Assessment of phosphatemia at admission to the intensive care unit to predict mechanical ventilation among patients with acute exacerbation of chronic obstructive pulmonary disease: a retrospective cohort study

Background: Hypophosphatemia has been reported to impair diaphragmatic function in patients with chronic obstructive pulmonary disease (COPD). However, little is known about the role of dysphosphatemia at admission [plasmatic phosphate concentration at intensive care unit (ICU) admission (T0-Ph)] to the ICU and respiratory outcomes among patients with severe acute COPD exacerbation. We aimed to assess the value of T0-Ph as a predictive factor of invasive mechanical ventilation (MV) during ICU stay. Methods: We retrospectively included consecutive patients admitted to the ICU for a severe acute exacerbation of COPD between May 2015 and December 2018. Logistic multivariate regression analysis was performed to identify association between T0-Ph and the need for invasive MV during the ICU stay. Results: We included 198 patients of whom 132 (67%) were male. The median age was 70 [interquartile range (IQR), 61–77] years. Nine (4.5%) patients died in the ICU. Median T0-Ph was significantly higher among patients requiring invasive MV as compared to non-intubated patients [1.23 (IQR, 1.07–1.41) and 1.09 (IQR, 0.91–1.27) mmol/L; P=0.005]. By multivariate analysis, pneumonia [odds ratio (OR) =6.42; 95% confidence interval (CI): 2.78–15.96; P<0.0001) and a history of intubation (OR =3.33; 95% CI: 0.97–11.19; P=0.05) were independently associated with the need for invasive MV, whereas T0-Ph was not (OR =1.75; 95% CI: 0.72–4.44; P=0.22). Conclusions: T0-Ph was significantly higher in patients requiring invasive MV. However, T0-Ph was not associated with the need for invasive MV in multivariate analysis.