and new onset weakness thought to be related to delayed deterioration of motor neuron function. When a patient with postpolio syndrome presents for surgery, special precautions are warranted, because these patients may have respiratory impairment, sleep apnea, swallowing difficulties, and cold intolerance. This article first reviews clinical features and some pathoetiologic theories of postpolio syndrome and then focuses on anesthetic considerations including the use of common anesthetics, neuromuscular blockade, regional anesthesia, and general anesthetic management strategies.
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PMID:Postpolio syndrome and anesthesia. 1612 91

Changes in cardiovascular parameters elicited during a maximal breath hold are well described. However, the impact of consecutive maximal breath holds on central hemodynamics in the postapneic period is unknown. Eight trained apnea divers and eight control subjects performed five successive maximal apneas, separated by a 2-min resting interval, with face immersion in cold water. Ultrasound examinations of inferior vena cava (IVC) and the heart were carried out at times 0, 10, 20, 40, and 60 min after the last apnea. The arterial oxygen saturation level and blood pressure, heart rate, and transcutaneous partial pressures of CO(2) and O(2) were monitored continuously. At 20 min after breath holds, IVC diameter increased (27.6 and 16.8% for apnea divers and controls, respectively). Subsequently, pulmonary vascular resistance increased and cardiac output decreased both in apnea divers (62.8 and 21.4%, respectively) and the control group (74.6 and 17.8%, respectively). Cardiac output decrements were due to reductions in stroke volumes in the presence of reduced end-diastolic ventricular volumes. Transcutaneous partial pressure of CO(2) increased in all participants during breath holding, returned to baseline between apneas, but remained slightly elevated during the postdive observation period (approximately 4.5%). Thus increased right ventricular afterload and decreased cardiac output were associated with CO(2) retention and signs of peripheralization of blood volume. These results indicate that repeated apneas may cause prolonged hemodynamic changes after resumption of normal breathing, which may suggest what happens in sleep apnea syndrome.
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PMID:Increased pulmonary vascular resistance and reduced stroke volume in association with CO2 retention and inferior vena cava dilatation. 1672 15

A five-year-old boy with recurring tonsillitis and sleep apnea was admitted for tonsillectomy and tympanic membrane tubing. He presented with a history of bronchial asthma and hereditary spherocytosis without obvious cardiac failure symptoms. Anesthetic agents for induction included nitrous oxide, oxygen, and sevoflurane. Because oxygen saturation decreased immediately to 90%, tracheal intubation was performed. The patient began to wheeze. Sevoflurane concentration was increased but cardiac murmur (gallop), cold limbs and jugular vein distension were noted. Acute cardiac failure was diagnosed following a chest X-ray and cardiac echo showing an enlarged heart, CTR of 80%, left ventricular dilation, and contractile failure. Tympanic membrane tubing only was performed. Sevoflurane was discontinued and the patient was treated for the cardiac failure under an ICU oxygen tent. The patient was discharged when his general condition improved. He showed elevated levels of viral antibodies, suggesting myocarditis. Later he was treated for dilating cardiomyopathy before undergoing a heart transplant.
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PMID:[Cardiac failure in a child during anesthetic induction with sevoflurane]. 1698 22

There are conflicting data on the effect of adding a heated humidifier to nasal continuous positive airway pressure (CPAP) therapy for patients with obstructive sleep apnoea syndrome (OSAS). The effects of heated humidification on sleep quality and treatment side-effects for patients who prefer a cold bedroom environment have not been studied. A randomised, controlled crossover trial involving 19 patients with a first-ever diagnosis of OSAS measured the effect of conventional heated humidification added to CPAP compared with a controlled heated breathing tube humidifier (ThermoSmart(R); Fisher and Paykel Healthcare, Auckland, New Zealand) on sleep quality. During the night in the sleep laboratory at a mean room temperature of 14 degrees C, less condensation formed with the controlled heated breathing tube humidifier (1.9 mL versus 35.3 mL) in the delivery system. In addition, the total sleep time, time spent in sleep stages 3 and 4, and rapid eye movement sleep phases were significantly longer and the overall side-effect score was lower than with conventional heated humidification. Patients on nasal continuous positive airway pressure desiring a cool bedroom temperature could benefit from controlled heated breathing tube humidification technology (with inputs from ambient temperature, set pressure and flow).
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PMID:Impact of a controlled heated breathing tube humidifier on sleep quality during CPAP therapy in a cool sleeping environment. 1818 78

Resistant hypertension is defined as failure to achieve goal blood pressure (BP) when a patient adheres to the maximum tolerated doses of 3 antihypertensive drugs including a diuretic. Although the exact prevalence of resistant hypertension is currently unknown, indirect evidence from population studies and clinical trials suggests that it is a relatively common clinical problem. The prevalence of resistant hypertension is projected to increase, owing to the aging population and increasing trends in obesity, sleep apnea, and chronic kidney disease. Management of resistant hypertension must begin with a careful evaluation of the patient to confirm the diagnosis and exclude factors associated with "pseudo-resistance," such as improper BP measurement technique, the white-coat effect, and poor patient adherence to life-style and/or antihypertensive medications. Education and reinforcement of life-style issues that affect BP, such as sodium restriction, reduction of alcohol intake, and weight loss if obese, are critical in treating resistant hypertension. Exclusion of preparations that contribute to true BP treatment resistance, such as nonsteroidal anti-inflammatory agents, cold preparations, and certain herbs, is also important. Lastly, BP control can only be achieved if an antihypertensive treatment regimen is used that focuses on the genesis of the hypertension. An example is volume overload, a common but unappreciated cause of treatment resistance. Use of the appropriate dose and type of diuretic provides a solution to overcome treatment resistance in this instance.
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PMID:Resistant hypertension: an overview of evaluation and treatment. 1932 67

