From the Guidelines
Standard AVAPS orders should include an initial IPAP range of 10-25 cmH2O, EPAP of 4-8 cmH2O, and a target tidal volume of 6-8 mL/kg of ideal body weight, as recommended by the American Academy of Sleep Medicine 1.
Key Settings for AVAPS Orders
- Initial IPAP range: 10-25 cmH2O
- EPAP: 4-8 cmH2O
- Target tidal volume: 6-8 mL/kg of ideal body weight
- Respiratory rate backup: 10-12 breaths per minute
- Rise time: 300-400 milliseconds
- Inspiratory time: 1.0-1.5 seconds
- Supplemental oxygen: titrated to maintain SpO2 above 90%
- AVAPS rate: 1-5 cmH2O per minute, with lower rates being more comfortable for patients
Adjusting AVAPS Settings
These settings should be adjusted based on arterial blood gas results, patient comfort, and clinical response 1. The gradual pressure adjustments of AVAPS help maintain consistent ventilation while maximizing patient comfort, as the device automatically adjusts pressure support to achieve the target tidal volume despite changes in patient effort or respiratory mechanics.
Special Considerations
AVAPS is particularly useful for patients with neuromuscular disorders, obesity hypoventilation syndrome, and COPD with hypercapnia 1. Pressure support may be increased if the SpO2 remains below 90% for 5 minutes or more and tidal volume is low (< 6 to 8 ml/kg) 1.
From the Research
Standard AVAPS Orders
- The standard orders for Average Volume-Assured Pressure Support (AVAPS) mode involve delivering a set tidal volume (TV) per kg by adjusting the pressure between upper and lower inspiratory positive airway pressures (IPAP) 2.
- The maximum IPAP is typically started at 20 cmH2O and the minimum IPAP is set at 5 cmH2O higher than expiratory positive airway pressure (EPAP) in AVAPS mode 2.
- IPAP levels are titrated up to 30 cmH2O during noninvasive mechanic ventilation (NIMV) with a targeted TV of 6-8 mL/kg 2.
- The initial IPAP setting in AVAPS mode is higher compared to bilevel positive airway pressure-spontaneous/timed (BPAP-S/T) mode, where IPAP is started at 15 cmH2O 2.
Key Considerations
- The effectiveness of AVAPS mode in critically ill patients with acute hypercarbic respiratory failure (HRF) is comparable to BPAP-S/T mode 2.
- There are no significant differences in pH, paCO2, HCO3, TV, and EPAP between AVAPS and BPAP-S/T modes when compared separately by days 2.
- Maximum IPAP levels are significantly higher in AVAPS mode at all times 2.