RESUMO
OBJECTIVE: To describe the incidence of hypophosphatemia in patients admitted to the ICU who have required mechanical ventilation. To analyze the presence of risk factors and its relationship with nutritional practice. DESIGN: Prospective observational study. SETTING: Polyvalent ICUs of 2 University Hospitals. PATIENTS OR PARTICIPANTS: Patients on invasive mechanical ventilation ≥72â¯h with normal level of phosphorus at admission. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Electrolyte levels (phosphorus, magnesium, potassium) were determined on admission to the ICU and at 96â¯h. Risk categories on admission, caloric intake, insulin doses and acid-base status during the first 4 days of admission were recorded. Incidence was calculated as the number of patients who developed hypophosphataemia after admission. Univariate analysis was performed for between-group comparison and multivariate analysis of potential risk factors. RESULTS: 89 patients were included. The incidence of hypophosphataemia was 32.6%. In these patients phosphorus decreased from 3.57⯱â¯1.02â¯mmol/l to 1.87⯱â¯0.65â¯mmol/l (52.3%). The mean kcal/kg/24â¯h provided in the first 4 days was 17.4⯱â¯4.1, with no difference between the group that developed hypophosphataemia and the group that did not. Significant risk factors were insulin doses administered and pH and PaCO2 values. CONCLUSIONS: The incidence of hypophosphataemia at 96â¯h from admission in mechanically ventilated patients is high and unrelated to the risk category and hypocaloric nutritional practice used. Insulin dosis and acid-base status are the main determinants of its occurrence.