Ventilation 2

Question 1

What is the PaCO₂ equation?

Answer 1

PACO₂ = (VCO₂ x 0.863)/V_A

V_A = RR x Vt(1-Vd/Vt)

Question 2

common causes of hypocapnia

Answer 2

pain

anxiety

fever

sepsis

asthma

pneumonia

pulmonary edema

pulmonary embolism

aspirin intoxication

stimulant overdose

liver failure

pregnancy

metabolic acidosis

hyperthyroidism

psychosis

Question 3

common causes of increase VCO₂

Answer 3

fever

excess movement

seizures

over-feeding

hypermetabolic states such as hyperthyroidism

Question 4

common causes of decreased V_E

Answer 4

head rauma with raised intracranial pressure

CNS tumor or infection (encephalitis)

CNS depressant drugs (opioids, benzodiazepines, barbiturates)

obesity leading to hypoventilation

hypothyroidism

neuromuscular disease

chest wall deformity

obstructive lung disease

restrictive lung disease

Question 5

common causes of increased Vd/Vt

Answer 5

pulmonary embolism

emphysema

pulmonary hyperinflation

use of low tidal volumes during mechanical ventilation

shallow breathing from illness

Question 6

three reasons for hypercapnia

Answer 6

increase VCO₂

decreased V_E

increased Vd/Vt