A multitude of drugs are capable of lowering blood pressure, including volatile anesthetics, sympathetic antagonists and agonists, calcium channel blockers, β-blockers, and angiotensin-converting enzyme inhibitors. This chapter examines agents that may be useful to the anesthesiologist for intraoperative control of arterial blood pressure.
Patients with an increasing “vascular age” routinely present for anesthesia and surgery. As patients chronologically age, so too does their vasculature. When a pulse wave is generated by ventricular contraction, it is propagated through the arterial system. At branch points of the aorta, the wave is reflected back toward the heart. In patients of young vascular age, the reflected wave tends to augment diastole, improving diastolic pressure. In patients with “older” vasculature, the wave arrives sooner, being conducted back by the noncompliant vasculature during late systole, which causes an increase in cardiac workload and a decrease in diastolic pressure (Figure 15-1). Thus, older patients develop increased systolic pressure and decreased diastolic pressure.
Illustration of the influence of increased vascular stiffness on peripheral (radial) and central (aortic) pressures. Note the similarity of peripheral radial pressures in individuals with normal (lower left panel) and increased (upper left panel) vascular stiffness. In young individuals with normal vascular stiffness, central aortic pressures are lower than radial pressures (lower panels). In contrast, in older individuals with increased vascular stiffness, central aortic pressures are increased and can approach or equal peripheral pressures as a result of wave reflection and central wave augmentation during systole (top panels). ...