ABG's Flashcards
when can blood pH be acidic or alkalotic
acidic- to much CO2 in blood, too little bicarbonate in the blood
alkalotic- too little CO2, too much bicarbonate
what is respiratory acidosis
is defined as a pH less than 7.35 with a PaCO2 greater than 6kPa. it is caused by an increase of CO2 which combines with water to produce carbonic acid, lowering the pH (H20+CO2=H2CO3=H+ + HCO3
how does respiratory acidosis work
carbon dioxide combines with water to produce carbonic acid making the blood more acidic. The carbonic acid dissociates quickly into hydrogen ions and bicarbonate. the bicarbonate is stored by the kidneys leaving a concentration of hydrogen ions= more acidic blood
what causes hypoventilation
CNS depressions related to head injury, impaired respiratory muscle function related to SCI or neuromuscular disease, pulmonary disorders such as atelectasis/ pneumonia/ pneumothorax/ pulmonary oedema/ COPD, chest pain
why does hypoventilation causes respiratory acidosis
CO2 build up
what is respiratory alkalosis
it is defined as a pH greater than 7.45 with a PaCO2 less than 4.7kPa. any condition that causes hyperventilation can result in respiratory alkalosis. It removes CO2 at a faster rate than normal, resulting in a decrease in H+
what conditions cause hyperventilation
psychiatric causes- anxiety/stress, CNS causes- stroke/ sub arachnoid haemorrhage, drug use: caffeine, moving to high altitude areas, fever- increase RR
what is metabolic acidosis
it is a pH less than 7.35 with a bicarbonate of less than 22 mol l-1. it is caused by either a deficit of bicarbonate in the bloodstream or an excess of acid
causes of metabolic acidosis
lactic acidosis, ketoacidosis, chronic renal failure, chronic diarrhoea
metabolic alkalosis
it is defined as a pH greater than 7.45 with a bicarbonate level greater than 26 mmol l-1. either an excess of bicarbonate or a loss of acid within the body can cause it
what are the causes of metabolic alkalosis
excess base occurs from ingestions of antacids, excess use of bicarbonate, or use of lactate in dialysis
loss of acids can occur secondary to protracted vomiting
What is the process of compensation
if a patient is in respiratory acidosis then the body tries to remove excess CO2 by increasing ventilation- too blow off excess CO2 reducing the acidic state. however the respiratory system is compromised and unable to get rid of excess CO2 through ventilation.
