The effect of lactulose and lactitol administration on fecal fat excretion in patients with liver cirrhosis

Sarcopenia in cirrhosis: Prospects for therapy targeted to gut microbiota

Decreased muscle mass and function, also known as sarcopenia, is common in patients with cirrhosis and is associated with a poor prognosis. Although the pathogenesis of this disorder has not been fully elucidated, a disordered gut-muscle axis probably plays an important role. Decreased barrier function of the gut and liver, gut dysbiosis, and small intestinal bacterial overgrowth (SIBO) can lead to increased blood levels of ammonia, lipopolysaccharides, pro-inflammatory mediators, and myostatin. These factors have complex negative effects on muscle mass and function. Drug interventions that target the gut microbiota (long-term use of rifaximin, lactulose, lactitol, or probiotics) positively affect most links of the compromised gut-muscle axis in patients with cirrhosis by decreasing the levels of hyperammonemia, bacterial translocation, and systemic inflammation and correcting gut dysbiosis and SIBO. However, although these drugs are promising, they have not yet been investigated in randomized controlled trials specifically for the treatment and prevention of sarcopenia in patients with cirrhosis. No data exist on the effects of fecal transplantation on most links of gut-muscle axis in cirrhosis; however, the results of animal experimental studies are promising.

Gut Microbes and Hepatic Encephalopathy: From the Old Concepts to New Perspectives

Hepatic encephalopathy (HE) is a severe complication of advanced liver disease and acute liver failure. The clinical spectrum ranges from minor cognitive dysfunctions to lethargy, depressed consciousness, and coma and significantly impact the quality of life, morbidity, and mortality of the patients. It is commonly accepted that the gut milieu is essential for the development of HE; however, despite intensive research efforts, the pathogenesis of HE is still not fully elucidated. As our knowledge of gut microbiota moves from the pioneering era of culture-dependent studies, the connection between microbes, inflammation, and metabolic pathways in the pathogenesis of HE is becoming increasingly clear, providing exciting therapeutic perspectives. This review will critically examine the latest research findings on the role of gut microbes in the pathophysiological pathways underlying HE. Moreover, currently available therapeutic options and novel treatment strategies are discussed.

Non-absorbable disaccharides versus placebo/no intervention and lactulose versus lactitol for the prevention and treatment of hepatic encephalopathy in people with cirrhosis

BACKGROUND

Non-absorbable disaccharides (lactulose and lactitol) are recommended as first-line treatment for hepatic encephalopathy. The previous (second) version of this review included 10 randomised clinical trials (RCTs) evaluating non-absorbable disaccharides versus placebo/no intervention and eight RCTs evaluating lactulose versus lactitol for people with cirrhosis and hepatic encephalopathy. The review found no evidence to either support or refute the use of the non-absorbable disaccharides and no differences between lactulose versus lactitol.

OBJECTIVES

To assess the beneficial and harmful effects of i) non-absorbable disaccharides versus placebo/no intervention and ii) lactulose versus lactitol in people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We carried out electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 10), MEDLINE, EMBASE, and Science Citation Index Expanded to 19 October 2015; manual searches of meetings and conference proceedings; checks of bibliographies; and correspondence with investigators and pharmaceutical companies.

SELECTION CRITERIA

We included RCTs, irrespective of publication status, language, or blinding.

DATA COLLECTION AND ANALYSIS

Two review authors, working independently, retrieved data from published reports and correspondence with investigators. The primary outcomes were mortality, hepatic encephalopathy, and serious adverse events. We presented the results of meta-analyses as risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI). We assessed the quality of the evidence using 'Grading of Recommendations Assessment Development and Evaluation' (GRADE) and bias control using the Cochrane Hepato-Biliary Group domains. Our analyses included regression analyses of publication bias and other small study effects, Trial Sequential Analyses to detect type 1 and type 2 errors, and subgroup and sensitivity analyses.

