Oxygen Delivery Devices theyre not what you think

Oxygen Delivery Devices they’re not what you think

Indications for oxygen use · · · Low ambient O 2 Hypoxemia Suspected hypoxemia · Increased work-of-breathing · Flaring · Tachypnea · Increased myocardial work · Acute head injury

O 2 delivery systems · High-flow · Venti-masks (air entrainment masks) · Mechanical aerosol systems · High-flow humidifier systems · Low-flow · Nasal cannula · Simple masks · Partial rebreathing masks · Non-rebreathing masks

Entrainment ratios

Delivered Fi. O 2 with low-flow

What’s my Pa. O 2? · · · a: b: c: On room air? On 0. 50 Fi. O 2? On 0. 80 Fi. O 2?

The answers: Pa. O 2 = Fi. O 2 x (barometric pressure water vapor pressure) - Pa. CO 2/RQ Pa. O 2 = Fi. O 2 X (760 - 43) - Pa. CO 2/0. 8 a: Pa. O 2 =. 21 X 713 - 40/0. 8 = 100 b: Pa. O 2 =. 50 X 713 - 40/0. 8 = 306 c: Pa. O 2 =. 80 X 713 - 40/0. 8 = 520

% Sat O 2 Hgb dissociation curve PO 2 mm. Hg

Resorption atelectasis 100% O 2 nitrogen oxygen A B PO 2 =673 PCO 2 = 40 PH 2 O = 47 After ~15 minutes, blood N 2 is depleted. Poorly ventilated & well perfused units (A) become atelectactic.

Non-rebreathing system Room air Gas source Expiratory gas Reservoir To patient One way valves

Air entrainment devices exhaled gas oxygen room air

O 2 Hgb dissociation curve shift % Sat ¯ p. H CO 2 temp PO 2 mm. Hg

What happens to your p. O 2 and sats when your p. H changes? ph = 7. 4, p. O 2 = 100, sat 96% ph = 7. 0, p. O 2 = ? , sat = ?

Oxygen delivery = # trucks X how full they are loaded X how fast they go DO 2 = 1. 38(hgb X sat X CI) + (p. O 2 X 0. 003)

Entrainment ratios

Estimating Fi. O 2

Simple mask Exhalation ports O 2 inlet · Open ports for exhaled gas · Air entrained through ports if O 2 flow through does not meet peak insp flow · 35 -55% O 2 at 6 -10 L/min

Partial rebreather mask Exhalation ports O 2 Reservoir · O 2 directed into reservoir · Insp: draw gas from bag & ? room air · Exp: first 1/3 of exhaled gas goes into bag (dead space) · Dead space gas mixes with ‘new’ O 2 going into bag · Deliver ~60% O 2

Non-rebreathing mask One-way valves O 2 Reservoir · Valve prevents exhaled gas flow into reservoir bag · Valve over exhalation ports prevents air entrainment · Delivers ~100% O 2, if bag does not completely collapse during inhalation