We have examined the back-diffusion of CO2 generated by buffering HCI with NaHCO, in the stomach, observed its influence on the pH in the wall of the gastric mucosa, and compared its effects with those of HCl. Isolated stomachs of 17 anesthetized dogs were exposed to either (I) 250 ml NaCl at pH 7, or (2) 125 ml HCl (12.5 meq) + 125 ml NaHCO, (12.5 meq) to generate 12.5 meq CO2 in the stomach, or (3) 250 ml HCI alone to give either 12.5 or 35 meq HCl in the stomach. Samples of gastric fluid and arterial blood were collected every 20 min for 6 hr and analyzed for pH and pC02. The intramural pH of the gastric wall was measured by hollow viscus tonometry. The pC02 in gastric juice rose to 1184 + 139 mm Hg upon the generation of CO2 in the stomach. The till of the CO2 generated by the buffering of acid was 32 + 4 min and of the pC02 was 18.7 f 0.7 min. The till of an equimolar amount of HCI was 2 hr 42 min f 40 min. The disappearance of the CO, was accompanied by a rise in intragastric pH from 6.0 f 0.01 to 6.8 + 0.09 (P < 0.05). and by a fall in intramural pH in the gastric wall from control values of 7.31 + 0.05 to 6.3 f 0.8 (P .Z 0.001). In contrast the pH in gastric fluid did not change and the pH in the intramural fluid did not fall below control values following the administration of 12.5 or 35 meq HCI alone.
Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.
Celiac artery aneurysms were encountered in nine patients, ranging in age from 39 to 76 years, at the University of Michigan Medical Center between 1961 and 1983. Developmental defects and atherosclerosis were etiologic factors in six cases. Four patients were without symptoms, whereas five experienced abdominal pain, including one with a ruptured aneurysm. Eight patients were subjected to surgical treatment; no deaths occurred and symptoms were resolved in all patients. A literature review of 108 celiac artery aneurysms revealed two distinct subgroups. Among 60 celiac artery aneurysms encountered before 1950, representing the historic era, 40% were infectious (usually luetic), 7% were traumatic, and 52% were of undetermined cause. Most were symptomatic, 87% ruptured, and 95% were diagnosed at postmortem examination. The contemporary era since 1950 consisted of 48 cases, including nine in the Michigan experience. Congenital or developmental medial defects of the arterial wall and atherosclerosis were the most common causes of aneurysms. Most aneurysms in the contemporary period were either asymptomatic or accompanied by vague abdominal discomfort. Rupture affected 13% of those aneurysms. Operative therapy was successfully undertaken in 91% of 43 patients during the contemporary era, including eight in the present series.
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