Ventilation in ARDS

HPI: This 34 yo male patient presented s/p MVC with femur fracture and acute blood loss requiring 3 units of pRBCs peri-operatively. 2 hours after the patient returns from the OR to the floor, he becomes acutely hypoxic to 73% on NRB. CXR is shown. He is transferred to the MICU and intubated for acute hypoxic respiratory failure with a PaO2:FiO2 of 73.

Patient Ht: 5’8”; Weight: 200lb (90 kg) ; Ideal Body Weight: 148 lb (67kg)

His initial gas: 7.20 / 65 / 73 on NRB

His most recent gas: 7.30 / 52 / 74 on 70% FiO2

His current vent settings: VC/AC — FiO2 70% / TV 600 / PEEP 8 / RR 14

In this setting, you should decrease the Tidal Volume (TV) to 402 (IBW x 6 ml/kg). In ARDS, your goal TV is 4-6 ml/kg to prevent barotrauma from noncompliant lungs. . The lung is full of fluid non-cardiogenic edema from inflammation, this severely decreases the compliance of the lungs. “Normal” lung volumes would necessitate high filling pressures to inflate the diseased alveoli. However, ARDS is not a homogenous process and some alveoli are normal – when subjected to high pressures they get barotrauma.

ARDS #GOALS

Lung Protective Vent Settings:

TV 4-6 ml/kg of IBD

Plateau Pressure <30

Permissive Hypercapnia with goal pH >7.25

Oxygenation Goals: PaO2 55-80; SpO2 88-92%

*** Achieved with alteration in FiO2 and PEEP

***Additional tactics include Proning and inhaled NO