This article will suggest that moderate sleep apnea may have an adaptive benefit, the reduction of nocturnal, respiratory heat loss, that may have caused it to be selected for despite the associated disadvantages. Sleep apnea is caused by the collapse of the throat, specifically the pharyngeal airway, during sleep and can result in discomfort and hypoxia. The large size of the fleshy structures in the pharynx and hypotonicity of the pharyngeal musculature are what cause humans, and many other species of mammals, to be susceptible to apnea. There are many functional and anatomical parallels between sleep apnea and a well known, thermoregulatory response that minimizes respiratory cooling in the lower airways known as reflex bronchoconstriction. Bronchoconstriction involves the constriction of the inner airways, the bronchioles, in response to cold air, a reaction that acts to warm inspired air before it makes contact with the more sensitive lower airways and alveoli. Because air is colder at night and body temperature drops severely during sleep, sleep apnea may represent a similar protective, thermoregulatory adaptation. When the pharynx is collapsed, the diameter of the pharyngeal airway decreases, allowing increased intermolecular collisions between inspired air and the epithelial walls of the upper airway. An increase in the number of collisions facilitates the transference of both warmth and humidity to inspired air before it reaches the more sensitive lower airway resulting in the maintenance of internal, core temperature and alveolar heat retention. In fact, sleep apnea can be conceptualized as a functional reversal of the thermoregulatory process of panting, where the pharynx is highly dilated instead of collapsed. Given the disorder associated with sleep apnea, the absence of a disease state secondary to surgical correction, the fact that the disorder is exclusive to warm-blooded animals, the high proclivity for collapse documented in pregnant mothers, and the functional similarities between collapse and reflex bronchoconstriction, it appears that the phenomenon may represent an evolutionary trade-off that helped to minimize respiratory cooling.
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PMID:Sleep apnea, respiratory cooling and thermoregulation. 1969 39

This article describes a snore reduction appliance that can be constructed to advance and hold the mandible in a comfortable prognathic position. The tongue is advanced concomitantly, producing more space in the pharynx while changing the relative positions of the soft palate, posterior tongue, and pharyngeal walls to reduce the incidence of snoring and ameliorate sleep apnea. A dual-laminate appliance, soft inside and hard outside, is vacuformfitted to casts of the maxillary and mandibular teeth and luted in a protrusive relation with cold pressure-cured acrylic. The appliance maintains the mandible and tongue in a protrusive position to open the upper airway, reducing snoring and facilitating breathing. Edentulous patients would require implant-retained appliances for appropriate retention and stability.
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PMID:A dual-laminate snore reduction appliance: a report of four cases. 2059 63

Glaucoma is now considered an abnormal physiology in the optic nerve head that interacts with the level of intraocular pressure (IOP), with the degree and rate of damage depending on the IOP and presumably the degree of abnormal physiology. Diagnosis of normal-tension glaucoma (NTG), defined as glaucoma without a clearly abnormal IOP, depends on recognizing symptoms and signs associated with optic nerve vulnerability, in addition to absence of other explanations for disc abnormality and visual field loss. Among the findings are a halo or crescent of absence of retinal pigment epithelium around the disc, bilateral pre-chiasmal visual field defects, splinter hemorrhages at the disc margin, vascular dysregulation (low blood pressure, cold hands and feet, migraine headache with aura, and the like), or a family history of glaucoma. Possibly relevant, is a history of hemodynamic crisis, arterial obstructive disease, or sleep apnea. Neurological evaluation with imaging is needed only for atypical cases or ones that progress unexpectedly. Management follows the same principle of other chronic glaucomas, to lower the IOP by a substantial amount, enough to prevent disabling visual loss. However, many NTG cases are non-progressive. Therefore, it may often be wise in mild cases to determine whether the case is progressive and the rate of progression before deciding on how aggressivene to be with therapy. Efforts at neuroprotection and improvement in blood flow have not yet been shown effective.
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PMID:Normal-tension glaucoma (Low-tension glaucoma). 2115 42

Hypothyroidism is a common endocrine disorder with characteristic clinical symptoms and signs. Typical symptoms of hypothyroidism are lethargy, cold intolerance, slowing of intellectual and motor activity, decreased appetite, weight gain, and dry skin. A 39-year-old female presented to the clinic with dysarthria as the chief symptom. Subsequent questions revealed that other symptoms were confined to the otolaryngeal region, which were episodes of mild dysphonia, dysphagia, sleep apnea, and snoring. Laboratory data revealed marked hypothyroidism and positive tests for antithyroglobulin and antimicrosomal antibodies. After administration of thyroxin, the dysarthria and the other symptoms rapidly disappeared. Dysarthria may be the presenting symptom of hypothyroidism and can be resolved after hormone replacement therapy.
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PMID:Hypothyroidism presenting with dysarthria. 2301 93


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