Bonazzi M, Lensi C, Migliavacca S, Bianchi de Grazia L, Cipolla M, Martino R, Riva A, Laveneziana D
Servizio di Anestesia e Rianimazione, Ospedale Bassini, Azienda USSL n. 31, Cinisello Balsamo, Milano.
Minerva Anestesiol. 1998 Mar;64(3):59-65.
A prospective double blind study has been carried out in order to evaluate the current incidence of stress ulceration and the efficacy of acid-reducing prophylaxis, in patients scheduled for major vascular surgery, without a documented history of ulcer disease or previous upper GI-tract surgery.
Seventy patients have been randomly assigned to treatment group with ranitidine 50 mg e.v. every six hours or to control group with placebo at the same intervals. Gastric juice has been evaluated for pH and for occult blood by a slide test four times a day and cultured once a day on a suitable ground in the postoperative period. Data have been analyzed on a "treatment efficacy" and not "intention to treat" basis: patients have been considered alkalinized if more than 80% of pH measurement were > 4.5. Patients have been therefore divided into two groups, the "alkaline" one (43 patients) and the "acid" one (27 patients).
Twenty-five patients (58.1%) in the alkaline group vs four patients (14.8%) in the acid group, showed positive gastric-juice cultures (p > 0.01). Twenty-three patients in the alkaline group (53.4%) and nine patients in the acid group (33.3%) showed occult gastric bleeding (p = NS). Overall, nine patients (12.8%) had overt gastrointestinal bleeding, four in the alkaline group (9.3%) and five in the acid group (18.5%) (p = NS). Endoscopic evaluation revealed erosive gastropathy in six patients, gastric ulcer in two patients and duodenal ulcer in one. Neither occult nor overt gastrointestinal bleeding did correlate with gastric pH values. On the contrary, the development of overt gastrointestinal bleeding has been positive associated with length of aortic cross-clamping and with postoperative score index.
This observation suggests that factors other than gastric acidity contribute to mucosal damage and bleeding, as intraoperative mesenteric ischemia/hypoperfusion, or oxygen free radicals damage produced during reperfusion of districts below the level of aortic cross-clamping. The results obtained suggest that routinary alkalisation of gastric juice is not warranted in the prevention of gastrointestinal bleeding in major vascular surgical patients.
