xxyzx wrote:raisedfist wrote:If she is using a mask, meaning non-invasive ventilation, then the Trilogy is simply assisting with breathing; the AVAPS mode just ensures adequate ventilation (assuming everything is set correctly). If she was sedated and/or unable to protect her airway, then she would be using invasive ventilation.
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and that is exactly what an ASV does
when the patient is not breathing it forces a RR and a given Vt
resmed and philips have different algorithms to determine RR and Vt
some machines let the dr. set the RR
the Vt really depends on the patient and their lungs so setting an average for everybody would not be as good as using the patients own Vt average
No. The ASV responds breath by breath and prevents over/under shoot of minute ventilation. Breath by breath = servo ventilation. AVAPS DOES NOT do that.
An ASV is for central/complex apnea. The algorithm works for the predictable types of breathing irregularities. It's not meant to respond to the erratic breathing patterns of someone with severe respiratory disease.
AVAPS is a MUCH MUCH slower algorithm and targets an AVERAGE tidal volume that you set differently for each person - based on HEIGHT AND IDEAL BODY WEIGHT. They are not the same. An ASV is NOT appropriate for someone with a neuromuscular disease or obesity hypoventilation syndrome. Further, an ASV would be TERRIBLE for someone with COPD due to hyperinflation.
"ASV is NOT for the following types of patients:
Those who have chronic and profound hypoventilation.
Those who have moderate to severe chronic obstructive lung disease.
Those who have chronically elevated partial pressure of carbon dioxide on ABG (arterial blood gas) (> 45 mm Hg).
Those who have restrictive thoracic or neuromuscular disease."
"ASV's pressure target is adjusted according to the input from the patient. What that means is that the target is not a fixed value but rather adapts to the patient's breathing patterns." So, an ASV targets the patient's actual ventilation, which is INADEQUATE for people suffering from HYPO ventilation.
Which would be a DISASTER for people with COPD and other respiratory diseases. Their breathing patterns (often even while awake) are SUB OPTIMAL, hence the point of AVAPS - to ensure adequate ventilation, regardless of respiratory changes during sleep. The goal of AVAPS is re: adequate ventilation. The goal of ASV is to treat central/complex apnea. AVAPS basically adjusts pressure support up and down to reach the target tidal volume set. The target tidal volume is obviously not the same for someone 60 inches tall as it is for someone 72 inches tall.
AVAPS has a backup rate in the S/T mode because people using it often fail to trigger the device while sleeping (mostly in REM sleep, at least early on in the disease process) due to muscular weakness, AND because often they cannot maintain an adequate respiratory rate while sleeping. At least the first reason does not apply to people using the ASV.
