Patients main clinical and metabolic parameters, ABG analysis, lactate, serum electrolytes and urinalysis.

Data expressed as Mean ± Standard Deviation.aStudent t-test for unpaired data. ABG = arterial blood gases; NIV = non invasive ventilation; FiO2 = Fraction of inspired O2; P(A-a)O2 = alveolar-arterial PO2 gradient; sNa+ = serum sodium; sK+ = serum potassium; sCl− = serum chloride; sCa2+ = serum calcium; sMg2+ = serum magnesium; uNa+ = urine sodium; uK+ = urine potassium; uCl− = urine chloride.