ch 3 how a breath is delivered Flashcards
During mechanical ventilation what are the two forces (pressures) that act on the respiratory system to produce transrespiratory pressure?
- muscle pressure
- ventilator pressure
what are the 4 control variables?
- pressure
- volume
- flow
- time
the amount of volume delivered will depend on compliance and resistance to what?
gas flow
what is the Rhorer equation of motion?
Pmus + Ptr = V/C + (Raw x flow)
there are only 2 pressures that can ventilate a patient what are they?
- patients muscles
- ventilator
The delivery of__________ is a ventilators single most important function?
inspiration
this is the primary variable that the ventilator manipulates to cause inspiration?
control variable
the volume and flow waveforms are constant pressure varies with changes in compliance and resistance?
volume control
what are 3 names used for volume ventilation?
- volume targeted
- volume controlled
- volume limited
what control is used in A/C and SIMV?
volume ventilation
pressure delivered constant, volume and flow vary with changes in compliance and resistance?
pressure control
what are 3 names used for pressure ventilation?
- pressure targeted
- pressure controlled
- pressure limited
pressure waveform will be unaffected by changes in compliance and resistance. The flow and volume waveforms change with comp/resist?
pressure controlled breath
what control are we in if flow usually starts out high and then tapers off?
pressure ventilation
high gas flows produce uneven distribution of gases. “slow spaces” are underventiated. at end inspiration what flows tend to ventilate better? what should the flow patter look like?
- reduced flows
- decelerating
what is the flow control formula?
flow= volume / time
or
volume= flow x time
if changes in comp/resist do not affect volume waveform they will not effect______ waveform?
flow
when both pressure and volume waveforms are affected by changes in lung characteristics the ventilator is _______controlled?
time
many high frequency jet and oscillators are ____controlled?
time
what are the 4 basic shaped for waveforms?
- rectangular (square or constant)
- exponential (increasing ((rising)) or decreasing((decaying))
- sinusoidal (sine)
- Ramp (ascending, descending) ((decelerating))
start of breath, initiation
trigger
what is controlled during breathing. Inspiration itself. one of the 4 phases of CMV
limit variable
what terminates breath, end of breath?
cycle
expiratory phase goes to what?
baseline
what begins or triggers inspiration?
- patient
- machine (time)
ventilator begins itself, machine is insensitive to patients efforts, rate of breathing controlled by the machine?
“machine” time triggered
if a rate was set at 12 breaths per minute how many seconds in between breaths?
5 sec
60/12
determines the amount of effort when a patient triggers?
sensitivity
how fast the machine responds. usually at 0.08 seconds. cannot be adjusted?
response time
machine begins inspiration when patient starts to inspire and removes a small amount of volume from the circuit which creates negative pressure?
there will be a drop below baseline
-pressure triggered (assist)
breaths may not occur at equal, timed intervals
(assist) pressure control
a patient has a baseline of 10cmH20 the sensitivity is set at -2cmH20 at what pressure will the ventilator sense a patient effort and start inspiration?
8 from base line
a continuous supply of low level flow is delivered past the patient during expiration is known as what trigger?
flow trigger (flow-by)
flow measuring devices are positioned at inlet and outlet side of circuit to compare flow. ________ triggering occurs when the net difference reaches a pre-selected level.
flow
patient has access to continuous flow during “response time” which lowers work of breathing what trigger is this?
flow triggered
for flow trigger the base flow must be at least twice the _____ flow
trigger
flow triggering can cause _______breaths due to leaks or movement caused by turbulent gas flow through circuit
spurious (auto trigger)
what does bias flow mean?
constant flow through machine
don’t forget to look over important slide on page
11 of power point slide
the machine cycles when a preset volume has been removed from the circuit. what are 2 machines that have this cycle capability? (volume cylcle)
- dragger babylog
- cardiopulmonary ventrui
a ______ button on the machine, when pushed, will initiate a positive pressure breath?
manual
one of the four physical parameters that can be reached but not exceed during a breath?
limits of ventilation
reaching a limit does not _____ the breath?
end
the volume is held in the airway until a pre-set time, then time will end the breath
volume limited
the machine signal the i -time display and will not permit patient to trigger a breath till a set time
time limited
what is a example of a ventilator that is time limited?
bear cub
during PSV and PCV the pressure is increased to pre-set level at the beginning of inspiration and is held at the airway until the breath ends is known as ?
pressure limit
can be used as a pressure pop-off to limit the amount of pressure in the airway but if reached will not terminate the breath is know as what?
pressure limit
what is a example of a pressure limit ventilator ?
NC humidifier
what is more comfortable of a patient pressure control or volume control?
pressure control because patient gets to pick there breath
vents begin inspiration( pressure limit) and achieve the set pressure as quickly as possible, this can cause discomfort in patients. what is the setting in ventilators that allow a more gradual rise?
rise time (PRAMP)
if you lengthen the rise time (Pramp) what will go away if pressure is to fast?
spike
if your rise time (Pramp) is too high what could happen?
patient will not receive a full lung volume before E time kicks in.
what is statics asthmatics
have trouble exhaling
decrease flow by decreasing the _____ _______?
pressure gradient
if flow reaches a constant value before the end of inspiration then the ventilator is considered what?
flow limited
prevent excessive pressure from going to the patient. If this control also ends inspiration the ventilator is considered to be _____ _______
pressure cycled
if the ventilator limits the amount of pressure that can be delivered to the patient but does not end the breath only limits more pressure from being applied is considered what?
pressure limited
what I:E ratios are best to set a patient on?
1:2 or 1:3
what is the pause, plateau or inflation hold used?
- therapeutically
- diagnostically
what parameter is responsible for terminating the breath for a single breath?
cycle parameter
volume delivered from machine is not all entering patients lungs. Positive pressure expands circuit and some of the gas is used up is known as ?
tubing compressibility
most circuits have how many mL/cmH20 lost to tubing compressibility?
3-4 mL/cmH20 more volume will be lost at higher pressures
if a vent is volume cycled it will continue to cycle even though it may be disconnected from the ventilator is known as a ________?
system leak
exception: if vents driving pressure is _____then it may lose volume at high pressure
low
what cycle would a patient be in if there end inspiration reaches 25% of peak flow?
flow cycle
if in this mode careful monitoring of waveforms is required?
flow cycled
machine starts breath, and machine controls and ends the breath. vent does all the work?
mandatory breaths
patient starts the breath, and machine controls and ends the breath?
assisted breath
patient starts the breath, patient controls and ends the breath. Machine augments breath?
spontaneous breath
