Template:COVID-19 Lung Phenotypes
Hypoxemic patients can be divided into two general phenotypes
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:
- 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.