respiratory failure Flashcards
what are the types of respiratory failure ?
type 1 - hypoxemic RF
type 2 - hypercapnic RF
what are the normal values of ABGs ?
PaO2 : 75-100
PaCO2 : 35-45
Hco3 : 22-26
pH :7.35 - 7.45
what are the ABG findings in type 1 vs type 2 RF ?
1- Pao2 is decreased in type 1 whilst PaCo2 is normal
2- Pao2 is decreased in type 2 whilst PaCo2 is increased
what are the main mechanisms that causes type 1 respiratory failure ?
intrapulmonary shunt
diffusion limitation
v/q mismatch
decreased Fio2
what are examples of diseases that cause intrapulmonary shunts ?
pneumonia - alveoli filled with pus
atelectasis - collapsed alveoli
ARDS - alveoli filled with exudate
what is the difference between type 1 and type 2 acute respiratory failure ?
1- o2 - both low
2- Co2 - normal or low in type 1, high CO2 in type 2
3- pH - normal or alkalotic in type 1 , normal or acidotic in type 2
4- bicarb - normal in both
what is the difference between type 1 and type 2 in chronic resp failure ?
1- O2- both low
2- CO2 - normal or low in type 1 , high in type2
3- pH- normal or alkalotic in type 1, normal or acidotic in type 2
4- bicarb - normal in type 1, high in type 2
what is the normal V/Q ratio ?
0.8
if the V/Q ratio is above the norrmal what is that an indicator of ?
decreased perfusion
if the V/Q ratio is below the normal what is that an indicator of ?
decreased ventilation
what is a physiological dead space ?
at the apex of the lung there is alot of ventilation with barely any perfusion ( wasted ventilation )
what is the V/Q in pulmonary embolism ?
very very high due to the creation of a dead space
what investigation are required in cases of respiratory failure ?
ABG
Chest X-ray
US
Ventilation-perfusion scan
what are the causes of decreased perfusion in the lungs ?
emphysema
pulmonary embolism
what are the indications for oxygen therapy ?
MAHA <3
1- peri and post cardiac or respiratory arrest
2- acute and chronic hypoxemia
3- low cardiac output and metabolic acidosis
what are the types of oxygen delivery devices ?
low flow devices - below normal insp flow rate
high flow devices - above normal insp flow rate
what are the types of low flow devices ?
nasal cannula 1-6 L
simple face mask 6-8 L
reservoir mask 8 - 12 L
what are the types of high flow devices ?
venture masks
high flow nasal cannula
what are the non invasive methods of ventilation ?
CPAP - in OSA only
BIPAP - better to start with it in type 2 RF if there is no indication for IMV especially in COPD
what are the causes of type 1 RF ?
shunt
decreased atmospheric pressure
ventilation perfusion mismatch
pneumonia
ARDS
pulmonary embolism
what is intrapulmonary shunting ?
lung areas with high ventilation low perfusion
ay V/Q mismatch y3mel what type of RF ?
type 1
any decrease in alveolar ventilation ye3mel what type of RF ?
type 2
what is thee target Spo2 in hypercapnic patients ?
88-92 to prevent killing the hypoxic drive
what are the indications for invasive MV ?
unable to tolerate the non invasive MV
disturbed conscious level
massive aspiration
inability to remove secretions
refractory haemodynamic instability
respiratory or cardiac arrest
hypoxemia
ventricular arrhythmia