Aeromedical/Gas Laws/ Mech. Ventilation Flashcards

1
Q

What is Tidal Volume? (Vte)

A

The volume of air drawn into the lungs during inspiration from the end expiratory position, which leaves the lungs passively during expiration in the course of quiet breathing.

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2
Q

What is Peak inspiratory pressure (PiP)?

A

The highest airway pressure measured during inspiration.

PiP is a product of Vt/Compliance/Resistance/ Flow. Measured in cm/h20

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3
Q

What is inspiratory time (Ti)?

Measured in seconds

A

The time duration from the end of exhalation to the end of inhalation

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4
Q

What is expiratory time (Te)?

Measured in seconds

A

The time duration from the end of inhalation to the end of exhalation.

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5
Q

What is Flow? (vCalc)

A

Flow is the speed of airflow during inhalation, it is measured in LMP

-Flow (vCalc) is the product of Vt, resistance, and Ti

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6
Q

What is Plateau Pressure (pPlat)

A

pPlat is the pressure applied to the small airways and alveoli during a pause during inspiration on the mechanical vent.

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7
Q

Describe positive end expiratory pressure (PEEP)

A

The pressure that remains in the lungs after exhalation has stopped and a no flow state exists.

PEEP is the product of the remaining volume of gas not exhaled during the respiratory cycle.

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8
Q

What is Auto PEEP?

A

The pressure that remains in the lungs after exhalation has stopped and a no flow state exists beyond the set PEEP.

This is the product of remaining volume of gas not exhaled during the respiratory cycle, usually this is caused by a lack of expiratory time (Te).

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9
Q

What is PEEP compensation?

A

is when the mechanical vent. recognizes PEEP and will deliver desired pressure breaths on top of set PEEP.

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10
Q

Non-PEEP compensation

A

When the mech. Vent. does not recognize PEEP and will deliver desired pressure breaths to a total pressure including PEEP.

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11
Q

I:E Ratio

A

The ratio of inspiratory time vs expiratory time (Ti VS Te)

I:E is set into the ventilator, however patients may need a specific I:E to support their condition (ie. Asthma)

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12
Q

What is Trans-Pulmonary pressure (Ptp)

A

The difference between the alveolar pressure and pleural pressures

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13
Q

What is Trans-Pulmonary PEEP?

A

The Pip calculated at end exhalation

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14
Q

Trans pulmonary plateau pressure (Pplat)

A

The Pip calculated at the end of inhalation

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15
Q

What is Bias Flow?

A

10 LMP of flow in the vent circuit

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16
Q

What is “patient triggering”

A

When the patient initiates a delivered breathe before the next set interval

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17
Q

what is Sensitivity in mechanical ventilation?

A

A measure of 1-9 indicates the detected change in bias flow required for the patient to trigger.

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18
Q

Name the 8 modes of ventilation

A
  1. Volume Control
  2. A/C Volume
  3. Pressure Control
  4. A/C Pressure
  5. Pressure Support
  6. SIMV
  7. CPAP
  8. BiPAP
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19
Q

Describe Volume Control mode

A

Volume control is a set volume with a defined rate, no patient triggering, volumes constant, pressure variable

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20
Q

A/C Volume

A

Allows for patient triggering, WOB dependent on sensitivity

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21
Q

Pressure control

A
  • Set pressure
  • Defined Rate
  • No patient triggering
  • Pressures constant, volume variable
22
Q

A/C Pressure

A

Allows for patient triggering, WOB dependent on sensitivity

23
Q

Pressure Support

A
  • Requires spontaneous respiratory efforts
  • Flow triggered
  • Flow terminated
  • Most physiological mode of ventilation
  • Most comfortable mode of ventilation
  • Volumes rate and pressure are variable
24
Q

Synchronized Intermittent mandatory ventilation (SIMV)

A
  • Garuteed minimum minute volume
  • Allows patient triggered breathes
  • Allows patient to assume WOB
  • Synchronicity with the ventilator.
25
Q

CPAP (Continuous positive airway pressure)

A
  • Provides a set pressure during exhalation

- Assuring a minimum airway pressure

26
Q

BiPAP (Bi level positive airway pressure)

A
  • Delivers inspiratory pressure
  • Maintains expiratory pressure
  • Practitioner sets E pressure and I pressure independently
27
Q

General Hypoxia

A

inadequate oxygen supply to the body as a whole.

