Mech Vent

Question 1

What are potential causes to hypercapneic respiratory failure?

Answer 1

1) Brain - drugs, CVA (ischemia), Bleed/Herniation, structural lesions, metabolic (liver/renal)
2) Spinal curve injury at C3, C4, C5
3) Phrenic nerve injury - GBS, Myasthenia gravis
4) Trachea problem (obstruction)
5) Chest wall problem - kyphosis
6) Pleural space - effusion, ptx
7) Small airway - asthma, COPD
8) Muscle - myositis

Question 2

What is the approach to a hypoxemic patient?

Answer 2

1) Increase FiO2 to 1
2) Optomize PEEP
3) Switch to pressure control mode
4) Increase RR
5) Recruitment manoever
6) Prone patient
7) Increase Ti time (Reverse IE)
8) Ecmo

Question 3

What are the 5 causes of hypoxemia?

Answer 3

1) Hypoventilation
2) V/Q mismatch
3) Right or left shunt
4) Diffusion abnormalities
5) Decreased FiO2

Question 4

What are the goals of CCP Practice?

Answer 4

1) Preserve life
2) Prevent deterioration
3) Promote healing

Question 5

What is myasthenia gravis?

Answer 5

Autoimmune disease that causes muscle weakness through destruction of nicotinic receptors.

Symptoms affect eyes (ptosis), face and swallowing.

Question 6

What is Guillain-Barre syndrome?

Answer 6

Autoimmune disorder in which the antibodies cause weakness secondary to peripheral nerve demyelanation

Question 7

What are 3 causes of myositis?

Answer 7

1) Trauma
2) Infection
3) Autoimmune

Question 8

What are 5 reasons why we would want to mechanically ventilate someone?

Answer 8

1) Oxygenate
2) Ventilate
3) Protect airway
4) Clinical Course
5) Uncompensated shock

Question 9

What is the formula for Venous Return?

Answer 9

(Mean systemic filling pressure - Pressure in Right Atrium) / Resistance

Question 10

With respect to right heart failure, why was Rivers protocol killing people?

Answer 10

Fluid overload increased CVP (right atrial pressure) to the point that there was no passive venous return possible

Question 11

Describe each of the west lung zones and some causes

Answer 11

Zone 1 -> V > Q (overdistended lungs)
Zone 2 -> V = Q (ideal)
Zone 3 -> V < Q (Infection, edema)

Question 12

How does a fluid bolus help a COPD patient before intubating?

Answer 12

COPD patient has lots of west zone 1 due to hyperinflation and this reduces alveolar perfusion - fluid bolus would increase perfusion and try to match V/Q prior to intubation increasing oxygenation

Question 13

What is the bathtub model of stressed and unstressed volume?

Answer 13

Stressed volume is volume above the drainpipe (flows by pressure increase drain). Stressed volume can be increased by adding fluid, or pressors increase stressed volume by shrinking the bathtub

Question 14

What is ventilation proportional to?

Answer 14

RR and Vt/VtDS (fraction of deadspace)

Question 15

Aside from increase PCO2, what is another risk of too low Vt?

Answer 15

Alveolar derecruitment

Question 16

What is a good starting RR?

Answer 16

10-20, but evaluate the patient intrinsic RR first

Question 17

What are the formulas for transpulmonary plat and transpulmonary peep?

What values do you want for transpulmonary plat and transpulmonary peep?

Answer 17

Transpulmonary Plat = Plat - Pleural Pressure (Pesophagus end inspiration)

Transpulmonary Peep = Peep - Pleural Pressure (Pesophagas end expiration)

Ideal Tplat = < 25
Ideal Tpeep = 0

Question 18

What is the purpose of peep?

Answer 18

To keep the alveoli open at end expiration, increasing FRC and allowing for oxygenation. TOO much peak causes west zone 1s and decreased perfusion, too little peep cause alveolar collapse and reduced FRC

Question 19

What is driving pressure, when is it used and what value would you want it be below?

Answer 19

Driving pressure is Plat - applied PEEP = It is studied in ARDS patients and should be less than 15. If you increase your PEEP and driving pressure decreases, then additional alveoli have been recruited

Question 20

What does the difference between PIP and Plat represent?

Answer 20

Resistance in the airways (circuit right down the alveoli)

Question 21

Why is it theorized that lower lung volumes protect ARDS lungs?

Answer 21

Not all lung units are available for gas exchange meaning higher volume will overdistend and damage those units that are ventilated

Question 22

What type of compliance can you measure with inspiratory hold?

Answer 22

Static no flow state compliance

Question 23

What happened if driving pressure decreases after increasing peep?

Answer 23

More recruitment of alveoli occurs which lower Pplat

Question 24

What happened if you increase PEEP and SpO2 decreases? How can you correct this? In what disease state would you not do this though.

Answer 24

You overdistended alveoli causing West zone 1 and decreased perfusion. Correct by providing fluid to decrease west zone 1. Do not do this in heart failure

Question 25

How does a patient die with dynamic hyperinflation?

Answer 25

Dynamic hyperinflation causes massive pulmonary pressure reducing venous return to the RA and the resultant drop in preload causing a drop in cardiac output

Question 26

When do you need to use peep matching?

Answer 26

When a patient is unable to trigger the vent due to high autopeeps