The Use of High Flow Nasal Cannula and Awake Prone - positioning in COVID - 19 Pneumonia in a Caribbean setting: A Case Series and Review of the Literature

COVID - 19 is associated with acute hypoxaemic respiratory failure and an ARDS like presentation. Traditional management generally involves the use of endotracheal intubation and mechanical ventilation. This approach can lead to significant resource consumption with the potential for patient morbidity. High Flow Nasal Cannula (HFNC) and prone ventilation can be used as alternative approaches. We present the successful use of this approach in three (3) COVID - 19 cases. All patients had multiple co - morbidities and were older than 50 years. Two patients were classified as having severe ARDS. All patients had improved oxygenation after 4 hours of proning and throughout their course. All three cases were successfully discharged from the ICU. No complications were reported from proning. High Flow Nasal Cannula (HFNC) and awake pronation can be an effective modality in COVID - 19 pneumonia.

year age groups as 76.4% and 97.2% respectively. 3 High Flow Nasal Cannula (HFNC) is a relatively new modality where a high concentration of humidified oxygen can be delivered safely and comfortably to patients. It also has the potential to prevent the need for intubation and mechanical ventilation. Initial international experience using this modality in COVID-19 has been promising so far. 4 Additionally, prone ventilation, a known adjunct used to improve oxygenation in ARDS can also be combined with HFNC. Although research is underway on the combined use of these modalities, no large-scale trial data exists.
We present three consecutive cases where prone CASE REPORT DOI: 10.48107/CMJ.2020. 12.004 Copyright: This is an open access article under the terms of the Creative Commons Attribution License which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
CMJ | Published online on December 12th, 2020 2 ventilation was successfully combined with the use of HFNC. The current evidence on the role of HFNC and prone ventilation is also discussed. On admission to ICU, patients were immediately placed on HFNC with a starting flow rate of 60 L/min and the estimated fraction of the inspired oxygen concentration (FIO 2 ) ranging between 85-95%, and subsequently weaned to maintain a SpO 2 of 91-96%. Additionally, awake proning was commenced using the 'roast pig technique' as described by the Intensive Care Society. 5 Patients spent a period of four hours in the prone position, then alternated with the lateral position for two hours, followed by a period of 30 minutes to one hour in the supine position and the cycle was repeated. All patient-position changes were made during the day, while the patients remained either supine or lateral during night. All patients were able to position themselves without assistance and tolerated the positioning well.     Recent evidence suggests that early awake proning with HFNC may avoid intubation in patients with moderate to severe ARDS. 13 Preliminary data in COVID-19 patients also suggest that awake proning and HFNC improves oxygenation and reduces need for intubation and mortality rates. In a small, single-centre cohort study it was found that prone positioning with HFNC improved oxygenation in COVID-19 severe hypoxemic respiratory failure. This study also found that patients with a SpO 2 of 95% or greater after one hour of proning was associated with a lower incidence of intubation. 14 With evidence being limited to case series and small observational studies, questions still need to be answered surrounding the efficacy of awake proning in both ARDS and COVID-19 hypoxaemic respiratory failure.

CASE SERIES
Further research with high quality RCTs is warranted to assess the benefits and risks, as well as the patient population which benefits the most. 15 There is also limited data regarding the optimal awake proning and HFNC regime in COVID-19 patients. The COVAYDE trial is currently underway to provide more information on the benefit of awake proning and HFNC in severe COVID-19 infections. 16 Negative aspects of HFNC in the treatment of COVID-19 hypoxemic respiratory failure include failure and need for intubation with a severely decompensated patient and the potential risk of infection with aerosolization.
A challenge exists in identifying patient characteristics that will predict HFNC failure and ensure intubation is not delayed. Vianello et al. found that a PaO 2 /FiO 2 < 100 was associated with an increased risk of HFNC failure. 10 The recently described ROX index is defined as the ratio of RCTs are warranted to evaluate the use of HFNC and awake proning in COVID-19 patients.

CONCLUSION
We report the successful use of HFNC and pronepositioning to avoid endotracheal intubation in all 3 patients in our case series. HFNC together with proning was well tolerated and safe to staff and patients. HFNC combined with awake self-proning has the potential to be a cost-effective and efficacious treatment option that should be investigated further in larger trials.