Lung mechanics in type L CoVID-19 pneumonia: a pseudo-normal ARDS

Hypoxaemia in the early stage of COVID-19: prevalence of physical or biochemical factors?

We read with interest the reply from Busanaet al. [1] to our correspondence [2]. We fully agree with the authors and with the cited references [3–6] stating that the affinity of haemoglobin (Hb) for oxygen (O₂) is not affected in the arteries or in the veins of coronavirus disease 2019 (COVID-19) patients. The confusion arises as our concept is based on the biochemical shunt due to the quaternary conformational change of Hb with a temporary decrease of Hb–O₂ affinity, which is applicable only to the affected alveolar-capillary bed.

The ventilation–perfusion mismatch can't explain the high P_aCO2–P_ETCO2 gap in the setting of COVID-19 induced hypoxaemia and cannot be considered as the sole pathophysiological basis for the treatment in the early stage of COVID-19https://bit.ly/3BKmGxJ

COVID-19: positive experience with differentiated tactics of mechanical ventilation of the lungs for different phenotypes (L-phenotype)

RELEVANCE

Studies have previously been published on a possible differential approach to respiratory therapy in patients with COVID-19 depending on the L- or H-phenotype.The authors believe that early tracheal intubation reduces the risk of lung injury. The use of deep sedation and low PEEP (6-8 cmH₂O) and early intubation may prevent transition to type H.

METHOD AND RESULTS

Eleven patients with COVID-19 type L pneumonia received respiratory support based on the proposed guidelines. Eight women and three men (ages 45 to 84) with COVID-19 type L pneumonia were treated in the intensive care unit. Did they all receive oxygen therapy up to 15 L/min. high-flow oxygen therapy up to 60 L/ min, non-invasive ventilation of the lungs. If it was impossible to reduce FiO₂ from 100 to 75% within 2-3 h or if the patient was intolerant to NIV, early tracheal intubation was used.The minute ventilation volume was set to maintain CO₂ <60 mmHg. and pH>7.25 in venous blood. Sedation was performed by intravenous titration of fentanyl and propofol. If deeper sedation was required to synchronize the patient to the ventilator, intravenous muscle relaxants were used over 24-48 hours (bolus or intravenous titration) instead of sedation.

CONCLUSION

All 11 patients were successfully weaned from the mechanical ventilation of the lungs. A differentiated approach to respiratory therapy for COVID-19 L-type pneumonia proved to be an effective approach in these patients.It is probably worth avoiding deep sedation of patients on mechanical ventilation with L-type pneumonia, which would reduce the time spent on mechanical ventilation and reduce the risk of mortality from nosocomial bacterial infection.The new MVL strategy for L-type pneumonia and the problem of deep sedation require more research. But the available data suggests that it probably has benefits.

Ventilation/perfusion mismatch is not the sole reason for hypoxaemia in early stage COVID-19 patients

It was a pleasure reading the work of Gattinoniet al. [1] dedicated to the pathophysiological mechanisms of hypoxaemia observed in coronavirus disease 2019 (COVID-19) patients. The authors recommend treating the hypoxaemia observed in the early stages of COVID-19 based on ventilation/perfusion (Vʹ_A/Qʹ) mismatch.

The transformation of alveolar microcirculation to a peripheral circulation type in COVID-19 patients leads to important decreases in haemoglobin–oxygen affinity and provokes biochemical shunthttps://bit.ly/3jE53pe

It is time to update the ARDS definition: It starts with COVID-19-induced respiratory failure

Coronavirus disease 2019 (COVID-19) may rapidly worsen respiratory failure, thereby leading to death. COVID-19-induced respiratory failure exhibits some atypical characteristics, silent hypoxemia, and high lung compliance. Some histopathological changes associated with COVID-19-induced respiratory failure differ from those of classic acute respiratory distress syndrome (ARDS). However, compared with classical ARDS, COVID-19-induced respiratory failure has a similar timing of onset, clinical syndromes, radiological profile, and mortality rate in the intensive care unit (ICU). Respiratory failure induced by COVID-19 is a type of ARDS and is currently underdiagnosed. This condition stretches the definition of classic ARDS; therefore, an updated definition is warranted.