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| EDITORIAL |
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| Year : 2022 | Volume
: 2
| Issue : 2 | Page : 47-48 |
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Oxygen therapy – What managing COVID 19 has taught us!
Kiran Vishnu Narayan
Department of Pulmonary Medicine, Government Medical College, Thiruvananthapuram, Kerala, India
| Date of Submission | 28-Mar-2022 |
| Date of Acceptance | 07-Apr-2022 |
| Date of Web Publication | 17-May-2022 |
Correspondence Address:
Dr. Kiran Vishnu Narayan
Department of Pulmonary Medicine, Government Medical College, Thiruvananthapuram - 695 011, Kerala
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/jalh.jalh_13_22
How to cite this article:
Narayan KV. Oxygen therapy – What managing COVID 19 has taught us!. J Adv Lung Health 2022;2:47-8 |
COVID-19 disease by the novel coronavirus (SARS-COV-2) was first reported on November 17, 2019, in Wuhan, China. Exploding into a global health emergency, it was declared a pandemic by the World Health Organization on March 11, 2020. Globally, it affected approximately 23.9 crore people with nearly 48.7 lakh deaths (2.03%). The first wave claimed high mortality globally.[1],[2]
Unfortunately, the second wave hit a predominantly unaffected unvaccinated high-risk Indian population with a vengeance. Most of the hospitals were overloaded with sick hypoxemic patients with the exhaustion of the oxygen supplies at hospitals. Supplemental oxygen was the life quencher. Although life-saving devices such as mechanical ventilators and noninvasive ventilators were being mass-produced by startup firms, rapid clinical experience, and quickly released preprint reviews proved that hypoxemic COVID patients on ventilators had higher mortality.[3],[4]
Next came the short era of the new kid on the block, “Heated Humidified High-Flow Nasal Cannula” (HHHFNC), but progression to higher forms of respiratory support and exhaustion of oxygen stores in most of the hospitals made it clear that HHHFNC was also uneconomical in terms of oxygen stores.[5] Left with venturi masks and nonrebreathing masks (NRBMs) to satisfy the oxygen thirst of hyperpneic patients, combinations of nasal prongs with noninvasive ventilators turned out practically to be the best bet for severely hypoxemic patients, and NRBMs for the moderately hypoxemic. Awake self-proning along with the oxygen devices had also shown to lower the rate of treatment failures in terms of a combined outcome of reduced reintubation or death at 28 days compared with patients who did not undergo pronation (40 versus 46%; relative risk of 0.86).[6]
In this issue, Dash et al. provide a retrospective analysis of the utility of NRBM in moderate-to-severe hypoxemic COVID-19 pneumonia.” About 1876 moderate-to-severe hypoxemic patients of 5024 polymerase chain reaction confirmed COVID-19 patients who were on NRBM were analyzed in the study. About 90.77% of the patients recovered well without any further deterioration on NRBM in their analysis. Among 9.3% of the NRBM failures, escalation to noninvasive support, a high flow nasal cannula, and invasive ventilation were seen in 6.92%, 0.74%, and 1.54%, respectively, as anticipated in clinical experience. Although NRBM is useful during the early stages of hypoxemia, it fails in most patients with air hunger and high inspiratory flow requirements with tachypnea (respiratory rate more than 30). NRBMs, which have an additional one-way valve, prevent room air entrainment and rebreathing of exhaled gases. It can deliver FiO2 above 0.8, provided there is a good mask fit, and oxygen airflow is more than three times of minute ventilation. However, in the event of high inspiratory demand, a feeling of suffocation can result due to a lack of air entrainment. They also outline that NRBMs have the lowest risk of aerosol dispersion with a maximum exhaled air distance of <0.1 mts at 10 LPM.[7] Wearing a surgical mask over an oxygen mask further reduces the aerosol dispersion and, in addition, may also appreciably increase the end-tidal oxygen concentration.[8]
Moreover, we must be reminiscent of the fact that too much oxygen is also not good in terms of hyperoxia-induced lung injury. A close titration of supplemental oxygen to keep a target peripheral oxygen saturation of >94% during initial resuscitation and >90% for maintenance oxygenation has been suggested by the World Health Organization. A smaller target may be alarming, as levels below 90% correspond to a steeper drop in PaO2 between 40 and 60 mm Hg because of the sigmoid shape of the oxyhemoglobin dissociation curve.
The pandemic has given us new life lessons in terms of oxygen conservation and oxygen titration. Research of different kinds is needed to identify if hyperoxia is also a reason for the post-COVID diffuse parenchymal lung disease. The selection of different oxygen devices in future will depend on the clinical condition of the patient, the availability of round-the-clock monitoring to provide titrated oxygen supply, the oxygen stores available at the institution, and the risk of aerosolization to health-care workers and patients.
| References | |  |
| 1. | Docherty AB, Mulholland RH, Lone NI, Cheyne CP, De Angelis D, Diaz-Ordaz K, et al. Changes in in-hospital mortality in the first wave of COVID-19: A multicentre prospective observational cohort study using the WHO Clinical Characterisation Protocol UK. Lancet Respir Med 2021;9:773-85.  |
| 2. | Jarrett SA, Lo KB, Shah S, Zanoria MA, Valiani D, Balogun OO, et al. Comparison of patient clinical characteristics and outcomes between different COVID-19 peak periods: A single center retrospective propensity matched analysis. Cureus 2021;13:e15777. |
| 3. | Bhatraju PK, Ghassemieh BJ, Nichols M, Kim R, Jerome KR, Nalla AK, et al. COVID-19 in critically ill patients in the Seattle Region – Case series. N Engl J Med 2020;382:2012-22. |
| 4. | Zhou F, Yu T, Du R, Fan G, Liu Y, Liu Z, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: A retrospective cohort study. Lancet 2020;395:1054-62. |
| 5. | Wang K, Zhao W, Li J, Shu W, Duan J. The experience of high-flow nasal cannula in hospitalized patients with 2019 novel coronavirus-infected pneumonia in two hospitals of Chongqing, China. Ann Intensive Care 2020;10:37. |
| 6. | Ehrmann S, Li J, Ibarra-Estrada M, Perez Y, Pavlov I, McNicholas B, et al. Awake prone positioning for COVID-19 acute hypoxaemic respiratory failure: A randomised, controlled, multinational, open-label meta-trial. Lancet Respir Med 2021;9:1387-95. |
| 7. | Dash T, Tipparapu K, Vikram Singh S, Roy K. A retrospective observational study of utility of Non-rebreathing mask (NRBM) in moderate to severe hypoxemic COVID-19 pneumonia. 2022;2:59-64. |
| 8. | Brown-Beresford K, Currie J, Thiruvenkatarajan V. The application of a surgical face mask over different oxygen delivery devices; a crossover study of measured end-tidal oxygen concentrations. BMC Anesthesiol 2022;22:62. |
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