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AS - N928 Basic Principles of Anesthesia > Ventilation Modes > Flashcards

Ventilation Modes Flashcards

1
Q

Peak Inspiratory Pressure

A

PIP
Total pressure required to distend the lungs & airway
Pressure used to calculate dynamic compliance

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2
Q

Plateau Pressure

A

Pplat
Distending pressure to expand only the lungs
Measures air redistribution flow through lungs
Used to calculate static compliance (reflects intrinsic lungs)

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3
Q

Mechanical Ventilation Variables

A

RR - respiratory rate
Vt - tidal volume
Pressure - PIP/Pplat/PAW
I:E ratio - inspiration to expiration

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4
Q

Trigger Variable

A

Represents inspiration start

*Pressure, volume, flow, time

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5
Q

Limit Variable

A

Target variable
Controls how inspiratory breath maintained
Once threshold reached will not exceed set limit

*Pressure, volume, flow

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6
Q

Cycling Variable

A

Transition from inspiration to expiration
Once achieved set cycling variable → start expiration

*Volume, pressure, flow, time

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7
Q

Baseline Variable

A

Pressure maintained at end expiration

Peak end expiratory pressure

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8
Q

PEEP

A

Alveolar pressure above atmosphere
Individualized to patient
Prevents atelectasis
Intrinsic - 2nd to incomplete expiration (auto-PEEP)
Extrinsic - applied PEEP via mechanical ventilator

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9
Q

Volume Control Ventilation

A 
Time = trigger
Volume = limit
Time = cycling
Airway pressure (upside down V) changes breath-by-breath based on changing respiratory compliance
Flow remains constant (flat box)

Set appropriate PIP/pressure alarms

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10
Q

Pressure Control Ventilation

A 
Time = trigger
Pressure = limit
Time = cycling

Airway pressure controlled (flat box)
Vt changes breath-by-breath based on changing respiratory compliance
Decelerating wave flow - homogenous gas flow through lungs (improves ventilation pattern ↓WOB)

Avoid barotrauma d/t excessive pressure
Set appropriate Vt alarms

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11
Q

Pressure Control Volume Guarantee

A

PCV-VG
Time = trigger
Pressure = limit
Time = cycling

Ventilator adjusts pressure delivered when current volume not at set #

  • Adjustments take 3-5 breaths to complete
  • Atelectasis development when ↓compliance & ventilator delayed in providing adequate pressure to distend lungs
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12
Q

Synchronized Intermittent Mandatory Ventilation

A 
SIMV
Delivers set Vt at set RR w/ patient initiated breaths
Time OR patient = trigger
Flow L/min = limit
Volume = cycling

Patient breaths are not supported (unless SIMV-PSV)
Appropriate mode when weaning from ventilator - less desynchrony w/ patient initiated breaths
Hypoventilation when inadequate Vt & RR w/ patient ↓respiratory effort
Hyperventilation when ↑PS level

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13
Q

Pressure Support Ventilation

A 
PSV
Supported ventilation mode for spontaneously breathing patient
Patient = trigger
Pressure = limit
Flow = cycling

Set Psupport & PEEP
Back-up mode Pinsp & RR

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14
Q

Oxygen Delivery Formula

A

DO2 = CO x CaO2 (arterial)

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15
Q

Oxygen Use Formula

A

VO2 = CO x O2a - O2v

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16
Q

Hypoxemia

A

O2 deficiency in the blood

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17
Q

Hypoxia

A

O2 delivery to the tissues not sufficient to meet metabolic demand

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18
Q

Anesthesia Goal

A

Maintain oxygenation & ventilation

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19
Q

Oxygen Therapy Goal

A

Prevent & correct hypoxemia & tissue hypoxia

20
Q

Hypoxia S/S

A 
Vasodilation
Tachycardia
Tachypnea
Cyanosis
Confusion
Lactic acidosis
21
Q

Nasal Cannula

A

Flow rates 1-6L/min

FiO2 ↑4% per L/min

22
Q

Simple Face Masks

A

FiO2 40-60%

Minimum 6L flow required to prevent rebreathing

23
Q

Face Masks w/ Reservoir

A

FiO2 60-100%

24
Q

Venturi Masks

A

FiO2 24-50%
Set flow rate to ensure exact oxygen delivery
Bernouilli’s principle application

25
Q

Oxygen Toxicity

A

↑FiO2 over long periods → harmful to lung tissue

↓ciliary movement (unable to expel mucus)
Alveolar epithelial damage
Interstitial fibrosis

Safe 100% O2 up to 10-20hr
Toxic 50-60% O2 >24-72hr

26
Q

Absorption Atelectasis

A

Nitrogen replaced by oxygen
Under-ventilated alveoli ↓volume
↑pulmonary shunting

27
Q

COPD

A

Chronic CO2 retention
Hypoxic drive - do not administer oxygen
Induced hypoventilation d/t ↑O2
*Theoretical only

28
Q

What triggers peripheral chemoreceptors?

