||SODIUM NITROPRUSSIDE (NiprideR)
- relaxes arterial and venous smooth muscle to decrease afterload and preload; afterload reduction arterial effect > venous
- decreases pulmonary artery pressure
- enhanced renal blood flow
- enhanced coronary blood flow
50mg/250D5W, NS or RL (maximum concentration 200mg/500mL)
- protect from light
- hypovolemia should be corrected concurrently with initiation of therapy
- drug should be weaned off
- each nitroprusside molecule contains 5 cyanide molecules
- healthy humans eliminate cyanide as follows:
- the cyanide contained in 18 mg of nitroprusside will combine with methemoglobin for elimination
- the cyanide from an additional 50 mg of nitroprusside is bound to thiosulfate to form thiocyanate, which is eliminated in the urine
- cyanide toxicity occurs when the total dose of nitroprusside exceeds the ability to eliminate the cyanide (total dose of 68 mg), or if thiosulfate stores are low (e.g. in smokers)
- thiocyanate toxicity develops if thiocyanate elimination is impaired due to renal failure
- Cyanide Toxicity (inhibits O2 utilization by tissues):
- increased HR
- metabolic acidosis
- increased lactate despite normal Sp02
- decreased response to drug
- increased mixed venous O2 saturation
- decreased oxygen extraction
- rapidly progressive tolerance is an important early indication of cyanide toxicity
- Thiocyanate Toxicity:
- confusion, hallucinations, delerium
- fatigue, weakness
- pupillary constriction
- hypothyroidism (blocks thyroid uptake and binding of iodine)
- renal failure, hyponatremia, hypovolemia, hypothyroidism (thiocyanate inhibits uptake and binding of iodine)
- hepatic failure, Vitamin B12 deficiency, Leber's optic atrophy
- nitroprusside + dopamine/dobutamine = enhanced hemodynamic effects
- HR, ECG
- blood gases ( arterial and mixed venous)
- arterial lactate ( increased in toxicity)
- cardiac index
- urine output
- SVRI, PVRI
- toxicity correlates with thiocyanate levels > 1.7 uM/L
- May be administered by IV infusion by an approved nurse in CCTC.
- May be titrated by an approved nurse in the CCTC.
- Must be administered via central line.
- Must be administered via infusion pump.
- Should not be administered via the proximal injectate port (blue) of the Swan Ganz catheter.
- Patient requires placement of an arterial line to monitor BP.