Risk of respiratory failure among hospitalized patients with various admission serum potassium levels

Abstract

ABSTRACT Background The objective of this study was to assess the relationship between admission serum potassium and the risk of respiratory failure requiring mechanical ventilation in all hospitalized patients. Methods All non-dialysis and non-mechanically ventilated patients who had serum potassium measurement at admission from 2011 to 2013 were studied. Serum potassium levels were stratified into five groups; ≤3.4, 3.5 to 3.9, 4.0 to 4.4, 4.5 to 4.9, 5.0 to 5.4, and ≥5.5 mEq/L. The outcome of interest was the respiratory failure requiring mechanical ventilation during hospitalization. Logistic regression analysis was performed to assess the independent risk of in-hospital respiratory failure requiring mechanical ventilation based on various admission serum potassium, using serum potassium of 4.0 to 4.4 mEq/L as the reference group. Results Of 67,034 eligible patients, with the mean admission serum potassium of 4.2 ± 0.5 mEq/L, 2,886 (4.3%) patients developed respiratory failure requiring mechanical ventilation during hospitalization. As demonstrated by U-shaped association, increased risk of in-hospital respiratory failure was significantly associated with low admission serum potassium ≤ 3.4 mEq/L (odds ratio 1.36, p-value <0.001) and high admission serum potassium ≥5.5 mEq/L (odds ratio 1.37, p-value = 0.01). Conclusion Increased risk of in-hospital respiratory failure requiring mechanical ventilation was noted when serum potassium was below 3.5 mEq/L or above 5.4 mEq/L at the time of hospital admission. Patients with either hypokalemia or hyperkalemia are at risk of respiratory failure requiring mechanical ventilation.