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Emc 2 test 1 > Mechanical Vent > Flashcards

Mechanical Vent Flashcards

1
Q

Why use mechanical ventilation

A

Mechanical ventilation is a useful modality for patients who are unable to sustain adequate oxygenation and ventilation

Mechanical ventilation may be indicated in conditions due to
* physiologic changes (e.g., deterioration of lung parenchyma),
* disease states (e.g.,respiratory distress syndrome),
* medical/surgical procedures (e.g., post anesthesia recovery), and
* many other causes (e.g., head trauma, drug overdose) leading to ventilatory
failure or oxygenation failure.

indication for tube = indication for vent

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2
Q

Goals of vent

A

Provide gas exchange safely
* adequate oxygenation
* max. alv. vent. and CO2 elim.
* Avoid alveolar overdistension
* maintain alveolar recruitment
* avoid auto peep
* minimize decreased perfusion
Challenges= lung compliance aw resistance

Provide pt comfort
* Synchronise btwn vent and pt
* dont want pt to fight the vent

Promote liberation from vent
* avoid Vent induced lung inj (VILI)
* Alv rupt.
* PTX
* P Ed
* sub cut emphysema

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3
Q

Compliance

A
  • The chest wall and the lungs are in a constant “tug-of-war” – the lungs want to collapse inward and the chest wall wants to expand outward.
  • These two systems work together to influence respiratory mechanics.
  • Δ volume / Δ pressure
  • n other words, a stiff system (low compliance) requires lots of pressure (large Δ pressure) to drive in a small volume of air (small Δ volume)
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4
Q

Tidal Volume

A

This is the volume of air required to distend the lungs in one single breath (normal breath without any active work to get more air in) and is normally around 7ml/kg when a person is at rest
* It’s important to note that Ideal Body Weight (IBW) is based on your patient’s height, not on their actual weight.
* TV is affected by compliance and resistance.

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5
Q

Respiratory Cycle

A
  • The respiratory cycle includes two phases:
  • inspiration of environmental air
  • expiration of gases from inside the lung including carbon dioxide
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6
Q

PEEP

A
  • Positive END-Expiratory pressure
  • This is the baseline pressure left over in the lungs once expiration is complete.
  • This is the pressure that allows the alveoli to stay partially open throughout the
    respiratory cycle
  • It can be set by the ventilator, or may be a reading of the intrinsic pressure
    that is left over due to air trapping in the asthma/COPD patient for instance
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7
Q

Plateau Pressure

A
  • This is the pressure applied to the alveoli and is measured at the end of inspiration (or during an inspiratory hold).
  • It is the pressure that is exerted on the actual tissues which can distend in the lungs
  • This pressure should not exceed 30cmH20
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8
Q

Peak Inspiratory Pressure

A
  • highest level of pressure applied to the lungs during inspiration
  • factor of airway resistance, PEEP and compliance of the lungs
  • should not exceed 35cmH20
  • adjusted to get TV
  • = AW resit pres + Plat Pres.
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9
Q

Mean Airway Pressure

A
  • Ave. pres applied throughout cycle
  • influenced by:
  • PIP
  • RR
  • PEEP
  • Inspiratory time
  • Inc Map= inc oxygenation
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10
Q

Flow

A
  • Flow is the maximum flow at which a set tidal volume breath is delivered by
    the ventilator
  • 60-120l/mon
  • If the peak flow rate is too low for the patient, dyspnea, patient-ventilator asynchrony,
    and increased work of breathing may result.
  • High peak flow rates increase peak airway pressures and lower mean airway pressures,
    which may decrease oxygenation
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11
Q

I:E Ratio

A
  • time of inspiration and expiration of air, normally a ratio of 1:2
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12
Q

Trigger

A

method used by the ventilator to decide when to give the next breath
* improve patient-ventilator synchrony
* f the trigger sensitivity is too high, artifacts can trigger the ventilator to give a breath
* If the trigger sensitivity is too low, the patient my have to work extremely hard to trigger a breath or may not be able to trigger one at all

