RE: Couple of questions
Very little,
EPR is limited to the values of 1,2, and 3, BiLevel can increment PS fractionally and can go considerably higher (21) if needed.
There are other setting differences available with a BiLevel. This includes settings to smooth out the change from inhale to exhale and back again.
BiLevel 101:
Pure CPAP delivers a single constant pressure. This pressure is what splints open the airway. APAP (AutoSet) is what we prefer to see as it can vary the pressure to suit the situation. For now, let's forget about APAP.
Basic BiLevel delivers two fixed independent pressures, EPAP is Exhale Pressure and is what actually splints the Airway open, It is the equivalent of "Pressure" in a CPAP and does the same thing.
IPAP or Inhale pressure is the higher of the two pressures. Once the Obstructive Apneas are resolved with the Exhale pressure (EPAP), IPAP is used to resolve hypopneas, flow limits, RERAs, and UARS.
The difference in these pressures is called Pressure Support or PS. PS is always added to EPAP by convention to get IPAP so IPAP = EPAP + PS
FYI if you were to set the EPAP = IPAP you would have a basic pure CPAP functionally.
The above info is derived from Titration guides.
BiLevel 102:
BiLevel models are not interchangeable. Each is designed for a specific condition.
up rate. On the most basic level this is fully applied everytime.
Backup rate is the frequency in breaths per minute that the BiLevel will initiate. The basic BiLevel does not have this feature and instead just follows your breathing with a mode called Spontaneous or "S". Timed mode or "T" initiates a 'breath' at the defined 'rate' in breaths per minute. How effective this is varies by individual and the settings defined includine EPAP, IPAP, and PS.
The Auto CPAP such as the ResMed AirSense 10 AutoSet is typically the initial machine of choice for treatment of obstructive apnea and hypopnea
Just to clarify The VAUTO, ASV, S, and the ST are all BiLevel machines for treating different conditions, they are NOT interchangeable. They are not a choice between them to treat a single condition.
They should be chosen to treat the specific condition that the user has, Here are the various CPAP Modes and what they are designed/intended to treat
The following info is from the ResMed Sleep Lab Titration Guide
* CPAP (continuous positive airway pressure) Fixed pressure delivered with optional expiratory pressure relief (EPR). It Treats OSA
* AutoSet/APAP (automatic positive airway pressure) Automatically adjusts pressure in response to flow limitation, snore and obstructive apneas. It treats OSA
* AutoSet for Her/APAP Automatically adjusts pressure in response to flow limitation, snore and obstructive apneas along with an increased sensitivity to each flow-limited breath, providing a more comfortable therapy for women. Increases sensitivity to each flow-limited breath, providing a more comfortable therapy for women (OK for men too). It Treats OSA
* VAuto Automatically adjusts pressure in response to flow limitation, snore and obstructive apneas; Pressure Support (PS) is fixed throughout the night and can be set by the clinician. It Treats OSA, non-compliant OSA
* S (Spontaneous) Senses when the patient is inhaling and exhaling, and supplies appropriate pressures accordingly. Both treatment pressures are preset: inspiration (IPAP) and expiration (EPAP). It treats Non-compliant OSA and COPD
* ST (Spontaneous/Timed) Augments any breaths initiated by the patient, but also supplies additional breaths if the breath rate falls below the clinician’s set “backup” respiratory rate. It Treats COPD, Neuromuscular disease (NMD), Obesity Hypoventilation Syndrome (OHS) and other respiratory conditions
* T (Timed) Supplies a clinician-set respiratory rate and inspiratory/expiratory time, regardless of patient effort. It Treats COPD, Neuromuscular disease (NMD), Obesity Hypoventilation Syndrome (OHS) and other respiratory conditions
* iVAPS (intelligent Volume-Assured Pressure Support) Maintains a preset target alveolar minute ventilation by monitoring delivered ventilation, adjusting the pressure support and automatically providing an intelligent backup breath. It Treats COPD, Neuromuscular disease (NMD), Obesity Hypoventilation Syndrome (OHS) and other respiratory conditions
* ASV (adaptive servo-ventilation) Targets the patient’s minute ventilation, continually learning the patient’s breathing pattern and instantly responding to any changes. It treats Central or mixed apneas, complex sleep apnea, Periodic Breathing (PB)
* ASVAuto Provides an ASV algorithm plus expiratory positive airway pressure (EPAP) that automatically responds on the patient’s next breath to flow limitation, snore and obstructive sleep apneas. It Treats Central or mixed apneas, complex sleep apnea, Periodic Breathing (PB)
* PAC (Pressure Assist Control, also known as Pressure Control) The inspiration time is preset in the PAC mode; there is no spontaneous/flow cycling. Inspiration can be triggered by the patient when respiratory rate is above a preset value, or delivered at a set time at the backup rate. It Treats Neuromuscular disease (NMD), pediatric patients
