CCP 108 - Fundamentals of Mech Vent

Question 1

What is Transpulmonary pressure (Ptp)

Answer 1

Transpulmonary pressure is the difference between the alveolar pressure and the intrapleural pressure in the pleural cavity.

Ptp = Palv – Pip. Where Ptp is transpulmonary pressure, Palv is alveolar pressure, and Pip is intrapleural pressure.

Question 2

What is Peak inspiratory pressure (PIP)

Answer 2

Peak inspiratory pressure (PIP) is the highest level of pressure applied to the lungs during inhalation.

Question 3

What is Peak Pressure (Ppeak):

Answer 3

it is the amount of airway pressure delivered by the ventilator to initially overcome the resistance of the ETT, airway, and alveoli

Ppeak = Airway Resistance / Compliance

Question 4

Plateau Pressure (Pplat)

Answer 4

Plateau pressure is the pressure in the lung after a certain volume is delivered into the lungs. This is measured by doing an inspiratory hold.

Question 5

What does an increasing Ppeak without increasing Pplateau suggest?

Answer 5

Airway resistance is increasing

Question 6

What does an increasing Pplateau suggest

Answer 6

Decreased lung compliance

Question 7

List some Volume Control Modes

Answer 7

Synchronized Intermittent-Mandatory Ventilation (SIMV)

Assist-Control Ventilation (ACV) also called continuous mandatory ventilation (CMV)

Question 8

List some Pressure Control Modes

Answer 8

Pressure-Controlled Ventilation (PCV)

Pressure Support Ventilation (PSV)

Pressure Controlled Inverse Ratio Ventilation (PCIRV)

Airway Pressure Release Ventilation (APRV)

Question 9

What is Paw

Answer 9

Mean Airway Pressure

Paw = ((Inspiratory Time x Frequency) / 60) x (PIP – PEEP) + PEEP

Question 10

What is a recruitment maneuver

Answer 10

a sustained increase in airway pressure with the goal to open collapsed alveoli, after which sufficient PEEP is applied to keep the lungs open

Question 11

What are the indications for mechanical ventilation? (4 categories)

Answer 11

1. Airway disease of compromise (airway obstruction due to DLOC or trauma or distal airways obstructed due to COPD or asthma)
2. Hypoventilation due to impaired drive, pump failure or inability to exchange gases resulting in hypercapnic resp failure (impaired central drive, respiratory muscle weakness, PNS defects, restrictive ventilatory defects)
3. Hypoxemic resp failure due to inability to exchange O2 or delivery to peripheral tissues (alveolar filling defects like pneumonia or pulm edema, pulm vascular defects like PE, or diffusion defects like severe pulm fibrosis)
4. Increased ventilatory demand (like in severe sepsis or metabolic acidosis)

Question 12

What is normal transpulmonary pressure?

Answer 12

25-30 cmH20

Question 13

Define pressure ventilation

Answer 13

The flow of air into the lungs is determined by a set pressure limit and the rate is determined by a set ventilator rate.
Tidal volume is variable and determined by compliance, airway resistance and tubing resistance.

Question 14

Define volume ventilation

Answer 14

Breaths are delivered at a predetermined tidal volume at a set ventilator rate such that a minimum minute ventilation is guaranteed.
Airway pressure is variable and determined by airway resistance, lung compliance and chest wall compliance.

Question 15

Define pressure support

Answer 15

Spontaneous breathing supported to a set pressure limit.