Effect of hypophosphatemia on weaning from mechanical ventilation in Respiratory ICU patients

Abstract

Background
One essential component of managing patients with respiratory failure in critical care is mechanical ventilation (MV). Weaning off MV is still a difficult procedure, so identifying predictors of successful weaning is crucial for optimizing patient outcomes.


Objective
This study aimed to assess the predominance of hypophosphatemia among mechanically ventilated patients admitted to the respiratory intensive care unit, and assess the relationship between hypophosphatemia and MV weaning outcome.


Patients and methods
This prospective cohort study was applied to 54 mechanically ventilated patients in the Respiratory Critical Care Unit at Ain Shams University Hospital. History taking, full clinical examination, serum phosphorus measurement at initiation of intubation, after 2 days of intubation, and within 1 day after extubation, and follow-up of weaning outcome were taken from the included patient. They were divided into two groups according to their phosphate levels during ICU admission: (1) hypophosphatemia with a serum phosphate level less than or equal to 2.5 mg/dl. (2) nonhypophosphatemia with a serum phosphate greater than 2.5 mg/d.


Results
Out of 54 patients, 34 were males and 20 were females. The ages of them ranged from 23 to 80 years, with a mean age was 57.17 ± 10.53 years. Pneumonia with septic shock was the most common cause of ICU admission. The mean phosphate level at initiation of intubation in the studied patients was 2.17 ± 0.79 mg/dl that changed to 2.15 ± 0.81 mg/dl after 2 days of intubation, then to 3.04 ± 0.62 mg/dl within 1 day after extubation. Patients with failed weaning had a significantly higher rate of hypophosphatemia in comparison with the successful weaning group at initiation of intubation, after 2 days of intubation, and within 1 day after extubation. There is a significant association between hypophosphatemia and the failure of the trial of extubation.


Conclusion
Pneumonia was the most common cause of MV in respiratory intensive care units. The level of hypophosphatemia affects weaning outcome, especially when it occurs during MV and within 24 h following weaning. The recommended cut-off value predictor for weaning failure is less than 1 mg/dl within 2 days and less than 2.8 mg/dl within 24 h following extubation.