How is carbon dioxide (CO2) managed in COVID-19 patients?

Carbon Dioxide Management in COVID-19 Patients

In COVID-19 patients, carbon dioxide (CO2) management requires careful monitoring and maintenance of appropriate ventilation strategies, with closed tracheal suction systems being mandatory to minimize aerosol generation while maintaining effective CO2 clearance. 1

Ventilation Strategies for CO2 Management

Non-invasive Approaches

• For patients with acute hypoxemic respiratory failure despite conventional oxygen therapy, high-flow nasal cannula (HFNC) is suggested over conventional oxygen therapy or non-invasive positive pressure ventilation (NIPPV) 1
• If HFNC is unavailable and there's no urgent indication for endotracheal intubation, a trial of NIPPV with close monitoring is recommended 1
• Close monitoring for worsening respiratory status is essential, with early intubation in a controlled setting if deterioration occurs 1

Invasive Mechanical Ventilation

• For mechanically ventilated COVID-19 patients with ARDS, low tidal volume ventilation (4-8 mL/kg of predicted body weight) is recommended over higher tidal volumes 1
• Target plateau pressures should be maintained below 30 cmH2O to prevent barotrauma while allowing adequate CO2 elimination 1
• Higher PEEP strategies (>10 cmH2O) are suggested for moderate to severe ARDS, with careful monitoring for barotrauma 1

Circuit Management for CO2 Control

• Use heat and moisture exchange (HME) filters close to the patient instead of heated humidified circuits to reduce viral load in the ventilator circuit 1
• Monitor airway cuff pressure carefully to avoid leaks that could compromise ventilation and CO2 elimination, ensuring the tracheal tube cuff pressure is at least 5 cmH2O above peak inspiratory pressure 1
• Closed tracheal suction systems are mandatory to maintain effective ventilation while minimizing aerosol generation 1, 2

Preventing CO2 Retention Complications

• Monitor for signs of hypercapnia, which can independently worsen outcomes in COVID-19 patients 3
• Decreased CO2 levels have been associated with increased mortality risk in COVID-19 patients, possibly due to hyperventilation during mechanical ventilation 3
• For procedures requiring circuit disconnection:
  1. Ensure adequate sedation
  2. Consider neuromuscular blockade
  3. Pause the ventilator
  4. Clamp the tracheal tube
  5. Separate the circuit with the HME filter attached to the patient 1, 2

Advanced CO2 Management Strategies

• For persistent hypercapnia despite optimal ventilation strategies, extracorporeal carbon dioxide removal (ECCO2R) may be considered 4, 5
• ECCO2R can be combined with continuous renal replacement therapy (CRRT) in patients with concurrent acute kidney injury 4, 5
• ECCO2R allows for reduction in tidal volume and airway pressure while correcting respiratory acidosis, potentially reducing ventilator-induced lung injury 4

Special Considerations

• Avoid disconnections and use push-twist connections to prevent accidental disconnections that could disrupt ventilation 1
• Be vigilant for HME filter blockage if it becomes wet, which can cause increased airway resistance and be mistaken for patient deterioration 1
• Monitor and record tracheal tube depth at every shift to minimize risk of displacement that could affect ventilation 1, 2
• Check cuff pressure and tube depth before and after patient repositioning, including prone positioning, which is recommended for 12-16 hours in moderate to severe ARDS 1

Pitfalls to Avoid

• Never clamp a bubbling chest tube, as this may convert a simple pneumothorax into a tension pneumothorax, further compromising ventilation 6
• Avoid excessive ventilation that could lead to decreased CO2 levels, as this has been associated with increased mortality in COVID-19 patients 3
• Be cautious with recruitment maneuvers, ensuring cuff pressure is adequate to prevent leaks that could compromise CO2 elimination 1, 2