How might categorizing severity of illness help in the management of my patient with Covid-19?

Although the criteria for Covid-19 severity of illness categories may overlap at times or vary across guidelines and clinical trials, I have found those published in the National Institute of Health (USA) Covid-19 Treatment Guidelines most useful and uptodate.1  Keep in mind that the primary basis for severity categories in Covid-19 is the degree by which it alters pulmonary anatomy and physiology and respiratory function (see my table below).

The first question to ask when dealing with Covid-19 patients is whether they have any signs or symptoms that can be attributed to the disease (eg, fever, cough, sore throat, malaise, headache, muscle pain, lack of sense of smell). In the absence of any attributable symptoms, your patient falls into “Asymptomatic” or “Presymptomatic” category.  These patients should be monitored for any new signs or symptoms of Covid-19 and should not require additional laboratory testing or treatment.

If symptoms of Covid-19 are present (see above), the next question to ask is whether the patient has any shortness of breath or abnormal chest imaging. If neither is present, the illness can be classified as “Mild” with no specific laboratory tests or treatment indicated in otherwise healthy patients. These patients may be safely managed in ambulatory settings or at home through telemedicine or remote visits. Those with risk factors for severe disease (eg, older age, obesity, cancer, immunocompromised state), 2 however, should be closely monitored as rapid clinical deterioration may occur.

Once lower respiratory tract disease based on clinical assessment or imaging develops, the illness is no longer considered mild. This is a good time to check a spot 02 on room air and if it’s 94% or greater at sea level, the illness qualifies for “Moderate” severity. In addition to close monitoring for signs of progression, treatment for possible bacterial pneumonia or sepsis should be considered when suspected. Corticosteroids are not recommended here and there are insufficient data to recommend either for or against the use of remdesivir in patients with mild/moderate Covid-19.

Once spot 02 on room air drops below 94%, Covid-19 illness is considered “Severe”; other parameters include respiratory rate >30, Pa02/Fi02 < 300 mmHg or lung infiltrates >50%. Here, patients require further evaluation, including pulmonary imaging, ECG, CBC with differential and a metabolic profile, including liver and renal function tests. C-reactive protein (CRP), D-dimer and ferritin are also often obtained for their prognostic value. These patients need close monitoring, preferably in a facility with airborne infection isolation rooms.  In addition to treatment of bacterial pneumonia or sepsis when suspected, consideration should also be given to treatment with corticosteroids. Remdesivir is recommended for patients who require supplemental oxygen but whether it’s effective in those with more severe hypoxemia (eg, those who require oxygen through a high-flow device, noninvasive or invasive mechanical ventilation or extracorporeal membrane oxygenation-ECMO) is unclear. Prone ventilation may be helpful here in patients with refractory hypoxemia as long as it is not used to avoid intubation in those who otherwise require mechanical ventilation.

“Critical” illness category is the severest forms of Covid-19 and includes acute respiratory distress syndrome (ARDS), septic shock, cardiac dysfunction and cytokine storm. In addition to treatment for possible bacterial pneumonia or sepsis when suspected, corticosteroids and supportive treatment for hemodynamic instability and ARDS, including prone ventilation, are often required. The effectiveness of remdesivir in patients with severe hypoxemia (see above) is unclear at this time.

 

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 References

  1. NIH COVID-19 Treatment Guidelines. https://www.covid19treatmentguidelines.nih.gov/. Accessed Aug 27, 2020.
  2. CDC. Covid-19.  https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medical-conditions.html/. Accessed Aug 27, 2020.  

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

 

How might categorizing severity of illness help in the management of my patient with Covid-19?

What is the role of prone ventilation in patients with Covid-19 and ARDS?

A 2017 guideline strongly recommends the use of prone ventilation for 12+ hours daily in individuals with severe ARDS (1). A JAMA article gave similar recommendations for critically ill patients with COVID-19 (2).

The recommendations are often based on a NEJM 2013 randomized-controlled study involving 466 patients with severe ARDS (3). While previous research had demonstrated improved oxygenation in the prone position (4), this study demonstrated a significant survival benefit (3).  Mortality at 28 days was 16.0% in prone patients versus 32.8% in supine patients (p<0.001; HR 0.39 with 95% CI, 0.29 – 0.67) (3). Mortality was also lower in prone patients at 90 days (3).  A meta-analysis of 4 additional randomized-controlled trials confirmed the survival benefits (1). 

In patients with Covid-19 and ARDS, a small retrospective study involving 12 patients showed a significant association between prone positioning and lung recruitability (ie, lung tissue in which aeration can be restored) (p = 0.020) (5).

Physiologically, numerous mechanisms have been proposed for these findings, including the possbility that while blood flow consistently favors the dorsal alveoli regardless of position, the prone position allows dorsal alveoli to reopen, improving ventilation/perfusion matching (6). 

Of note, some institutions find difficulties with prone positioning, including higher rates of pressure sores and endotracheal tube obstruction (1).

 

Contributed by Grant Steele, Harvard Medical Student, Boston, MA.

 

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References:

1. Fan E, Del Sorbo L, Goligher E, et al. An official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline: mechanical ventilation in adult patients with acute respiratory distress syndrome.” Am J Respir Crit Care Med 2017;195:1253-1263. https://www.atsjournals.org/doi/abs/10.1164/rccm.201703-0548ST 
2. Murthy S, Gomersall C, & Fowler R. Care for critically ill patients with COVID-19. JAMA – Published online March 11, 2020. doi:10.1001/jama.2020.3633 https://jamanetwork.com/journals/jama/fullarticle/2762996
3. Guérin C, Reignier J, Richard J-C, et al. Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 2013;368:2159-2168. https://www.nejm.org/doi/full/10.1056/nejmoa1214103
4. Abroug F, Ouanes-Besbes L, Elatrous S, et al. The effect of prone positioning in acute respiratory distress syndrome or acute lung injury: a meta-analysis. Areas of uncertainty and recommendations for research. Intensive Care Medicine – Published online March 19, 2008. doi: 10.1007/s00134-008-1062-3 https://link.springer.com/article/10.1007/s00134-008-1062-3
5. Pan C, Chen L, Lu C, et al. Lung Recruitability in SARS-CoV-2 Associated Acute Respiratory Distress Syndrome: A Single-center, Observational Study. Am J Respir Crit Care Med – Published online March 23, 2020. doi: 10.1164/rccm.202003-0527LE. https://www.atsjournals.org/doi/pdf/10.1164/rccm.202003-0527LE 
6. Nyrén S, Mure M, Jacobsson H, et al. Pulmonary perfusion is more uniform in the prone than in the supine position: scintigraphy in healthy humans. J Appl Physiol 1999;86:1135-1141. https://www.physiology.org/doi/abs/10.1152/jappl.1999.86.4.1135

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What is the role of prone ventilation in patients with Covid-19 and ARDS?