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Average Volume Assured Pressure Support (AVAPS) vs Conventional Bi-level Pressure Support (BiPAP): Key Differences and Benefits

Average Volume Assured Pressure Support (AVAPS) vs Conventional Bi-level Pressure Support (BiPAP): Key Differences and Benefits Image

By Terrence Shenfield MS, RRT-ACCS, RPFT, NPS, AE-C

Advancements in respiratory therapy technology have revolutionized patient care, providing clinicians with diverse tools to manage respiratory insufficiency. Among these innovations, Average Volume Assured Pressure Support (AVAPS) and Conventional Bi-level Positive Airway Pressure (BiPAP) stand out as leading methods of noninvasive ventilation (NIV). While both ensure effective gas exchange and enhanced oxygenation, their mechanisms and applications differ significantly.

This article explores "What is AVAPS in respiratory therapy", the Best uses for BiPAP and AVAPS, and compares the AVAPS advantages over BiPAP to help clinicians and caregivers make informed decisions.

What is Bi-level Positive Airway Pressure (BiPAP)?

BiPAP is a widely used noninvasive ventilation (NIV) mode designed to treat respiratory insufficiency in conditions like chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA), and acute respiratory failure. This modality delivers two levels of airway pressure:

  • Inspiratory Positive Airway Pressure (IPAP): A higher pressure during inhalation to assist ventilation and reduce the work of breathing.

  • Expiratory Positive Airway Pressure (EPAP): A lower pressure during exhalation to keep the airways open and improve oxygenation.

Key Features of BiPAP

  • Fixed Pressure Settings: IPAP and EPAP levels are manually adjusted to meet the patient's ventilation needs.

  • Non-Guaranteed Tidal Volume: BiPAP focuses on maintaining consistent pressure rather than delivering a fixed volume of air.

  • Ideal for Acute and Chronic Conditions: Effective for short-term acute failures and chronic diseases requiring regular support.

Best Uses for BiPAP

  • Obstructive Sleep Apnea (OSA): Reduces airway resistance and prevents apneas during sleep.

  • COPD Exacerbations: Reduces elevated carbon dioxide (hypercapnia) and eases the respiratory workload.

  • Acute Respiratory Failure: Stabilizes patients in emergency settings with immediate pressure support.

Learn more about BiPAP applications on our Mechanical Ventilation page.

What is AVAPS in Respiratory Therapy?

Average Volume Assured Pressure Support (AVAPS) builds upon the BiPAP framework by ensuring a target tidal volume is delivered to patients. This dynamic adjustment in inspiratory pressure makes AVAPS suitable for patients with fluctuating respiratory needs, such as those with neuromuscular disorders or obesity hypoventilation syndrome (OHS).

How AVAPS Works

  1. Target Tidal Volume: The clinician sets a desired tidal volume, and the ventilator adjusts IPAP dynamically to achieve it.

  2. Adaptive Pressure Support: Pressure support changes within a defined range to maintain consistent ventilation as patient needs fluctuate.

  3. Hybrid Mode: Combines volume control with the comfort of noninvasive ventilation, making it ideal for progressive or complex conditions.

Key Features of AVAPS:

  1. Volume Guarantee: Ensures consistent tidal volume even during changing lung mechanics or respiratory demands.

  2. Safe Pressure Adjustments: Adjusts IPAP within preset limits, ensuring patient safety and comfort.

  3. Advanced Monitoring: Tracks real-time respiratory data to enhance clinical decision-making.

Best Uses for AVAPS

  • Obesity Hypoventilation Syndrome (OHS): Delivers stable ventilation despite reduced lung compliance in OHS.

  • Neuromuscular Disorders: Ideal for progressive diseases like ALS or muscular dystrophy, where respiratory needs evolve over time.

  • Complex Hypoventilation: Helps manage irregular or unstable breathing patterns by maintaining steady tidal volumes.

To see AVAPS in action, watch our comprehensive YouTube lecture here.

Comparing AVAPS and Conventional BiPAP

Both AVAPS and BiPAP play a pivotal role in noninvasive ventilation but differ significantly in operation, adaptability, and the conditions they treat.

1. Pressure Adjustments

  • BiPAP delivers fixed IPAP and EPAP levels, which require manual adjustments for changes in patient conditions.

  • AVAPS, on the other hand, dynamically alters inspiratory pressure to ensure the target tidal volume is consistently met.

2. Tidal Volume Control

  • BiPAP does not guarantee tidal volume, which can result in insufficient ventilation if patient lung mechanics fluctuate.

  • AVAPS ensures tidal volume control, making it a superior option for addressing progressive hypoventilation.

3. Monitoring and Data Analysis

  • BiPAP offers basic parameter monitoring, such as respiratory rate and pressure levels.

  • AVAPS provides real-time, data-driven insights, empowering clinicians to make precise adjustments to therapy.

4. Patient Comfort and Compliance

  • While BiPAP is effective for short-term or stable respiratory issues, its fixed pressures can feel less comfortable over time.

  • AVAPS minimizes abrupt pressure changes and ensures smoother transitions, leading to higher patient compliance.

AVAPS Advantages Over BiPAP

  1. Adaptive Ventilation: Automatically adjusts to meet respiratory needs, offering targeted and individualized therapy.

  2. Reduced Manual Intervention: With self-adjusting pressure support, AVAPS eliminates the need for frequent adjustments, saving time and resources.

  3. Improved Ventilation Outcomes: Greater consistency in tidal volume promotes better oxygenation and CO2 elimination.

  4. Enhanced Long-Term Comfort: Smooth pressure transitions make it more suitable for patients needing long-term therapy.

For an in-depth comparison of the two modes, visit our Mechanical Ventilation insights.

Clinical Applications and Ideal Scenarios

Here’s a quick-reference guide for selecting the right mode based on clinical scenarios:

Scenario

Recommended Mode

Acute respiratory failure

BiPAP

Chronic obstructive pulmonary disease (COPD)

BiPAP

Obstructive sleep apnea (OSA)

BiPAP

Neuromuscular disorders

AVAPS

Obesity hypoventilation syndrome

AVAPS

Complex respiratory conditions

AVAPS

Limitations of AVAPS

Despite its many advantages, AVAPS presents some challenges:

  1. Slower Pressure Adjustments: Adaptation happens gradually, making it unsuitable for emergencies requiring rapid changes in ventilation.

  2. Higher Costs: AVAPS devices are typically more expensive compared to BiPAP, limiting their accessibility in some healthcare settings.

  3. Complex Setup: AVAPS requires expertise for proper configuration, making it challenging for non-specialists.

Advancing Respiratory Therapy with AVAPS and BiPAP

Technological advancements in respiratory therapy, such as AVAPS, push the boundaries of what noninvasive ventilation can achieve. From better compliance and adaptability to improved clinical outcomes, AVAPS sets a new standard for treating progressive and complex respiratory conditions.

While BiPAP remains a valuable tool for managing short-term and stable respiratory insufficiencies, AVAPS advantages over BiPAP make it indispensable for conditions marked by evolving breathing needs. With targeted therapies and minimized manual intervention, AVAPS is likely to see broader adoption in the years to come.

Curious to learn how to integrate these advanced modes into your clinical practice? Explore our PDF and video resources here.

AVAPS vs BiPAP | Key Differentiators in Noninvasive Ventilation