To the best of our knowledge, there were no studies to report the use of HFNC in patients with NCIP. Our study originally reported that 41% of patients required upgraded treatment from HFNC to NIV. Patients with lower PaO2/FiO2 were more likely to experience HFNC failure. In successful patients, the clinical signs improved after the use of HFNC. However, it deteriorated in unsuccessful patients.
In our study, we found that the number of HFNC patients were much higher than NIV patients when the HFNC or NIV was used as an initial oxygen support. It means that physicians were more likely to use HFNC among the critically ill patients caused by NCIP. As the outbreak of NCIP in China, thousands of clinical staffs joined in the patient management. Most of them had no experience on how to use HFNC or NIV. The current knowledge shows that 1) the HFNC is non-inferior to NIV on intubation rate in critically ill patients ; 2) the use of HFNC is more comfortable than NIV and the skin breakdown is less likely to occur [15, 16]; and 3) the manipulation of HFNC is much easier than NIV. Therefore, the clinical staffs were more likely to use HFNC in NCIP patients.
Person-to-person transmission of NCIP has been confirmed. In the early stages, the epidemic doubled in size every 7.4 days, and the estimated basic reproductive number was 2.2 (95% CI, 1.4 to 3.9) . The virus is believed transmitted mostly via droplets or contact and possibly via aerosol . People are all generally susceptible to the virus. As of February 11, 2020, 1716 clinical staffs have been infected with NCIP, and 5 of them died . Therefore, a device with less production of droplets or aerosol is required. The exhaled air dispersion produced by HFNC was limited and the risk of hospital-acquired infection did not increase [18, 19]. Therefore, the use of HFNC in NCIP patients is feasible. However, the amount of condensation in the circuit increased when the ambient temperature decreased . The condensed water became an important source of infection for NCIP. So, avoidance or reduction of condensation was very important when the HFNC was used.
A previous study reported that 38% of HFNC patients required intubation . In this study, 13% of patients experienced HFNC failure and upgraded to NIV. Among the NIV patients who experienced HFNC failure, the intubation rate was 64%. However, in our study, 41% of patients experienced HFNC failure. Among the unsuccessful patients, all of them directly switched to NIV (no one directly switched to intubation). It means that the physicians who managed the NCIP patients were more likely to use NIV than intubation when the HFNC was unable to maintain the oxygenation. We speculated that the process of intubation made the physicians at high risk of infection because of close encounter and irritable cough. However, among the patients with HFNC failure in our study, only 14% received intubation. It indicates that the successful rate is high after transition to NIV.
Our study has several limitations. This is a retrospective observational study. We did not predefine how to manage the HFNC. The transition to NIV or intubation was decided by the attending physicians. Different physician has different opinions on the point to switch to NIV or intubation. However, this study can reflect how the HFNC has been used in the real world among the NCIP patients. In addition, we only enrolled 17 patients in this study as the enrollment period is short. To our knowledge, there were no studies to report how the HFNC was used in NCIP patients. The rapid publication is very important for public health. It also can provide an important reference for clinical physicians when the used HFNC in NCIP patients.