Mechanical Ventilation for COVID-19
Airway resistance - correct answer the resistive forces encountered during the mechanical
respiratory cycle and is ≤5 cm H2O.
Lung compliance - correct answer describes the ease with which lungs stretch and expand to
accommodate a change in volume or pressure. People with high lung compliance have more
difficulty with the exhalation process while those with low compliance have difficulty with
inhalation.
Derecruitment - correct answer the loss of gas exchange surface area due to atelectasis. It can be
minimized by increasing PEEP.
Recruitment - correct answer the restoration of gas exchange surface area by applying pressure
Initiation phase - correct answer the start of the mechanical breath, whether triggered by the
patient or the machine.
Inspiratory phase - correct answer the portion of mechanical breathing during which there is a
flow of air into the patient's lungs to achieve a maximal pressure, the peak airway pressure (PIP or
Ppeak), and a tidal volume (TV or VT).
Plateau phase - correct answer does not routinely occur in mechanically ventilated breaths but
may be checked as an important diagnostic maneuver to assess the plateau pressure (Pplat). With
cessation of air flow, the plateau pressure and the tidal volume (TV or VT) are briefly held
constant.
Exhalation - correct answer a passive process in mechanical breathing. The start of the exhalation
process can be either volume cycled (when a maximum tidal volume is achieved), time cycled (after
a set number of seconds), or flow cycled (after achieving a certain flow rate).
Peak inspiratory pressure - correct answer the maximum pressure in the airway at the end of the
inspiratory phase. Since this value is generated during a time of airflow, the PIP is determined by
both airway resistance and compliance. By convention, all pressures in mechanical ventilation are
reported in "cm H2O." It is best to target a PIP <35 cm H2O.
Plateau pressure - correct answer the pressure that remains in the alveoli during the plateau phase,
during which there is a cessation of air flow, or with a breath-hold. To calculate this value, the
clinician can push the "inspiratory hold" button on the ventilator. The plateau pressure is
effectively the pressure at the alveoli with each mechanical breath and reflects the compliance in
the airways. To prevent lung injury, the Pplat should be maintained at <30 cm H2O.
Positive end-expiratory pressure (PEEP) - correct answer the positive pressure that remains at the
end of exhalation. This additional applied positive pressure helps prevent atelectasis by preventing
the end-expiratory alveolar collapse. PEEP is usually set at 5 cm H2O or greater, as part of the
