AcidBase Pathology

Question 1

how do we assess acid base status

Answer 1

what is the ph ie above 7.45 or below 7.35

is the primary disorder metabolic or respiratory

is there compensation - normal respiratory or metabolic compensation

Question 2

how do respiratory acidosis and metabolic differ

Answer 2

RAc = increased pCO2
MAc = decrease NpCO2

Question 3

how do respiratory alkalosis and metabolic differ

Answer 3

RAl = decreased PCO2
MAl = increase in NpCO2

Question 4

how does respiratory vs metabolic compensation differ

Answer 4

RC - changes in CO2 (help metabolic disturbances)

MC - changes in HCO3 (help respiratory disturbances)

Question 5

how do we measure bicarbonate levels

Answer 5

main lab bicarbonate - calculated in part from CO2
standard bicarbonate - removes respiratory contribution ie normal standard bicarbonate = all respiratory
abnormal = metabolic component

Question 6

what is base excess (BE)

Answer 6

amount of acid or alkali to titrate blood pH to 7.40 - tells us if there is a metabolic component

Question 7

what does a negative vs a positive BE mean

Answer 7

negative (less than 2.3mmol/l) = metabolic acidosis

positive BE (greater than 2.3 mol/L) = metabolic alkalosis

Question 8

what is an anion gap

Answer 8

difference between the sum of measured anions and cations

Question 9

what does an increased anion gap mean

Answer 9

significant amounts of unmeasured anions such as ketones, lactate, salicyate, proteins)

Question 10

what are the physiological characteristics of metabolic acidosis

Answer 10

decreased pH increased H+
normal or decreased pCO2
deceased HCO3
increased pO2

Question 11

what are the signs and symptoms of metabolic acidosis

Answer 11

nausea, vomiting, anorexia
tachypnoea due to respiratory compensation
kussmaul breathing in severe acidosis

Question 12

what are the causes of metabolic acidosis

Answer 12

increased acid formation
decreased acid excretion (renal failure)
loss of bicarbonate (diarrhoea)
acid ingestion

Question 13

what is the normal physiological response to metabolic acidosis

Answer 13

protein and bicarbonate buffering try to help
respiratory compensation - hyperventilation
increase HCO3 regen
increase H+ excretion in urine

Question 14

what are the physiological characteristics of metabolic alkalosis

Answer 14

increased pH and decreased H+
normal or increased pCO2
increased HCO3
decreased pO2

Question 15

what are some causes of metabolic alkalosis

Answer 15

loss of H+ eg vomiting
administration of HCO3
potassium depletion

Question 16

what is the normal physiological response to metabolic alkalosis

Answer 16

release of H+ buffers

respiratory compensation - reduce breathing

Question 17

what are the physiological characteristics of respiratory acidosis

Answer 17

decreased pH and increased H+
increased pCO2
normal or increased HCO3
deceased pO2

Question 18

what are the signs of respiratory acidosis

Answer 18

relate to underlying disorder or dyspnoea

Question 19

what are the causes of repository acidosis

Answer 19

defective control of respiration

defective respiratory function eg pneumothorax or pulmonary disease

Question 20

what is the physiological response

Answer 20

limited buffering by hb
try to have respiratory compensation ie breathe quicker
max bi carb reabsorption and excretion of NH4 and H2PO4

Question 21

what are the physiological characteristics of respiratory alkalosis

Answer 21

pH increased and H+ decreased
decreased pCO2
normal or lower HCO3
increased pO2

Question 22

what are the signs and symptoms of respiratory alkalosis

Answer 22

severe = hypocalceamia - headache, lethargy, delirium and seizures

Question 23

what are some causes of respiratory alkalosis

Answer 23

central - head injury, stroke, hyperventilation
pulmonary - PE, pneumonia, asthma
iatrogenic - excessive mechanical ventilation

Question 24

what is the normal physiological response to respiratory alkalosis

Answer 24

release of H+ from non-bicarbonate buffers

decreased renal regen of HCO3