Decrease In Pulmonary Capillary Wedge Pressure Research Articles

Haemodynamic studies with a phasic release nitroglycerin patch system

The use of transdermal nitroglycerin (GTN) patches in patients with coronary artery disease is of uncertain value as numerous investigators have failed to confirm clinical efficacy for more than 8h. This relatively short duration of action is an indication of rapidly developing tolerance due to the relatively constant GTN plasma levels following GTN patch application. We investigated the efficacy of a newly developed GTN patch with a discontinuous release profile in 28 patients with coronary heart disease. Two hours after initial administration, pulmonary capillary wedge (PCW) pressure decreased by 25.7% at rest and by 25.1% during exercise. Cardiac index at rest decreased by 12.2%. No significant changes were observed in systemic blood pressure and heart rate. No significant haemodynamic effects were apparent after 24h. Following renewed GTN patch application, a decrease in PCW pressure occurred, similar to that observed after acute administration. After 1 week of daily therapy, similar changes were observed: 24h after patch application, PCW was similar to baseline values but showed a significant decrease 2h after patch re-application. These data suggest that the phasic release GTN patch is not associated with tolerance to the haemodynamic effects during sustained once daily therapy.

Esmolol Attenuates Hemodynamic Responses during Fentanyl-Pancuronium Anesthesia for Aortocoronary Bypass Surgery

We evaluated the effects of esmolol, a short acting (t1/2 beta = 9 min) beta-blocker on hemodynamics during noxious stimulation associated with aortocoronary bypass surgery. Group E (n = 10) and P (n = 10) patients had their morning dose of beta- or calcium blockers withheld except for nifedipine, and were given infusions of esmolol (E) or placebo (P) beginning prior to anesthetic induction and continuing until mediastinal dissection. Group S (n = 10) patients received their usual medication the morning of surgery and received neither esmolol nor placebo. All patients received fentanyl infusions for anesthesia and pancuronium for relaxation. Esmolol patients had no changes in heart rate throughout the study. In contrast, significant increases in heart rate occurred during induction, intubation, and surgical stimulation in Groups P and S. Esmolol patients had a statistically significant but transient increase in pulmonary capillary wedge pressure (PCWP) after intubation, which did not require treatment. There were no significant changes in PCWP in Group S and a decrease in PCWP in Group P patients. We conclude that esmolol was effective in attenuating potentially deleterious responses to noxious stimulation during fentanyl-pancuronium anesthesia.

Cardiovascular responses to clamping of the aorta during epidural and general anesthesia.

The cardiovascular responses of aortic cross-clamping and declamping with normal and high ventricular filling pressures were compared during epidural and nitrous oxide-morphine anesthesia in 32 male patients undergoing reconstructive aortic surgery. The patients were divided into four groups. Groups I and II had lumbar epidural blocks with bupivacaine and received nitrous oxide in oxygen to breathe; groups III and IV were anesthetized with morphine (2 mg/kg) and nitrous oxide. During aortic occlusion groups I and III received Ringer's lactate at a rate which maintained mean pulmonary capillary wedge pressure (PCWP) 3 to 4 torr above pre-anesthetic values whereas groups II and IV were given Ringer's lactate rates which kept PCWP similar to pre-anesthetic values. Prior to cross-clamping mean arterial blood pressure and systemic vascular resistance were lower in groups I and II than in groups III and IV but cardiac output, PCWP, and pulmonary vascular resistance were similar in the four gropus. Cross-clamping of the aorta produced no significant change in any cardiovascular variable measured in any group. Declamping did not significantly alter any variable in groups I and III but produced moderate hypotension in group IV and severe hypotension in group II as well as significant decreases in PCWP in both groups. Our data demonstrate that aortic cross-clamping and release result in little change in cardiovascular dynamics in patients anesthetized with epidural or morphine-nitrous oxide and given balanced salt solutions intravenously in amounts adequate to increase left ventricular filling pressures prior to release of the aortic cross-clamp. Our findings also indicate that hypotension can occur in patients in whom left ventricular filling pressures are maintained at normal levels prior to cross-clamp release, especially in patients given epidural anesthesia.