Non-Invasive Ventilation in Children with Paediatric Acute Respiratory Distress Syndrome.

INTRODUCTION: Evidence supporting non-invasive ventilation (NIV) in paediatric acute respiratory distress syndrome (PARDS) remains sparse. We aimed to describe characteristics of patients with PARDS supported with NIV and risk factors for NIV failure. MATERIALS AND METHODS: This is a multicentre retrospective study. Only patients supported on NIV with PARDS were included. Data on epidemiology and clinical outcomes were collected. Primary outcome was NIV failure which was defined as escalation to invasive mechanical ventilation within the first 7 days of PARDS. Patients in the NIV success and failure groups were compared. RESULTS: There were 303 patients with PARDS; 53/303 (17.5%) patients were supported with NIV. The median age was 50.7 (interquartile range: 15.7-111.9) months. The Paediatric Logistic Organ Dysfunction score and oxygen saturation/fraction of inspired oxygen (SF) ratio were 2.0 (1.0-10.0) and 155.0 (119.4- 187.3), respectively. Indications for NIV use were increased work of breathing (26/53 [49.1%]) and hypoxia (22/53 [41.5%]). Overall NIV failure rate was 77.4% (41/53). All patients with sepsis who developed PARDS experienced NIV failure. NIV failure was associated with an increased median paediatric intensive care unit stay (15.0 [9.5-26.5] vs 4.5 [3.0-6.8] days; P <0.001) and hospital length of stay (26.0 [17.0-39.0] days vs 10.5 [5.5-22.3] days; P = 0.004). Overall mortality rate was 32.1% (17/53). CONCLUSION: The use of NIV in children with PARDS was associated with high failure rate. As such, future studies should examine the optimal selection criteria for NIV use in these children.

On-line lung volume measurement during high-frequency oscillatory ventilation.

OBJECTIVE: A bag-in-box system using a closed-circuit helium-dilution technique was used to determine the functional residual capacity during conventional mechanical ventilation. The purpose of this study was to determine whether the bag-in-box system could be used to measure mean lung volume without interrupting high-frequency oscillatory ventilation. DESIGN: Laboratory study. SETTING: Hospital intensive care medical research laboratory. SUBJECTS: Six mechanical lung models and ten New Zealand adult rabbits. INTERVENTIONS: The bag-in-box system was introduced into the respiratory circuit during the study. The rabbits were randomly divided into a healthy group and an acute lung injury group. Acute lung injury was induced by intravenously infusing oleic acid during conventional mechanical ventilation. MEASUREMENTS AND MAIN RESULTS: In a lung model study, a series of rebreathing processes were performed. By measuring the helium concentration in each process, the rebreathing time needed for equilibration was found to be about 50 secs. We compared the measured volume with a known lung volume to test the method's accuracy. The volumes differed by -0.5% to 4.4%. Measured and known volumes of different size lung models correlated well (p <.001). Equilibration of helium in the system occurred after 40-50 secs of rebreathing in healthy rabbits and 30-40 secs of rebreathing in rabbits with acute lung injury. Of 45 mean lung volume determinations in ten rabbits, the coefficient of variation ranged from 0.5% to 6.5%. When mean airway pressure changed, the mean lung volume alteration was detected by the method, but it was inconsistent in each mean airway pressure variation. CONCLUSION: A bag-in-box apparatus using a helium-dilution technique could be evaluated as a method to measure gas-containing lung volumes ranging from 10 to 60 mL in patients receiving high-frequency oscillatory ventilation.