WHO REGIONAL OFFICE FOR AFRICA COVID-19 RAPID POLICY BRIEF SERIES
SERIES 2: COVID-19 CASE MANAGEMENT - INTERVENTION MEASURES
NUMBER 002-01: Effectiveness of different forms of oxygen therapy for COVID-19 management
Based on information as at 25 May 2020
Number 002-01: Effectiveness of different forms of oxygen therapy for COVID-19 management
WHO/AF/ARD/DAK/04/2020
© WHO Regional Office for Africa 2020
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RAPID POLICY BRIEF
1
NUMBER: 002-01
RESEARCH DOMAIN: COVID-19 Case management: Intervention measures
TITLE: Effectiveness of different forms of oxygen therapy for COVID-19 management RAPID POLICY BRIEF NUMBER: 002-01
1 RAPID POLICY BRIEF NUMBER: 002-01
2 RESEARCH DOMAIN: COVID-19 Case management: Intervention measures
3 TITLE: Effectiveness of different forms of oxygen therapy for COVID-19 management
4 DATE OF PUBLICATION: 03/06/2020
5 BACKGROUND
The 2019 Coronavirus Disease (COVID-19) presents in various forms, ranging from mild, moderate, severe or critical disease. Mild disease is associated with non-debilitating symptoms and no radiology features; moderate disease with fever, respiratory symptoms and radiological features;
severe disease with either tachypnoea or oxygen saturation <93% or PaO2/FiO2 >300 mg; and critical disease with respiratory failure, septic shock or multiorgan failure. Deaths occur amongst patients with severe or critical disease both of which are associated with acute hypoxemic respiratory failure. Several features have been suggested for the substantial hypoxemia seen in many patients [1]. These include pulmonary oedema, haemoglobinopathies, vascular occlusion, and a mismatch between ventilation and perfusion.
The available histopathology, however, shows diffuse alveolar damage [2] consistent with acute respiratory distress syndrome (ARDS), the pathology seen in patients with COVID-19 is very similar to established descriptions of ARDS. The use of ventilators to deliver oxygen in cases of severe and critical COVID-19 has been championed, though its use has remained controversial [3].
This rapid policy brief is focused on consolidating the evidence on appropriateness of different forms of oxygen therapy for the types of respiratory failure seen with COVID-19 patients.
6 SEARCH STRATEGY / RESEARCH METHODS
Three databases were searched: PUBMED, WHO COVID-19 and IRIS (WHO Institutional Repository for Information Sharing) employing search terms: (COVID-19 OR SARS-CoV-2) AND (Oxygen Inhalation Therapy).
We further identified relevant papers from the reference lists of key publications. We reviewed papers published from 1
stDecember 2019 to 25 May 2020. The initial search yielded 96 papers, 84 were excluded based on the review of titles and abstracts as these did not focus on our research area. Twelve publications were retained, and full texts were reviewed to produce this Rapid Policy Brief (RPB).
Search terms: COVID-19 OR SARS-CoV-2 in Africa AND Oxygen Inhalation Therapy= 96 results.
RAPID POLICY BRIEF NUMBER: 002-01
7 SUMMARY OF GLOBALLY PUBLISHED LITERATURE RELATED TO THE SUBJECT
The literature can be broadly classified in 2 areas: (1) who needs supplemental oxygen, and (2) what type of delivery mechanism is most effective.
There has been debate about focusing oxygen therapy on patients with dyspnea (shortness of breath), as a proxy for hypoxaemia (low Oxygen in the blood). However, hypoxaemia is a poor stimulus for dyspnea, and so is not a good measure – some patients with ARDS have been shown to tolerate higher levels of hypoxaemia with minimal associated dyspnea and vice versa . A recent randomized trial comparing liberal (target oxygen saturation ≥96%) and conserva tive (target 88- 92%) strategies for oxygen therapy in patients with ARDS was stopped early after it became clear that the conservative approach was unlikely to benefit patients and might cause harm [4]. Recent guidance recommends a target oxygen saturation of 92-96% in adults with covid-19, using supplemental oxygen as needed [5]. The focus for decision on oxygen therapy is the oxygen saturation, not dyspnea.
There are different ways Oxygen can be delivered, depending on the amount required. Common options beyond supplemental oxygen include use of high flow nasal cannula, non-invasive positive pressure ventilation, or early intubation. Issues of providing the patient with the right Oxygen needs need to be balanced against the need to protect healthcare workers from exposure to viral aerosols while providing optimal care, and what a given health system can feasibly provide.
Oxygen therapy is recommended for all severe and critical COVID-19 patients, with low doses ranging from 1-2 L/min in children and starting at 5 L/min in adults with nasal cannula, moderate flow rates for use with venturi mask (6-10 L/min); or higher flow rates (10-15 L/min) using a mask with reservoir bag. Higher flow rates and concentrations require use of high-flow nasal cannula (HFNC) devices, non-invasive ventilation (NIV) and invasive ventilation devices [6]. Compared with standard oxygen therapy, HFNC and NIV devices may reduce the need for intubation, which may be a consideration in settings where there is limited availability of mechanical ventilation [7].
Oxygen delivered through high flow nasal cannulas is beneficial in hypoxaemic respiratory failure [8] that can provide up to 60 L/min of nearly 100% oxygen. The risk of virus aerosols from this delivery method is probably low, [9], [10], although patient selection remains critical; those with moderate to severe hypoxaemia are unlikely to get enough oxygen through high flow nasal cannulas and will usually require intubation [11]. Stable patients with isolated mild to moderate hypoxaemia can be given oxygen through nasal cannulas but should be monitored carefully for signs of deterioration.
