dobutamine

introduction

inotrope with vasodilatation
primarily used in refractory heart failure or cardiogenic shock but avoided a sole agent in septic shock due to the risk of hypotension from the vasodilatation.
unlike dopamine, it does not selectively cause renal vasodilatation.
a synthetic sympathomimetic agent which acts mainly on beta-1 adrenoceptor but with beta-2 agonist actions and some alpha-1 actions as well (the (-) isomer is an agonist at alpha-1 whereas the (+) isomer is an antagonist at alpha-1 with net effect being vasodilation)
it is useful in reducing after load in low cardiac output states such as post-MI or post-op cardiac surgery.
it can be used in Mx of sepsis / septicaemia in combination with noradrenaline or high dose dopamine to reduce the after load that these agents induce via their alpha-1 actions.
C/I in patients with idiopathic hypertrophic subaortic stenosis
half-life = 2 minutes

allergy and hypersensitivity reactions in those sensitive to sulphites, take care in patients with PH asthma
tachycardia, potential risk of ventricular tachycardia (VT), especially if halogenated anaesthetics which sensitise the myocardium
vasodilatation
hypertension
hypotension risk if used alone in septic shock
theoretical risk of increased myocardial ischaemia in patients with acute myocardial infarction (AMI/STEMI/NSTEMI)
category B2 in pregnancy

usual titrated dose 2.5-15 microgram/kg/min (rarely up to 40 microgram/kg/min)
determine concentration based upon fluid restriction requirements of the patient
vials are usually 250mg/20ml, can be diluted in 5% dextrose or 0.9% saline to 50ml-500ml solutions.
following the initiation of a constant rate infusion, or upon changing the rate, a steady-state dobutamine plasma concentration is achieved within approximately ten minutes.
avoid abrupt cessation, always wean dose rate where possible
bolus doses are not recommended
not compatible with alkaline solutions (eg. bicarbonate), blood transfusions, or those containing both bisulphite and ethanol

should ideally be infused via a central venous line
if CVC line is unavailable it can be administered via a large peripheral line for a maximum of six hours until alternative access is obtained.
peripheral use may lead to phlebitis, infection or extravasation
change line and infusion every 72 hours
250mg in 500mls fluid = 500 mcg/ml
peripheral infusion concentration may be increased to 250mg in 250mls of fluid if fluid loading is a problem and central line access has failed.