Resp failure Flashcards
Describe alveolar changes across the lungs
Larger & less compliant at the top
Describe West Zone 1
Alveolar, arterial and venous pressures
Alveolar pressure > arterial > venous
More ventilation than perfusion
Describe West Zone 2
Alveolar, arterial and venous pressures
Arterial > alveolar > venous
Perfusion = ventilation
Describe West Zone 3
Alveolar, arterial and venous pressures
Arterial > venous > alveolar
More blood flow than ventilation here
Compliance
Definition and equation
Tendency of airways to distort under pressure
= ∆V/∆P
Elastance
Definition and equation
Tendency to recoil to original volume
= ∆P/∆V
What is ARDS? What are the diagnostic criteria?
Acute respiratory distress syndrome
1. acute onset of <1 week
2. bilateral opacities seen CXR
3. PaO2/FiO2 <300mmHg on CPAP or PEEP
PaO2/FiO2 is ratio of arterial to inspirated oxygen
What are the classifications of ARDS?
Give examples of each
- Acute - infection, aspiration, lung transplant dysfunction, sepsis
- Chronic - COPD, lung fibrosis, CF, muscular dystrophy
- Acute on chronic - infective exacerbation of chronic conditions, myasthenic crisis
Which lung capacity is increased in patients with reduced lung compliance? Why?
Functional residual capacity
Can’t breathe out as much, as diaphragm is pushed up
Pregnancy, COPD, surgery w/ inflated abdomen
Equation for minute ventilation
Units
Tidal volume x breathing rate
L/min
Equation for alveolar ventilation
Units
(tidal volume - dead space) x breathing rate
L/min
What is Type I respiratory failure?
Hypoxemic, failure of oxygen exchange
PaO2 <60 at sea level
What is Type II resp failure?
Hypercapnic, failure of CO2 removal
PaCO2 >45 at sea level
What is Type III resp failure?
Perioperative, lungs collapsing down during surgery
Increased intraabdo pressure and FRC
Decreased ventilatory volume
What is Type IV resp failure?
Shock (septic/cardiogenic/neurologic)
