assessment of acid-based balance part 1 W3 Flashcards
what metabolic process contributes most to acid production? why? how is this removed?
cellular respiration
produces CO2 which reacts with water to form carbonic acid
CO2 removed in the lungs
what are non-volatile acids? examples?
acids that cannot be readily removed by the lungs.
eg ketones, lactate
quickest way our body maintains acid based homeostasis?
buffers (proteins eg haemoglobin (Hb), bicarbonate)
how is removal of CO2 by the lungs limited
limited by bicarbonate reserves. the lungs cannot replenish bicarbonate levels
how do the kidneys play a role in acid base homeostasis
excrete H+, regenerate bicarbonate
pathologies leading to respiratory acidosis?
any pathology affecting ability to remove CO2:
-lung disease (COPD)
-airway obstruction
-neuro problems resulting in reduced resp rate (head injury, opiate overdose)
pathologies leading to respiratory alkalosis?
unusual rapid removal of CO2 leading to resp alkalosis:
-panic attack
-acute asthma exacerbation
-response to pain
3 types of pathologies leading to metabolic acidosis?
overproduction of acid
impaired excretion (by kidneys)
unusual loss of bicarbonate
pathologies causing overproduction of acid leading to metabolic acidosis?
-hypovolaemia
-severe anaemia
-damage to major arteries
-cardioresp arrest
-ketoacidosis
pathologies causing ketoacidosis? (secondary to inadequate cellular glucose supply)
type 1 diabetes
starvation
alcohol intoxication
pathologies causing impaired excretion from the kidneys resulting in metabolic acidosis?
-severe acute kidney injury
-end stage chronic kidney disease
-impairment of renal tubules ability to excrete acid
pathologies causing unusual loss of bicarbonate?
severe diarrhoea
surgical formation of fistula in small bowel
renal tubular acidosis
pathologies causing metabolic alkalosis?
unusual loss of hydrogen ions
ingesting high quantities of bicarbonate
pathologies causing unusual loss of hydrogen ions?
-protracted vomiting
-severe hypokalaemia (kidneys)
-hypoaldosteronism (kidneys)
pathophysiology behind unusual loss of hydrogen ions through the kidneys?
reabsorption of sodium in exchange for hydrogen ions given a low availability of potassium causes hydrogen ions instead of potassium to be excreted into the urine.
what can cause a high quantity of bicarbonate to be ingested
overdose of sodium bicarbonate
measurements obtained in acid based disorders?
hydrogen ion concentration (obtained from blood sample)
pH
meanings of different hydrogen ion concentrations?
H+>45mmol/L = acidaemia
H+ 35-45mmol/L = homeostasis
h+<35mmol/L = alkalaemia
meanings of different pH levels?
pH<7.35 = acidaemia
pH 7.35-7.45 = homeostasis
pH>7.45 = alkalaemia
body’s compensation for respiratory acidosis?
increase bicarbonate by kidneys
body’s compensation for respiratory alkalosis?
decrease bicarbonate by kidneys (usually marginal)
body’s compensation for metabolic acidosis?
decrease CO2 by rapid deep breathing (Kussmaul breathing)
increase bicarbonate by kidneys (if possible)
body’s compensation for metabolic alkalosis?
both marginal:
increase CO2 by hypoventilation (restricted by need for O2)
decrease bicarbonate by kidneys
key aspects of history for acid-base disorders?
respiratory system
fluid balance
intoxication/drugs
anything suggesting inadequate blood supply to tissues
important physical examinations for acid-base disorders?
Glasgow coma scale
pupil response
resp rate
oxygen saturation
heart rate
bp
temperature
investigations for acid-base disorders?
arterial blood gas:
pO2
pCO2
H+ or pH
HCO3- (calculated)
total CO2 (95% bicarbonate)
