ABSTRACT
BACKGROUND: It has been reported that two common vasodilators, nitroglycerin (NTG) and sodium nitroprusside (SNP), inhibit regional HPV and decrease arterial oxygenation as a result. The purpose of the present study was, therefore, to determine the comparative effect of NTG and SNP on HPV in a rabbit model of isolated lung perfusion with exclusion of the influential factors on HPV. METHODS: In adult white rabbits (n=20), lungs were isolated and perfused with the constant pulmonary blood flow. The acid-base status and temperature of perfusate was also constantly maintained. Thirty minutes later, baseline hypoxic pressor response (HPR) was measured as the difference of pulmonary artery pressure (PAP) between a period of 95% hyperoxic gas inhalation and that of 3% hypoxic gas inhalation. ED50 of NTG and SNP was calculated from the hypoxic pressor response measured in the same way, according to changes of doses (0.5, 1.0, 2.0, and 5.0 microgram/kg). RESULTS: Both NTG and SNP significantly decreased the baseline PAP in the doses of 1.0 microgram/kg and above, and also decreased the HPR in a dose-related manner. ED50 of SNP was significantly lower than that of NTG. CONCLUSIONS: NTG and SNP dilated directly the pulmonary vasculature and inhibited HPV in a dose- related manner. SNP had a greater inhibiting effect on HPV than NTG.
Subject(s)
Adult , Humans , Rabbits , Inhalation , Lung , Nitroglycerin , Nitroprusside , Oxygen , Perfusion , Pulmonary Artery , Vasoconstriction , Vasodilator AgentsABSTRACT
BACKGREOUND: The ideal drug for treatment of pulmonary hypertension would be a vasodilator which acts preferentially on the pulmonary vascular bed. The aim of this study was to compare the effects of prostaglandin I2 (PGI2) on central hemodynamics and right ventricular function with the more widely used vasodilators, prostaglandin E1 (PGE1) and nitroglycerin (NTG) and to investigate whether PGI2 is more selective to the pulmonary vascular bed compared with PGE1 and NTG in dogs. METHODS: We have used a method for producing sustained pulmonary hypertension in vivo by continuous infusion of U46619 adjusting the infusion rate until a mean pulmonary artery pressure (PAP) exceeded 25 mmHg. And the pulmonary and systemic effects of the three pulmonary vasodilators were compared at doses producing equivalent, lowered approximately 20% of mean arterial pressures (MAP) or mean PAP returned to baseline. RESULTS: After infusion of the three vasodilators, heart rate, cardiac output, and mean PAP/MAP ratio were significantly increased, but there was no statistical significant differences among the three vasodilators. PGI2 and PGE1 significantly increased (worsened) the PVR/SVR ratio, but NTG decreased. However there was no significant difference among the three vasodilators. After infusion of the three vasodilators, the arterial oxygen tension (PaO2), mixed venous oxygen tension (PO2), O2 deliver, and O2 uptake were increased, and shunt ratio (s/t(%)) were significantly decreased, but there were no significant differences among three vasodilators. CONCLUSIONS: PGI2, PGE1, and NTG all decreased both PVR and SVR. None of these vasodilatorswere more selective to the pulmonary vascular bed, myocardial performance, and improved gas exchange.
Subject(s)
Animals , Dogs , 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid , Alprostadil , Arterial Pressure , Cardiac Output , Epoprostenol , Heart Rate , Hemodynamics , Hypertension, Pulmonary , Nitroglycerin , Oxygen , Pulmonary Artery , Vasodilator Agents , Ventricular Function, RightABSTRACT
Retained placenta around which the uterus firmly contracted occurs in about 1% of all vaginal deliveries and may require uterine muscle relaxation to facilitate manual extraction. It is associated with profuse hemorrhage and life threatening shock. Therefore anesthesiologist may face the difficulty to provide analgesia and rapid uterine relaxation. A 32-yr-old multigravida was transferred to the emergency room in hypovolemic shock state at 1 hour after vaginal delivery. Ketamine 30 mg, fentanyl 50 mcg were given intravenously for analgesia and sedation. Oxygen 6 L/min was supplied via face mask. With ongoing fluid resuscitation, nitroglycerin 500 mcg was injected as an intravenous bolus. Within 80 seconds, the uterus relaxed enough to extract the retained placenta. The recovery of uterine muscle tone occurred approximately 1 minute after manual removal with administration of intravenous methylergonovine. In summary, the use of intravenous nitroglycerin may be a useful and safe alternative to general anesthesia in cases of manual removal of retained placenta.