Initial NIV Settings for Metabolic Acidosis with Compensatory Respiratory Alkalosis

Understanding the Underlying Pathophysiology

The respiratory system attempts to compensate for metabolic acidosis by increasing minute ventilation to eliminate CO2, resulting in a lower PaCO2 1

Bi-level pressure support ventilation is recommended as the initial mode for most cases of acute respiratory failure, according to the British Thoracic Society 3, 1
Start with low inspiratory positive airway pressure (IPAP): 10-12 cmH2O, as recommended by the European Respiratory Society 1, 5
Set expiratory positive airway pressure (EPAP): 4-5 cmH2O, based on guidelines from the American Thoracic Society 1
Gradually titrate IPAP upward by 2-3 cmH2O increments based on patient comfort and respiratory rate, as suggested by the European Respiratory Society 4, 1

Target oxygen saturation of 88-92% to avoid worsening hypercapnia if there's an underlying respiratory component, according to the British Thoracic Society 1, 6

Obtain arterial blood gas (ABG) measurement prior to starting NIV and 1-2 hours after initiation, as recommended by the American Thoracic Society 1, 5
Closely monitor respiratory rate, work of breathing, patient comfort, and synchrony with the ventilator, based on guidelines from the European Respiratory Society 4, 1

Consider the underlying cause of metabolic acidosis and address it concurrently, as suggested by the American College of Chest Physicians 1, 2
Be cautious with sedation as it may suppress the compensatory respiratory drive, according to the Society of Critical Care Medicine 1

Delaying escalation to invasive mechanical ventilation when NIV is failing, as warned by the American Thoracic Society 1, 5
Overlooking the treatment of the underlying cause of metabolic acidosis, according to the European Respiratory Society 1, 2