PHYS Acid-Base Disorders & Compensation - Week 11

Question 1

What system is the fastest compensatory mechanism for buffering?

Answer 1

Carbonic acid-bicarbonate.

Question 2

Primary & secondary changes in metabolic acidosis.

Answer 2

P - decrease in HCO3-
S - decrease in pCO2

Question 3

Primary & secondary changes in metabolic alkalosis.

Answer 3

P - increase in HCO3-
S - increase in pCO2

Question 4

Primary & secondary changes in respiratory acidosis.

Answer 4

P - increase in pCO2
S - increase in HCO3-

Question 5

Primary & secondary changes in respiratory alkalosis.

Answer 5

P - decrease in PCO2
S - decrease in HCO3-.

Question 6

Normal body pH range

Answer 6

7.35-7.45

Question 7

Respiratory acidosis pH and paCO2

Answer 7

pH < 7.35 & PaCO2 > 45mmHg

Question 8

Respiratory alkalosis pH and paCO2

Answer 8

pH >7.45 & PaCO2 < 35mmHg

Question 9

Metabolic acidosis pH and HCO3- changes

Answer 9

pH < 7.35 & HCO3- < 22mmol/L

Question 10

Metabolic alkalosis pH and HCO3- changes

Answer 10

pH > 7.45 & HCO3- > 26mmol/L.

Question 11

Acidaemia definition

Answer 11

Arterial blood pH < 7.35

Question 12

Alkalaemia definition

Answer 12

Arterial blood pH > 7.45

Question 13

Acidosis definition

Answer 13

The abnormal process that decreases the arterial blood pH to < 7.35.

Question 14

Alkalosis definition

Answer 14

The abnormal process that increases the arterial blood pH to > 7.45.

Question 15

Metabolic acidosis causes

Answer 15

Lactate, toxins, ketones, renal impairment/failure.
Remember LTKR.

Question 16

What is the anion gap?

Answer 16

Refers to the unmeasured anions (-vely charged) like proteins, phosphates, sulphates & organic anions.

Question 17

NAGMA

Answer 17

Normal anion gap metabolic acidosis

Question 18

HAGMA

Answer 18

High anion gap metabolic acidosis

Question 19

Hyperchloraemia & anion gap relationship

Answer 19

NAGMA, but increased Cl-

Question 20

What is acute acidosis & possible causes?

Answer 20

Sudden elevation of PCO2 due to insufficient ventilation (e.g., chest wall injuries, asthma, Gillian-Barre syndrome).

Question 21

What is the relationship btw PaCO2 & minute volume?

Answer 21

Inversely proportional
PaCO2 = 1/MV.

Question 22

What is chronic acidosis & possible causes?

Answer 22

Chronic lung disease w restrictive lung disease w V/Q mismatch (e.g., obstructive disease, chronic neuromuscular disease).

Question 23

What is metabolic alkalosis & possible causes?

Answer 23

Caused by an increase in HCO3- (e.g., impaired renal excretion of HCO3-, nasogastric drainage, vomiting, diuretics).

Question 24

Simple vs mixed disturbances

Answer 24

Simple disturbances are one of the four primary disturbances.
Mixed disturbances are when a pt has more than one disorder - which may worsen/cancel each other out.

Question 25

Mixed disorder location on the arterial blood pH-plasma nomogram?

Answer 25

Outside yellow shaded areas.

Question 26

Severe vomiting is an example of what kind of alkalosis/acidosis?

Answer 26

Metabolic alkalosis.

Question 27

Renal failure is an example of what kind of alkalosis/acidosis?

Answer 27

Metabolic acidosis.

Question 28

Nerve disease leading to a partial paralysis of respiratory mms is an example of what kind of alkalosis/acidosis?

Answer 28

Chronic respiratory acidosis.

Question 29

Student having a panic attack & hyperventilating is an example of what kind of alkalosis/acidosis?

Answer 29

Acute respiratory alkalosis.

Question 30

Anaemia is an example of what kind of alkalosis/acidosis?

Answer 30

Chronic respiratory alkalosis.

Question 31

Pt who has fallen and broken their ribs is an example of what kind of alkalosis/acidosis?

Answer 31

Acute respiratory acidosis.

Question 32

2 x of classifications of acidosis based on anion gap? Provide example of what conditions normally cause this and the chemistry behind it.

Answer 32

• High anion gap acidosis (e.g., increased lactic acid, ketoacids, formic acid, oxalic acid) – more organic acid being produced/ingested
• Normal anion gap acidosis (e.g., via diarrhoea, vomiting, renal tubular acidosis ) - loss of HCO3-

Hyperchloraemia often occurs with normal anion gap acidosis due to Cl- loss.

Question 33

When should anion gap be calculated? Why?

Answer 33

When metabolic acidosis is suspected - to help determine cause.

Question 34

Severe diarrhoea is an example of what kind of alkalosis/acidosis?

Answer 34

Metabolic acidosis.

Question 35

PaO2 arterial vs venous.

Answer 35

75-100mmHg & 40mmHg.

Question 36

2 x compensation & situations when these compensations are seen in acid-base disorders.

Answer 36

Renal & respiratory.
Maximal renal seen in chronic resp disorders.
Maximal respiratory seen in metabolic disorders.
Has to be chronic for renal, as kidneys respond within 2-4 days.