Haematology

Question 1

What is an acid

Answer 1

Acidic solutions have more hydrogen ions in them. Acids can give away an H+ or can dissociate to release H+ in solution leading to an increase in the acidity of a solution (a decrease in pH).

Question 2

What is acidaemia

Answer 2

Acidaemia refers to the acid state of the blood or a pH of < 7.4

Question 3

What is acidosis

Answer 3

Acidosis is process causing an acidaemia

Question 4

What is alkalaemia

Answer 4

Alkalaemia refers to the alkaline state of the blood or a pH of > 7.4

Question 5

What is alkalosis

Answer 5

Alkalosis is process causing an alkalaemia

Question 6

What is a base

Answer 6

Bases can accept and bond H+, in effect ‘buffering’ or reducing the acidity of a solution such as blood plasma.

Question 7

What is a base excess or deficit

Answer 7

An increase or decrease in the amount of base compared with the amount of acids present

Question 8

What is Hb and what does it signify in the blood

Answer 8

Amount of haemoglobin (and therefore the oxygen-carrying capacity) in blood

Question 9

What is HCO3-

Answer 9

Concentration of hydrogen bicarbonate in blood. With pH and CO2, used to determine source of acid-base imbalance.

Question 10

What is lactate/lactic acid

Answer 10

When aerobic metabolism decreases or ceases due to inadequate O2 supply, glycolysis results in the production of lactate (instead of pyruvate) which then leads to intracellular, then systemic lactic acidosis if tissue hypoxia persists.

Question 11

What is FiO2

Answer 11

Fraction of inspired oxygen. This refers to the percentage of inspired O2 expressed as a decimal, e.g., FiO2 1.0 = 100% O2

Question 12

What is PaO2

Answer 12

Arterial oxygen tension. This is the partial pressure in mmHg of oxygen dissolved in each 100 mL of plasma in arterial blood. It should always be interpreted in conjunction with the patient’s fraction of inspired oxygen.

Question 13

What is SaO2

Answer 13

Calculated haemoglobin saturation of arterial oxygen.

Question 14

What is PaCO2

Answer 14

Carbon dioxide partial pressure in mmHg (tension) of CO2 dissolved in plasma. This measurement reflects the adequacy of alveolar ventilation.

Question 15

What does the pH of body fluids indicate

Answer 15

The pH provides an indication of the effectiveness of buffer systems, the respiratory system and the renal system in maintaining normal acid base balance.

Question 16

What is the normal arterial blood pH

Answer 16

Normal arterial blood pH is between 7.35 and 7.45

Question 17

What is the main chemical buffer in the human body

Answer 17

Bicarbonate

Question 18

What is the bicarbonate buffering system

Answer 18

Carbon dioxide + water form carbonic acid, which can dissociate to form acid (H+) and bicarbonate

Question 19

Consequences of severe acidaemia?

Answer 19

impairs cardiac contractability and output
induces arteriolar vasodilation - hypotension
induces pulmonary vasoconstriction
increases resp rate and wob
induces cerebral vasodilation ( intracranial pressure)
insulin resistance
hyperkalaemia

Question 20

consequences of alkalaemia

Answer 20

muscle spasms
cardiac arrhythmia due to hypokalaemia