A

Hypoxemia

29
Q

Fire Hazard

A 
Extreme caution in head & neck cases
Vigilance when administering O2
Notify surgeon when ↑O2 
Risk w/ cautery instruments
Chronic ICU patients receiving tracheostomy = high risk d/t ↑FiO2 requirements
30
Q

Retinopathy

A

ROP
O2 therapy → vascular proliferation, fibrosis, retinal detachment, & blindness
Premature neonates <36wk (up to 44wk) gestation or weigh <1500gm

Safe O2 admin = PaO2 60-80mmHg

31
Q

Hypercapnia Causes

A

↑alveolar dead-space
↓alveolar perfusion
Impaired pulmonary circulation
Lung disease

↓alveolar ventilation (central or peripheral)
Respiratory depression most common cause

32
Q

Hypercapnia Considerations

A
  • Ventilatory drive regulation
  • Cerebral blood flow
  • Smooth & cardiac muscle depression
  • ↑catecholamine release
  • Vasodilation vs. vasoconstriction
  • ↑RR & PVR
33
Q

Hypercapnia Treatment

A

Identify cause

↑minute ventilation

34
Q

Hypocapnia

A

Cause typically iatrogenic

Clinical manifestations:
↓CBF
↓CO & coronary constriction
Hypoxemia d/t hypoventilation

Treatment ↓minute ventilation

35
Q

Anesthesia & Surgical Impact on Lungs

A 
Neuromuscular blockers ↓muscle tone
Abdominal contents cephalad displacement
Alveolar compression
↑intra-abdominal pressure ↑BMI
Trendelenburg position
↓FRC (upright → supine + paralysis + induction agents)
36
Q

Functional Residual Capacity

A

Decreases w/ age

↓1.2-1.5L or 30mL/kg

37
Q

Recruitable vs. Non-Recruitable

A

Recruitable

  • General anesthesia
  • ↓FRC
  • Atelectasis

Non-Recruitable

  • ARDS
  • Cellular debris
  • Edema
38
Q

Ventilation Induced Lung Injury

A

VILI

Ventilator SETTINGS cause injury

39
Q

Ventilation Associated Lung Injury

A

VALI
Specific to OR setting

Volutrauma - damaged epithelium, ↓surfactant, ↑capillary leak
Barotrauma - damage from + pressure effects
Atelectrauma - repeated collapse & re-inflation (under-utilized PEEP alveoli closed)
Biotrauama - inflammatory mediator release

40
Q

Factors that Contribute to Alveolar Collapse

A

Position ↓FRC
Induction loss muscle tone
FiO2 reabsorption → atelectasis
Maintenance ↓compliance → progressive airway closure
Emergence high FiO2 promotes postop atelectasis
Absence CPAP after extubation → continued lung collapse

41
Q

Lung Protective Ventilation Settings

A 
Vt 6-8mL/kg IBW
FiO2 <30% 
PEEP 30% BMI
I:E 1:1.5
Alveolar recruitment maneuvers
42
Q

Induction Strategies

A

Initial FiO2 100%
Elevate HOB >30% or reverse Trendelenburg
Apply CPAP w/ bag-mask APL valve or vent mode
Oral or nasal airway as needed

43
Q

LPV Goals

A

Restore lung volume w/ alveolar recruitment maneuver
Maintain lung volume & minimize atelectasis formation (individualized PEEP)
Maximize lung compliance
- Use lowest possible driving pressure ΔP
- Compliance = Vt / ΔP

44
Q

Alveolar Recruitment Maneuvers

A

BMI <30 → 40cmH2O
30-40 → 40-50cmH2O
40-50 → 50-55cmH2O
>50 → 50-60cmH2O

45
Q

Emergence FiO2

A

<80%

Reduce atelectasis formation

46
Q

Pressure-Volume Loop

A

Assesses driving pressure
Maximize volume delivered at lowest pressure
*See OneNote graphs

47
Q

Flow-Volume Loop

A

Represents expiratory flow

*See OneNote graphs

AS - N928 Basic Principles of Anesthesia (18 decks)

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