[Clinical use of nitroglycerin as an hypotensive agent during general anesthesia (author's transl)]

Nitroglycerine has a direct vasodilating action on both venous and arterial smooth muscle fibers. On account of this, it has been used as hypotensive agent, in aqueous solution, on 22 surgical patients, 10 of them in neurosurgery. The total doses used were 0.76 +/- 0.12 mg/kg during 94 +/- 30 minutes (rate = 8.1 microgram/kg/min). Nitroglycerine induces a rapid onset of hypotension (3 to 4 min), spontaneously reversible in 27 +/- 8 minutes after the arrest of the infusion. The mean drop in mean arterial blood pressure achieved has been 34 p. cent. It is accompanied by a 67 +/- 9 p. cent fall of filling pressures and a fall 13 +/- 4 p. cent of cardiac index, without modification of the heart rate. Tachyphylaxis was noted 15 +/- 6 minutes following nitroglycerine infusion at rate lower than 2 microgram/kg/min, but not when the rate was above 10 microgram/kg/min. Therefore, if the drug is used to achieve controlled hypotension, high doses are necessary. No signs of toxicity were noted. In 4 cases, other hypotensive agents had been used to bring the mean arterial blood pressure below 50 Torr, which could not be achieved with nitroglycerine alone.