A 68-year-old male with moderate chronic obstructive pulmonary disease (COPD) and obesity suffers an inferior wall myocardial infarction. He recovers from the acute event; 6 weeks later, he is left with chronic systolic congestive heart failure (CHF) with an ejection fraction (EF) of 25% and paroxysmal atrial fibrillation (PAF). He is managed medically at the time with aspirin, statin therapy, antiplatelet therapy, and low-dose beta-blockers. He is slowly improving and tolerating these medications, but his wife complains that the patient is always tired, often sleepy. He has a history of loud snoring with nocturnal choking and gasping sensations that pre-date his recent cardiac events, but his fatigue is worse. His heart rate and blood pressure are on the lower end of normal range, and he is mildly orthostatic. On physical examination his lungs are clear, and there is no pedal edema. He has quit smoking, is taking his medications and eating healthier, and is motivated to improve his health.
Based on the above, his cardiologist orders an overnight sleep study (his COPD and CHF preclude a home sleep apnea test), and the results of the diagnostic portion indicate severe obstructive sleep apnea (OSA), with an apnea-hypopnea index of 61.3 events/hour and oxygen desaturations down to 63% on room air. Episodes of PAF are again noted. The sleep technologist applies continuous positive pressure therapy (CPAP) during the second half of the study and at 7 cm H20 most of the obstructive events improve. However, at 8 cm H20, he exhibits more desaturations now associated with dramatic episodes of central sleep apnea (CSA), similar to Cheyne-Stokes respiration patterns. The technologist is unable to find an “ideal” CPAP pressure.
Which of the following statements describes the most appropriate medical management?
The correct answer is: C. Start patient with CPAP at 7 cm of water pressure, and follow clinical response.
This case illustrates the need for the cardiologist to understand some of the major issues affecting sleep-disordered breathing and cardiovascular health. Treating obstructive sleep apnea in a symptomatic patient can improve cardiovascular outcomes, and more severe cases (such as this patient with over 60 events/hour and severe oxygen desaturations) are also more likely to benefit from treatment. Given this information, answer option A is then inappropriate since it dismisses the relevance of the clinical and symptomatic positive effects that PAP therapy may have in this patient. Concordantly, answer option D is also not a good option because the patient is intravascularly dry (even orthostatic) on clinical examination and optimized in terms of treatment with his beta-blocker; therefore, nocturnal severe hypoxemia is unlikely to significantly improve from further diuretic or beta-blocker adjustment.
This case goes further and asks the cardiovascular professional to understand a bit about the different PAP therapies and the applications of specific ones. Of the two remaining answer options, many might have suggested ASV as ideal based on older studies and theoretical benefit; ASV is a mode of PAP therapy in which the machine provides bilevel therapy (expiratory positive airway pressure [EPAP] and inspiratory positive airway pressure [IPAP]), self-adjusting the pressures within a given range, and even provides a backup respiratory rate when central apneas occur. That might have seemed initially attractive in this patient since CSA events, in which no respiratory effort is elicited, were documented.1,2 However, in the recent Treatment of Predominant Central Sleep Apnoea by Adaptive Servo Ventilation in Patients With Heart Failure (Serve-HF) trial, it was noteworthy that in patients with systolic CHF (EF < 40%) and CSA, all-cause mortality was higher in those treated with ASV.3 The mechanisms of this are still being understood; nevertheless, the findings had a dramatic impact on how sleep-disordered breathing is being treated in patients with cardiovascular diseases. Therefore, many sleep clinicians are unsure of the value and safety of ASV therapy in patients with low EFs.4
Therefore, at this time, the best option in the opinion of this author is to start with straightforward CPAP therapy; clearly, the patient has significant subjective and objective evidence of OSA that is severe enough and worthy of consideration of PAP therapy. Starting with a trial of CPAP therapy at a relatively low pressure of 7 cm H20 seems safe, may provide significant symptomatic and cardiovascular benefit, and allows the clinical team to better understand how this patient responds to all of his therapies. In the future, he may benefit from adjustment of this pressure or even the device modality, but such decisions can be made over the course of treatment.