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Flashcards in Respiratory Failure Deck (10):

What are the normal values for ABG?

  • pH:      7.35-7.45
  • pCO2: 4.5-6.0kPa
  • pO2:    11-13kPa
  • HCO3:  22-26mmol/l
  • BE:        -2 to+2
  • SaO2:    >95%
  • PaO2 should be equiv to FiO2%-10%
  • Alveolar arterial gradient: <10 (inc in emphysema, fibrosing alveolitis, age)
  • Lactate <2


Causes of type 1 respiratory failure?

Type 1 = 1 gas abnormal = Low 02, normal CO2:

  • Low V/Q: areas of lung are perfused with deoxygenated blood but not ventilated with oxygen (ie airway obstruction)
  • Causes: mucus plug in asthma/COPD, airway collapse in emphysema
  • High V/Q: areas of lung are ventilated with oxygen but not perfused with deoxygenated blood (ie block in blood flow)
  • Causes: PE


Why is CO2 normal in type 1 respiratory failure?

  • Because areas of the lung which are perfused and ventilated can blow off xs CO2 by increasing ventilation
  • Making CO2 low in this area and high where V/Q mismatch, which makes it normal all over
  • However extra oxygen cannot be absobed because the max amount of O2 diffuses across the alveolar membrane in normal circumstances anyway


What are the cause of type 2 respiratory failure?

Type 2 = 2 gasses abnormal = low O2/High CO2:

  • Caused: by alveolar hypoventilation, O2 cannot get into alveoli and CO2 cannot get out
  • Causes: Obstructive lung disease (COPD), Restrictive lung disease, decreased respiratory drive, neuromuscular disease, thoracic wall disease


What is Lactic Acidosis?

Lactic acid is a product of anaerobic metabolism



What are the types of Lactic Acidosis?

Types of Lactic Acidosis?

TYPE 1 (Hypoxic) 

  • produce too much lactic acid
  • DKA, starvation, CV/Resp depression

TYPE 2 (non Hypoxic)

  • cannot breakdown lactic acid
  • secondary to metformin or poisening


  • an enzyme involved in anaerobic metabolism pathway
  • inc in tissue breakdown etc, muscle trauma, MI, stroke, haemolysis, cancer, acute pancreatitis, HIV, meningitis/encephalitis


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