니트로프루시드 나트륨

혈관확장제

**니트로프루시드 나트륨(Nitroprusside sodium)**은 중환자실 환경에서만 전적으로 사용되는 매우 강력하고 초단기 작용을 하는 **혼합형 혈관확장제**입니다. 주요 임상 요점: * **주요 적응증**: 고혈압 위기, 중증 승모판 역류에 속발하는 급성 심부전 및 불응성 울혈성 심부전(CHF)의 관리. * **혈역학적 효과**: 동맥 및 정맥 평활근을 이완시켜 전부하와 후부하를 빠르게 감소시킵니다. * **임상 팁**: 심각한 저혈압 효과와 매우 짧은 반감기 때문에 반드시 **지속적인 직접 동맥 혈압 모니터링**과 함께 지속적 정맥 주입(CRI)으로 투여해야 합니다. * **독성 위험**: 장기간 사용(>48-72시간)하거나 고용량을 투여하면, 특히 신장이나 간 기능이 손상된 환자에서 독성 대사산물(시안화물 및 티오시안산염)이 축적될 수 있습니다.

작용 기전: Nitroprusside acts as a **nitric oxide (NO) donor**. * Once in the bloodstream, it interacts with tissue sulfhydryl groups to release NO. * NO activates the enzyme **soluble guanylate cyclase** in vascular smooth muscle cells. * This leads to an increase in intracellular **cyclic guanosine monophosphate (cGMP)**. * Elevated cGMP activates protein kinase G, which reduces intracellular calcium concentrations → **vascular smooth muscle relaxation**. This mechanism causes direct peripheral vasodilation of both arterioles and venules (independent of autonomic innervation), resulting in: * Lowered blood pressure * Significant reduction in total peripheral resistance (afterload) * Reduced left ventricular end-diastolic pressure (preload) * Mild decrease in cardiac output (though in severe heart failure, CO may actually increase due to afterload reduction) * Reflex tachycardia (increase in heart rate)

동물 종별 용량

Cats

Hypertensive crisis (systolic arterial BP >200 mm Hg) · Initiate dose at 0.5 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes until a predetermined target BP is attained. Reduce BP 25% over 4-hour period to allow readaptation of cerebral blood vessels. · IV · CRI · Titrate to effect
Adjunctive treatment of heart failure (cardiogenic shock; fulminant pulmonary edema) · Initiate dose at 0.5 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes. Goal to decrease or maintain mean arterial pressure to support vital organ functions-approx. 70 mmHg. · IV · CRI · Titrate to effect · Concurrent use of dobutamine (1-5 micrograms/kg/min) often indicated.
Adjunctive treatment of heart failure · Initiate dose at 0.5 micrograms/kg/minute constant rate infusion and increase by 0.5-1 microgram/minute every 5 minutes to desired systolic pressure (90-100 mmHg). · IV · CRI · Titrate to effect · Cats are more sensitive to oxidative damage; keep total dosages to a minimum. Use dedicated line; never flush.
Catastrophic pulmonary edema · As a CRI initiated at 1 microgram/kg/min and carefully titrated to effect by increasing by 1 microgram/kg/min increments every 15 minutes as long as BP remains stable and until perfusion and pulmonary function improves (cats usually requires between 1-2 micrograms/kg/min with the upper limit being 2 micrograms/kg/min). · IV · CRI · Maintain most effective dose for 12-15 hours · Systolic BP must remain >90 mm Hg. Wean nitroprusside over 6 hours first, then dobutamine over 6 hours.

Dogs

Hypertensive crisis (systolic arterial BP >200 mm Hg) · Initiate dose at 1-2 micrograms/kg/minute; increase dosage incrementally every 3-5 minutes until a predetermined target BP is attained. Reduce BP 25% over 4-hour period to allow readaptation of cerebral blood vessels. · IV · CRI · Titrate to effect

투여 경로

금기

Compensatory hypertension (e.g., AV shunts, coarctation of the aorta, Cushing's reflex)
Inadequate cerebral circulation
Emergency surgery in patients near death

이상반응

Profound hypotension
Nausea
Retching
Restlessness
Apprehension
Muscle twitching
Dizziness
Infusion site irritation (avoid extravasation)
Thiocyanate and cyanide toxicity (with prolonged use)

약물 상호작용

General Anesthetics (e.g., halothane, enflurane) · May enhance the hypotensive effects of nitroprusside.
Dobutamine · Synergistic effects (increased cardiac output and reduced wedge pressure) may result; often used together beneficially in severe heart failure.
Other Hypotensive Agents (e.g., beta-blockers, ACE inhibitors) · Patients may be more sensitive to the hypotensive effects of nitroprusside.

모니터링

Blood pressure (constant, direct arterial monitoring preferred)
Acid/base balance (to detect early metabolic acidosis/cyanide toxicity)
Electrolytes (especially Na+)
Respiratory effort and thoracic auscultation
Serum thiocyanate levels (if on prolonged therapy or concurrent renal dysfunction)

과용량

**Acute Overdosage**: Manifests as profound hypotension. * **Treatment**: Reduce or stop the infusion and administer IV fluids. Blood pressure will typically recover within 1-10 minutes. Monitor BP constantly. **Toxicity (Cyanide/Thiocyanate)**: Excessive doses, prolonged therapy (>3 days), depleted hepatic thiosulfate, or severe hepatic/renal insufficiency may lead to cyanogen or thiocyanate toxicity. * **Signs**: Metabolic acidosis (early sign of cyanogen toxicity), tolerance to therapy, delirium (thiocyanate toxicity in dogs). * **Monitoring**: Monitor acid/base status. Serum thiocyanate levels >100 mcg/mL are considered toxic. * **Treatment**: Hydroxocobalamin (Vitamin B12a) may prevent or treat cyanogen toxicity. Contact an animal poison control center for specific antidotal protocols if suspected.

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