Formulas/Calculations for Vent settings

Question 1

RAW

airway resistance

Answer 1

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)

Question 2

V (flow)

2 ways to calculate

Answer 2

V(flow)= (Vt(L) /Ti)x60
Or
Flow(V)= Ve x (I:E) ***add the I:E

Question 3

Spontaneous Ve (minute ventilation)

Answer 3

Total Ve-mechanical Ve

**total Ve is what’s set and what pt is doing

Question 4

Spontaneous Vt (tidal volume)

Answer 4

Spontaneous Ve (ml)\ Spontaneous Rate

Question 5

Spontaneous rate

Answer 5

Total rate - Set rate

Question 6

a/A ratio

Answer 6

Norm

>or equal to 70% *the higher the better

Question 7

A–a gradient

Answer 7

Normal

Question 8

Pao2/Fi02

Answer 8

Normal

>or equal to 400

Question 9

CAO2

Total O2 content

Answer 9

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

Question 10

VO2

O2 Tissue consumption

Answer 10

Normal
3.5 to 5.0 vol %

Measures 02 consumption in the tissues.

5% = infection/sepsis or decreased C.O.

Question 11

Ve (min. Ventilation)

Answer 11

Vt x RR

Question 12

Vt (tidal volume)

Answer 12

Ve/ RR

Question 13

VD ( dead space)

Answer 13

1 ml per lb. of IBW (estimation)

Question 14

CV02

Answer 14

Normal
13-15vol %

(Hgb x 1.36 x SvO2) + (PvO2 x .003)

Determines how well the tissues take up O2

Question 15

VA (alveolar Ventilation)

Answer 15

Normal
4-6 L/min

(Vt-VD) RR

Volume of inspired air that participates in gas exchange per minute

Question 16

VD/Vt

Dead space to tidal volume

Answer 16

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

Question 17

CD (dynamic compliance)

Answer 17

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.

Question 18

CS (static compliance)

Answer 18

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.

Question 19

Spontaneous Ve
Spontaneous Vt
————————————
spontaneous Vt

Answer 19

1. Calculate mechanical ventilation
   mechVe = mechRR x Vt (divide by 10000
   to turn to L).
2. Calculate spontaneous Vt
   sponVt = sponVe/ sponRR
   —————————————————————-
3. SponVt =sponVe/sponRR

Question 20

ICP

Answer 20

Keep

Question 21

Ve for desired PaC02

Answer 21

Actual Ve x actual PaC02/ desired PaC02

Question 22

New Vt for desired PaC02

Answer 22

Current Vt x actual PaC02/desired PaC02

Question 23

Desired Fi02

Answer 23

Desired PaO2 x known FiO2/ known PaO2

Question 24

PA02 (Alveolar partial pressure of 02)

Answer 24

(Pb-47 cm h20)*Fi02 - (Pa02 x 1.25)

Question 25

IBW (ideal body weight)

Answer 25

M= 106+(6 x inches over 60in) /2.2

F= 105+(5 x inches over 60 in)/2.2