Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
25 Cards in this Set
- Front
- Back
What is PEEP?
|
Positive End Expiratory Pressure
physiological = 3 to 5 cmH20 keeps alveoli inflated Expiration maneuver |
|
What is auto-PEEP?
|
intrinsic or inadvertent PEEP
result of too short E time air trapping --> increased PCO2 |
|
Describe PIP
|
Peak Inspiratory Pressure
Pressure required to force the gas through the resistance of the airways and the gas volume as it fills the alveoli |
|
Describe Plateau Pressure
|
Pressure measurement taken after a breath has been delivered to the pt and before expiration has begun
used to measure Cs of alveoli |
|
What is elastance?
|
The tendency of an object to return to its original state after being stretched-
|
|
Define pulmonary compliance.
|
change Volume / change Pressure
l/cmH2O how easily the lungs expand normal = 0.1 l/cmH2O c ETT = .04 - .05 l/cmH2O |
|
How is pulmonary compliance measured?
|
use Plateau Pressure
Cs = ExhVt/ (Pplateau - PEEP) |
|
What is resistance?
|
AKA: frictional forces
Raw = PTA/flow (sec) PTA = PIP- Pplateau normal = 0.6 - 2.4 cmH2O/l/sec |
|
How can resistance be manipulated?
|
changing length and diameter of tube
increase length = increased R increase diameter = decreased R changing flow rate increase flow = increased R |
|
Normal values for resistance.
|
non-intubated = 0.6 - 2.4 cmH2O/l/sec
intubated = 5-7 cmH2O/l/sec |
|
Normal values for compliance
|
non-intubated = 0.1 l/cmH2O
intubated = 0.035 - 0.5 l/cmH2O |
|
What are time constants?
How are the calculated? |
The rate at which individual lung units fill or empty
Product of compliance and resistance C*R normal = 0.1 sec |
|
How do compliance and resistance affect time constants?
|
increased R, increased C = Long TC
decreased R, decreased C = Short TC |
|
How many TC's represent 95% filling or emptying of the lung?
|
3
|
|
How are ventilators pneumatically powered?
|
Depend entirely on a compressed gas source for power
50 PSI Like the Bird |
|
How are ventilators electrically powered?
|
Rely on electricity to function
On/Off switch controls I,E, flow and alarms |
|
How do ventilators use combined power?
|
Use both power sources
One or two gas sources (variable FiO2) Electric: internal functions Gas: provide energy to deliver breath |
|
Describe the Internal Circuit, including both the single and double circuits
|
Single: allows gas to go directly from power source to pt. Currently used.
Double: generates gas flow that compresses another mechanism |
|
Pressure-controlled vs. Volume-controlled breaths
|
Pressure-Controlled: volume and flow may vary depending on pt's lung characteristics
Volume-Controlled: pressure varies depending on lung characteristics |
|
Define mandatory mechanical breaths
|
Started, controlled and ended by ventilator.
Ventilator does ALL WOB |
|
Define assisted mechanical breaths
|
Started by pt. but controlled and limited by ventilator
|
|
How is a breath triggered? With pressure and flow?
|
Pt. triggering
vent can "sense" attempts to breath. Negative P or flow will trigger vent to begin inspiration |
|
How is a breath "limited"? With what variables?
|
Inspiration can be timed (ventilator triggered)
Can also control max. pressure, volume or flow. Doesn't end I just limits variables |
|
What is the difference between Pressure-limiting and Pressure-cycling?
|
Limiting: max P is set as a safety feature, will never exceed, but doesn't end I
Cycling: when max P is reached I ends |
|
How does CPAP or PEEP improve oxygenation?
|
CPAP: mode or ventilation, but pt is spontaneously breathing
PEEP: mehanically vented pt. both prevent early airway closure and increase FiO2 |