Nasal high flow (NHF) therapy is a less invasive alternative to ventilator care for many seriously ill coronavirus patients, UnityPoint Health experts say.
During the coronavirus disease 2019 (COVID-19) pandemic, ventilator care has been used commonly for coronavirus patients experiencing acute respiratory distress. However, ventilator care has posed several challenges, including shortages ventilators and the staff needed to manage patients on mechanical ventilation.
NHF therapy is delivered to a patient through a high flow nasal cannula. According to the American Association for Respiratory Care (AARC), an NHF therapy system usually features four elements:
- Gas blender
- Flow meter display
- Nasal interface and heated circuit
- Humidification system
"One of the hallmarks of an efficient NHF system is to be able to deliver optimally humidified gas at body temperature pressure and humidification," an AARC document says.
At three UnityPoint Health hospitals in Iowa, using NHF therapy has allowed clinicians to keep 73% of seriously ill COVID-19 patients off ventilators. In addition, the duration of NHF therapy for these patients has averaged about three days compared to about eight days for patients placed on mechanical ventilation.
For seriously ill COVID-19 patients, several criteria indicate or contraindicate use of NHF therapy, says Matthew Trump, DO, medical director of UnityPoint Health pulmonary rehabilitation, and co-medical director of the Palliative Care Department at The Iowa Clinic, which is based in West Des Moines, Iowa.
Seriously ill COVID-19 patients are good candidates for NHF therapy if they are awake, breathing spontaneously, and hemodynamically stable, he says. Seriously ill COVID-19 patients are poor candidates for NHF therapy if they cannot maintain their airway and/or have severe respiratory acidosis with a pH of less than 7.2, he says.
Advantages of NHF therapy
In the treatment of severe COVID-19, there are several benefits to using NHF therapy rather than mechanical ventilation, according to Trump and Julie Jackson, respiratory care services manager at UnityPoint Health.
- With NHF therapy, the patient is able to be awake, able to mobilize, able to communicate, and able to eat and drink. The ability to mobilize patients avoids some of the weakness and debilitation patients experience when they are on mechanical ventilation.
- A physiologic benefit is that the patient's lungs are not subjected to potentially injurious pressure from a ventilator.
- Patients receiving NHF therapy can be managed in an inpatient ward as opposed to the ICU setting, which generates multiple benefits including lower demand for ICU beds and avoidance of ICU-related complications such as infections.
- Unlike patients placed on mechanical ventilation, patients receiving NHF therapy can be active participants in their care such as involvement in medical decision-making and self-proning. "They can move themselves into a prone position, so their oxygenation is improved. Whereas, if the patient is on a ventilator, it takes a lot of resources and a lot of staff to prone the patient," Jackson says.
- NHF therapy can be used when a patient is extubated, which has lowered the rate of re-intubation at the UnityPoint Health hospitals.
- When small community hospitals need to transfer a seriously ill COVID-19 patient to a larger hospital for advanced care, many of the patients can receive NHF therapy during transport rather than being intubated.
Christopher Cheney is the senior clinical care editor at HealthLeaders.
At three UnityPoint Health hospitals, using nasal high flow therapy has allowed clinicians to keep 73% of seriously ill coronavirus patients off ventilators.
At the hospitals, duration of nasal high flow therapy for seriously ill coronavirus patients has average about three days, compared to about eight days for patients on ventilators.
Seriously ill coronavirus patients are good candidates for nasal high flow therapy if they are awake, breathing spontaneously, and hemodynamically stable.
High flow oxygen therapy involves the use of warm, humidified oxygen delivered via nasal cannula (also referred to as high flow nasal cannula oxygen therapy - HFNO) under positive end expiratory pressure (PEEP).[1] High flow oxygen therapy was originally implemented for neonates, but has gained more attention in adults due to several factors.
By administering warm and humidified gas, airway dehydration is reduced, and secretion clearing is increased. There is also a higher FiO2 delivery when compared to face mask use. Plus, using PEEP allows for an increase in end-expiratory lung volume and alveolar recruitment.1
During the COVID-19 pandemic where more patients may experience acute respiratory failure, healthcare professionals and organizations have turned to high flow oxygen therapy as a way to support these patients.
In addition to clinical benefits of high flow oxygen therapy, the practical benefit of using an oxygen delivery system that does not require critical care oversight is extremely valuable in healthcare settings overwhelmed with patients needing respiratory support.1
This article discusses both the clinical and practical benefits of high flow oxygen therapy and how they’ve been successfully applied to COVID-19 patients who have acute hypoxemic respiratory failure.
Patient Comfort Increases with High Flow Oxygen Therapy2
It’s been well established that face masks with a reservoir bag, while a first line therapy, provide little when it comes to patient comfort. The air is dry, and the masks prevent patients from doing many basic functions.
Wearing a face mask hinders the patient from communicating, drinking, or eating without removing the mask. Face masks can also cause patient distress and increase the risk of skin breakdown.2
High flow oxygen therapy mitigates both of these concerns. Firstly, the air is warmed and humidified, reducing the drying effects of oxygen therapy.2 This also reduces the risk of airway dehydration, which can lead to pain and discomfort, epistaxis, and other pulmonary issues.
