Mechanical Ventilation.'

Question 1

What are the most common causes of hypoxemic respiratory failure?

Answer 1

ventilation-perfusion (V/Q) mismatch or shunt caused by processes such as:
- pneumonia
- pulmonary edema
- alveolar hemorrhage
- acute respiratory distress syndrome (ARDS)
- sequelae of trauma or surgery

Question 2

What are the most common causes of hypercapnic respiratory failure?
- PaCO2 > 45 mmHg with pH < 7.35

Answer 2

1) severe exacerbations of obstructive lung diseases, including:
- asthma
- chronic obstructive pulmonary disease (COPD)
2) loss of central respiratory drive from acute neurologic events, such as:
- stroke
- intracranial hemorrhage
- drug overdose
- respiratory muscle weakness from diseases such as Guillain-Barré syndrome, stiff person syndrome

Question 3

Which ventilator setting prevents alveolar collapse d/t too low lung volumes at the end of exhalation?

Answer 3

Positive End-Expiratory Pressure (PEEP)

Question 4

What is the tidal volume goal for an intubated patient to prevent end-inhalation from exceeding 30 cmH20 and minimizing the risk of barotrauma and volume induced lung injury?

Answer 4

6mL/kg of ideal body weight

Question 5

Setting the tidal volume to 6mL/kg of ideal body weight on a vented patient reduces the risk for what?

Answer 5

• barotrauma: damage d/t pressure
• volume induced lung injury

Question 6

What does AC-VC stand for as a ventilator mode?

Answer 6

Assist Control-Volume Control
- set tidal volume = guaranteed min tidal volume
- set RR = guaranteed minute ventilation or resp/min

Question 7

What are the advantages of the AC-VC mode on a ventilator?

Answer 7

• Assist Control-Volume Control
• guaranteed tidal volume and minute ventilation

Question 8

What are the disadvantages of the AC-VC mode on a ventilator?

Answer 8

• potential for barotrauma from high plateau pressure in patient with reduced lung compliance
• patient-ventilator dyssynchrony and increased work of breathing d/t patient breathing over the ventilator set rate

Question 9

What does AC-PCV stand for as a ventilator mode?

Answer 9

Assist Control-Pressure Control Ventilation

Question 10

What does CPAP stand for?

Answer 10

Continuous Positive Airway Pressure

Question 11

What does BiPAP stand for?

Answer 11

Bilevel positive airway pressure
- delivers different pressures during inspiration and expiration

Question 12

What is the normal PaO2 value?

Answer 12

90-100 mmHg

Question 13

What are the adverse/negative affects of hypercapnia?

Answer 13

• lowers pH = more acidic
• pulmonary arterial vasoconstriction
• rightward shift of oxyhemoglobin disassociation curve
• increased ICP
• reduced cardiac contractility

Question 14

What is Post Extubation Stridor and how is it caused?

Answer 14

inspiratory wheeze following extubation caused by vocal cord injury r/t:
- traumatic intubation
- intubated > 7 days
- ETT to large
- previous PES
- head/neck trauma