Mechanical Ventilation Flashcards

1
Q

Resistance

A
  • How hard is it to get air in?
  • The difficulty of a tube to carry gas
  • opposition to airflow
  • “airway resistance”

Difference between PIP and Plateau. The closer the plateau to PIP the lower the pressure loss

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2
Q

Compliance

A
  • How difficult is it to inflate?
  • Characteristics of the lung to make it strechy
  • “static compliance”
  • Balloon
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3
Q

Mandatory breath

A
  • the start or end (or both) of the breath is determined by the ventilator, independent of the pt
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4
Q

Plateau pressure

A
  • end inspiratory alveolar pressure attained during mechanical ventilation
  • <30
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5
Q

Adaptive pressure control

A

A volume feedback mechanism for pressure-controlled or pressure supported breaths, the desired tidal volume is set and the vent adjusts the inspiratory pressure to deliver the minimal tidal volume

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6
Q

Flow triggering

A

A alternate to pressure triggering in mechanical vent, in which the vent responds to a change in flow rather than pressure drop

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7
Q

Mean airway pressure (MAP)

A
  • Average airway pressure during a breathing cycle.
  • directly related to insp time, RR and peak insp pressure and end- exp pressure
  • <12
  • associated with oxygenation
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8
Q

Positive end-expiratory pressure

PEEP

A
  • Baseline pressure applied during exhalation with mech vent
  • reestablished FRC and makes it easier for the pt to breath
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9
Q

Volume control

A

Vent controls the inspiratory flow and tidal volume;

tidal volume in this mode is delivered regardless of resistance or compliance

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10
Q

Pressure control

A

Airway pressure set and remains constant regardless of resistance or compliance

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11
Q

Auto-PEEP

A

End expiratory alveolar pressure that is greater than the pressure at the proximal airway, which results from high airway resistance and a short expiratory time

AKA air trapping

Breath stacking

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12
Q

Indications for mechanical ventilation

A

apnea

Acute ventilatory failure

Impending ventilatory failure

OD

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13
Q

Goals of mechanical ventilation

A

Provide adequate oxygenation

Provide adequate alveolar oxygenation

Avoid autoPEEP

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14
Q

Pulmonary barotrauma

A

Excessive pressure and volume delivery to the lung and is a consequence of alveolar overdistention to the point of rupture

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15
Q

Lung protective ventilator strategy

A

Vent technique where the target tidal volume is 6mL/kg of predicted body weight, the plateau pressure is kept below 30 cm H2O and PEEP is applied to maintain alveolar recruitment

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16
Q

Phases of a breath

A
  • Initiation of inspiration
  • Inspiration
  • End of inspiration
  • Expiration
17
Q

assisted breath

A

A breath during which all or part of inspiratory (or expiratory) flow is generated by the ventilator doing work for the patient

18
Q

What is the cycle?

A

The signal that ends the inspiratory phase of breathing

19
Q

elastic load

A

a component of the patient-ventilator interaction, describing the elastance of the respiratory system (lungs and chest wall) and the volume of flow as a function of time

20
Q

Equation of motion

A

Pvent(t) = EV(t) + R

21
Q

What factors increase resistance?

A
  • Bronchospasm
  • Mucous
  • Airway inflammation
  • tumor

Any factors that decrease airway radius increase the resistance

associated with size and patency of airways as well as turbulence of airflow

22
Q

what is normal resistance

A
  • spontaneously breathing adult 1-3 cmH2O/LPM
  • Intubated adult ( increase resistance due to tube): 4-7 cm of H2O/LPM
23
Q

Peak Inspiratory Pressure

PMax, PIP, PAW

A
  • highest pressure produced during the inspiratory phase
24
Q

Volume control pros and cons

A

Cons

  • risk of barotrauma
  • machine controls flow (more asynchrony)
  • pressure changes with changes in Raw and Cst

Pro

  • Min vent guaranteed
25
Q

Pressure control pros and cons

A

Pro:

  • less risk for barotrauma
  • patient controls flow

Con

  • volume changes with changes in Raw and Cst
  • minute vol not guaranteed
26
Q

What is the P/F ratio?

A
  • PaO2/FiO2 ratio quantifies ventilator-induced lung injury
  • normal P/F is > 300
27
Q

What is the P/F for ALI?

A

200-300

28
Q

What is the P/F for ARDS?

A

Less than 200

29
Q

What causes Ventilator-associated pneumonia?

A

A result of the aspiration of contaminated oral and gastric secrections

30
Q

What are factors that help prevent VAP?

A
  • 30o head up
  • good airway cuff seal, subglottic ET
  • good oral hygiene
  • maintain gastric acidity
31
Q

What are the potential adverse effects of mechanical ventilation?

A
  • increased intrathoracic pressure
    • decreased CO
    • Decreased urine output
    • Gastrointestinal ischemia
    • increased intracranial pressure (ICP)
  • Increased Deadspace
  • increased shunt
  • ventilator-induced lung injury
  • VAP
  • Psychological stress/sleep disturbances
32
Q

What can cause increased airway resistance?

A
  • Bronchospasm
  • aspiration
  • secretions
  • obstruction
  • small ETT
33
Q

What can cause a decreased compliance?

A
  • atelectasis
  • Auto-PEEP
  • pneumothorax
  • pulmonary edema
34
Q

what are the advantages of volume control?

Disadvantages?

A

Advantages: guaranteed minute volume

Disadvantages:

  • risk of barotrauma
  • machine controls the inspiratory flow
  • pressure change with changes in compliance and resistance
35
Q

What are the advantages of pressure control?

Disadvantages?

A

Advantages:

  • Less risk of barotrauma
  • patient can control flow (and so can we)
  • improved synchrony

Disadvantages

  • Minute volume changes with changes in compliance and resistance
  • minute volume is not guaranteed