Abstract
Introduction: The indications of non-invasive ventilation (NIV) have widened in the recent years, which is now used in treating hypercapnia with acidosis in a variety of patients. However, in many of the patients treated with NIV, the acidosis may have preceded the hypercapnia. The current case series from our 11-bedded ward based NIV unit describes such acidotic hypercapnia: hypercapnic respiratory failure following metabolic acidosis.
Methods: Time series of Arterial Blood Gas (ABG) findings in 4 patients with acidotic hypercapnia with a background of COPD confirmed with spirometry.
Results:The ABGs for cases 1 and 2 showed a rising CO2 following the onset of a metabolic acidosis; a mixed metabolic and respiratory acidosis in patients 3 & 4 - with the acidosis preceding hypercapnia (Case 3) or being out of proportion to CO2 rise (Case 4). All four patients improved with initiation of NIV combined with active fluid/electrolyte management. A sample ABG time series (Case 3) showing initial eucapnia with acidosis leading to hypercapnia is shown:
Discussion: Acidotic hypercapnia could be a further subtype of respiratory failure (akin to previously described Type 4 or shock-muscle hypoperfusion related respiratory failure) for which larger confirmatory studies and prospective trials to establish the efficacy and timing of NIV are required.
- © 2012 ERS