Acid Base Disturbance Flashcards
responses to changes in plasma H+
instantaneous
rapid
slow
instantaneous response to changes in plasma H+
buffering by plasma buffers
phosphate and proteins and deoxygenation of haemoglobin with erythrocytes
HbO2 + H+ -> HbH+ + O2
rapid response to changes in plasma H+
ventilation of CO2 by lungs
slow response of changes in plasma H+
elimination of non volatile acids by kidneys - excretion of H+, regeneration of HCO3-
carbon dioxide - bicarbonate buffer system
co2 + h2o <-> h2co3 <-> h+ + hco3- <-> h+ - co3 2-
what levels of h+ are life threatening
<20 nmol/L or >120 nmol/L
types of acid base disturbance
acidaemia - respiratory or metabolic
alkalaemia - respiratory or metabolic
resp acidaemia
increased H+
increased PaCO2
metabolic acidaemia
increased H+
decreased HCO3-
resp alkalaemia
decreased H+
decreased PaCO2
metabolic alkalaemia
decreased H+
increased HCO3-
compensation of resp acidaemia
metabolic compensation
increased HCO3-
compensation of metabolic acidaemia
resp compensation
decreased PaCO2
compensation of resp alkalaemia
metabolic compensation
decreased HCO3-
compensation of metabolic alkalaemia
resp compensation
increased PaCO2
compensation of acid base disturbances
compensatory response changes parameter that was not affected by primary disturbance
change is always in same direction as in the parameter affected by primary disturbance, as to restore co2/hco3- ratio
resp compensation occurs quickly, metabolic much slower
normal range of h+
36-44nmol/L
normal range paco2
4.8-6 kPa
normal hco3-
21-27.5 mmol/L
what happens when plasma H+ falls
free Ca2+ also falls
- H+ dissociates from the side chains of plasma proteins
- proteins now have greater charge, so bind more Ca2+
- total plasma Ca2+ unchanged but since more Ca2+ is protein bound, free Ca2+ concentration falls
thoracic crushing
