Speaker's Highlight

• Don Sin University of British Columbia, St. Paul Hospital (Canada)
  Kenneth R. Chapman Toronto General Hospital Research Institute (Canada)
• Parameswaran Nair McMaster University (Canada)
  Carolyn Calfee UCSF (U.S.A.)
• Gregory P. Downey University of Colorado School of Medicine (U.S.A.)
  David A. Schwartz University of Colorado School of Medicine (U.S.A.)
• Neil Schluger Tuberculosis Control Branch, California Department of Public Health (U.S.A.)
  Nick Kim Critical Care & Sleep Medicine, University of California San Diego (U.S.A.)
• Nicola Hananiah Baylor College of Medicine (U.S.A.)
  Jae-Joon Yim Seoul National University College of Medicine (Republic of Korea)
• Koichiro Asano Tokai University School of Medicine (Japan)
  Diahn-Warng Perng Taipei Veterans General Hospital (Taiwan)
• Konstantinos Kostikas University of Ioannina (Greece)
  Karin Klooster University Medical Center Groningen (Kingdom of the Netherlands)

• Advances in mechanical ventilation for acute respiratory distress syndrome

  Acute respiratory distress syndrome (ARDS) remains one of the most demanding conditions in critical care. Severe hypoxemia, reduced lung compliance, pulmonary inflammation, and heterogeneous alveolar collapse make respiratory support both essential and potentially harmful. Mechanical ventilation must therefore improve gas exchange while limiting ventilator-induced lung injury.

  Recent progress has shifted the focus from simply correcting oxygen levels to protecting the remaining functional lung. Low tidal volumes, individualized positive end-expiratory pressure (PEEP), prone positioning, careful sedation strategies, and earlier consideration of extracorporeal support now form an integrated approach.

  These developments are central to respiratory medicine and intensive care discussions featured through the APSR 2022 congress site, which connects clinicians and researchers around advances in pulmonary and critical care practice.

  Lung-protective ventilation as the foundation

  The strongest evidence in ARDS supports a low-tidal-volume strategy based on predicted body weight rather than actual body weight. Initial settings commonly target approximately 6 mL/kg of predicted body weight, with adjustment toward 4 mL/kg when plateau pressure remains high. This reduces overdistension in relatively healthy lung regions that continue to receive most of the delivered breath.

  Plateau pressure should generally remain below 30 cmH₂O, while driving pressure—the difference between plateau pressure and PEEP—provides an additional view of respiratory system stress. A rising driving pressure may indicate that the delivered volume is excessive for the patient’s available aerated lung, even when other values appear acceptable.

  Permissive hypercapnia may be accepted when it allows safer ventilation, provided pH, hemodynamics, intracranial pressure, and other clinical factors remain within acceptable limits. Ventilator adjustments should always be paired with frequent reassessment rather than applied as fixed rules.

  Personalizing PEEP and recruitment

  PEEP prevents end-expiratory alveolar collapse and can improve oxygenation by increasing functional residual capacity. However, higher PEEP is not automatically better. Excessive airway pressure may overdistend compliant lung units, impair venous return, increase right ventricular strain, and reduce cardiac output.

  Clinicians can individualize PEEP by considering compliance, driving pressure, oxygenation, recruitability, hemodynamic response, and imaging or electrical impedance tomography where available. In patients with moderate-to-severe ARDS and recruitable lung, a higher-PEEP approach may be beneficial when carefully monitored.

  Routine prolonged recruitment maneuvers have become less favored because aggressive pressure application can cause barotrauma and cardiovascular compromise. A brief, measured response to PEEP changes is usually more informative than pursuing a predetermined airway pressure regardless of the patient’s physiology.

  Prone positioning and distribution of stress

  Prone positioning is a major advance for patients with severe ARDS and persistent hypoxemia despite optimized ventilation. Turning the patient prone redistributes transpulmonary pressure, improves dorsal lung recruitment, reduces ventilation-perfusion mismatch, and may make stress more evenly distributed across the lungs.

  Evidence supports prolonged sessions, often around 16 hours, when there are no contraindications. The intervention requires a trained team, secure airway and vascular access, pressure-injury prevention, and attention to facial, ocular, and brachial plexus protection. Oxygenation may improve quickly, but the broader goal is to reduce ventilator-induced injury and improve outcomes.

