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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.58 no.4 Campinas July/Aug. 2008
LETTERS TO THE EDITOR
Remifentanil can reduce the diameter of the bowel
During balanced general anesthesia with continuous infusion of remifentanil for laparotomies, we have been alerted by the surgical team of an accentuated reduction in the diameter of the bowel. According to those reports, this reduction could hinder enteric anastomosis.
The main advantages of remifentanil, the most recent opioid introduced in clinical practice, include fast, intense, and titratable analgesia 1-4. Despite the knowledge that opioids can compromise gastrointestinal function, there are no reports in the literature on the possibility of changes in the size of the intestines during the use of remifentanil 4,5. Considering the observation of the surgical team, we developed a clinical study to evaluate the hypothesis of the undesirable effects of remifentanil on the diameter of the bowel.
After approval by the Institutional Ethics Committee and signing of the informed consent by the patients, we measured the diameter of the jejunum before and after continuous infusion of remifentanil in two adult patients who underwent hepatectomy. Patients with factors that could interfere with intestinal contractility, such as diabetes mellitus, peripheral neuropathies, chronic renal failure, Chaga's disease, inflammatory bowel disease, collagen diseases, severe malnutrition, malabsorption syndromes, fasting for more than 48 hours, or the preoperative presence of nausea, vomiting, or diarrhea, were excluded.
The diameter of the intestine was determined using a sterile stainless steel mechanical pachymeter (Starrett®) calibrated in millimeters. The same surgeon performed the measurements at a predetermined site marked with brilliant green, 20 cm after the duodeno-jejunal angle. The first measurement was made immediately after opening the abdominal cavity before starting the continuous infusion of remifentanil, and the second was done 120 minutes after the institution of the continuous infusion of this drug.
Balanced general anesthesia was induced with 1.5 to 2.5 mg.kg-1 of propofol, 0.25 to 0.5 µg.kg-1 of sufentanil, and 0.15 mg.kg-1 of cisatracurium. Isoflurane on an expired fraction of up to 1.2% was used for maintenance, and neuromuscular blockade was maintained with boluses of 10% to 20% of the initial dose of cisatracurium when needed. After the initial measurement of the intestinal diameter, the continuous infusion of remifentanil was instituted (0.5 µg.kg-1.min-1), and titrated according to the surgical stimulus.
The first case evaluated was a 44-year old female with hepatitis B who underwent partial right hepatectomy for a hepatocellular carcinoma. After opening the abdominal cavity, the baseline measurement of the jejunal segment was 31 mm and, after 120 minutes of remifentanil infusion, the diameter measured 21 mm (a 10-mm reduction - 32% - in the diameter of the jejunum). The second case was a 57-year old female patient with breast malignancy who underwent left segmental hepatectomy for a metastatic hepatic node. After opening the abdominal cavity, baseline jejunal diameter was 27 mm, and after 120 minutes of remifentanil infusion it measured 21 mm (a 6-mm reduction - 30% - in jejunal diameter).
Considering this clinical observation that demonstrated a significant reduction in the jejunal diameter in both cases and the several factors that could possibly interfere with this study, such as age, comorbidities, and length of the surgery, among others, we elaborated an experimental study protocol to continue to investigate this hypothesis.
Joel Avancini Rocha
Mary Yumi Takei Torniziello
Ricardo Souza Nani, TSA
Marcel Cerqueira César Machado
Maria José Carvalho Carmona, TSA
Discipline of Anesthesiology, Faculdade de Medicina da Universidade de São Paulo
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