28
Q

Tissue Hypoxia

A

Lack of oxygen to a specific region

29
Q

4 types of hypoxia

A
  1. Hypoxic hypoxia
  2. Histotoxic Hypoxia
  3. Stagnant Hypoxia
  4. Hypemic Hypoxia
30
Q

Hypoxic Hypoxia

A

Caused by a decreased amount of oxygen in the blood due to a reduction in O2 pressure in the lungs, reduced gas exchange area, exposure to high altitude or lung disease.

31
Q

Histotoxic Hypoxia

A

Caused by the inability of the tissues to utilize oxygen. Usually a result of poisoning (cyanide/carbon monoxide)

32
Q

Stagnant Hypoxia

A

Hypoxia caused by a malfunction of the circulatory system resulting in a decrease in blood flow.

(Cardiogenic shock, Distributive shock)

33
Q

Hypemic Hypoxia

A

Hypoxia caused by a decreased level of hemoglobin carrying capacity or a reduced number of red blood cells.

34
Q

Describe the “Physiologic Zone”

A

The area of sea level to 10,000ft. Barometric pressure is an average of 760mmHg, 101.3 kilopascal, 14.7 psi aka 1 atm.

35
Q

What are the air contents at sea level?

A

78% Nitrogen, 21% oxygen, 1% Argon, 0.04% carbon dioxide. Remainder is all trace gases.

36
Q

What is the “physiologic deficient” Zone?

A

The area from 10,000-50,000ft. Above 10,000ft barometric pressure begins to decrease resulting in hypoxic hypoxia

37
Q

What are the 4 stages of hypoxia

A
  1. Indifferent stage
  2. Compensatory Stage
  3. Disturbances stage
  4. Critical Stage
38
Q

Indifferent stage

A

ranges from sea level to 10,000ft. However symptoms may manifest themselves as low as 5,000ft.

Minor effects, spo2 varies to 97-98%

39
Q

Compensatory stage

A

Ranges from 10,000 and 15,000ft OR 39,000 to 42,000 ft if breathing 100% oxygen.

At this stage the Body is able to compensate physiologically by increasing respiratory rate and depth, cardiac output. Spo2 ranges from 80-87%.

40
Q

Disturbance Stage

A

Ranges from 15,000 to 20,000ft

-The body is no longer able to depend upon physiologic compensatory mechanisms. Hypoxia occurs leading to impaired physiology.

41
Q

Critical Stage

A

Ranges from 20,000 - 25,000ft

Spo2 less tha. 65%. Badness.

42
Q

Name 5 primary stressors of flight.

A
  • Decreased PaO2
  • Thermal Changes
  • Vibration
  • Decreased Humidity
  • Gravitational forces
43
Q

Name 3 patient populations that will no tolerate moderate to severe turbulence or severe G-forces

A
  • TBI
  • SCI
  • Hemodynamically compromised patients
44
Q

what are the 7 Gas-Laws?

A
  • Boyles Law
  • Charles Law
  • Daltons Law
  • Ficks Law
  • Henrys Law
  • Gay-Lussacs Law
  • Grahams Law
45
Q

Boyles Law

A

As barometric pressure drops, Gas will expand. Increased altitude causes decreased pressure, causing gas expansion.

46
Q

Charles Law

A

Volume of gas is directly proportional to the temperature, pressure remains constant.

as altitude increases, pressure decreases and so does temperature, and volume.

As temperature increases, air becomes thinner.

47
Q

Daltons Law

A

The total of a mix of gas is the sum of all its parts.

As altitude increases pressure goes down and so do the individual components of a gas

48
Q

Ficks Law

A

Diffusion rate of gas across a membrane depends on pressure, surface area, and inversely proportionate to membrane thickness.

49
Q

Henrys Law

A

As pressure decreases, gas dissolved in liquid will also decrease. These are directly proportionate.

50
Q

Gay-Lussacs Law

A

As altitude increases, pressure decreases and temperature decreases

51
Q

Grahams Law

A

Molecullar weight alters rate of diffusion. The heavier the molecule the faster it diffuses.