GTN

Question 1

GTN - Mechanism of action

Answer 1

Vascular smooth muscle
cause venous and arterial vasodilation
predominant effect on veins

GTN results in formation of nitric acid (vasodilator)

PRE-LOAD is reduction of VENOUS return reducing ventricular filling/miocardial oxygen demand.

AFTERLOAD is ARTERIAL reducing peripheral resistance left ventricle has to overcome to eject blood into the arteries reducing miocardial oxygen demand.

Question 2

GTN - Indicated for (3)

Answer 2

Myocardial ischaemia

Cardiogenic pulmonary oedema

Hypertension associated with autonomic dysreflexia

Question 3

GTN - Contraindications (5)

Answer 3

Systolic BP less than 100

Heart rate less than 40/min

Heart rate greater than 130/min if miocardial ischaemia, Stemi or cardiogenic pulmonary oedema.

Heart rate greater than 150/min if autonomic dysreflexia

Ventricular tachycardia

Question 4

GTN - Cautions (6)

Answer 4

STEMI. (significant fall in cardiac output)

small and fail/physiologically unstable.

Poor perfusion

Dysrhythmia

erectile dysfunction drug last 24 hrs

Known aortic or mitral stenosis

Question 5

GTN - Dosage

Answer 5

Myocardial ischaemia: 0.4mg every 3 to 5 minutes.

Cardiogenic pulmonary oedema: 0.8mg every 3 to 5 minutes

Increase the dosage interval to 10 minute interval if caution is required.

Autonomic dysreflexia: 0.4 to 0.8mg every 3 to 5 minutes.

Question 6

GTN - Common adverse effects (5)

Answer 6

Light headedness

Headache

Flushing

Tachycardia

Hypotension

Question 7

GTN - Onset of effect

Answer 7

1 - 2 minutes

Question 8

GTN - Duration of effect

Answer 8

15 - 30 minutes