* 1-2 μg/kg/min: Acts on dopaminergic receptors to stimulate cerebral, renal and mesenteric vasculature to dilate; HR and B/P are usually unchanged; may increase urine output
* 2-10 μg/kg/min: ß1 stimulant action is primary effect (increases cardiac output and partially antagonizes the α-adrenergic-mediated vasoconstriction. Overall effect is increased cardiac output and only modest increase in systemic vascular resistance (SVR)
* 10-20 μg/kg/min: α-adrenergic effects predominate resulting in renal, mesenteric and peripheral arterial and venous vasoconstriction with marked increase in SVR, pulmonary vascular resistance and further increased preload
* > 20 μg/kg/min: Produces hemodynamic effects similar to norepinephrine; may increase HR and O2 demand to undesirable limits
Indications and Field Use
* Symptomatic bradycardias.
* Hemodynamically significant hypotension in the absence of hypovolemia (Cardiogenic or septic shock only after fluid admin.; assess breath sounds first).
* Hypovolemic shock (relative)
* MAO inhibitors, such as Marplan, Nardil, or Parnate
* CV: Cardiac arrhythmias may occur due to increased myocardial oxygen demand (usually tachydysrhythmias), hypertension, hypotension at low doses.
* GI: Nausea and vomiting
* GU: Renal shutdown (at higher doses)
* Other: Extravasation may cause tissue necrosis
* (dosage range 2-10 μg/kg/min)
* Preparation: (If premixed not carried) Add 400 mg/ 250 ml NS or Dextrose = 1600 μg/ml.
* Bradycardia: Start at 5 μg/kg/min
* Shock: cardiogenic or septic (non-hypovolemic)
BP < 70 systolic: Start drip at 5 μg/kg/min
BP > 70 systolic: Start drip at 2.5 μg/kg/min
* 2-10 μg/kg/min for circulatory shock or shock unresponsive to fluid administration.
* To prepare infusion for small children: 6 x body wt. in kg = mg added to NS to make 100 ml. With this mixture 1 ml/hr delivers 1 μ/kg/min; titrate to effect.
* Always monitor drip rate, never run "wide open".
* An infusion pump is required for interfacility transports; a minimum of microdrip tubing is required for field use.
* It is important to remember that even in low dose ranges dopamine elevates pulmonary artery occlusive pressure and may induce or exacerbate pulmonary congestion despite a rise in cardiac output.
Mechanism of Action
* Pharmacological Effects: Direct acting α and ß agonist; α-bronchial, cutaneous, renal, and visceral arterial constriction (increased systemic vascular resistance)
* ß1 = positive inotropic and chronotropic actions (increases myocardial workload and oxygen requirements), increases automaticity and irritability
* ß2 = bronchial smooth muscle relaxation and dilation of skeletal vasculature. Other: blocks histamine release
* Clinical Effects: Cardiac Arrest - increases cerebral and myocardial perfusion pressure; increases systolic and diastolic blood pressures; increases electrical activity in the myocardium; can stimulate spontaneous contractions in asystole.
* Pulseless Arrest – 1 mg of 1:10,000 solution IV/IO; repeat every 3 - 5 minutes or;
* ET: Give 2-2.5 mg via the ET. May use 1:10,000 or dilute 1:1000 to equal 10 mL via ET tube for adult. 2 mg 1:1,000 epi. with 8 mL NS in a 10 mL syringe
* Infusion for Hypotension or Symptomatic Bradycardia: 1 mg added to 500 mL of NS administered at 1 mcg/min titrated to desired hemodynamic response (range 2-10 mcg/min); not first-line therapy.
* Anaphylaxis and asthma: Give 0.3 - 0.5 mg of 1:1,000 solution IM (preferred), SC, or inject SL, may repeat every 15 to 20 minutes; in extreme cases only, may be asked to use 1:10,000 solution and give 0.1 mg every 5 minutes IV/IO or continuous IV/IO infusion of 1-4 mcg/min to prevent multiple injections.
* Pulseless Arrest or Refractory Bradycardia: 0.01 mg/kg of 1:10,000 IV/IO repeat every 3 - 5 minutes, maximum single dose 1 mg.
* ET: 0.1 mg/kg of 1:1,000; mix with NS to a total of 3-5 mL in syringe; repeat every 3 - 5 minutes, maximum single dose 1 mg.
* Asthma/anaphylaxis: Use 1:1,000 solution; give 0.01 mg/kg IM (preferred), SC (maximum single dose of 0.5 mg/dose).
* IV Infusion: 0.1-1 mcg/kg/min; prepare for children 0.6 x body wt. in kg = mg added to NS to make 100 mL. Delivery of 1 mL/hr delivers 0.1 mcg/kg/min.
* Croup: 3 mg 1:1,000 mixed in 3 mL NS via SVN.
Neonatal Dosage for First 12 hours of life
* Initial and Repeat Dose for Cardiac Arrest/ Refractory Bradycardia: 0.01-0.03 mg/kg IV/IO of 1:10,000 every 3-5 minutes
* ET: 0.1 mg/kg of 1:10,000 every 3 – 5 minutes if neonate has no vascular access
* Organic Nitrate
Mechanism of Action
* Smooth muscle relaxant acting on vascular, uterine, bronchial, and intestinal smooth muscle
* Reduces workload on the heart by causing blood pooling (decreased preload)
* Arteriolar vasodilation (decreased afterload)
* Coronary artery vasodilation
* Increases blood flow to myocardium
* Decreases myocardial O2 demand
Indications and Field Use
* Myocardial Infarction
* Congestive heart failure with pulmonary edema
* Increased Intra cranial pressure
* CV: Hypotension, reflex tachycardia, bradycardia, decreased coronary perfusion at high doses (secondary to hypotension), headache secondary to dilation of meningeal vessels.
* SL for Chest pain: 0.4 mg sublingual tablets or spray. May be repeated x2, every 5 minutes as long as BP remains >90
* SL for Pulmonary edema: 0.4 mg sublingual tablets or spray. May be repeated x2 every 5 minutes as long as BP remains >90
* Not USED
Incompatibilities / Drug Interactions
* Other vasodilators
* Viagra, Cialis, and Levitra
* NTG is heat and light sensitive; stock rotation assures fresh supply.
* SL: Cautiously administer NTG to a patient who has never received it, consider establishing an IV prior to administration.
* Closely monitor vital signs, cardiac rhythm.
* Bradydysrhythmias and hypotension usually respond to Trendelenburg position; atropine and vasopressors may be administered if needed.