Immediate detection of postreconstructive ischaemia by intra-operative Doppler ankle pressure index monitoring during aortic reconstructions

Blood pressure responses after carotid surgery: relationship to postoperative baroreceptor sensitivity

BACKGROUND AND PURPOSE

Among hypertensive patients after carotid surgery, a group of patients with increased baroreflex sensitivity was identified. In the other group of hypertensive patients, blood pressure and reflex sensitivity were unchanged postoperatively. We hypothesized that a partial readjustment of baroreceptor sensitivity would produce more stable blood pressure profiles.

METHODS

In order to test this hypothesis, a prospective, long-term follow-up study was designed. Blood pressure was monitored in 18 hypertensive and 6 normotensive patients during 6 months using a self-measurement technique. In addition, continuous 24-hour blood pressure monitoring was performed 6 months after surgery. The mean values and the ranges (amplitudes) of systolic and diastolic blood pressure were calculated as indicators for the stability of the circulatory system.

RESULTS

Hypertensive patients with unchanged postoperative baroreceptor sensitivity showed significantly more pronounced instabilities of their blood pressure profiles (amplitudes of systolic and diastolic blood pressure p < 0.05 to p < 0.001). A relationship between baroreceptor function and antihypertensive therapy could also be demonstrated, with adequate therapy being much more difficult in patients with reduced or unchanged baroreceptor sensitivity.

CONCLUSIONS

In contrast to vascular surgery on the aorta or in the region of the lower limbs, carotid surgery is frequently associated with blood pressure changes, demonstrating the essential role of the baroreceptors in the carotid sinus for the regulation of postoperative blood pressure. Since it seems to be the variability of blood pressure, and not the blood pressure level alone, that is critical, close blood pressure monitoring--allowing for an assessment of blood pressure variability--appears to be of particular importance in such patients.

Arterial baroreflex sensitivity and blood pressure variabilities before and after carotid surgery

Carotid surgery is frequently associated with postoperative blood pressure alterations. The role of baroreceptors with regard to these alterations was assessed in 50 patients by determining the pre- and postoperative mechanoreceptor sensitivity after Valsalva maneuver and intravenous injections of angiotensin and nitroglycerine as described by Smyth, Sleight and Pickering. In addition, blood pressure was monitored perioperatively and renin and aldosterone levels were measured. In patients with arterial hypertension a postoperative increase of receptor reactivity can be seen necessitating a reduction of antihypertensive therapy in more than 50% of cases. In normotensive patients no uniform response can be observed. A possible explanation for this effect might be the local increase of pressure in the operated vascular segment. The postoperative reintegration of receptor areas which had been adjusted to a reduced pressure level might induce a more sensitive response than can be seen for the remaining receptors, which usually are less responsive in hypertensive patients.