Abstract and Introduction
Abstract
Background: Advanced respiratory support modalities such as non-invasive positive pressure ventilation (NiPPV) and heated and humidified high flow nasal canula (HFNC) served as useful alternatives to invasive mechanical ventilatory support for acute respiratory failure (ARF) during the peak of the SARS-CoV-2/COVID-19 pandemic. Unlike NiPPV, HFNC is a newer modality and its role in the treatment of patients with severe ARF is not yet clearly defined. Furthermore, the characteristics of responders versus non-responders to HFNC have not been determined. Although recent evidence indicates that many patients with ARF treated with HFNC survive without needing intubation, those who fail and are subsequently intubated have worse outcomes. Given that prolonged use of HFNC in patients with ARF might exacerbate patient self-inflicted lung injury, we hypothesized that among those patients with ARF due to COVID-19 pneumonia, prolonged HFNC beyond 24 h before intubation would be associated with increased in-hospital mortality.
Methods: This was a retrospective, multicenter, observational cohort study of 2720 patients treated for ARF secondary to SARS-CoV-2/COVID-19 pneumonia and initially managed with HFNC within the Banner Health system during the period from March 1st, 2020, to July 31st, 2021. In the subgroup of patients for went from HFNC to IMV, we assessed the effect of the duration of HFNC prior to intubation on mortality.
Results: 1392 (51%) were successfully treated with HFNC alone and 1328 (49%) failed HFNC and were intubated (HFNC to IMV). When adjusted for the covariates, HFNC duration less than 24 h prior to intubation was significantly associated with reduced mortality.
Conclusions: Among patients with ARF due to COVID-19 pneumonia who fail HFNC, delay of intubation beyond 24 h is associated with increased mortality
Introduction
During the peak of the SARS-CoV-2/COVID-19 pandemic, there was a dramatic increase in the demand for advanced respiratory support modalities such as non-invasive positive pressure ventilation (NiPPV), heated and humidified high flow nasal canula (HFNC), as alternatives to invasive mechanical ventilation (IMV).[1] In the early phase of the pandemic, concerns about potential aerosolization of SARS-CoV-2 viral particles and healthcare personnel infection limited the use of NiPPV and HFNC for patients presenting with acute respiratory failure (ARF) due to COVID-19 pneumonia.[2–6] However, during subsequent waves of the pandemic, there was a better appreciation of the transmission risk associated with SARS-CoV-2 hence a gradual and sustained increased in the use of these non-invasive modalities for ARF.[7–10] Increased capacity strain on healthcare systems caused by the influx of critically ill patients together with intensive care unit (ICU) resource limitations led to further increases in use of NiPPV and HFNC for patients with ARF as alternatives to invasive mechanical ventilation.[8,10]
Although the standard of care for patients with acute respiratory failure (ARF) has traditionally been early IMV with lung protective strategies,[11] it has long been recognized that some patients might be more appropriate for non-invasive modalities such as NiPPV or HFNC.[12–14] For example, in patients with ARF due to acute exacerbations of chronic obstructive pulmonary disease (COPD) or congestive heart failure (HF) with pulmonary edema, early non-invasive positive pressure ventilation (NiPPV) has been shown to reduce rates of intubation and improve survival.[13,14] Unlike NiPPV, HFNC is a newer modality for treatment of ARF and its role in the treatment of patients is not yet clearly defined.[12] Furthermore, the characteristics of responders versus non-responders have not been determined.[12,15–18] Current clinical practice guidelines strongly recommend a trial of HFNC in patients with ARF with hypoxemia,[19] however the subset of patients presenting with ARF who are ideal for trial of HFNC has not been defined. Nor has the optimal timing of HFNC before considering intubation and invasive mechanical ventilation (IMC) been defined. We previously showed, using data prior to the COVID-19 pandemic, that among patients with ARF, those who failed NiPPV or HFNC and were subsequently intubated had a significantly increased mortality compared to IMV alone.[12] Studies have shown that the ratio of oxygen saturation as measured by pulse oximetry/fraction of inspired oxygen to respiratory rate (ROX index) of less than 5.99 (ARF due to COVID-19)[20] and less than 4.88 (non-COVID-19 ARF)[21] at 12 h post initiation is a good predictor of HFNC failure.[22] Nevertheless, the optimal duration of an HFNC trial prior to endotracheal intubation and IMV is not clear. In patients with severe ARF with poor lung compliance, prolonged use of HFNC might exacerbate patient self-inflicted lung injury (SILI).[23] SILI might lead to physiologically difficult intubations and possibly negatively affect other organs such as the brain, the heart, and the kidneys. We hypothesized that among those patients with ARF due to COVID-19 pneumonia who failed a trial of HFNC and were subsequently intubated, a delay of intubation beyond 24 h would be associated with increased in-hospital mortality. Older age is a major risk factor for COVID-19 pneumonia severity and mortality.[24] Therefore, we wanted to test for effect modification by age on the response to HFNC among patients with ARF due to COVID-19.
BMC Anesthesiol. 2023;23(234) © 2023 BioMed Central, Ltd.
