Central sleep apnoea syndrome (CSAS), like obstructive sleep apnoea (OSA) involves repeated periods of decreased ventilation. Patients with sleep disordered breathing can present with CSAS, OSA or a combination of both. There are two basic mechanisms the trigger central respiratory events: post-hyperventilation central apnoea which may be triggered by a variety of clinical conditions and central sleep apnoea secondary to hypoventilation (eg opioid use, high altitude). The former mechanism has been noted in many patients with congestive heart failure (CHF). In 2012 the American Academy of Sleep Medicine (AASM) released “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses” which listed the treatment options in the categories: Standard, Guideline and Option with Standard being the recommendations with the highest quality of evidence.
AASM 2012:
Adaptive Servo-Ventilation (ASV) targeted to normalize the apnea-hypopnea index (AHI) is indicated for the treatment of CSAS related to CHF. (STANDARD)
In 2015, ResMed, a manufacturer of the ASV flow generators used to treat CSA released a field safety notice stating that ASV therapy is contraindicated for patients in a specific population; those with a left ventricular ejection fraction of 45% or less and moderate or severe CSAS. They had found that ASV increased mortality in this patient population (10% vs 7.5% in the control). 7% of ResMed’s total revenue was from ASV sales and that an estimated 25% of these patients using ASV were a part of this contraindicated patient population. On Thursday the 12th of March ResMed shares dropped 15% overnight (fell to $6.73 from $8.25 the Wednesday before).
The AASM have now released an updated ASV recommendations for the 2012 guideline: “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses”. The expert task force that produced the original guideline was assembled and performed another literature review and meta-analysis. The outcome of this process is a change to the recommendations:
AASM2016:
Recommendation 1: Adaptive servo-ventilation (ASV) targeted to normalize the apnoea-hypopnea index (AHI) should not be used for the treatment of CSAS related to CHF in adults with an ejection fraction ≤ 45% and moderate or severe CSA predominant, sleep-disordered breathing. (STANDARD AGAINST)
Recommendation 2: Adaptive servo-ventilation (ASV) targeted to normalize the apnea-hypopnea index (AHI) can be used for the treatment of CSAS related to CHF in adults with an ejection fraction > 45% or mild CHF related CSAS. (OPTION)
The AASM do note: “The application of these recommendations is limited to the target patient populations; the ultimate judgment regarding propriety of any specific care must be made by the clinician.”
