What are the management steps for a patient with acute-on-chronic liver failure (ACLF) who is intubated and experiencing high expiratory tidal volume?

Management of High Expiratory Tidal Volume in Intubated ACLF Patients

Immediately reduce tidal volume to 6 mL/kg predicted body weight and ensure plateau pressure remains below 30 cm H₂O to prevent ventilator-induced lung injury and minimize systemic cytokine-mediated organ dysfunction. 1

Immediate Ventilator Adjustments

Calculate and Set Appropriate Tidal Volume

• Calculate predicted body weight (PBW) using: Males = 50 + 0.91[height (cm) - 152.4] kg; Females = 45.5 + 0.91[height (cm) - 152.4] kg 2
• Set tidal volume to 6 mL/kg PBW regardless of whether acute lung injury (ALI) is present, as this lung-protective strategy has been shown to improve mortality in general critical care 1
• Verify plateau pressure remains <30 cm H₂O after adjustment 1
• Monitor driving pressure (plateau pressure minus PEEP) as it may be a better predictor of outcomes than tidal volume or plateau pressure alone 2

The rationale for this aggressive reduction is critical in ACLF patients: low tidal volume ventilation not only minimizes alveolar barotrauma but specifically decreases the risk of systemic cytokine-mediated nonpulmonary organ dysfunction, which is particularly important in patients with ACLF who are already at high risk of multiorgan failure 1. The 2024 AASLD guidance emphasizes that this strategy may also have beneficial hemodynamic effects by minimizing the negative effects of positive pressure ventilation on preload in patients with systemic vasodilation 1.

Optimize PEEP Strategy Based on Oxygenation

For mild ALI (PaO₂/FiO₂ 200-300 mm Hg):

• Use low PEEP strategy (<10 cm H₂O) to minimize impairment of venous return and cardiac preload 1
• High PEEP is specifically contraindicated as it can induce or exacerbate hypotension in patients with baseline vasodilated state and possible superimposed septic vasodilation 1

For moderate to severe ALI (PaO₂/FiO₂ <200 mm Hg):

• Consider higher PEEP strategy to improve oxygenation, but with careful hemodynamic monitoring for side effects 1
• Monitor for hypotension, decreased cardiac output, and signs of impaired venous return 1, 3

Address Underlying Causes Contributing to High Tidal Volumes

Assess for cirrhosis-related pulmonary complications:

• Perform therapeutic thoracentesis if hepatic hydrothorax is present 1
• Perform therapeutic paracentesis if tense ascites is present, as this can compromise respiratory mechanics and hemodynamics 1, 3
• Evaluate for hepatopulmonary syndrome 1

Identify and treat precipitating events:

• Obtain blood cultures, urinalysis, diagnostic paracentesis for spontaneous bacterial peritonitis, and chest imaging to identify infections 3
• Start empiric broad-spectrum antibiotics if infection is suspected, as early identification and treatment of bacterial infections is vital to patient survival 3

Hemodynamic Monitoring During Ventilator Adjustments

Perform bedside transthoracic echocardiography to assess cardiac function, inferior vena cava preload, fluid responsiveness, and differentiate between hypovolemic versus vasodilatory versus cardiogenic shock 3. This is particularly important when reducing tidal volumes and adjusting PEEP, as these changes can affect preload and cardiac output in patients with baseline circulatory dysfunction 1, 3.

Monitor dynamic changes in stroke volume, stroke volume variation, or pulse pressure variation with fluid boluses or passive leg raise to guide resuscitation if hypotension develops 3.

Critical Pitfalls to Avoid

• Never delay reduction of high tidal volumes even if oxygenation appears adequate, as ventilator-induced lung injury can develop insidiously and worsen multiorgan failure 1
• Avoid using high PEEP or aggressive positive pressure ventilation in hypotensive patients, as this further compromises venous return 1, 3
• Do not use tidal volumes >10 mL/kg PBW in patients without ARDS, as the PREVENT trial showed no benefit and lung-protective ventilation is advocated 1
• Avoid excessive PEEP in hemodynamically unstable patients, particularly those with ACLF who have baseline vasodilation 2

Ongoing Monitoring Parameters

• Continuously monitor plateau pressure, driving pressure, and dynamic compliance 2
• Monitor patient-ventilator synchrony to ensure adequate ventilation with reduced tidal volumes 2
• Titrate FiO₂ to maintain SpO₂ 88-95% 2
• Maintain PaCO₂ between 35-45 mmHg, avoiding hyperventilation which can cause cerebral vasoconstriction 2