Unit 4 Test - Amy's Class Flashcards
(37 cards)
Define alveolar ventilation
The volume of air that ventilates perfused alveoli and takes part in gas excahnge
Define deadspace unit
Ventilation without perfusion
Give an example of a deadspace unit
Pulmonary embolism
List some things that will cause deadspace to increase
Positive pressure ventilation, pressure in the thorax, pulmonary embolism
To calculate VD anatomical what parameter will you need?
Its weight in pounds
What is normal VT/VD in a healthy adult?
33%
A VD/VT of .06 (60%) usually requires
Mechanical ventilation
What affect does increase deadspace have on CO2?
It increases it
To determine if a patient has a pulmonary emboli, the respiratory therapist should evaluate
VD/VT, V/Q scan
Define a shunt unit
Perfusion without ventilation
List causes of a shunt
Atelectasis, pneumothorax, pneumonia, ARDS
What is normal anatomical shunting?
2-5%
Define intrapulmonary shunting
Blood going from the right side of the heart to the left side without participating in gas exchange
What veins contribute to normal anatomical shunting?
Thebesian, bronchial, pleural
What is the clinical use of the shunt calculation?
Differentiate causes of hypoxemia, assessment of spontaneous ventilatory capabilities in mechanically ventilated patients, assessment of intrapulmonary shunting
A-a gradients are used to determine:
Amount of intrapulmonary shunting
5% shunt
Normal
40% shunt
Usually requires aggressive cardiopulmonary support
25% shunt
May result in ventilatory failure
18% shunt
Represents minor pulmonary disease
15% shunt
Represents minor pulmonary disease
What does “Qt” stand for
Total cardiac output
What does “CcO2” stand for
Capillary oxygen content
What does “CvO2” stand for
Mixed venous oxygen content
