Formulas/Calculations for Vent settings Flashcards
RAW
airway resistance
Normal
.6 to 2.4
PIP-Pplat/V(flow) (l/sec) ***divide flow by 60 1st.
Increases due to airway narrowing in intubated patient.
***caused by secretions (suction) to improve RAW), Obstructions, or bronchospasm (give bronchodilators to improve)
V (flow)
2 ways to calculate
V(flow)= (Vt(L) /Ti)x60
Or
Flow(V)= Ve x (I:E) ***add the I:E
Spontaneous Ve (minute ventilation)
Total Ve-mechanical Ve
**total Ve is what’s set and what pt is doing
Spontaneous Vt (tidal volume)
Spontaneous Ve (ml)\ Spontaneous Rate
Spontaneous rate
Total rate - Set rate
a/A ratio
Norm
>or equal to 70% *the higher the better
A–a gradient
Normal
Pao2/Fi02
Normal
>or equal to 400
CAO2
Total O2 content
Normal
17-20 %vol
(Hgb x 1.36 x SaO2) + (Pa02 x .0031)
Total amount of 02 carried in 100 ml of blood can be reduced due to
VO2
O2 Tissue consumption
Normal
3.5 to 5.0 vol %
Measures 02 consumption in the tissues.
5% = infection/sepsis or decreased C.O.
Ve (min. Ventilation)
Vt x RR
Vt (tidal volume)
Ve/ RR
VD ( dead space)
1 ml per lb. of IBW (estimation)
CV02
Normal
13-15vol %
(Hgb x 1.36 x SvO2) + (PvO2 x .003)
Determines how well the tissues take up O2
VA (alveolar Ventilation)
Normal
4-6 L/min
(Vt-VD) RR
Volume of inspired air that participates in gas exchange per minute
VD/Vt
Dead space to tidal volume
Normal
20 to 40%
> 60%= need for mechanical ventilation
Causes for increase: P.E,
(***PEC02 is from capon graphs)
PaC02 - PEC02/ PaC02 x 100
Relates to ventilation. Percentage of title volume that is unavailable for gas exchange
CD (dynamic compliance)
Normal
30-40 cm h20 on vent
70-90 cm h20 off vent
Vt/ PIP-PEEP
Can decrease due to: secretions bronchospasm, biting tube, small or a endotracheal tube.
CS (static compliance)
Normal
100 cm h20Off vent
40-60 cm h20on vent
Vt/ Pplat- PEEP
A decrease can be due to :pulmonary edema, pneumothorax,atelectasis, Pleural effusion, obesity, and ARDS.
Spontaneous Ve
Spontaneous Vt
————————————
spontaneous Vt
- Calculate mechanical ventilation
mechVe = mechRR x Vt (divide by 10000
to turn to L). - Calculate spontaneous Vt
sponVt = sponVe/ sponRR
—————————————————————- - SponVt =sponVe/sponRR
ICP
Keep
Ve for desired PaC02
Actual Ve x actual PaC02/ desired PaC02
New Vt for desired PaC02
Current Vt x actual PaC02/desired PaC02
Desired Fi02
Desired PaO2 x known FiO2/ known PaO2
PA02 (Alveolar partial pressure of 02)
(Pb-47 cm h20)*Fi02 - (Pa02 x 1.25)
