Crit Care

Question 1

What is CPAP indicated for (acute settings)

Answer 1

APO

Question 2

What is BPAP indicated for

Answer 2

COPD, NMD, Kyphoscoliosis

Atelectasis and asthma can be used but have less evidence

Question 3

A-a gradient - what is it and how to calculate it (differentials is another question)

Answer 3

PAO2 is the partial pressure of O2 in the alveolar
PaO2 is the partial pressure of the O2 in the arterial blood

A-a gradient is PAO2-PaO2

PAO2 is measured from the alveolar gas equation at room air and sea level - 150 mmHg - (PaCO2/0.8)

Normal A-a gradient increases with age. An equation is Normal A-a gradient (mmHg) = (Age/4) +4

Question 4

Hypoxia vs hypoxaemia

Answer 4

hypoxia is a pathophysiological state where all or part of the body does not receive enough oxygen

hypoxaemia is where the arterial oxygenation is decreased

other causes of hypoxia is: anaemia, dyshaemoglobinaemia

Question 5

How much oxygen in blood is bound to haemoglobin

Answer 5

98.5%

Question 6

Hypoxaemia and normal A-a gradient

Answer 6

Hypoventilation
Low Pi (extreme elevation)

Question 7

Hypoxaemia and elevated A-a gradient

Answer 7

Shunt

Mismatch

Question 8

PaO2/FIO2 - what is normal

Answer 8

100mmHg/0.21 = 476

Question 9

Disadvantages of inotropes

Answer 9

Associated w increased mortality
Pro arrthyhmic
Increased myocardial oxygen demand
Lactate acidosis
May cause hypotension

Question 10

inotrope mechanism of action

Answer 10

Electrical impulse causes calcium influx which leads to the contraction of actin-myosin and causes further release of calcium

The Beta-receptor causes activation of cAMP which leads to calcium influx

Likewise, digoxin is a potent inhibitor of cellular Na+/K+-ATPase. By inhibiting the Na+/K+-ATPase, cardiac glycosides cause intracellular sodium concentration to increase.

Most inotropes increase intracellular calcium

Question 11

dobutamine mechanism of action

Answer 11

beta-1-receptor agonist which causes ATP to turn into cAMP and calcium influx

There is both contraction and dilatation so there is variable effect on BP (increases or reduces). But increases flow to tissues overall.

Increases arrhythmias

Question 12

Milrinone

Answer 12

Impairs enzyme that inhibits production of cAMP
More expensive
Useful for patients on beta blockers

Question 13

Adrenaline mechanism of action

Answer 13

Increases afterload
Agonises Alpha1, Beta1 and Beta2

Lactic elevation but thought not to be haemodynamically inducing

Arrhythmias

Question 14

Levosimendan

Answer 14

Not commonly used
Makes troponin C more sensitive to calcium
Inodilator
24hour infusion and half life 80hr
Hard to titrate

Question 15

Role of inotropes in acute heart failure patients without shock

Answer 15

No difference in primary outcomes milrinone vs placebo

Hypotension in milrinone

Question 16

Role of inotropes in acute heart failure patients with shock

Answer 16

no inotrope shown better benefit over another

Question 17

First line inotrope in sepsis

Answer 17

noradrenaline then vasopressin

Question 18

when do you use vasopressin instead of norad in right sided heart failure (shock)

Answer 18

In pulmonary hypertension because vasopressin spares the pulmonary circulation