mechanical ventilator

Question 1

positive pressure ventilation

Answer 1

application of positive pressure within the airway to cause lung expansion
usually used in conduction with artificial airway
can be used in non-invasive
sometimes referred to as conventional ventilation

Question 2

negative pressure ventilation

Answer 2

application of negative pressure outside the chest to cause lung expansion
example: Iron lungs,chest curass

Question 3

ventilatory work

Answer 3

airway resistance
elastic force
equation of motion for lungs
pressure=volume/compliance+(resistance)flow
resistance-airway resistance
elastic forces-compliance

Question 4

motor and piston

Answer 4

linearly driven
rotary drive
sinusoidal waveform output

Question 5

internal/external compressor

Answer 5

puritan bennet Ma-1

Question 6

output control valves

Answer 6

most contempory valves
p-b 840
servo i
dragger evita XL

Question 7

pneumatic diaphragm

Answer 7

simplest type

just and inflatable diaphragm or ballon

Question 8

ventilator control circuit

Answer 8

pneumatic poppet valves
electro pneumatic poppet valves
electro pneumatic proportional solenoid valves

Question 9

subsystem responsible for controlling the drive mechanism

Answer 9

types: mechanical- levers,cam,gears
pneumatic: diaphragms, entrainment devices, piston
fluidic
electric: limit switches
electronic : microprocessor today

Question 10

control variable

Answer 10

a variable that is measured and used as a feed back signal to control the inspiratory phase
must be measure: must be used as a feed back control signal: modifies the ventilator output

Question 11

mushins ventilator phase

Answer 11

change from expiration to inspiration
inspiration
change from inspiration to expiration
expiration

Question 12

chatburns phase variables

Answer 12

trigger: what initiates the breath?
limit: is there a variable that doesn’t change during inspiration?
cycle: how does the breath end?
baseline: is the expiratory phase controlled?
conditional: how do the above control variables influence one another

Question 13

what is sensed and used as feedback to initiate inspiration?

Answer 13

pressure
flow
volume
time
electronic

Question 14

pressure trigger

Answer 14

typically setting are 0.5 to 2 cm h2o
be aware of ventilator design
some ventilator have a long pathway to the pressure sensor/diaphragm

Question 15

volume trigger

Answer 15

looks for a change in volume

not commonly used

Question 16

flow triggering

Answer 16

very sensitive
basel flow
trigger sensitivity
ventilator looks for a difference in base flow equal to sensitivity
level
fas is available at all times for patients
called flow by and flow triggering

Question 17

time

Answer 17

a set time lapsed before the next breath begins

common for mandatory breath trigger

Question 18

limit variable

Answer 18

one of the three variables reaches a constant level and no longer increase
it is limited and no longer increases