Alternatively, high flow oxygen therapy is administered via nasal cannula rather than a face mask. This frees the patient’s mouth to talk, drink, and eat while benefiting from oxygen therapy.2 And while the risk for skin breakdown still exists with a cannula, there is less surface area contacting the patient during oxygen administration.
High Flow O2 Therapy Provides Noninvasive Benefit to Patients with Severe COVID-19 Related HRF
Using humidified high flow nasal oxygen is useful in patients with severe COVID-19 related hypoxemic respiratory failure (HRF) as a noninvasive intervention.2
Patients using high flow oxygen may be able to be safely weaned without the need of mechanical ventilation.[2] Using noninvasive respiratory support in patients with COVID-19-related respiratory failure has been critical in areas that lack proper respiratory support. This may be due to lack of physical resources (ventilators or oxygen) or due to a lack of healthcare personnel available.
In a study exploring the use of high flow oxygen for patients with COVID-19 in hospitals lacking sufficient respiratory resources, nearly half (47%) of patients treated with high flow oxygen therapy were considered successful. These patients did not require invasive maneuvers including intubation. Patients utilized high flow oxygen therapy for an average of six days.2 This study also notes 93% of those successful patients were safely discharged from the hospital.2
High Flow O2 Therapy Provides Interventions Obtainable Outside the ICU Setting
A major challenge for healthcare providers and organizations caring for patients with COVID-19 is access to beds and rooms. ICUs and step-down units were often beyond capacity, highlighting the need for interventions that can be done safely outside of an ICU setting.
High flow oxygen therapy has proven to be one of these vital interventions that can be done in a non-critical care setting. This alone increases the volume of COVID-19 patients in which a hospital or institution can support where they may experience hypoxemic respiratory failure.3
Furthermore, high flow oxygen therapy is a type of respiratory support that does not require advanced training to implement and monitor. This allows healthcare workers outside of critical care settings to safely administer and monitor patients using high flow O2.4
High Flow O2 Therapy May Reduce Intubation Rates in Patients with COVID-195
The use of high flow oxygen therapy (HFNO) has been evaluated in several studies specifically focused on patients with COVID-19. A retrospective study out of France found patients who undergo HFNO were less likely to need mechanical ventilation (56% of HFNO group versus 71% in non-HFNO group).5 The mortality rate of these patients with COVID-19 respiratory failure was reduced when they received HFNO.6
These studies found high flow oxygen therapy to be a safe and effective intervention in patients with COVID-19 related respiratory failure and works well as a way to avoid escalation. HFNO was also shown to both improve overall oxygenation and reduce pneumonia in these patients.6
Most of these studies with COVID-19 patients are considered small to medium size (ranging for 100-379 patient sample sizes), but the congruent outcomes of these trials show the benefit and efficacy of implementing HFNO in patients with acute respiratory failure due to COIVD-19 infections.6
But when looking at high flow oxygen therapy versus conventional oxygen in general (as opposed to COVID-19 patients specifically) a systematic review and meta-analysis of nine trials and over 2,000 patients found no difference in mortality.6 This review further supports that high flow oxygen therapy is safe and effective when it comes to noninvasive respiratory support in patients with acute hypoxemic respiratory failure.
Additional Benefits of High Flow Oxygen Therapy
High flow O2 therapy is not only a practical intervention for patients with COVID-19 related hypoxemic respiratory failure, but it also provides additional physiological benefits. These benefits include: 2
- Alveolar recruitment
- Improved perfusion matching
- Reducing airway resistance
- Reduced respiratory effort
- Decreased oxygen dilution
- Decreased dead space
- High levels of humidification
While more studies are needed to explore the use of high flow oxygen therapy in patients with COVID-19 specifically, there is clearly a benefit of using this treatment in these patients. Patient comfort is increased, it is noninvasive and can be done outside of a critical care setting, all while being a very effective and successful way to support certain patients from a respiratory standpoint.
As with all interventions, careful monitoring of respiratory parameters is required to maintain patient safety and implement additional measures as quickly as possible.
References
- Ashraf-Kashani, N et al. (2017) High-flow nasal oxygen therapy. BJA Education, 17 (2):57–62.
- Calligaro G. et al. (2020) The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained setting: a multi-center prospective observational study. E Clinical Medicine 28:100570.
- Lyons, C & Callaghan, M. (2020). The use of high-flow nasal oxygen in COVID-19. Anaesthesia. 75(7): 843-847.
- Jackson, J et al (2021). Implementation of high-flow nasal cannula therapy outside the intensive care setting. Respiratory Care. 66(3): 357-365.
- Demoule, A et al. (2020). High-flow nasal cannula in critically iii patients with severe COVID-19. American journal of respiratory and critical care medicine.202(7):1039-1042.
- Rochwerg, B. et al. (2019). High flow nasal cannula compared with conventional oxygen therapy for acute hypoxemic respiratory failure: a systematic review and meta-analysis. Intensive Care Med. 45:563-572.
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