Respiratory Failure

##Ventilatory Failure

Work of breathing

Not synonymous with respiratory rate

Phasic contraction of sternocleinomastoid is most sensitive exam maneuver.

Think about the effect of deadspace (Vd/Vt) - increase will lead to an increased minute ventilation required to maintain a given pCO2.

Consider requirements (not necessarily hypercarbic, e.g. in DKA)

Why do we get short of breath in pneumonia? TODO

##Hypoxemic Respiratory failure

##Devices

Low flow = nasal cannula (no reservoir), simple face mask (no reservoir), oxymask/partial rebreather (no 1 way valve for co2 exhalation control)/non-rebreather (reservoir-based)

Note on Non-reserveroir devices, including NC: fio2 decreases when your total inspiratory rate (usually 25-40 lpm, 60-100 lpm in respiratory distress) is much faster than the device inspiratory rate (because you suck in room air)

Reservoir = when you breath faster, you bring in O2 from the bag. Idea is to control fio2 better.

Intermediate flow = venturi mask (controls entrainment of O2 by diameter of tube to give more control over FiO2)

High flow - Note: HFNC is O2 AND CO2 support. Also allows controlling fio2 because rate is fast enough that patient does entrain much air. The flow rate will help more with ventilation (never less than 30 min, 45-60 is most common).

NIPPV: titration similar to ventilator where RR+TV (controlled by IPAP - EPAP) = vent parameters, Fio2 and Mean airway pressure (primarily EPAP, as more of time is spent exhaling) control oxygenation.