Time
Pressure inhalation uses neg pres (inc pt work)
flow

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13
Q

Limit

A

A limit restricts a variable before the end of inspiration.
* Pressure-limited: a pressure that will not be exceeded during inspiration
* Volume-limited: a volume that will not be exceeded during inspiration
* Flow-limited: a flow rate that will not be exceeded during inspiration

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14
Q

Cycling

A
  • The cycling variable dictates how the ventilator “cycles” between inspiration and passive expiration.
  • Pressure-cycled: after achieving the peak inspiratory pressure (PIP), exhalation occurs
  • Volume-cycled: after the target volume is delivered, exhalation occurs
  • Flow-cycled: exhalation occurs when the inspiratory flow rate falls below a preset threshold
  • Time-cycled: purely based on time
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15
Q

Positive Pressure Ventilation

A

pressures greater than atmospheric pressure to push air into the alveoli

O2 in and CO2 out

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16
Q

Types of Delivery

A

Volume control
* In this mode of ventilation, the parameter that is controlled is the volume administered to the patient (tidal volume)
* Pressure control
* In this mode of ventilation, the controlled parameter is the pressure

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17
Q

Types of breaths

A
  • Controlled
  • Assisted
  • Supported
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18
Q

Controlled breaths

A
  • No respiratory effort from the patient
  • Ventilator delivers breaths at set rate
    Patients should be sedated effectively or no respiratory effort i.e. brainstem death
19
Q

Assisted breaths

A

assisted breaths will be delivered to your patient if they attempt to trigger a breath

20
Q

Supported

A
  • triggered by patient effort (like assisted breaths)
    some support, but not full
  • support like an assisted breath
21
Q

Volume Modes

A
  • e ventilator is triggered, a pre-set tidal volume
  • observe how much pressure it takes for that breath to be delivered
  • PEEP, FiO₂, and RR can be adjusted
  • regulate TV + MV(mv= TVxRR)
  • CMV (Continuous Mandatory Ventilation) or IMV (Intermittent mandatory ventilation)
  • Assist Control Ventilation (ACV)
  • Synchronized Intermittent-Mandatory Ventilation (SIMV)
22
Q

CMV (Continuous Mandatory Ventilation) or IMV (Intermittent
mandatory ventilation)

A
  • pre-set volume and time(10bpm= 1b/6secs
  • Do not use if patient has any respiratory effort
23
Q

AC (Assist Control Ventilation)

A
  • both assisted and controlled breaths
  • Can have controlled breaths
  • when pt triggers inbtwn time it will deliver breath
  • mechanical breath is still delivered at the set time= stacking
  • set tv every breath
24
Q

Synchronized Intermittent-Mandatory Ventilation (SIMV)

A
  • breaths can be patient- or ventilator-initiated
  • Mandatory breaths are synchronized to coincide with spontaneous respirations to avoid breath stacking
  • Disadvantages of SIMV are increased work of breathing and a tendency to reduce cardiac output, which may prolong ventilator dependency.
  • The addition of pressure support on top of spontaneous breaths can reduce some of the work of breathing (P-SIMV)
25
Q

pros of vol mode

A
  • Tidal volume is set and won’t change
  • Minute volume also does not change unless respiratory rate changes
  • Flow rate is lower at the start of inspiration
26
Q

COns of vol mode

A
  • Mean Airway pressure is not as high(bad in hypox pt)
  • does not vent collapsed alv.
  • does not accom for leaks
27
Q

Pressure Modes

A

pre-set pressure (PIP) will be delivered to the patient once the ventilator is triggered
PIP is reached almost instantly and remains at that pressure for a set time

28
Q

Pressure support ventilation

A

o lower the work of spontaneous breathing and augment a patient’s spontaneous tidal volume better for pt synch
commonly applied in the SIMV mode

29
Q

Pressure Control

A

pressure plateau is created and maintained for a pre-set inspiratory time
Used for sedated, apnoeic patients

30
Q

Pressure Mode pros

A

increased mean airway pressure which helps to assist in the improvement of oxygenation.
Increased alveolar recruitment
alv opened earlier and for longer= more o2

dec chance of barotrauma
inc pt comfort (most like normal negative pt insp

31
Q

pressure mode cons

A

patient has any dysynchrony, then the ventilator will not be able to deliver the breath(pressure limit will be reached
if pt compliance improves then tv will inc due to lower need of pres.

