Blog

woman

Acute Respiratory Distress Syndrome During the COVID-19 Pandemic

The infection due to SARS‐CoV‐2 can be confirmed by the positive detection of the presence of the viral RNA in the nasopharyngeal secretions with the help of the specific PCR test. The COVID‐19 infection is often confirmed by the history of epidemiological contact, consistent clinical presentation, and a positive result of the SARS‐CoV‐2 test.

Acute Respiratory Distress Syndrome during (ARDS) is diagnosed in patients with a confirmed COVID‐19 infection when they meet the diagnostic criteria recommended by the Berlin 2012 ARDS, which includes the following symptoms:

  1. Acute hypoxemic respiratory failure
  2. Presentation with the worsening of the respiratory symptoms within 1 week
  3. Bilateral airspace disease detected on the chest x‐ray, ultrasound, and computed tomography (CT) which is not fully explained by lobar or pulmonary collapse, effusions, or nodules
  4. Cardiac failure not being the primary cause of the acute hypoxemic respiratory failure.

ARDS is often underdiagnosed in the intensive care settings. It develops in nearly 42% of patients who present with COVID‐19 pneumonia, and nearly 61 to 81% of patients who require intensive care.

COVID‐19 ARDS has been found to follow a predictable course over a few days, with the median time to intubation of about 8.5 days after the onset of the symptoms. This pattern is similar to the previous reports wherein ARDS was found to develop on days 8 or 9 after the onset of the symptoms.

Therefore, it is important to monitor the patients for the signs of ARDS as their symptoms of COVID‐19 infection progress. The SpO2 and respiratory rate are 2 important parameters to be monitored for assessing the patients’ clinical condition and allowing early diagnosis of ARDS.

Patients who fit into any 1 of the following conditions might have a severe disease that requires further evaluation. The conditions include having a respiratory rate more than or equal to 30 breaths per min; SpO2 less than or equal to 92%, and FiO2/PaO2 less than or equal to 300 mm of Hg.

Some blood tests may also be helpful for the early diagnosis of ARDS. It is noted that the elevated C‐reactive protein level and blood neutrophil count together with lymphopeniaare more common in patients who require invasive mechanical ventilation for the management of COVID‐19 ARDS.

These factors need to be assessed for the early diagnosis of ARDS in COVID-19 patients. You can attend our respiratory webinars to learn more about the early diagnostic signs of ARDS and the most effective interventional strategies to treat the patients.

Lung pathology in COVID-19 ARDS

COVID‐19 ARDS is found to cause the typical pathological changes linked to ARDS such as diffuse alveolar damage. It is found to cause diffuse alveolar damage in the pulmonary tissues. The formation of the hyaline membrane is noted in the alveoli during the acute stage. This is often followed by the interstitial widening and edema. Fibroblast proliferation is noted in the organizing stage o ARDS.

As the patients progress through the course of the illness, the long-term outcomes of ARDS such as lung fibrosis are also being reported. One study has reported that nearly 17% of patients develop stripes of fibrous tissues in the chest CT scans. It was considered that the fibrotic lesions may form in the tissues during the healing of the pulmonary chronic inflammatory or proliferative stages, with the slow replacement of the cellular components by the development of scar tissues.

Thrombotic events

Pulmonary thrombosis is one of the common features in patients with sepsis‐associated ARDS. The dysfunctions related to coagulation appear to be more common in COVID‐19 patients. It is detected by the elevated levels of D‐dimer in the blood.

In some fatal cases, there may be diffuse microvascular thrombosis, indicating a thrombotic microangiopathy. Most deaths linked to COVID‐19 ARDS have had an evidence of the development of the thrombotic disseminated intravascular coagulation. This might explain some of the unexpected and atypical manifestations noted in the lung, like the dilated pulmonary vessels on the chest CT, and the episodes of pleuritic discomfort or pain.

Vascular enlargement has also been reported, though rarely, in patients with typical ARDS.

Mortality risk

The risk of mortality linked to ARDS in patients with COVID‐19 appears to behigher than that of the ARDS linked to other causes. The hospital and intensive care unit mortality due to typical ARDS is 40.0% and 35.3%, respectively. In COVID‐19 ARDS patients, the mortality has been found to be between 26% and 61.5% of cases, in those who were admitted to the critical care settings. In patients who were provided mechanical ventilation, the mortality was found to be between 65.7% and 94% of cases.

The risk factors for the poor outcomes are older age, the presence of comorbidities like cardiovascular diseases, hypertension, and diabetes, a lower lymphocyte count, renal injury, and increased D‐dimer levels.

The risk of death due to COVID‐19 ARDS is linked to respiratory failure, respiratory failure with cardiac failure, circulatory failure, myocardial damage, or death due to an unknown cause. Our AARC approved CEU’s are aimed at training doctors about the factors that can worsen the prognosis and the most effective treatments to improve the chances of recovery in patients with ARDS.

Management of ARDS

Other than antiviral therapy, the strategy of providing breathing support has been found to be effective in the management of COVID‐19 ARDS.

The key elements for providing the breathing support include:

  • Prone ventilation
  • Use oxygen by nasal cannulae for achieving SpO2 more than 92%
  • Avoidance of the non‐invasive ventilation
  • High-flow nasal oxygen depending on the treatment location
  • Extracorporeal membrane oxygenation

Adjunct treatment such as the use of high-dose corticosteroids, continuous neuromuscular blocking agents, and recruitment manoeuvers might help to improve the prognosis.

Conclusion

Early diagnosis of ARDS is critical for reducing the risk of mortality in COVID-19 patients. Doctors and other medical professionals can attend our respiratory therapy CEU to learn more about the latest guidelines for the treatment of ARDS in COVID-19 patients.

Our respiratory therapy conferences are aimed at educating healthcare professionals about the most effective ways to manage COVID-19 ARDS to help them improve the treatment outcomes and reduce the incidences of mortality linked to this condition.