assessment of acid-based balance part 1 W3

Question 1

what metabolic process contributes most to acid production? why? how is this removed?

Answer 1

cellular respiration
produces CO2 which reacts with water to form carbonic acid
CO2 removed in the lungs

Question 2

what are non-volatile acids? examples?

Answer 2

acids that cannot be readily removed by the lungs.
eg ketones, lactate

Question 3

quickest way our body maintains acid based homeostasis?

Answer 3

buffers (proteins eg haemoglobin (Hb), bicarbonate)

Question 4

how is removal of CO2 by the lungs limited

Answer 4

limited by bicarbonate reserves. the lungs cannot replenish bicarbonate levels

Question 5

how do the kidneys play a role in acid base homeostasis

Answer 5

excrete H+, regenerate bicarbonate

Question 6

pathologies leading to respiratory acidosis?

Answer 6

any pathology affecting ability to remove CO2:
-lung disease (COPD)
-airway obstruction
-neuro problems resulting in reduced resp rate (head injury, opiate overdose)

Question 7

pathologies leading to respiratory alkalosis?

Answer 7

unusual rapid removal of CO2 leading to resp alkalosis:
-panic attack
-acute asthma exacerbation
-response to pain

Question 8

3 types of pathologies leading to metabolic acidosis?

Answer 8

overproduction of acid
impaired excretion (by kidneys)
unusual loss of bicarbonate

Question 9

pathologies causing overproduction of acid leading to metabolic acidosis?

Answer 9

-hypovolaemia
-severe anaemia
-damage to major arteries
-cardioresp arrest
-ketoacidosis

Question 10

pathologies causing ketoacidosis? (secondary to inadequate cellular glucose supply)

Answer 10

type 1 diabetes
starvation
alcohol intoxication

Question 11

pathologies causing impaired excretion from the kidneys resulting in metabolic acidosis?

Answer 11

-severe acute kidney injury
-end stage chronic kidney disease
-impairment of renal tubules ability to excrete acid

Question 12

pathologies causing unusual loss of bicarbonate?

Answer 12

severe diarrhoea
surgical formation of fistula in small bowel
renal tubular acidosis

Question 13

pathologies causing metabolic alkalosis?

Answer 13

unusual loss of hydrogen ions
ingesting high quantities of bicarbonate

Question 14

pathologies causing unusual loss of hydrogen ions?

Answer 14

-protracted vomiting
-severe hypokalaemia (kidneys)
-hypoaldosteronism (kidneys)

Question 15

pathophysiology behind unusual loss of hydrogen ions through the kidneys?

Answer 15

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.

Question 16

what can cause a high quantity of bicarbonate to be ingested

Answer 16

overdose of sodium bicarbonate

Question 17

measurements obtained in acid based disorders?

Answer 17

hydrogen ion concentration (obtained from blood sample)
pH

Question 18

meanings of different hydrogen ion concentrations?

Answer 18

H+>45mmol/L = acidaemia
H+ 35-45mmol/L = homeostasis
h+<35mmol/L = alkalaemia

Question 19

meanings of different pH levels?

Answer 19

pH<7.35 = acidaemia
pH 7.35-7.45 = homeostasis
pH>7.45 = alkalaemia

Question 20

body’s compensation for respiratory acidosis?

Answer 20

increase bicarbonate by kidneys

Question 21

body’s compensation for respiratory alkalosis?

Answer 21

decrease bicarbonate by kidneys (usually marginal)

Question 22

body’s compensation for metabolic acidosis?

Answer 22

decrease CO2 by rapid deep breathing (Kussmaul breathing)
increase bicarbonate by kidneys (if possible)

Question 23

body’s compensation for metabolic alkalosis?

Answer 23

both marginal:
increase CO2 by hypoventilation (restricted by need for O2)
decrease bicarbonate by kidneys

Question 24

key aspects of history for acid-base disorders?

Answer 24

respiratory system
fluid balance
intoxication/drugs
anything suggesting inadequate blood supply to tissues

Question 25

important physical examinations for acid-base disorders?

Answer 25

Glasgow coma scale
pupil response
resp rate
oxygen saturation
heart rate
bp
temperature

Question 26

investigations for acid-base disorders?

Answer 26

arterial blood gas:
pO2
pCO2
H+ or pH
HCO3- (calculated)

total CO2 (95% bicarbonate)