10.4 PARDS Refractory Hypoxemia & Adjuncts

10.4 PARDS Refractory Hypoxemia & Adjuncts

Refractory Hypoxemia: Reassess Before Adding Rescue Therapy

Confirm the airway and circuit, exclude pneumothorax and mainstem intubation, recruit secretion-obstructed lung, treat shock, and use echocardiography when ventricular dysfunction or pulmonary hypertension may explain the oxygenation problem. A rising OI/OSI is a signal for senior multidisciplinary review and early contact with an ECMO-capable center, not an instruction to follow a rigid ladder.

Prone Positioning

PALICC-2 found insufficient data to recommend for or against prone positioning in PARDS. It may be considered for hypoxemia that does not respond to other interventions. If used, assess whether oxygenation, ventilation, and mechanics improve. PALICC-2 does not prescribe a session duration for children. Protect the airway, eyes, pressure points, lines, and tubes; use a trained team and a turn checklist. Do not borrow the adult 16-hour regimen and present it as a pediatric mandate.

Proning may improve dorsal recruitment and distribute transpulmonary stress more uniformly, but response varies. Stop or modify the maneuver for accidental airway risk, severe hemodynamic deterioration, or other patient-specific contraindication.

Recruitment, HFOV & Other Adjuncts

PALICC-2 does not recommend for or against recruitment maneuvers. Sustained inflation maneuvers are not recommended. If a team performs recruitment, use cautious incremental and decremental PEEP changes with continuous oxygenation, compliance, and hemodynamic monitoring.

There is no recommendation that HFOV replace conventional ventilation routinely. It may be considered when lung-protective goals cannot be achieved with conventional ventilation; when used, explore optimal lung volume with stepwise mean-airway-pressure changes while monitoring oxygenation, carbon dioxide, and circulation.

Do not use inhaled nitric oxide routinely. A time-limited trial may be considered with documented pulmonary hypertension, severe right-ventricular dysfunction, or as a bridge to extracorporeal support; assess objective benefit within the first hours and stop when there is no response. Surfactant and corticosteroids are likewise selective rather than routine PARDS therapies.

ECMO Evaluation

ECMO is considered for potentially reversible, life-threatening respiratory failure despite optimized conventional and appropriate rescue care. No single OI automatically orders cannulation. Severity trajectory, duration of injurious ventilation, neurologic prognosis, bleeding risk, organ dysfunction, diagnosis, cannulation feasibility, and center expertise all matter. A historically used OI above 40 is a trigger for urgent ECMO-center consultation and preparation, not a universal standalone threshold.

Exam Method

1. Recalculate OI/OSI and identify the severity category.
2. Check tube, circuit, lung mechanics, perfusion, and reversible causes.
3. Verify plateau/driving pressure, tidal volume, PEEP, saturation, and pH goals.
4. Select adjuncts for the patient's phenotype and measure a response.
5. Escalate early to an ECMO-capable team when the trajectory worsens.

Choosing and Stopping an Adjunct

Each rescue intervention needs a hypothesis. Proning tests whether redistribution and dorsal recruitment improve gas exchange. iNO tests whether pulmonary hypertension or right-ventricular loading contributes. HFOV tests whether protective conventional targets are unattainable while recruitment remains possible. An ECMO consultation assesses whether extracorporeal support can bridge a reversible process without disproportionate harm.

Write an endpoint before starting: a defined improvement in OI/OSI, FiO2, pressure, ventricular function, or perfusion within a defined interval. Stop a toxic or burdensome therapy when the endpoint is not met. Improvement in saturation alone may be misleading if blood pressure or cardiac output falls.

Safe prone turn

Brief the team; assign the airway, head, lines, torso, and limb positions; preoxygenate only as necessary; secure the tube; empty or manage the stomach; protect eyes and pressure points; and confirm tube depth, bilateral air entry, ventilator waveforms, and all lines after the turn. Reassess oxygenation and hemodynamics. Duration remains an individualized protocol choice because PALICC-2 does not specify one.

Communication During Escalation

Use a structured callout: current OI or OSI and trajectory, FiO2, plateau and driving pressure, PEEP, tidal volume, pH and PaCO2, hemodynamics, ventricular findings, response to prior steps, and suspected reversible cause. State what resource is needed—bedside imaging, echocardiography, experienced proning team, HFOV preparation, iNO trial, or ECMO consultation—and when response will be judged. This prevents serial unmeasured rescue therapies from accumulating without a stop rule.

Avoid simultaneous changes

Whenever the situation permits, change one major support variable or adjunct at a time and record the response. Simultaneously increasing PEEP, starting iNO, turning prone, and changing vasoactive drugs makes it impossible to know which intervention helped or harmed. Emergencies may require parallel actions, but the team should still timestamp each step and reassess oxygenation, ventilation, mechanics, and perfusion. A reproducible response supports continuation; absent benefit supports de-escalation.