3am in the ICU, a puzzled RN approaches "Hey Doc! This patient is breathing funny on the monitor !!"

Appetizer:

• Middle aged female was admitted to ICU for Metabolic encephalopathy. She has a history of ESRD on HD, missed last 2 sessions of dialysis. Also has dCHF from uncontrolled HTN. 
• Working differentials were uremic encephalopathy; polysubstance overdose; septic encephalopathy; hypertensive encephalopathy (systolic BP on admisssion was 220mm Hg). 
• BP was treated with nicardipine drip (hypertensive emergency), later nephrology team dialyzed her. Overnight, while patient was asleep, the monitor showed the following breathing pattern: 

 

• This pattern was present for more than an hour, making the RN uncomfortable. Oxygen saturation (SaO2) was normal. 
• This patient seemed to have Cheyne Stokes Variant (CSV). No apneic spells were noted. After noting this pattern, we have started CPAP. 4 hours after initiation of CPAP, the breathing pattern returned to normal. 
• CT head did not show any bleed. However, work up for PRES syndrome in underway. Her dCHF and acid base imbalance might have contributed to this breathing pattern. There is also association of central sleep apnea with this breathing pattern. So further outpatient work up with polysomnography should be pursued. 

Entrée:

Introduction:

• CSV is associated commonly with CNS pathology (strokes, bleeds) and heart failure. 
• In CSV there is hypopnea but no apneic spells, in contrast to Cheyne Stokes breathing where apneic spells replace the hypopneic spells.  
• Cheyne-Stokes Breathing : Cyclic crescendo-decrescendo respiratory effort and airflow during wakefulness or sleep, without upper airway obstruction. 
• When the decrescendo effort is accompanied by apnea during sleep, it is considered a type of central sleep apnea syndrome. 

Pathogenesis: 

• Related to PaCO2 variations in patients with heart failure, Central sleep apnea, neurologic disease, sedation, normal sleep, acid-base disturbances, prematurity, and altitude acclimatization. 

Diagnosis:

• These patient must get an overnight polysomnogram = gold standard diagnostic test. 

Management:

1. Treatment of the underlying cause = Optimizing heart failure etc 
2. Nocturnal continuous positive airway pressure (CPAP), There is sufficient data to show that CPAP may improve cardiac function, blood pressure, exercise capacity, and quality of life in these patients. 
3. Supplemental oxygen, or adaptive servoventilation (ASV)

Dessert:

• Unfortunately, none this time ;)