Vents

Question 1

2 Classification of Ventilators

Answer 1

1) Type of Reservoir
Bellows, Piston, Volume
2) Drive mechanism
Pneumatic vs Mech

all under eletrical control

Question 2

Bellows Classified by

Answer 2

Direction bellow move during expiration

1. Ascending
2. Descending

Question 3

Older Machine Modes

Answer 3

Time triggered, time cycled
Cycle to exp phase after set interval elapses from start of inspiraiton
TV product of set insp time and insp flow rate
“Controller Ventilators”

Question 4

Modern Machines

Answer 4

Pt can trigger breath =
“Non-controlled ventilators”
SIMV, AC, PSV

Question 5

Bellow driving gas

Answer 5

separate from pt gas circuit =
Double circuit
Air or O2

Question 6

Bellows

Answer 6

Serve as reservoir for breathing gas

Question 7

Bellows during Insp Phase

Answer 7

driving gas enters chamber and
1. Vent Relief valve closes (pop off) =
no escape to sacavenging
2. compresses bellow & gas delivered to pt

Question 8

Bellows during Exp phase

Answer 8

drive gas leave chamber = 
P drop to 0 =
Vent Relief valve to open
Once exhaled pt gas fills bellows
   -scavenging (only happen when bellow filled completely)

Question 9

Relief / Pop off valve

Answer 9

only open during exhalation

Question 10

Bellow Problems

Answer 10

Leaks: improper seating
hole in bellow (hyperinflate, change O2)
Vent Relief valve issue: 
  -hypoventilatle (gas to scavenging not drive)
  -disconnection, ruptured valve, damage
  - Stuck closed = >P/PEEP
 - >scavenging sxn => closed valve

Question 11

Piston Ventialtor

Answer 11

Use computer controlled stepper motor
Single circuit
Less gas used
Accurate TV

Question 12

Piston during Ins Phase

Answer 12

PEEP valved closed,
P in circuit from piston closes decoupling valve
FGF directed –> Res Bag
extra goes through APL bypass to scavenging

Question 13

Ti =

Answer 13

Ti = TV / Flow Rate

Flow rate in ml/min so need to x 60 sec

Question 14

TE

exp time

Answer 14

TE =

[ 60 sec / (RR/60sec) ] - Ti

Question 15

MV

Answer 15

MV = TV x RR

Question 16

I:E ratio

RR

Answer 16

1:2 or greater

8-12

Question 17

Flow Rate

MV

Answer 17

~ 4-6 x MV

MV = TV x RR

Question 18

Controlled Mech Ventilation

Answer 18

VC: vol controlled
SIMV
PC: Pressure controlled

Question 19

Volume Controlled

Answer 19

Set TV delivered, ends inspiration
-most have 2nd limit on insp P
% of TV lost to system compliance (5cc/cmH2O)

Question 20

Pressure Controlled

Answer 20

Cycle into Exp phase when airway P reaches set level

TV & Ti vary

Question 21

Piston During Exp Phase

Answer 21

exhaled gas –> CO2 Scrub –> reservoir bag
FGF flows retrograde (-> bag)
Piston “opens” drawing gas in from bag & FGF
Once full, FGF retrograde flows

Question 22

Piston Problems

Answer 22

Refill even if disconnections
W/ circuit leak, entrain RA =
dilute O2 & agent =
hypoxia / awareness

Question 23

Positive P Relief valve

Answer 23

Prevent excessive high circuit P

(60-80 cm H2O)