Correlation between serum phosphorus levels and outcomes of weaning from mechanical ventilation in elderly chronic obstructive pulmonary disease patients with type Ⅱ respiratory failure / 中华老年医学杂志

ABSTRACT

Objective:To investigate the correlation between serum phosphorus levels and outcomes of weaning from mechanical ventilation in elderly chronic obstructive pulmonary disease(COPD)patients with type Ⅱ respiratory failure.Methods:A total of 142 hospitalized elderly COPD patients with type Ⅱ respiratory failure receiving mechanical ventilation in our hospital from August 2016 to December 2018 were retrospectively enrolled.Patients were divided into the successful weaning group(n=101)and the unsuccessful weaning group(n=41)based on weaning outcomes.General data, blood phosphorus levels on admission and before spontaneous breathing trials(SBT)and the incidence of hypophosphatemia were compared between the two groups.The logistic regression equation was used to analyze the related factors for the unsuccessful weaning, and the receiver operating characteristics(ROC)curve was drawn to analyze the value of serum phosphorus levels in predicting the failure of weaning.Methods:Compared with the successful weaning group, Acute Physiology and Chronic Health evaluation Ⅱ(APACHEⅡ)scores, rapid shallow breathing index(RSBI), and serum creatinine(Cr), C-reactive protein(CRP)levels were higher, while the oxygenation index(PaO 2/FiO 2), serum albumin(ALB)and magnesium levels were lower in the unsuccessful weaning group than in the successful weaning group( P<0.05). The incidences of hypophosphatemia on admission and before SBT were higher in the unsuccessful weaning group than in the successful weaning group(34.2% or 34/41 vs.17.8% or 18/101, 46.3% or 19/41 vs.25.7% or 26/101, χ2=4.452 and 5.716, P<0.05). Serum phosphorus levels on admission and before SBT were lower in the unsuccessful weaning group than in the successful weaning group[(0.82±0.21) mmol/L vs.(1.05±0.23) mmol/L, (0.71±0.19) mmol/L vs.(1.02±0.22) mmol/L, t=5.171 and 7.646, P<0.05)]. Multivariate logistic regression analysis showed that hypophosphatemia on admission or before SBT was an independent risk factor for unsuccessful weaning in elderly COPD patients with type Ⅱ respiratory failure( P<0.05). The areas under the ROC curve(AUC)of hypophosphatemia on admission and before SBT for predicting the failure of weaning was 0.657 and 0.776, respectively, and with 0.84 mmol/L and 0.76 mmol/L as the respective optimal threshold values, the sensitivity and specificity were 67.3% and 68.3% for AUC on admission and 76.5% and 85.6% for AUC before SBT, respectively.AUC of the serum phosphorus level was higher before SBT than on admission( Z=3.142, P<0.05). Conclusions:The decrease of blood phosphorus levels is common in elderly COPD patients with type Ⅱ respiratory failure, and hypophosphatemia has a high incidence and may be an independent risk factor for the failure of weaning.Blood phosphorus levels should be closely monitored in order to guide clinical weaning.