Oxygen Therapy

Oxygen Therapy

·        Ensure PO₂ is on plateau of O₂ saturation curve (ie PaO₂ > 70 mmHg)

·        Shunt is resistant to O₂ therapy, whereas a diffusion abnormality and V/Q mismatch respond well

·        Complications:

o   Reduced respiratory drive in CORD. Consider if ­PCO₂ but pH not as low as you‟d expect. Don‟t give too much O₂ otherwise ¯respiratory drive ® ­CO₂. Aim for saturation of ~ 90%

o   Loss of nitrogen splint, etc

·        Levels of O₂ therapy:

o   21%: Room air

o   24%: nasal prongs at 1 litre

o   28%: nasal prongs at 2 litres

o   32%: nasal prongs at 3 litres

o   35%: Hudson mask at 6LO2/min

o   40%: Hudson mask at 8LO2/min. Maximum level obtainable with a mask (inspiratory flow > flow from wall) 

o   50%: Hudson mask with rebreather bag

·        Types of ventilation:

o   CPAP: Continuous positive airways pressure – splints airways open at end of respiration

o   BiPAP: Positive pressure for inspiration only. Good if CO₂ retention – makes it easier to blow off CO₂

o   IPPV = intermittent positive pressure ventilation: complete control

o   PEEP = positive end expiratory pressure ventilation: splints collapsed or fluid filled alveoli

o   Complications of ventilation: 

§  Application of pressure to lungs ® rupture, ­thoracic pressure ® ¯venous return

§  Artificial airway ® obstruction, trauma to teeth, pharynx, cilial damage, infection

§  Ventilation mismanagement ® inappropriate ventilation, hypoxic gas mixture, equipment failure