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Summary: High-velocity nasal insufflation in the treatment of respiratory failure: a randomized clinical trial.
Topic: Primary Support
Doshi P, Whittle JS, Bublewicz M, et al High-velocity nasal insufflation in the treatment of respiratory failure: a randomized clinical trial. Ann Emerg Med 2018; 72(1):73-83 e5
Vapotherm’s high velocity therapy is a viable alternative to noninvasive positive pressure ventilation (NiPPV) as a tool to treat the signs and symptoms of undifferentiated respiratory distress in adult patients, as demonstrated by the non-inferiority, randomized controlled trial, “High-Velocity Nasal Insufflation in the Treatment of Respiratory Failure: A Randomized Clinical Trial”, published by Doshi and colleagues in the Annals of Emergency Medicine. The trial found no difference between high velocity nasal insufflation (HVNI) and NiPPV therapies in intubation rates or treatment failure rates.
This prospective multi-center trial enrolled 204 adult patients presenting to the emergency department (ED) with respiratory failure requiring noninvasive positive-pressure ventilation. Eligible patients were randomly assigned to high-velocity nasal insufflation (initial flow 35 L/min; temperature 35°C to 37°C; FiO2 1.0) or noninvasive positive pressure ventilation using an oronasal mask (IPAP 10 cm H2O; EPAP 5 cm H2O). The primary outcomes were treatment failure rate, defined as the need for intubation, and arm failure rate, defined as the decision for crossover to the alternate therapy, within 72 hours of initiation of assigned therapy.
The results showed that 7% of patients randomized to HVNI were intubated, and 13% of patients randomized to NiPPV were intubated. The risk difference was -6%, which meets non-inferiority. The crossover rate was higher in HVNI than NiPPV (26% vs. 17%) however the non-inferiority margin was still met (20 including 95% confidence interval).
The primary limitation of the study was the technical inability to blind the clinical team. The authors note that the arm failure rate induced an element of subjectivity which was expected to be greater than the intubation rate. Despite this, the arm failure rate met the noninferiority criteria and indicates there is no increased risk of intubation using HVNI in place of NiPPV, even if the patient is ultimately crossed over.
The authors note another important finding was the demonstration of the ventilatory effect with HVNI that is similar to that of NiPPV, as evidenced by the improvement in the PCO2 level over time in both arms and at a similar rate in all patients. In addition, vital signs and blood gas analyses improved similarly over time.
As secondary outcome measures, physicians gave superior scores for HVNI for respiratory response, patient comfort and tolerance, and simplicity of use, and similar ratings for their perception of each technology’s technical difficulty and their perception of the need for patient monitoring.
The authors note the most important study limitation was the technical inability to blind the treating team. It was noted that the lack of blinding can contribute to bias, especially when clinical judgment affects an outcome that is being evaluated. This study was also not powered for subanalyses across specific respiratory failure causes. Although criteria for failure were presented in the protocol, the determination of arm failure and need for intubation were ultimately at the discretion of the attending physician. Last, the mix of arterial and venous blood samples limited the interpretation of blood gas parameters such as PaO2. Because of lack of invasive monitoring to assess various respiratory physiologic variables, it is difficult to define all the potential clinical benefits of these therapies.
The authors conclude that Vapotherm’s high velocity therapy is noninferior to NIPPV for the treatment of adult patients experiencing undifferentiated respiratory failure in the Emergency Department and suggest HVNI as a suitable alternative to an NiPPV approach as a non-invasive ventilation strategy.
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