Pulmonary Disorders I

respiratory rate and tidal volume plus additional spontaneous, self-generated breaths at whatever tidal

volume they can generate. Not ideal for the treatment of ARDS, given patients’ ability to exceed the

present tidal volume for spontaneous breaths in excess of 6 mL/kg

PS ventilation

Usually used as a weaning mode of MV from a more intensive mode of MV (i.e., AC ventilation)

The patient initiates each breath with assistance from the ventilator in the form of a preset pressure

value. The ventilator is set to provide a correct amount of pressure to assist with each inspiratory

effort. The tidal volume and respiratory rate depend on the patient.

Fio2

Amount of oxygen that is delivered with each breath, from 21% to 100% at sea level

Fio2 is generally tapered to provide the minimal oxygenation needed to meet patient needs. Concerns

for oxygen toxicity with high Fio2 requirements over prolonged period

Volume of air inspired in a breath (delivered by MV or spontaneously)

Set according to oxygenation and ventilation requirements. Patients with ARDS are treated with a

low tidal volume strategy.

Respiratory rate

Set to provide a minimal number of breaths from the ventilator at the set tidal volume

Titrated by minute ventilation, Paco2, and pH. Minute ventilation (liters per minute) = tidal volume

(liters) × respiratory rate (breaths/minute).

Flow rate

Velocity of air delivered

Velocity is greatest initially upon inspiration and decelerates toward the end of the inspiratory effort.

PEEP

Positive pressure in the alveoli during expiration

Pressure at the end of expiration promotes alveoli recruitment while minimizing the risk of collapse

in ARDS.

Titrated with Fio2 to provide the minimum necessary support to meet the patient’s oxygenation

requirements

Value

Normal Range

Tidal volume (mL/kg)

5–10

Respiratory rate (breaths/min)

12–20

Minute ventilation (L/min)

5–10

Paco2 (mm Hg)

35–45

Pao2 (mm Hg)

80–100

Sao2 (%)

95–100