Inclusion Criteria:

Study subjects must meet all of the following criteria:

   - Subject is less than 17 years of age

   - Neonates must be full-term gestation and have a body weight of at least 2.5 kg

   - Subject requires pharmacologically-induced hypotension for acute blood pressure
   management for surgery or other invasive procedure, e.g., cerebral artery embolization

   - Duration of the subject's controlled hypotension is expected to be ≥ 2 hours

   - Subject requires general anesthesia with endotracheal intubation

   - Subject requires placement of intra-arterial line during the surgical or medical
   procedure

   - The subject's parent or legal guardian gives permission (informed consent) and subject
   gives assent when appropriate.

Exclusion Criteria:

Subjects will be excluded if any of the following criteria exist:

   - Subject has a known allergy to SNP

   - Subject has a known mitochondrial cytopathy with a disorder of oxidative
   phosphorylation or of respiratory chain enzymes

   - Subject has a contraindication to vasodilator therapy for control of blood pressure
   during surgery or procedures

   - Subject has participated in other clinical trials for investigational drugs and/or
   devices within 30 days prior to enrollment

   - Subject has any serious medical condition which, in the opinion of the investigator,
   is likely to interfere with study procedures

   - Subject is moribund (death likely to occur within 48 hours)

   - Subject has a positive result for the urine or serum human chorionic gonadotropin
   (HCG) test administered at screening.