Dopamine

Aka: Dopamine

1. Mechanism
   1. Low dose (2-5 ug/kg/min)
      1. Increases splanchnic flow
      2. Increases coronary perfusion
      3. Increases cerebral flow
      4. Increases renal perfusion
         1. Previously recommended for oliguric Renal Failure
         2. No longer recommended due to lack of GFR effect
   2. Mid-dose (5-10 ug/kg/min)
      1. Direct Beta Adrenergic Receptor effects
         1. Increases cardiac contractility
         2. No effect on Blood Pressure
         3. No effect on Heart Rate
      2. Stimulates Norepinephrine release
         1. Effect blunted if Norepinephrine stores depleted
   3. High Dose (10-20 ug/kg/min)
      1. Increase in Blood Pressure
      2. Tachycardia may be significant problem
      3. Vasoconstriction of renal and splanchnic beds
   4. Half life of Dopamine is short and requires infusion
2. Indications
   1. Hemodynamically significant Hypotension
      1. Systolic Blood Pressure under 90 mmHg
      2. Poor Tissue perfusion
         1. Oliguria or anuria
         2. Altered Level of Consciousness
      3. No hypovolemia
   2. Hypotension following Resuscitation
      1. Symptomatic Bradycardia
      2. Return of Spontaneous Circulation
3. Absolute Contraindications
   1. Pheochromocytoma
      1. Risk of Hypertensive Crisis
4. Relative Contraindications (or use low dose Dopamine)
   1. Increased vascular resistance
   2. Pulmonary congestion or Congestive Heart Failure
   3. Increased Preload
5. Pediatric Infusion (Same as Dobutamine preparation)
   1. Preparation
      1. Draw up "x" mg of Dopamine
      2. Where "x" = 6 x Weight in Kilograms
      3. Add enough D5W or NS to Dopamine for 100 ml total
      4. At this dilution
         1. Infusion rate of 1 ml/h provides 1.0 ug/kg/min
   2. Start Dose: 10 ug/kg/min or 10 ml/hour
   3. Titrate to effect
      1. Perfusion
      2. Urine output
      3. Blood Pressure
6. Adult Infusion
   1. Preparation
      1. Start with 1-2 ampules Dopamine (400 mg each)
      2. Dissolve 400-800 mg Dopamine in 250 ml D5W
      3. Final Concentration: 1600-3200 ug/ml
   2. Start Dose: 1-5 ug/kg/min
   3. Titrate: 5-20 ug/kg/min to clinical response
      1. Perfusion
      2. Urine output
      3. Blood Pressure
7. Adverse Effects
   1. Tachycardia
      1. Increases myocardial oxygen demand
   2. Arrhythmias
      1. Premature Ventricular Contraction (PVC)
      2. Supraventricular Tachycardia (SVT)
      3. Ventricular Tachycardia (VT)
   3. Hypertensive Crisis
   4. Increases Pulmonary artery wedge pressure
      1. May worsen pulmonary congestion
      2. May provoke Congestive Heart Failure
   5. Gastrointestinal
      1. Nausea and Vomiting
8. Precautions
   1. Avoid Dopamine dose over 20 ug/kg/min
      1. Results in severe Vasoconstriction and ischemia
      2. Consider adding Norepinephrine if inadequate BP
   2. Use caution with Dopamine in Congestive Heart Failure
      1. Consider adding Vasodilator
         1. Nitroprusside
         2. Nitroglycerin
      2. Consider using Dobutamine instead of Dopamine
   3. Taper Dopamine gradually to avoid Hypotension
   4. Use Dopamine via central venous catheter
      1. Extravasation causes severe local tissue damage
      2. Antidote for extravasation
         1. Phentolamine 5-10 mg diluted in 10-15 ml NS
         2. Infiltrate area of extravasation with Phentolamine
9. Drug Interactions
   1. Sodium Bicarbonate inactivates Dopamine
      1. Also occurs with Epinephrine
   2. Monoamine Oxidase Inhibitors potentiate Dopamine effect
      1. Use only one tenth of regular dose
   3. Bretylium effects may be synergistic with Dopamine
   4. Phenytoin may cause Hypotension with Dopamine