Positive Airway Pressure Therapy With Adaptive Servoventilation: Part 1: Operational Algorithms
The following are important details to know about adaptive servoventilation (ASV) from a contemporary review on the topic:
1. Continuous positive airway pressure (CPAP) therapy was introduced in 1981 as a treatment for obstructive sleep apnea (OSA), the most common form of sleep breathing disorders.
2. Although CPAP is effective in OSA, only one-half of patients adhere to the treatment, leading some to search for alternative treatments, particularly among those with congestive heart failure (CHF) or central sleep apnea (CSA).
3. The large CHF trial to randomize CPAP therapy showed no overall benefit in this population. However, post-hoc analysis did show a survival benefit in those CHF patients with CSA who could tolerate CPAP. Therefore, in those who cannot tolerate CPAP, alternative therapies have been sought.
4. The motivation to develop this technology has been driven by patients with CHF who display wide swings in periodic breathing, called Cheyne-Stokes breathing (CSB). These repetitive cycles of crescendo-decrescendo swings in breathing are separated by periods of central apneas.
5. ASV is the most recent PAP device that acts to maintain a stable level of ventilation, regardless of the large swings in ventilation seen in CSB.
6. ASV devices act to counterbalance the tidal breathing by providing inspiratory pressure support during the low ventilation and withdrawing this support during crescendo breathing. This technology thus provides an anticyclic support to the patient’s periodic crescendo-decrescendo breathing.
7. The other support provided by ASV is PAP during obstructive apneas (like CPAP) and mandatory breaths for frank apneas.
8. Two US manufacturers supply this ASV technology (ResMed and Philips Respironics). They have similar features, but each uses a different target parameter to guide its technology. The VPAP Adapt by ResMed measures inspiratory airflow to calculate minute ventilation. The BiPAP autoSV Advanced System by Philips monitors peak inspiratory flow to target goals for ventilatory support.
Durable medical equipment, such as CPAP, is the cornerstone of treatment prescribed for patients with OSA. However, clinicians are aware of compliance issues. Less than ideal adherence to CPAP in cardiology practices may be due to complex sleep-disordered breathing, not just obstructive apneas. Clinicians must be aware of these advanced therapies when providing treatments focused on individual patients, such as those with CHF.
Keywords: Motivation, Polysomnography, Complementary Therapies, Cheyne-Stokes Respiration, Continuous Positive Airway Pressure, Sleep Apnea, Central, Heart Failure, Durable Medical Equipment, Sleep Apnea, Obstructive
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