Sleep and Respiratory Disorders Lecture Review

Flashcards covering sleep-disordered breathing (OSA, OHS), narcolepsy, REM sleep behavior disorder, and methemoglobinemia based on lecture notes.

Obstructive Sleep Apnea (OSA)

A condition characterized by intermittent nocturnal upper-airway obstruction while daytime breathing remains normal.

Obesity Hypoventilation Syndrome (OHS)

Obesity associated with awake daytime alveolar hypoventilation and hypercapnia ($PaCO_{2} \text{ } \text{≥} 45 \text{ } mmHg$) after excluding other causes.

Polysomnography

A diagnostic test used to confirm sleep-disordered breathing, calculate the apnea-hypopnea index, and titrate positive-airway-pressure therapy.

Continuous Positive Airway Pressure (CPAP)

The first-line positive-airway-pressure therapy for Obstructive Sleep Apnea.

Bilevel Positive Airway Pressure (BiPAP)

Ventilatory support used in OHS when needed to improve $CO_{2}$ clearance.

Awake room-air ABG

A test performed when OHS is suspected; a $PaCO_{2} \text{ } \text{≥} 45 \text{ } mmHg$ supports OHS, while a normal daytime $PaCO_{2}$ favors isolated OSA.

OSA Diagnostic Criteria (Asymptomatic)

The occurrence of $\text{≥} 15$ obstructive events per hour based on overnight polysomnography in the absence of symptoms.

OSA Diagnostic Criteria (Symptomatic)

The occurrence of $\text{≥} 5$ obstructive events per hour based on overnight polysomnography in the presence of compatible symptoms or comorbidities.

Unilateral diaphragmatic paralysis

A condition presenting with dyspnea when supine, an elevated hemidiaphragm on imaging, and an exaggerated fall in supine FVC.

Fluoroscopic sniff testing

A diagnostic test for diaphragmatic paralysis that demonstrates paradoxical upward movement of the affected side.

Narcolepsy Type 1

A sleep disorder characterized by excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, and low CSF hypocretin-1.

Multiple sleep latency test

A diagnostic test for narcolepsy that follows polysomnography and shows short sleep latency and sleep-onset REM periods.

Modafinil

A medication used to treat the excessive daytime sleepiness associated with narcolepsy.

REM sleep behavior disorder

Dream-enactment behavior caused by the loss of normal REM atonia, which may precede synucleinopathies and is commonly treated with melatonin.

Methemoglobinemia

A condition characterized by cyanosis after oxidant exposure, an oxygen-saturation gap, and pulse oximetry tending toward approximately $85 \text{ }$.

Methylene blue

A treatment for significant symptomatic methemoglobinemia, though it should be used with caution in patients with G6PD deficiency.

Secondary erythrocytosis

A potential laboratory finding in Obesity Hypoventilation Syndrome (OHS) resulting from chronic hypoxemia.