Template:COVID-19 Lung Phenotypes

Hypoxemic patients can be divided into two general phenotypes[1]

COVID L Lung Phenotype

  • Characterized by Low elastance (i.e., high compliance), Low ventilation to perfusion ratio, Low lung weight and Low recruitability
  • Often referred to as the “happy hypoxemic”
  • Normal lung volumes and low lung recruitability.
  • Hypoxemia may be due to loss of regulation of perfusion and loss of hypoxic vasoconstriction.
  • These patients can be damaged iatrogenically if you respond to their pulse ox with standard vent modes
  • Do poorly with low tidal volume (TV) and high PEEPs
  • Best managed with high FiO2 which allows you to limit the PEEP
  • Recommended initial vent settings:
    • 8 ml/kg TV, 100% FiO2
    • Increase the PEEP only if the patient is desaturating on a high FiO2.
    • Can turn into COVID H patients on the vent.

COVID H Lung Phenotype

  • Characterized by High elastance, High right-to-left shunt, High lung weight and High recruitability.
  • Increased permeability of the lung leads to edema, atelectasis, decreased gas volume, and decreased TV for a given inspiratory pressure.
  • High degree of lung recruitability.
  • 20 – 30% of patients fit ARDS criteria:
    • Hypoxemia
    • Bilateral infiltrates
    • Decreased the respiratory system compliance
    • Increased lung weight and potential for recruitment
  • The ARDS ladder applies only to this subset of COVID patients.
  • Gattinoni L et al. Covid-19 pneumonia: different respiratory treatment for different phenotypes. Intensive Care Medicine. 2020. https://www.esicm.org/wp-content/uploads/2020/04/684_author-proof.pdf