2018.2 SAQ 10 – positive inotropes

Outline the mechanisms of action of the drugs, with examples, which increase myocardial contractility.

BT_PO 1.52  Describe the mechanism of action of sympathomimetic … drugs used clinically
BT_PO 1.53  Describe the pharmacology and clinical application of adrenergic agonists
BT_PO 1.60  Describe the pharmacology of drugs used to manage acute or chronic cardiac failure, including: sympathomimetics, phosphodiesterase inhibitors, digoxin, ….

T / F  noradrenaline has no inotropic effect because it is a pure alpha-1 adrenergic agonist

T / F  adrenaline exerts a positive inotropic effect via beta-2 adrenergic receptors on the cardiac myocytes

T / F  milrinone is a phosphodiesterase inhibitor – it works by inhibiting the breakdown of phosphokinase A

T / F  glucagon is a positive inotrope – it works in this way by upregulating the numbers of adrenergic receptors

T / F  levosimendan works by ‘sensitising’ troponin C to the effect of calcium

T / F  digoxin’s positive inotropic effect stems from its inhibition of the Na/K-ATPase

Vasopressin

BT_RT 1.18  With reference to cardiopulmonary resuscitation, describe the pharmacology of adrenaline, vasopressin, amiodarone and lignocaine

BT_RT 1.17  With reference to the management of shock, describe the pharmacology of vasopressors and inotropes, including: … vasopressin

 

T / F  vasopressin is the same thing as anti-diuretic hormone

T / F  vasopressin acts on vascular smooth muscle via a G protein coupled receptor, type V1a, which causes an increase in IP3, and increased calcium entry into the cell

T / F  a vasopressin infusion may be effective in refractory septic shock, refractory anaphylaxis, or the vasoplegia which occurs after cardiopulmonary bypass

T / F  vasopressin does not increase pulmonary vascular resistance

T / F  during CPR, a bolus of 40 U vasopressin has been used, although this is not recommended by ANZCOR as routine therapy

T / F  an ampoule of vasopressin contains 10 units in 1 mL

References:
1. Goodman & Gilman p.701-708
2. product information
3. ANZCOR and ILCOR resus guidelines
4. ANZCA anaphylaxis guidleines  http://www.anzca.edu.au/resources/endorsed-guidelines

Further discussion points:
– what is the difference between vasopressin and desmopressin?
– what are the uses of desmopressin?

BT_RT 1.17 and 1.18 Adrenaline in shock and resuscitation

Not sure that these fit the topic, but they were beautiful and I am a sucker for a rainbow (viewed at the V&A). I think these would give you a surge of dopamine rather that adrenaline, but we will save that for another day…

The current ARC guidelines (see 11.5) provide a very minimalist approach to drug therapy in cardiopulmonary resuscitation, emphasising the importance of high quality and minimally interrupted CPR. However of the couple of drugs left, adrenaline in front and centre.

BT_RT 1.17 With reference to the management of shock, describe the pharmacology of vasopressors and inotropes, including:

adrenaline,

and lots of other drugs (click on the link to view them)

BT_RT 1.18 With reference to cardiopulmonary resuscitation, describe the pharmacology of

adrenaline,

vasopressin,

amiodarone and

lignocaine

 

During cardiac arrest, adrenaline has a role in the treatment of both shockable and non shockable rhythms     TRUE/FALSE

Adrenaline has been shown to improve the chances of return of spontaneous circulation in arrest situations   TRUE/FALSE

Adrenaline is useful in the treatment of anaphylactic shock, in part, because it prevents further mast cell degranulation  via a beta mediated response TRUE/FALSE

Adrenaline may improve myocardial blood flow in low flow states as it causes aortic diastolic pressure to rise   TRUE/FALSE

If giving adrenaline via the endotracheal tube, the dose should be increased by 10 fold TRUE/FALSE