oxygen Flashcards
hypoxaemia
not enough oxygen in blood
causes of hypoxamia
low partial pressure of oxygen hypoventilation diffusion limitation right-left shunt V/Q mismatch
causes of tissue hypoxia
hyperaemia
amaemia
blood flow obstruction
tissue hypoxia meaning
failure oxidative energy metabolism
anaerobic energy metabolism - lactate accumulation - decrease in pH
chronic hypercapnia
desensitises chemoreceptors to CO2
still sensitive to oxygen concentration and pH
CO2 narcosis
caused by chronic hypercapnia
causes sleep
targets for O2 saturation
normocapnic - 94-96%
hypercapnic or chronic lung disease with risk of CO2 insensitivity - 88-92%
conditions where hypercapnia is a risk
chronic lung disease, commonly COPD
portable oxygen cylinder
lower end of the ball should sit as desire Flow rate L/min
pulse oximetry
monitoring oxygen therapy
shines a red light or two different wavelengths through a fleshy peripheral part of the body
displaces % of Hb oxygen saturation
poor performance in patients with poor blood supply
does not give info about CO2 or pH
nasal prongs
suitable only for stable patients requiring low oxygen flow rates of 2-4L/min
don’t interfere with talking or eating - used for home oxygen
Hudson mask
5-10 L/min
mildly hypoxaemic but not critically ill
patient breathes back in expired air
non-rebreather mask
eliminates problem of rebreathing CO2 has a reservoir bag 6-15 L/min suitable for sicker patients pneumonia or severe asthma attack 40-60% oxygen
venturi mask
variable concentration mask
come with a selection of diluter jets
expensive but safer if you need to know how much oxygen your patient is getting
CPAP
continuous positive airway pressure oxygen with extra pressure delivered through a tight fitting mask 60-80% concentrations intensive care acute pulmonary oedema
