Blood flow acceleration in the carotid and brachial arteries of healthy volunteers: respective contributions of cardiac performance and local resistance

Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (V_m) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (G_max = +dV/dt_max). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, G_max was of a similar magnitude (551 ±30 and 555 ± 44 cm/s², respectively) despite major differences in the respective D, V_m, Q and R values. In neither artery was there a relationship between G_max and either resting Q or R. At the brachial artery level, G_max was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between G_max and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow.     

Iotrol versus metrizamide in lumbar myelography: a double-blind study

In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.     

Replacement of the ascending aorta. Early and late results

From 1978 through 1987, 225 patients underwent operations that included replacement of the ascending aorta. One hundred twenty-three patients underwent composite aortic valve and ascending aortic replacement, 30 had aortic valve replacement with separate graft replacement of the ascending aorta, and 72 underwent replacement of the ascending aorta without aortic valve replacement. Thirty-one (13.8%) in-hospital deaths occurred. Univariate testing of preoperative and operative variables followed by logistic regression analyses identified miscellaneous aortic disease, coronary artery bypass grafting, aortic arch replacement, emergency operation, surgical date (1978 to 1983), and age (all p less than 0.05) as factors having independent association with in-hospital mortality. Follow-up of in-hospital survivors (mean interval 46 months, range 8 to 123 months) documented an overall 5-year survival rate of 76%, 83% after primary operation and 37% after reoperation. Univariate analyses followed by multivariate testing indicated that previous operation (p less than 0.0001) and a history of preoperative neurologic symptoms (p = 0.021) were associated with decreased late survival. At follow-up 88% of late survivors were free of symptoms. Seven patients have undergone reoperation 1 day to 69 months postoperatively. Although the in-hospital mortality for operations that include ascending aortic replacement exceeds that for isolated aortic valve replacement, the late death rate and rate of reoperation are low.     

Early laparoscopic cholecystectomy for acute cholecystitis

Background: The timing of laparoscopic cholecystectomy for acute cholecystitis remains controversial. Methods: One hundred ninety-four patients with acute cholecystitis were reviewed. The conversion rates for the various number of days of symptoms before surgery were analyzed. The conversion rate dramatically increased from 3.6% for those patients with 4 days of symptoms to 26% for those patients with 5 days of symptoms. The mean number of days of symptoms prior to surgery in those patients who underwent successful laparoscopic cholecystectomy was 4.1 as compared to 8.0 in those patients who required open cholecystectomy (p < 0.0001). Based on this data the patients were divided into two groups. Group 1 consisted of 109 patients who underwent laparoscopic cholecystectomy within 4 days of onset of symptoms and group 2 consisted of 85 patients who underwent laparoscopic cholecystectomy after more than 4 days following onset of symptoms. Results: The conversion rate from laparoscopic to open cholecystectomy was 15%. The conversion rate for group 1 was 1.8% as compared to 31.7% for group 2 (p < 0.0001). Indications for conversion were inability to identify the anatomy secondary to inflammatory adhesions (68%), cholecystoduodenal fistula (18%), and bleeding (14%). The major complication rate for group 1 was 2.7% as compared to 13% for group 2 (p= 0.007). The mortality rate for all patients with attempted laparoscopic cholecystectomy for acute cholecystitis was 1.5%. The average procedure time for group 1 was 100 ± 37 min vs 120 ± 55 min in group 2. The average number of postoperative hospital days in group 1 was 5.5 ± 2.7 days as compared to 10.8 ± 2.7 days in group 2. Conclusions: We advocate early laparoscopic cholecystectomy within 4 days of onset of symptoms to decrease major complications and conversion rates. This decreased conversion rate results in decreased length of procedure and hospital stay. Received: 28 March 1996/Accepted: 12 September 1996     

Intraoperative cholangiography revisited.

The charts of 1351 patients undergoing cholecystectomy at our institutions from 1985 through 1989 were reviewed retrospectively to evaluate the indications for and the success of intraoperative cholangiography. A total of 800 patients underwent intraoperative cholangiography. They were divided into two groups based on the absence (CR-) or presence (CR+) of clinical and/or operative criteria suggestive of the existence of common bile duct stones. Intraoperative cholangiography in CR- patients was of limited benefit, being negative (normal) in 95.7%, true-positive (abnormal) in 3.3%, and false-positive in 1%. False-positive intraoperative cholangiography resulted in unnecessary common bile duct explorations. Intraoperative cholangiography in CR+ patients proved useful, avoiding unnecessary common bile duct exploration in 55%. In those select CR+ patients with palpable common bile duct stones or cholangitis, little additional information was gained by the intraoperative cholangiography. We conclude that routine screening intraoperative cholangiography in CR- patients be reconsidered, as should the use of intraoperative cholangiography in CR+ patients with a palpable common bile duct stone or cholangitis. Intraoperative cholangiography in the remainder of CR+ patients proved beneficial and should be continued.