Def: insufficient minute ventilation during sleep, reduced breathing with reduced gas exchangeBMI ≥30, awake PaCO2 ≥45 mmHg, other causes excludedCauses prolonged nocturnal O2 desaturation and elevated CO2Increased risk of pulmonary HTN and consequent HF AASM scoring (either):a. PaCO2 or surrogate >55 mmHg for ≥10 minb. PaCO2 rise ≥10 mmHg vs awake supine to >50 mmHg… Continue reading →

Def: Recurrent cessation or reduction of airflow during sleep due to absent or reduced respiratory effortCaused by loss of central drive from the brainstem, not airway obstruction Associated conditions Cheyne-Stokes Respiration (CSR): CSA is of particular clinical relevance in HF. Crescendo-decrescendo pattern, vigorous effort gradually dwindles until breathing stops TreatmentFocus on improving or removing underlying… Continue reading →

Def: Increased upper airway resistance during sleep causing repeated respiratory effort-related arousals (RERAs)At sleep onset, dilator muscle tone falls and upper airway narrowsSignificant rise in airflow resistance increases inspiratory effort until pt arouses from sleepNo apneas, hypopneas or desaturations as seen in OSA, pts keep breathing and do not desaturateRepeated arousals fragment sleep and cause… Continue reading →

Def: Recurrent episodes of complete (apnea) or partial (hypopnea) upper airway collapse during sleep, despite ongoing respiratory effort, Leads to intermittent hypoxia, sleep fragmentation and arousalsMost common type of SDB of medical concernOSA + excessive daytime sleepiness = OSA syndromeAffects up to 10% of middle-aged men and 3% of middle-aged women Severity: Mild OSA: AHI… Continue reading →

Respiratory function is significantly altered by sleepPts with normal awake breathing can develop significant respiratory compromise in sleepAfter sleep onset, central motor neuron output fallsReduced upper airway dilator muscle function narrows the upper airwayReduced inspiratory muscle activity causes shallower breathing vs awake state Complicating factors: Obesity, Enlarged neck circumference, Upper airway obstruction (enlarged tonsils, adenoids,… Continue reading →