Is Adaptive Ventilation (AVAPS) used with Veletri (epoprostenol) and proning in patients with severe respiratory distress?

AVAPS with Veletri and Proning in Severe Respiratory Distress

AVAPS (Average Volume Assured Pressure Support) is not specifically addressed in ARDS guidelines, which focus on invasive mechanical ventilation with lung-protective strategies; however, Veletri (inhaled epoprostenol) and prone positioning are both established adjunctive therapies that should be used together in severe ARDS before escalating to ECMO.

Ventilation Strategy in ARDS

Standard Approach

• Lung-protective mechanical ventilation with low tidal volumes (4-8 mL/kg predicted body weight) is the cornerstone of ARDS management, not non-invasive modes like AVAPS 1.
• AVAPS is a non-invasive ventilation mode typically used for chronic respiratory conditions or less severe acute respiratory failure, not severe ARDS requiring intubation 1.
• Guidelines consistently recommend invasive mechanical ventilation with protocolized tidal volume limitation for patients meeting severe ARDS criteria 1.

Key Ventilator Parameters

• Target tidal volumes of 6 mL/kg predicted body weight with plateau pressures <28-30 cmH₂O 1.
• Higher PEEP strategies (≥12 cmH₂O) should be employed in severe ARDS 1.
• Permissive hypercapnia is well tolerated in this population 2.

Prone Positioning Protocol

Indications and Timing

• Prone positioning should be initiated early (within 48 hours) in patients with severe ARDS (PaO₂/FiO₂ <150 mmHg) for at least 12-16 hours per day 1, 3, 4.
• The PROSEVA trial demonstrated significant mortality reduction with prone positioning sessions of at least 16 hours (28-day mortality 16.0% prone vs 32.8% supine, P<0.001) 4.
• Prone positioning must be used before considering VV-ECMO escalation 1.

Physiological Benefits

• Improves oxygenation through more homogeneous ventilation distribution and better ventilation-perfusion matching 3, 5.
• Reduces ventilator-induced lung injury through more uniform tidal volume distribution 3.
• PEEP and prone positioning have additive effects on oxygenation 3.

Monitoring and Safety

• Continue prone positioning until PaO₂/FiO₂ ≥150 under de-escalated ventilation (PEEP ≤10 cmH₂O, FiO₂ ≤0.6) 3.
• Monitor for endotracheal tube obstruction (RR 1.76) and pressure ulcers (RR 1.22) 1, 3.
• Prone positioning is generally hemodynamically well tolerated and may improve right ventricular function 3.

Veletri (Inhaled Epoprostenol) Use

Role in ARDS Management

• Inhaled epoprostenol (Veletri) serves as a selective pulmonary vasodilator that can improve oxygenation in ARDS patients, particularly those with pulmonary hypertension or right ventricular dysfunction 6, 7, 8.
• Veletri produces pulmonary vasodilation in ventilated lung regions, optimizing ventilation-perfusion matching 7, 8.

Evidence and Efficacy

• Veletri demonstrated equivalent effectiveness to Flolan in improving PaO₂/FiO₂ ratios after 1 hour of therapy (mean improvement ~30 mmHg) 6.
• Can be used as rescue therapy in patients who are non-responders to inhaled nitric oxide 7, 8.
• Provides pulmonary vasodilation with minimal systemic effects compared to intravenous vasodilators 8.

Safety Considerations

• Monitor for hypotension (incidence 95.5% in one study) and thrombocytopenia (29.5%) 6.
• Veletri can be safely used in conjunction with prone positioning and lung-protective ventilation 6, 7.

Integration of Therapies

Stepwise Approach

1. Initiate lung-protective invasive mechanical ventilation with tidal volumes 4-8 mL/kg PBW and appropriate PEEP 1.
2. Apply prone positioning early (within 48 hours) for ≥12-16 hours daily in severe ARDS 1, 3, 4.
3. Consider inhaled epoprostenol (Veletri) as adjunctive therapy for refractory hypoxemia or pulmonary hypertension 6, 7, 8.
4. Add neuromuscular blockade if needed for ventilator synchrony 1.
5. Escalate to VV-ECMO only if PaO₂/FiO₂ <80 mmHg or pH <7.25 with PaCO₂ >60 mmHg persists despite optimal conventional management 1.

Critical Pitfall

• Do not use non-invasive ventilation modes like AVAPS as a substitute for invasive mechanical ventilation in severe ARDS—this delays definitive management and worsens outcomes 1, 2.
• Less invasive therapies (lung-protective ventilation, PEEP, neuromuscular blockade, prone positioning) should be optimized before considering ECMO 1.

Timing Considerations

• VV-ECMO should only be considered in patients early in their ARDS course (<7 days) with reversible etiologies 1.
• The combination of prone positioning and Veletri can be used simultaneously with invasive mechanical ventilation 6, 7, 4.