Basic science

Question 1

Poiseuilles Law

Answer 1

Resistance = 8xviscosityx length / pi r ^4

Q Flow = Delta P / R

Question 2

High risk HPV types

Answer 2

16, 18, 31, 33, 35

HPV causes cancer by integrating viral genome into cellular DNA

HPV vaccine is a whole virus, chemically inactivated vaccine

Question 3

Types of RTA

Answer 3

Type 1 = distal defect in H excretion (and therefore K reabsortion), leading to a alkaline urine (>5.5) and hypokalaemia. Caused by autoimmune conditions, drugs (lithium and amphotericin), cirrhosis, obstructive uropathy. Usually more severe with HC03 <15 as distal nephron cannot compensate.

Type 2 = a proximal defect in HC03 reabsorption, leading to high bicarb in the urine, hypokalaemia and a variable urine pH. May be isolated or part of fanconi syndrome. Causes include MM, amyloidosis, heavy metal poisoning or drugs (tenofovir).

Type 4 RTA = Hypoaldosteronism causing reduced K and H+ secretion into the collective duct. Leading to a hyperkalaemia and late excretion of H+ by the distal nephron and therefore acidic urine (<5.3). Therefore the acidosis is usually mild (HCO3 > 17)

Question 4

Type 1 RTA

Answer 4

Distal defect in H+ secretion.
Hypokalaemia
HC03 usually <15
Urine pH >5.5
Causes:
- Autoimmune
- Drugs (lithium, amphotericin)
- Cirrhosis

Question 5

Type 2 RTA

Answer 5

Proximal defect in HC03 reabsorption
Isolated or Fanconi
Urine pH Variable
Hypokalaemia
High fractional excretion of HC03
Causes:
- Tenofovir
- MM, Amyloidosis, Heavy metals

Question 6

Type 4 RTA

Answer 6

Hypoaldosteronism
Decreased secretion of H+ and K +
Hyperkalaemia
Urine pH <5.5 (distal kidney can secrete H+)
Usually mild with Hco3 > 17
Causes:
- Renal failure especially diabetic nephropathy
- NSAIDs, ACEI, ARB, Spiro
- Adrenal Insuffiency, Ciclosporin, 21 hydroxylase deficiency

Question 7

Equation for A-a gradient

Answer 7

A-a gradient = PA02 - Pa02

Pa02 = measured

PA02 must be estimated from the alveolar gas exchange equation.

PA02 = (Fi02 x (Pi - PH20)) - (PC02 / RQ)
= 0.21 (760 -47) - (PC02 / 0.8)
= 150 - (PaC02 x 1.25)

A-a Gradient = {150-PaC02 x 1.25 } - Pa02

Normal - hypoventilation
abnormal - VQ MM, Shunting, Impaired Diffusion

Question 8

Metabolic alkalosis compensation

Answer 8

PC02 = 40 + (0.7 x delta HC03)
= 40 + (0.7 x HC03 - 24)

Question 9

Metabolic acidosis compensation

Answer 9

Winters Formula
PC02 = 1.5xHC03 + 8

Question 10

Egg allergy and vaccination

Answer 10

MMR-V - No egg

Influenza - tiny amount of egg (<1 micro-g of egg protein) and is safe to give to egg allergic or anaphylactic people.

Yellow Fever and Q fever vaccines contain more egg and require referral to specialist for assessment.