Vapotherm high velocity therapy has received clinical consensus recommendation as an early option for mild to moderate symptoms of acute respiratory distress/failure associated with COVID-19 1,2. Clinical experts have reported that non-invasive options, including high velocity therapy, to support COVID-19 patients, including some severely ill ones, may reduce the numbers of patients requiring intubation, mechanical ventilation, and ICU admissions.3 While this consensus included all forms of high flow, a new study conducted by Chavarria and colleagues and published in Therapeutic Advances in Infectious Disease examined the outcomes specifically for Vapotherm high velocity therapy, which is an advanced form of high flow. The study showed that 71.4% of patients with SARS-CoV-2 pneumonia and hypoxemic respiratory failure did not require mechanical ventilation when treated with high velocity therapy4.
The Primary Objectives
Chavarria and colleagues conducted a prospective observational study to investigate the efficacy of high velocity therapy in patients with hypoxemic respiratory failure due to severe SARS-CoV-2 pneumonia to reduce the risk of requiring invasive mechanical ventilation (IMV). The researchers also aimed to identify risk factors of disease progression among patients with severe SARS-CoV-2 pneumonia who were treated with high velocity therapy.
The Patient Population
The researchers enrolled 378 patients aged >18 years who were admitted to the temporary COVID-19 hospital in Mexico City with a confirmed diagnosis of COVID-19 [verified by a positive polymerase chain reaction (PCR) test] and hypoxemic respiratory failure (Pa02 <60mmHg) due to severe SARS-CoV-2 pneumonia.
Table 1: Patient Characteristics
|Activity ID||Total , n=378|
|Age Median||54.5 yrs. (46-64)|
|Type 2 Diabetes||35.5% (n=134)|
|Obesity (≥30)||47.6% (n=180)|
The study outcome showed that the high velocity therapy success rate, defined as patients who did not require IMV, was 71.4% (n=270) compared with 28.6% (n=108) of patients who required IMV. Of the 270 patients who were successfully treated with high velocity therapy, 262 patients (97.0%) were discharged, seven patients (2.6%) were referred, and one patient (0.4%) died. Among the 108 patients who required IMV, 61.1% (n=66) were successfully extubated. In addition, the proportion of patients with high velocity therapy success increased over time from when treatment was started. The median number of days of high velocity therapy administration was 13 (10-18) days in patients who had success compared with 2 (1-3) days in patients who then also required IMV. Patients requiring increased escalation of respiratory support were identified and transitioned early in the course of treatment. Similarly, in a prospective multicenter pilot study published by Plotnikow et al (2021), high velocity therapy was successful as supportive treatment in 83% of moderate to very severe COPD patients, demonstrating that high velocity therapy causes early and sustained changes in the clinical and blood gas parameters while failure of CO2, pH, and respiratory rate to respond well in first hour may predict failure of the therapy in these patients5.
The following were identified as predictors of high velocity therapy outcome: CALL score, or comorbidity-age-lymphocyte count-lactate dehydrogenase score, as well as the ROX index, a measure of hypoxemia severity that predicts the need for IMV6, at 1 hour after starting high velocity therapy, and the presence/absence of steroid treatment. The CALL score at admission was a significant predictor of high velocity therapy failure and the ROX index at 1 hour (per 1-point increase) and prior treatment with steroids were significant predictors of high velocity therapy success. Patients who were successful on high velocity therapy had steadily increasing ROX scores from baseline at 1, 2, 4, 6, 12 and 16 hours, while the failures had a slightly lower baseline and stayed low across 16 hours, providing a good predictor of which patients may require more support and need for escalation of care.
Patients with high velocity therapy success rarely required admission to the ICU (7.0%) and had shorter lengths of hospital stay at 15.0 days compared to those who required IMV (96.3%), and hospital stays averaging 26.5 days.
Table 2: Data are presented as n [%] or median [IQR]
|Criteria||High Velocity (n=270)||High Velocity + IMV (n=108)|
|Steroid Treatment at Hospitalization||78.2%||54.6%|
|Hospital LOS||15.0 days||26.5 days|
IMV= Invasive mechanical ventilation; ICU=Intensive Care Unit; LOS=Length of Stay
* Of the 41 patients who died in the high velocity therapy + IMV group, 1 of 66 patients who had been successfully extubated died, while 40 of 42 patients who failed to be extubated died.
Overall, the study showed that 71.4% of patients with SARS-CoV-2 pneumonia and hypoxemic respiratory failure did not require IMV when treated with high velocity therapy. The authors conclude that treating patients with high velocity therapy at admission led to improvement in respiratory parameters in many patients with COVID-19 which reinforces the benefits of the timely use of high velocity therapy. The authors note that the results should be validated in prospectively registered, randomized controlled trials.
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 Alhazzani W, Møller MH, Arabi YM, et al. Surviving Sepsis Campaign: guidelines on the management of critically ill adults with Coronavirus Disease 2019 (COVID-19). Intensive Care Medicine. 2020; http://doi.org/10.1007/s00134-020-06022-5.
 WHO. Clinical management of severe acute respiratory infection when Novel coronavirus (2019-nCoV) infection is suspected: Interim Guidance. WHO/nCoV/Clinical/2020.3 January 28 2020.
 Whittle et al. Respiratory Support for Adult Patients with COVID-19. JACEP OPEN, April 2020. https://doi.org/10.1002/emp2.12071
 Chavarria Ap, Lezama ES, Navarro MG et al. High-flow nasal cannula therapy* for hypoxemic respiratory failure in patients with COVID-19. Therapeutic Advances in Infectious Disease 2021.Vol 8:1-10. DOI: https://doi.org/10.21203/rs.3.rs-466888/v1
 Plotnikow G, Accoce M, Fredes S, et al. High-Flow Oxygen Therapy Application in Chronic Obstructive Pulmonary Disease Patients with Acute Hypercapnic Respiratory Failure: A Multicenter Study. Critical Care Explorations February 2021;3:1-8 p e0337.
 Roca 0, Caralt B, Messika J, et al. An index combining respiratory rate and oxygenation to predict outcome of nasal high-flow therapy. Am J Respir Crit Care Med 201′); 199: 1368-1376.