In the cases of Obstructive sleep apnoea, Apneas are defined in adults as breathing pauses lasting ?1:
Ans. C. 10 secs. (Ref. Q. 184 of MH'2010; Harrison's medicine 18th/pg. 1165, 174)Obstructive sleep apnea/hypopnea syndrome (OSAHS) :OSAHS may be defined as the coexistence of unexplained excessive daytime sleepiness with at least five obstructed breathing events (ap nea or hypopnea) per hour of sleep. This event threshold may need to be refined upward in the elderly. Apneas are defined in adults as breathing pauses lasting ? 10 s and hypopneas as ? 10 s events where there is continued breathing but the ventilation is reduced by at least 50% from the previous baseline during sleep.The factors predisposing to OSAHS by narrowing the pharynx include obesity--around 50% have a body mass index (BMI) >30 kg/m2 in western populations--and shortening of the mandible and/or max- ilia. This change in jaw shape may be subtle and can be familial. Hypothyroidism and acromegaly predispose to OSAHS.Cardiovascular events, DM, hepatic dysfucntion can occur.Findings on History andDiagnostic Physical ExaminationEvaluationDiagnosisTherapyObesity, snoring, hypertensionPolysomnography with respiratory monitoringObstructive sleep apneaContinuous positive airway pres- sure; ENT surgery (e.g., uvulo- palatopharyngoplasty); dental appliance; pharmacologic therapy (e.g, protriptyline); weight lossCataplexy, hypnogogic hallucinations, sleep paralysis, family historyPolysomnography with multiple sleep latency testingNarcolepsy- cataplexy syndromeStimulants (e.g, modafinil, methyl- phenidate); REM-suppressant an- tidepressants (e.g., protriptyline); genetic counselingRestless legs, disturbed sleep, predisposing medical condition (e.g., iron deficiency or renal failure)Assesment for pre- disposing medical conditionsRestless legs syndromeTreatment of predisposing condition, if possible; dopamine agonists (e.g., pramipexole, ropinirole)Disturbed sleep, predisposing medical conditions (e.g., asthma) and/or predisposing medical therapies (e.g., theophylline)Sleep-wake diary recordingInsomnias (see text)Treatment of predisposing condition and/or change in therapy, if possible; behavioral therapy; short-acting benzodiazepine receptor agonist (e.g., zolpidem)Rx:Rectifiable predispositions should be discussed; this often includes weight loss and sometimes reduction of alcohol onsumption to reduce caloric intake and because alcohol acutely decreases upper-airway dilating muscle tone, thus predisposing to obstructed breathing. Sedative drugs, which also affect airway tone, should be carefully withdrawn.Surgery: Four forms of surgery have a role in OSAHS, although it must always be remembered that these patients have a raised perioperative risk. Bariatric surgery can be curative in the morbidly obese. Tonsillectomy can be highly effective in children but rarely in adults. Tracheostomy is curative but rarely used because of the associated morbidity; nevertheless, it should not be overlooked in extremely advanced cases. Jaw advancement surgery--particularly maxillo-mandibular osteotomy--is effective in those with retrognathia (posterior displacement of the mandible) and should be particularly considered in young and thin patients. There is no robust evidence that pharyngeal surgery, including uvulopalatopharyngoplasty (whether by scalpel, laser, or thermal techniques) helps OSAHS.Drugs: Unfortunately, no drugs are clinically useful in the prevention or reduction of apneas and hypopneas.
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Respiratory