Induction with Intravenous 0.3 mg/kg Etomidate Maintains Venous Capacitance of Normovolemic Rat / 대한마취과학회지

BACKGROUND: Etomidate is short-acting non-barbiturate intravenous anesthetic with minimal cardiovascular depression. As a small change in venous capacitance significantly alters venous return and thus cardiac output, it is important to know the effects of intravenous anesthetics on venous capacitance. The purpose of this study was to examine the effect of etomidate or pentobarbital (control agent) on venous capacitance. METHOD: All twenty rats (etomidate group: 10, pentobarbital group: 10), weighing 350-450 gram, were anesthetized with pentobarbital 50 mg/kg given intraperitoneally for surgical preparation. Mean arterial pressure (MAP), heart rate (HR), and mean circulatory filling pressure (MCFP) were measured in the awake state(recovered from pentobarbital anesthesia for surgical preparation) as well as during anesthesia with etomidate or pentobarbital. Venous capacitance was assessed before and during anesthesia with etomidate or pentobarbital by measuring MCFP. MCFP was measured during a brief period of circulatory arrest produced by inflating a balloon inserted in right atrium. RESULTS: As compared with MCFP in the corresponding awake state, MCFP was not significantly altered by etomidate but significantly decreased by pentobarbital. As compared with MAP in the corresponding awake state, MAP was not significantly altered by etomidate but significantly decreased by pentobarbital. CONCLUSION: The results suggest that unaltered venous capacitance by etomidate may contribute to a maintained MAP but increased venous capacitance by pentobarbital decrease in MAP of the normovolemic rat.

Effect of Ketamine or Sodium Thiopental on the Venous Capacitance in Dog / 대한마취과학회지

BACKGROUND: A small change in venous capacitance significantly alters venous return and thus cardiac output. It is therefore important to know the effects of intravenous anesthetics on venous capacitance, particularly in a hypovolemic state. As ketamine does not suppress sympathetic activity, it has been suggested that ketamine may be the drug of choice for anesthesia during hypovolemia. The purpose of this study was to examine the effects of ketamine or sodium thiopental on venous capacitance and total vascular compliance in dogs. METHODS: Twenty mongrel dogs, weighing 10~15 Kg, were divided into two group (ketamine group: 10, sodium thiopental group: 10) of 10 each. Venous capacitance was assessed before and after drug (ketamine 1 mg/kg or sodium thiopental 5 mg/kg) injection by measuring mean circulatory filling pressure (MCFP) in the normovolemia and hypovolemia. MCFP was measured after arresting the circulation by tightening of superior vena cava and inferior vena cava snares simultaneously. RESULTS: As compared with MCFP in the normovolemia and hypovolemia, MCFP was significantly increased by ketamine in the normovolemia and hypovolemia. As compared with MCFP in the hypovolemia, MCFP was significantly decreased by sodium thiopental in the hypovolemia. The slope of the regression line relating MCFP and blood volume was not significantly altered by ketamine or sodium thiopental, which suggests that ketamine or sodium thiopental did not alter total vascular compliance. CONCLUSIONS: These results suggest that ketamine decreases venous capacitance in the normovolemia and hypovolemia but sodium thiopental increases venous capacitance in the hypovolemia.

Effects of Sodium Nitroprusside and Nitroglycerin on the Venous Capacitance during Induced Hypotension in Halothane Anesthetized Dogs / 대한마취과학회지

BACKGROUND: Since a change in venous capacitance significantly alters venous return and thus affects cardiac output, it is important to know the effects of vasodilators on venous capacitance. The purpose of this study was to examine the effects of sodium nitroprusside and nitroglycerin on venous capacitance during induced hypotension in halothane anesthetized dogs. METHODS: Fourteen mongrel dogs(SNP group: 7, NTG group: 7), weighing 10~15 kg, were anesthetized with N2O 1.5L/min-O2 1.5L/min-halothane 0.5vol%. Each dog received only one drug. In dogs anesthetized with N2O-O2-halothane, mean arterial pressure(MAP) was decreased by 15%(mild hypotension) and 30%(deep hypotension) of control value by sodium nitroprusside(SNP) and nitroglycerin (NTG), respectively. Venous capacitance was assessed before and during induced hypotension by measuring mean circulatory filling pressure(MCFP). MCFP was measured after arresting the circulation by tightening of superior vena cava and inferior vena cava snares simultaneously. RESULTS: As compared with MCFP before induced hypotension, MCFP was significantly decreased by SNP at deep hypotension and NTG at mild hypotension and deep hypotension. As compared with MCFP at mild hypotension, MCFP at deep hypotension was significantly decreased by NTG and SNP, respectively. CONCLUSIONS: These results suggest that NTG has potent venodilating effect at mild and deep induced hypotension, whereas SNP has venodilating effect only at deep induced hypotension.

Comparison of Effects of Nitroglycerin and Diltiazem on Venous Capacitance in Rats / 대한마취과학회지

The change of venous capacitance has an influence on venous return to the heart and cardiac output, and causes the alteration of preload, cardiac filling pressure and myocardial wall tension. Venous capacitance is assesed by measuring the mean circulatory filling pressure (MCFP), and MCFP is measured during brief periods of circulatory arrest produced by inflating an indwelling balloon in the right atrium It is important to know the effects of vasodilator and anesthetic drugs on venous capacitance. Therefore, this study was performed to know the effects of nitroglycerin and diltiazem on venous capacitance in rats. Rats were anesthetized with ketamine 125 mg/kg given intraperitoneally and added 10 mg/kg every 30 minutes. Their mean arterial pressure (MAP) was lowered to 60 mmHg by intravenous injection of 0.82+/-0.36 mg/kg nitroglycerin and/or 6.7+/-1.5 mg/kg diltiazem. Hemodynamic parameters such as MAP, heart rate, central venous pressure and MCFP were measured before and after drug-injection. Hemodynamic values measured before drug-injection in two groups were little differences statistically. However, the MCFP of nitroglycerin was significantly decreased (p<0.01) from 7.3+/-0.61 mmHg to 5.4+/-0.58 mmHg after drug-injection, and that of diltiazem was not significantly changed from 7.1+/-0.54 mmHg to 6.9+/-0.63 mmHg. The results suggested that nitroglycerin was predominantly a venous dilator in terms of MCFP but diltiazem had little effect of venodilation.