What is ASV or Auto Servo Ventilation

It hit the news that that ASV should not be used for certain patients due to the poor outcomes of a study that was being done.  The question is what is ASV and why is it prescribed for some sleep disorders?   It starts with the fact that this is not a common mode of therapy.

It is specifically used for those who have central apnea or complex sleep apnea.  Central apnea is when the brain does not tell you to breathe.  This is usually due to other health issues such as brain injury, hormone imbalances such as diabetic ketoacidosis, or neuromuscular disorders.  Complex sleep apnea is a combination of obstructive apnea and central apnea. The central part of it has to due to the changes in brain chemistry that occurs when a person has obstructive sleep apnea. 

Cardiac problems will also contribute to central apnea.  A study that was recently being conducted by Resmed found that people who had central apnea and heart failure where there hart only puts out less than 45% of the expected amount of blood could have negative results from the use of ASV.  This is a very small percent of people who are currently using this mode of therapy. 

ASV is basically Bilevel therapy with a respiratory rate.  The computer internally look at each breathe and decides how much pressure is needed.  The technician who titrated you found the expiratory support needed to keep your airway open.  The machine decides how much pressure you need during inspiration to take a normal breath.  It also decides when it needs to give you a breath because you have not taken one quick enough.  Ultimately the fact is that it will help you to breathe when yoru body forgets to breathe. 

It is essential that if you have questions about your therapy that you talk to your ordering doctor.