3 ee Se
RESPIRATORY CARE
ANATOMY and
PHYSIOLOGY
Foundations for Clinical Practice
THIRD EDITION
WILL BEACHEY
, VENTILATORY MECHANICS: LUNG-THORAX COMPLIANCE (C,,;) AND
AIRWAY RESISTANCE (R,w)
C.7 = AV (liters)/AP
(cm H20)
Normal Ci; =0.1L/cm H20 or 100 m
Raw = Pressure (cm H20)/flo
Normal Raw = 0.6 — 2.4 cm H20/L/sec
Time constant = C x R=(L/cm H20) x(c
Mechanically Ventilated patients: i
= af |
comp ce )
lung § complian
Cayse = Peak pressure — PEEP Cui ic |
Peak pressure — plateau pressure airway resista |
Ra
Inspiratory flow rate
) VENTILATION |
Ve=Vrixf VCO, x 0.863
A ig P eee ae
Ve=Vo+Va ee ak
Va=Ve-Vo ._VCO2 x 0.863
Ve eva, ae ~~
PacO, |
PaCO>z = P-COz F
Vp/V> = ——————__ (Bohr dead space equation
aoe PaCO, ( ie )
Va =V_(1- [Vp/Vr])
Vp =(Vpb/Vr)VE
|)ALVEOLAR GAS EQUATION
P\O2 = F,O2(Pg — 47)
P,O2 =P,O2 — (PaCOz) 1.2 (for F,O, less than 0.60)
P,O2 = P,O2 — PaCOz (for F;O, greater than 0.60)
| OXYGEN CONTENTS AND OXYGENATION
PO2 x 0.003 = mL/dL dissolved O2 VOz =[C(a—v)O2 x 10 dL/L] x Or (Fick VO} equation)
Hb x 1.34= mL/dL bound O2 Q; = VO2/C(a — v)Oz x 10 dL/L (Fick cardiac output equation)
All contents expressed in mL/dL: Qs — (CéO2 — CaO2) ;
CaO2 =([Hb] x 1.34 x SaO2) + (PaOz x 0.003) Q; = (CéO2 — CVO) (Shunt equation)
CvO2 =([Hb] 1345 SvO>) SF (PvO- x 0.003)
CéO2 =([Hb] x 1.34) + (PaO2 x 0.003) FO, needed to obtain a desired PaO):
Cla 7 v)O2 = CaO2 = CvOz re [desired PaO2/(PaO2/P,0>2)] ar PaCO>, (1 .2)
Oz ER=C(a—v)O2 / CaOz (O; extraction ratio) F\Oz needed = peea7 i
Oz DEL (mL/min) = CaQz x 10 dL/L x Q (OQ) delivery) 3
| CO, AND ACID-BASE BALANCE
H20 + COz + H2CO3 — HCO; + H* (CO, hydration reaction)
PCO? x 0.03 = mmol/L dissolved CO>
pH = —log|H * |
{[HCO;|
pH=6.1+log |(Henderson-Hasselbalch equation)
(PCO x 0.03)
[HCO; ]=antilog (pH — 6.1) x (PCO> x 0.03)
PCO, =([ HCO; ]/antilog[pH —6.1]) + 0.03
RESPIRATORY CARE
ANATOMY and
PHYSIOLOGY
Foundations for Clinical Practice
THIRD EDITION
WILL BEACHEY
, VENTILATORY MECHANICS: LUNG-THORAX COMPLIANCE (C,,;) AND
AIRWAY RESISTANCE (R,w)
C.7 = AV (liters)/AP
(cm H20)
Normal Ci; =0.1L/cm H20 or 100 m
Raw = Pressure (cm H20)/flo
Normal Raw = 0.6 — 2.4 cm H20/L/sec
Time constant = C x R=(L/cm H20) x(c
Mechanically Ventilated patients: i
= af |
comp ce )
lung § complian
Cayse = Peak pressure — PEEP Cui ic |
Peak pressure — plateau pressure airway resista |
Ra
Inspiratory flow rate
) VENTILATION |
Ve=Vrixf VCO, x 0.863
A ig P eee ae
Ve=Vo+Va ee ak
Va=Ve-Vo ._VCO2 x 0.863
Ve eva, ae ~~
PacO, |
PaCO>z = P-COz F
Vp/V> = ——————__ (Bohr dead space equation
aoe PaCO, ( ie )
Va =V_(1- [Vp/Vr])
Vp =(Vpb/Vr)VE
|)ALVEOLAR GAS EQUATION
P\O2 = F,O2(Pg — 47)
P,O2 =P,O2 — (PaCOz) 1.2 (for F,O, less than 0.60)
P,O2 = P,O2 — PaCOz (for F;O, greater than 0.60)
| OXYGEN CONTENTS AND OXYGENATION
PO2 x 0.003 = mL/dL dissolved O2 VOz =[C(a—v)O2 x 10 dL/L] x Or (Fick VO} equation)
Hb x 1.34= mL/dL bound O2 Q; = VO2/C(a — v)Oz x 10 dL/L (Fick cardiac output equation)
All contents expressed in mL/dL: Qs — (CéO2 — CaO2) ;
CaO2 =([Hb] x 1.34 x SaO2) + (PaOz x 0.003) Q; = (CéO2 — CVO) (Shunt equation)
CvO2 =([Hb] 1345 SvO>) SF (PvO- x 0.003)
CéO2 =([Hb] x 1.34) + (PaO2 x 0.003) FO, needed to obtain a desired PaO):
Cla 7 v)O2 = CaO2 = CvOz re [desired PaO2/(PaO2/P,0>2)] ar PaCO>, (1 .2)
Oz ER=C(a—v)O2 / CaOz (O; extraction ratio) F\Oz needed = peea7 i
Oz DEL (mL/min) = CaQz x 10 dL/L x Q (OQ) delivery) 3
| CO, AND ACID-BASE BALANCE
H20 + COz + H2CO3 — HCO; + H* (CO, hydration reaction)
PCO? x 0.03 = mmol/L dissolved CO>
pH = —log|H * |
{[HCO;|
pH=6.1+log |(Henderson-Hasselbalch equation)
(PCO x 0.03)
[HCO; ]=antilog (pH — 6.1) x (PCO> x 0.03)
PCO, =([ HCO; ]/antilog[pH —6.1]) + 0.03
