Mechanical Ventilation Basics

Question 1

What is hypoxemia?

Answer 1

PaO2 <80mmHg, severe if below 60

Question 2

What is hypercapnia?

Answer 2

PaCO2 >45, severe if above 75mmHg

Question 3

What can cause low FiO2?

Answer 3

high elevation

Question 4

What can cause hypoventilation?

Answer 4

Drugs such as opioids, benzos, general anesthetics; can result in hypoxemia and hypercapnia

Question 5

What R to L shunts can lead to hypoxemia?

Answer 5

Pulmonary AVMs, cardiac shunt, hepatopulmonary syndrome; alveoli filled with fluid (puss, blood, edema) results in bypass of lung tissue

Question 6

How can V/Q mismatch lead to hypoxemia?

Answer 6

Low ventilation to perfusion, COPD, ILD, vascular dz

Question 7

What neurological disorders can lead to hypercapnia?

Answer 7

Spinal cord injury, GBS, brain tumor, increased intracranial pressure

Question 8

What thoracic cage disorders can lead to hypercapnia?

Answer 8

trauma, kyphoscoliosis, pectus excavatum

Question 9

What pulmonary disorders can lead to hyercapnia?

Answer 9

epiglottitis, laryngeal edema, COPD, OSA, ARDS

Question 10

What are the signs of respiratory failure?

Answer 10

Dyspnea, tachypnea, cyanosis, sweating, use of accessory muscles of respiration, agitation or lethargy, flaring of nostrils, wheezing or crackles, low O2 saturations

Question 11

Compensation is always in the same direction as what?

Answer 11

the primary disorder

Question 12

The pH changes in opposite directions to the HCO3 and PCO2 with what?

Answer 12

respiratory disorders

Question 13

The pH, HCO3 and pCO2 all point in the same direction with what?

Answer 13

metabolic disorders

Question 14

What is the main purpose for mechanical ventilation?

Answer 14

to augment or replace respiratory system

Question 15

What does mechanical ventilation provide when there is an oxygenation issue?

Answer 15

provides positive pressure and supplemental oxygen, reduces excessive work of breathing

Question 16

What does mechanical ventilation provide for ventilation issues?

Answer 16

aids with airway obstruction, increases respiratory rate, assists with respiratory fatigue

Question 17

What are the types of mechanical ventilation?

Answer 17

Invasive ventilation (intubation) and non-invasive positive pressure ventilation (NPPV)

Question 18

What are the advantages for NPPV?

Answer 18

improved oxygenation, shorter length of stays in ICU and hospital, improved survival; preservation of upper airway reflexes, improved pt comfort, decreased work of breathing, avoids complications associated with intubation

Question 19

What are the disadvantages for NPPV?

Answer 19

claustrophobia, unprotected airway; increased workload for practitioner, nasal pressure lesions, inability to suction deep airway, gastric dissension with use of face mask or helmet, delay in intubation

Question 20

What are the absolute contraindications for NPPV?

Answer 20

cardiac or respiratory arrest and unstable cardiac arrhythmia

Question 21

What are the relative contraindications for NPPV?

Answer 21

Hemodynamic instability, unable to cooperate, inability to protect airway, active GI hemorrhage, encephalopathy

Question 22

When are NPPV used in clinical practice?

Answer 22

Acute COPD exacerbations (hypercapnic respiratory acidosis), hypoxemic respiratory failure (COVID, bacterial pneumonia), acute pulmonary edema from cardiac etiology

Question 23

What are the advantages for intubation?

Answer 23

Decreasing risk of aspiration, allowing ventilation with 100% oxygen, facilitating tracheal suctioning, eliminate need to maintain mask to face seal

Question 24

What are the disadvantages for intubation?

Answer 24

injury to teeth, throat and/or trachea, risk of improper placement, may increase respiratory resistance, need for advanced training to properly perform, need for specialized equipment

Question 25

What is an absolute contraindications for intubation?

Answer 25

advanced directive

Question 26

What are the relative contraindications for intubation?

Answer 26

facial or upper airway trauma, laryngeal edema (burns, anaphylaxis, infections), difficult anatomy, clinician skill set

Question 27

When are incubations performed in clinical practice?

Answer 27

Acute respiratory failure (oxygenation, ventilation), airway protection (AMS [encephalopathy, drugs, EtOH, seizure], perioperative setting)

Question 28

What are the settings for mechanical ventilation?

Answer 28

Positive end expiratory pressure (PEEP), FiO2, tidal volume, and respiratory rate

Question 29

Ventilation = what?

Answer 29

CO2 management

Question 30

What is PEEP?

Answer 30

aids in alveolar recruitment and improves oxygenation

Question 31

What is FiO2?

Answer 31

Increases concentration of oxygen and improves oxygenation

Question 32

What is tidal volume?

Answer 32

amount of air delivered with each breath, will affect ventilation

Question 33

What is respiratory rate?

Answer 33

frequency of delivered breaths, will affect ventilation

Question 34

What are the parameters that affect oxygenation?

Answer 34

PEEP and FiO2

Question 35

What are the parameters that affect ventilation?

Answer 35

RR and TV

Question 36

What are the risks associated with PEEP?

Answer 36

Too much pressure can result in barotrauma, typically limit PEEP to 15cm H2O; can go higher but you must reduce/sacrifice TV

Question 37

What are the risks associated with FiO2?

Answer 37

There is such a thing as too much oxygen; higher levels are associated with damage to lung parenchyma; hyperoxia is also associated with increased mortality and increased hospital stay

Question 38

What are the risks associated with TV?

Answer 38

too large of a TV may result in barotrauma; avoid >10mL/Kg of ideal body weight; in ARDS lung conservation strategy is to reduce TV in order to increase PEEP

Question 39

What are the risks associated with RR?

Answer 39

Must allow time to exhale; if RR is too quick in patients with prolonged expiratory phases (COPD), auto-PEEP will result (not good)