麻豆传媒

CHICAGO – A 2-week-long restrictive diet appears to shrink obese patients' livers enough to make gall bladder laparoscopic surgery quicker and easier, researchers reported here.

"We were able to reduce operation times by an average of 6 minutes – a reduction from 31 minutes for treatment of controls and 25 minutes for the patients who were on the pre-surgery diet program," said , consultant surgeon at Norfolk & Norwich University Hospital in England.

While a 6-minute reduction may not seem like a big difference, it represents a 20% reduction in surgical time and was statistically significant (P=0.004), Lewis said at the annual Digestive Disease Week. Across a busy service, the time savings could allow one or two additional surgeries a day, he suggested.

"When obese individuals diet, their livers actually shrink and that permits surgeons to more easily perform the laparoscopic surgery," Lewis told 麻豆传媒. "The shorter surgery time also means less anesthesia for the patients, and allows the patients to be up and moving more quickly." He also noted that when livers have less fat, they are not as rigid and can be moved more easily in the surgery, with less physical damage occurring.

While the patients are being followed for long-term outcomes, Lewis suggested that a study to determine if the short-term dietary restriction would reduce surgery complications was not feasible. "The complication rate in cholecystectomy is very low as it is, so we would need vast numbers of people to determine a difference in that area," he said.

In the study reported here, 25 patients represented controls and were advised to document their dietary intake. The comparator group of 21 patients were given similar request to document food intake and were told to maintain a diet of 500 calories to 800 calories a day, Lewis said. "In a diet with calories levels that low there necessarily had to be low levels of fat," he said.

"The patients on the restrictive diet appeared to stick to it for the 2 weeks, judging by an overall weight reduction of 4 kilograms (about 8.8 pounds)," Lewis said. After the surgery the participants were allowed to go back to their normal diets.

He said that it is unlikely that patients could have remained on the diet for more than the 2 weeks. "This is a pretty restrictive diet," he said. "Two weeks they can handle, but more than that would be difficult."

Lewis said his research team observed that using a very-low-calorie diet before bariatric surgery appeared to reduce liver volume and improve bariatric access. He said that they thought that if the same thing could be achieved prior to cholecystectomy, it might ease dissection of the gall bladder as well as improve operative views and reduce hepatic bleeding caused by surgical trauma.

In a related study, , professor of surgery and director of Tampa General Hospital/University of South Florida Health Bariatric Center, said that bariatric surgery that produces weight loss in obese and morbidly obese patients also appears to cause favorable changes in the histology of the liver.

"What we found surprised us," Murr said in a press briefing. "Not only did we find that bariatric surgery reduced fat deposits in the liver, but we also saw that the procedure reduced liver inflammation. We also found that the procedure reversed early-stage liver fibrosis and scarring."

In Murr's study, biopsies were collected at baseline among 152 patients undergoing bariatric surgery over a 15-year period. The majority of the procedures were gastric bypass surgery, he said. The biopsy procedure was repeated an average of 29 months after the surgery.

"In reviewing the postoperative biopsy we found improvements in steatohepatitis -- that is, inflammation of the liver and Stage 2 liver fibrosis," he said.

"These findings suggest that bariatric surgery should be considered as a treatment of choice for nonalcoholic fatty liver disease patients with a body mass index greater than 35 kg/m² and obesity-related comorbidities, or patients with a body mass index greater than 40 kg/m². The findings of our study are especially relevant for the group of patients who has a low success rate with traditional conventions such as medicines and dieting."

Murr told 麻豆传媒 that predicting who would benefit from the surgery as far as liver histology was concerned was still difficult to determine.

"The majority of our patients are women who come in for bariatric surgery. It would be difficult to determine if there would be a difference in sex," he said.

"We looked at age and it did not show any correlation, and we also looked at body mass index and weight and it was difficult to tell or predict how people would do. Stage 3 and 4 liver fibrosis patients did not change, but there were few patients in these stages so it would be difficult to make any conclusions. However, in the early stages – mainly Stage 1 and Stage 2 fibrosis – there was improvement in about 60% of these patients."

He said the type of bariatric surgery may not make a difference in benefit. "In many ways, as long as weight loss is induced, then you are going to be able to see improvement in liver histology," Murr said.

"What appears critical is to reduce the inflammation in the liver, which can be achieved through weight loss and the removal of the fat deposits in the liver. In our animal studies we have observed that the liver turns from an organ that stores fat to an organ that burns fat after bariatric surgery," he said. "We are on to something important in the way that weight loss affects liver histology."

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