  Proning works best as part of a bundle that includes low tidal volume, appropriate PEEP, fluid management, and assessment for neuromuscular blockade when patient-ventilator dyssynchrony cannot be controlled by other measures.

  Sedation, synchrony, and spontaneous breathing

  Patient-ventilator interaction has a substantial effect on lung stress. Double triggering, excessive inspiratory effort, and flow starvation can produce large transpulmonary pressure swings even when airway pressure appears modest. Recognizing these patterns on ventilator waveforms is therefore important.

  Short-term neuromuscular blockade may be considered in selected patients with severe dyssynchrony, refractory hypoxemia, or a need to facilitate prone positioning. It should not replace careful analgesia and sedation assessment. Daily evaluation of sedation depth and readiness to reduce support can limit weakness, delirium, and prolonged ventilation.

  As the acute inflammatory phase improves, assisted modes can help restore respiratory muscle activity. Pressure support and neurally adjusted ventilatory assist may improve synchrony in suitable patients, although spontaneous breathing must be introduced cautiously. Excessive respiratory effort can worsen lung injury, particularly when compliance is very low.

  Monitoring beyond oxygen saturation

  Pulse oximetry is useful but incomplete. A stable oxygen saturation does not prove that ventilation is protective, and increasing oxygen concentration can conceal worsening mechanical stress. Arterial blood gases, plateau pressure, driving pressure, respiratory rate, compliance, and ventilator waveforms should be interpreted together.

  Bedside ultrasound, chest imaging, and electrical impedance tomography can contribute to decisions about recruitment, fluid balance, and regional ventilation. Trends are often more valuable than isolated measurements. A falling compliance or rising driving pressure may signal deterioration before oxygenation changes significantly.

  When conventional ventilation, proning, and optimization of reversible causes fail, referral for extracorporeal membrane oxygenation (ECMO) may be appropriate in carefully selected patients. Venovenous ECMO can provide gas exchange while allowing ultra-protective ventilation, but it requires specialized expertise and carries risks such as bleeding, thrombosis, infection, and neurological complications.

  Strategy	Main purpose	Key benefit	Important limitation
  Low tidal volume	Reduce alveolar overdistension	Lowers ventilator-induced lung injury	May increase carbon dioxide
  Individualized PEEP	Prevent cyclic collapse	Improves recruitment in selected patients	Can impair circulation or overdistend lung
  Prone positioning	Improve ventilation distribution	Supports oxygenation and outcome in severe ARDS	Requires staff, monitoring, and pressure-injury prevention
  Neuromuscular blockade	Control severe dyssynchrony	Facilitates protective ventilation	May contribute to weakness and prolonged recovery
  Venovenous ECMO	Provide extracorporeal gas exchange	Enables ultra-protective ventilation	Invasive, resource-intensive, and complication-prone

  Building a safer bedside strategy

  Advances in ARDS management are most effective when applied as a coordinated process rather than as isolated interventions. Teams should define targets, document responses to each change, and reassess both respiratory mechanics and cardiovascular tolerance.

  Practical priorities include:

  • Calculate tidal volume from predicted body weight and reassess plateau and driving pressures.
  • Use PEEP according to recruitability, compliance, oxygenation, and hemodynamic response.
  • Consider early prolonged prone positioning for severe hypoxemia despite optimized ventilation.
  • Review waveforms for dyssynchrony and avoid unnecessary deep sedation or paralysis.
  • Discuss ECMO referral promptly when refractory respiratory failure persists in an appropriate candidate.

  Research continues to explore closed-loop ventilation, personalized recruitment assessment, diaphragm monitoring, artificial intelligence, and biomarkers that may distinguish recruitable from non-recruitable lung. These tools could make mechanical ventilation more responsive to changing physiology, but clinical judgment remains essential.

  The most meaningful progress comes from combining precise ventilator settings with skilled nursing, physiotherapy, mobilization planning, infection control, and post-ICU follow-up. Clinicians seeking to deepen their understanding of respiratory critical care can use the APSR congress resources as a starting point for ongoing education and multidisciplinary discussion.

  Richard Russell Nuffield Department of Clinical Medicine, University of Oxford (United Kingdom)
• Mona Bafadhel King’s College London (United Kingdom)
  David Jackson Guy’s and St Thomas’ Hospital, King’s College London (United Kingdom)
• James Chalmers University of Dundee (United Kingdom)
  David Price University of Aberdeen (United Kingdom)