8 SUMMARY OF AFRICA-SPECIFIC LITERATURE ON THE SUBJECT
None identified
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NUMBER: 002-01
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TITLE: Effectiveness of different forms of oxygen therapy for COVID-19 management RAPID POLICY BRIEF NUMBER: 002-01
9 POLICY FINDINGS
▪ It is critical to have capacity to measure hypoxaemia levels as part of the Oxygen therapy, as this helps identify which patients require the different forms of Oxygen supplementation. This is easy in a large well equipped facility, but less so in smaller, more rural facilities
▪ There is significant value in use of Hyperbaric Oxygen Therapy (HBOT) particularly when hypoxaemia is still mild. This prevents the need for mechanical ventilation [12], which is associated with higher risk of aerosol infection of health workers.
▪ High Flow Nasal Oxygen Therapy (HFNOT) can be effectively used in patients with types I and II respiratory Failure. However, clinicians should be cautious identifying patients at risk of escalation of symptoms. Additionally, the capacity for provision of HFNOT is low in most countries of the region.
▪ The nasal device to provide the Oxygen supplementation depends on the amount of Oxygen needed
o Children require 1 – 6 L/minute which can be provided with a nasal cannula. Adults requiring up to 6-10L/min can also benefit from this.
o For needs above 6L per minute, a venturi mask is needed. This can be used up to a need of 10L per minute, but will need a reservoir bag if needs of up to 15L/min are needed.
o Above 15L per minute, then a mechanical device like a ventilator is needed to deliver oxygen above 15L per minute.
10 ONGOING RESEARCH IN THE AFRICAN REGION None identified
11 AFRO RECOMMENDATIONS FOR FURTHER RESEARCH
Additional areas for evidence in the region are varied, and include
- How to make oxygen therapy available in low resource settings, and in lower capacity health facilities. This is crucial, as many countries are functioning with limited Oxygen Supplementation approaches
- Ways to build capacity in use and management of the oxygen applications in the health institutions in the Region
- Outcomes from combining oxygen therapy with other management options specifically drugs
- Introduction of the provision of HNFOT in their essential health packages, given its
effectiveness in this and other similar situations causing types I and II respiratory failure
RAPID POLICY BRIEF NUMBER: 002-01
12
REFERENCES
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[3] Ieva Norkienė 1, Raquel d'Espiney 1, Juan F Martin-Lazaro.Effectiveness of High-Flow Nasal Oxygen Therapy in Management of Acute Hypoxemic and Hypercapnic Respiratory Failure. Acta Med Litu. 2019;26(1):46-50. doi:
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[3] Barrot L, Asfar P, Mauny F, et al., LOCO2 Investigators and REVA Research Network. Liberal or conservative oxygen therapy for acute respiratory distress syndrome. N Engl J Med2020; 382:999- 1008. doi:10.1056/NEJMoa1916431 pmid:32160661.
[4] 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 Med2020:1-34. [Epub ahead of print.]pmid: 32222812.
[5] Frat JP, Thille AW, Mercat A, et al., FLORALI Study Group, REVA Network. High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med2015; 372:2185- 96. doi:10.1056/NEJMoa1503326 pmid:25981908
[6] Rochwerg B, Brochard L, Elliott MW, et al. Official ERS/ATS clinical practice guidelines: Noninvasive ventilation for acute respiratory failure. Eur Respir J. 2017;50(4). doi:10.1183/13993003.02426-2016
[7] Susan R Wilcox, chief. Management of respiratory failure due to covid-19.
BMJ 2020; 369 doi: https://doi.org/10.1136/bmj.m1786; Division of Critical Care, Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
[8] Hui DS, Chow BK, Lo T, et al. Exhaled air dispersion during high-flow nasal cannula therapy versus CPAP via different masks. Eur Respir J2019; 53:1802339. doi:10.1183/13993003.02339- 2018 pmid:30705129
[9] Rello J, Pérez M, Roca O, et al., CRIPS investigators. High-flow nasal therapy in adults with severe acute respiratory infection: a cohort study in patients with 2009 influenza A/H1N1v. J Crit Care2012; 27:434-9.
doi: 10.1016/j.jcrc.2012.04.006 pmid:22762937
[10] Yufeng Luo, Rong Ou, Yun Ling, Tiehe Qin. The Therapeutic Effect of High Flow Nasal Cannula Oxygen Therapy for the First Imported Case of Middle East Respiratory Syndrome to China.
[11] Clinical management of severe acute respiratory infection (SARI) when COVID-19 disease is suspected;
Geneva: World Health Organization; 2020 (https://www.who.int/docs/default-source/coronaviruse/clinical - management-of-novel-cov.pdf, accessed 10 April 2020).
[12] Kerry Thibodeaux1, Marcus Speyrer1, Amer Raza2, Raphael Yaakov 3, Thomas E Serena3. Hyperbaric Oxygen Therapy in Preventing Mechanical Ventilation in COVID-19 Patients: A Retrospective Case Series.
PMID: 32412891. DOI: 10.12968/jowc.2020.29.Sup5a.S4
BRIEF PRODUCED BY: Jean Claude Nshimirimana, Humphrey Karamagi, Kwami Dadji, Regina Titi-Ofei, Aminata Wahebine-Benitou Seydi, Pascal Mouhouelo, Julie Nabyonga, Hillary Kipruto, James Asamani, Prosper Tumusiime, and Felicitas Zawaira.