32
Q

how to fix air trapping on vent

A

reduce rr or insp time

33
Q

Complications of positive pressure ventilation Cardiovascular

A
  • Increase intra-thoracic pressure, leads to compression of great vessels,
    causing a decrease venous return, thus decrease cardiac output
  • Decrease in Cardiac output leads to
  • VQ mismatch and hypoxaemia
  • Decrease cerebral blood flow
  • Decrease kidney perfusion
34
Q

Complications of positive pressure ventilation Barotrauma

A
  • Barotrauma is lung injury that results from the hyperinflation of alveoli past the rupture
    point.
  • Although each patient is different, a PEEP greater than 10 cmH2O (or mean airway
    pressure >30mmHg, or a peak inspiratory pressure >50mmHg) is associated with an
    increased incidence of alveolar rupture
  • Alveolar rupture can produce pneumothorax, tension pneumothorax
35
Q

Complications of positive pressure ventilationVolutrauma

A
  • This is damage caused by over-distension due to large volumes
36
Q

Complications of positive pressure ventilation

A

Biotrauma
* When you injure the lung with violent ventilation, it fights back by flooding the
bloodstream with potent pro-inflammatory mediator

37
Q

Ventilator alarms – High pressure

A

High TV or PIP settings
* Kinks in the patient circuit
* Increased or thicker mucus or other secretions blocking the airway
* Bronchospasm
* Pneumothorax
* Decrease lung compliance
* Coughing, gagging, or “fighting” the ventilator breath

38
Q

Ventilator alarms – Low pressure

A
  • Low TV or PIP settings
  • The patient becomes disconnected from the ventilator circuit
  • Inadequate inflation of the tube cuff
  • Poorly fitting non-invasive masks or nasal pillows/prongs
  • Loose circuit and tubing connections
  • The patient demands higher levels of air than the ventilator is putting
    out
  • Low oxygen pressure in portable ventilators
39
Q

Ventilator alarms – High / Low volume

A

High and low volume alarms
* High volume alarms (normally minute volume) may indicate a high respiratory
rate, high tidal volume as well as increased patient demand for air because of
pain, anxiety, or improper ventilator settings
* Low volume alarms typically are caused by air leaks, mucous plugging, a need
for suctioning, tube obstruction, a slower respiratory rate or shallow
breathing

40
Q

Initial Ventilator Settings

A
  • Mode: Practitioner choice
  • FiO2: Start at 1.0 and wean asap
  • Tidal volume (TV): 6-8ml/kg IBW
  • Inspiratory flow rate (IFR): 50 – 70 L/min
  • Rate: 12 – 14 bpm
  • Peek Inspiratory Pressure (Pmax): 10 – 30 mmHg (Remember to add PEEP)
  • PEEP: 5 cmH2O
  • Pressure Support: 10 cmH2O – Lower PS makes patient work harder
  • Plateau pressure: <30 mmHg
  • Trigger pressure: 2cmH2O
  • I:E Ratio: 1:2
41
Q

how to change oxygenation

A

Varying the amount of oxygen delivered to the patient (FiO2)
* Varying the amount of pressure delivered to the patient which influences alveolar
recruitment
* PEEP
* Mean Airway Pressure
* PIP
* RR
* PEEP
* Inspiratory time

42
Q

how to change ventalation

A

The ventilator can influence ventilation in two primary ways:
* Varying the tidal volume (Vt) delivered to the patient, which can be either
directly set (as in volume controlled ventilation) or measured as a result of
the set pressure and lung compliance (as in pressure controlled ventilation)
* Varying the respiratory rate
* To adjust ventilation on the ventilator, set or adjust the tidal volume
to the goal range for the patient, and then once in goal range, adjust
the breath rate

TV
RR
IE

43
Q
A

Emc 2 test 1 (4 decks)

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