Discussion
Hypercapnic respiratory failure during acute COPD exacerbation
is an alarming event that requires careful management of the
resulting respiratory acidosis. The final outcome depends on
various factors, such as the patient’s overall health status and
concomitant comorbidities, the baseline lung function, and the
disease severity as judged by the need for assisted ventilation and
the degree of acidosis [16]. Our observations provide evidence that
mixed acid-base and lactate disorders in patients with hypercapnic
respiratory failure due to COPD exacerbation lead to the need for
and longer duration of NIV. More data should be provided to
evaluate this association with combined mixed acid-base and
hydroelectrolyte disorders.
Mixed respiratory acidosis–metabolic alkalosis
We observed that metabolic alkalosis with hyponatremia and/
or hypochloremia aggravated the respiratory acidosis due to the
COPD exacerbation. Mixed respiratory acidosis–metabolic alkalosis
patients were more likely to use NIV and were subjected to
longer periods of ventilation compared to those with pure
respiratory acidosis. The requirement for and duration of NIV
was associated with low serum sodium and chloride, common
findings in diuretic-induced metabolic alkalosis. The clinical
parameters and ABG analysis indicated more severe ventilatory
impairment in the patients with mixed respiratory acidosis–
metabolic alkalosis than in those with pure respiratory acidosis,