Regional blood flow in dogs during halothane anesthesia and controlled hypotension produced by nitroprusside or nitroglycerin

• Published in: Anesthesia and analgesia Vol. 63; no. 5; pp. 503 - 510
• Main Authors: COLLEY, P. S, MURALI SIVARAJAN
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott 01-05-1984
• Subjects: Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Biological and medical sciences; Blood Circulation - drug effects; Dogs; Ferricyanides - pharmacology; General anesthesia. Technics. Complications. Neuromuscular blocking. Premedication. Surgical preparation. Sedation; Halothane; Hemodynamics - drug effects; Hypotension - chemically induced; Medical sciences; Nitroglycerin - pharmacology; Nitroprusside - pharmacology; Regional Blood Flow - drug effects; Vascular Resistance - drug effects; Induced arterial hypotension; Fissipedia; Carnivora; Vertebrata; Mammalia; General anesthesia; Hemodynamics; Experimental study; Dog; Blood flow
• ISSN: 0003-2999; 1526-7598
• DOI: 10.1213/00000539-198405000-00007

We used the radioactive microsphere method to measure and compare the effects of sodium nitroprusside (SNP) and nitroglycerin (NTG) on organ blood flow during hypotension induced by each drug. The study was done in 10 dogs anesthetized using 0.7% end-tidal halothane. Each animal received both SNP and NTG to decrease the mean arterial blood pressure (MABP) to 45 mm Hg, but the sequence in which the drugs were administered was alternated. Five of the dogs received SNP first and five received NTG first. Organ blood flow was measured after a stable period of hypotension that was brief by necessity in order to avoid cyanide toxicity due to increasing dose requirements for SNP. Measurements were made before and during hypotension induced with each drug. The mean duration of stable hypotension was shorter (P less than 0.05) with NTG (5 +/- 1 min) (mean +/- SEM) than with SNP (7 +/- 1 min). During NTG-induced hypotension, blood flows to the brain, kidneys, liver, gastrointestinal tract, pancreas, and skeletal muscle were maintained at control levels. During SNP-induced hypotension, blood flows to the myocardium, liver, gastrointestinal tract, pancreas, and skeletal muscle were maintained at control levels. NTG increased myocardial blood flow (P less than 0.05), while SNP decreased blood flow to brain (P less than 0.05) and kidneys (P less than 0.01). Both drugs decreased blood flow to the spleen (P less than 0.001). Our results indicate that during the first few minutes of NTG-induced hypotension, blood flows to all organs except the spleen are well-maintained, while the first few minutes of SNP-induced hypotension are associated with decreases in blood flow to brain and kidneys as well as to the spleen.