Respiratory Faliure Flashcards
what does hypoventilation mean
under breathing
what can hypoventilation cause
type 1 and 2 RF
what is hypoventilation caused by
inadequate alveolar ventilation resulting in low alveolar pO2 (and high pCO2)
when does hypoventilation occur
when the respiratory drive is impared
what does low FIO2 result in
low alveolar PO2
how do you manage low FIO2
supplemental o2
what does disease or damage to the basement membrane
a reduction in the amount of oxygen that diffuses across the interstitium and this results in Hypoxaemia
what are the oxygen values like for diffusion impairment
Normal PAO2 but reduced PaO2
what does TLCO measure
difusion capacity
how do you calculate TLCO
small amount of CO
what is the alveolar- arterial gradient used for
if theres a problem in diffusion capacity
what factors affect diffusion of gasses
surface area
thickness
diffusion coefficient
partial pressure
how do you manage diffusion impairment
- Treatment of underlying condition if possible
Supplemental oxygen
what are the types of shunt
physiological
anatomical
cardiac
pulmonary
what is an anatomical shunt
blood that goes from the right side to the left side of the heart without traversing pulmonary capillaries
What is the main difference between anatomical and physiological shunts
Anatomic shunts cause a ventilation-perfusion ratio of zero, and physiologic shunts cause a low ventilation-perfusion ratio, contributing to the lowering of partial pressure of oxygen (PaO2)
what does anatomical shunts result in
mixing of venous and arterial blood
how does anatomical shunts result in the mixing of venous and arterial blood
- Deoxygenated blood from bronchial circulation → pulmonary veins
- Deoxygenated blood from coronary circulation → Thebesian vein → left ventricle
what is a cardiac shunt
A cardiac shunt is a pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system. It may be described as right-left, left-right or bidirectional, or as systemic-to-pulmonary or pulmonary-to-systemi
how can cardiac shunts arise
either congenital or acquired
what is a pulmonary shunt
passage of deoxygenated blood from the right side of the heart to the left side without participating in gas exchange in the pulmonary capillaries
what is a physiological shunt
when nonventilated alveoli remain perfused, thus functioning as a shunt even though there is not an anatomic anomaly
what are reasons for physiological shunts forming
consolidation e.g. pneumonia
atriovenous malformation
hypoxaemia
what is ventilation (v)
flow of oxygen into the alveoli
what is perfusion (Q)
the flow of blood of alveolar capillaries
what is a normal V/Q value
0.8 ratio