MAIN RESULTS

We included 38 RCTs with a total of 1828 participants. Eight RCTs had a low risk of bias in the assessment of mortality. All trials had a high risk of bias in the assessment of the remaining outcomes. Random-effects meta-analysis showed a beneficial effect of non-absorbable disaccharides versus placebo/no intervention on mortality when including all RCTs with extractable data (RR 0.59, 95% CI 0.40 to 0.87; 1487 participants; 24 RCTs; I(2) = 0%; moderate quality evidence) and in the eight RCTs with a low risk of bias (RR 0.63, 95% CI 0.41 to 0.97; 705 participants). The Trial Sequential Analysis with the relative risk reduction (RRR) reduced to 30% confirmed the findings when including all RCTs, but not when including only RCTs with a low risk of bias or when we reduced the RRR to 22%. Compared with placebo/no intervention, the non-absorbable disaccharides were associated with beneficial effects on hepatic encephalopathy (RR 0.58, 95% CI 0.50 to 0.69; 1415 participants; 22 RCTs; I(2) = 32%; moderate quality evidence). Additional analyses showed that non-absorbable disaccharides can help to reduce serious adverse events associated with the underlying liver disease including liver failure, hepatorenal syndrome, and variceal bleeding (RR 0.47, 95% CI 0.36 to 0.60; 1487 participants; 24 RCTs; I(2) = 0%; moderate quality evidence). We confirmed the results in Trial Sequential Analysis. Tests for subgroup differences showed no statistical differences between RCTs evaluating prevention, overt, or minimal hepatic encephalopathy. The evaluation of secondary outcomes showed a potential beneficial effect of the non-absorbable disaccharides on quality of life, but we were not able to include the data in an overall meta-analysis (very low quality evidence). Non-absorbable disaccharides were associated with non-serious (mainly gastrointestinal) adverse events (very low quality evidence). None of the RCTs comparing lactulose versus lactitol evaluated quality of life. The review found no differences between lactulose and lactitol for the remaining outcomes (very low quality evidence).

AUTHORS' CONCLUSIONS

This review includes a large number of RCTs evaluating the prevention or treatment of hepatic encephalopathy. The analyses found evidence that non-absorbable disaccharides may be associated with a beneficial effect on clinically relevant outcomes compared with placebo/no intervention.

Non-absorbable disaccharides versus placebo/no intervention and lactulose versus lactitol for the prevention and treatment of hepatic encephalopathy in people with cirrhosis

BACKGROUND

Non-absorbable disaccharides (lactulose and lactitol) are recommended as first-line treatment for hepatic encephalopathy. The previous (second) version of this review included 10 randomised clinical trials (RCTs) evaluating non-absorbable disaccharides versus placebo/no intervention and eight RCTs evaluating lactulose versus lactitol for people with cirrhosis and hepatic encephalopathy. The review found no evidence to either support or refute the use of the non-absorbable disaccharides and no differences between lactulose versus lactitol.

OBJECTIVES

To assess the beneficial and harmful effects of i) non-absorbable disaccharides versus placebo/no intervention and ii) lactulose versus lactitol in people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We carried out electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 10), MEDLINE, EMBASE, and Science Citation Index Expanded to 19 October 2015; manual searches of meetings and conference proceedings; checks of bibliographies; and correspondence with investigators and pharmaceutical companies.

SELECTION CRITERIA

We included RCTs, irrespective of publication status, language, or blinding.

DATA COLLECTION AND ANALYSIS

Two review authors, working independently, retrieved data from published reports and correspondence with investigators. The primary outcomes were mortality, hepatic encephalopathy, and serious adverse events. We presented the results of meta-analyses as risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI). We assessed the quality of the evidence using 'Grading of Recommendations Assessment Development and Evaluation' (GRADE) and bias control using the Cochrane Hepato-Biliary Group domains. Our analyses included regression analyses of publication bias and other small study effects, Trial Sequential Analyses to detect type 1 and type 2 errors, and subgroup and sensitivity analyses.

MAIN RESULTS

We included 38 RCTs with a total of 1828 participants. Eight RCTs had a low risk of bias in the assessment of mortality. All trials had a high risk of bias in the assessment of the remaining outcomes. Random-effects meta-analysis showed a beneficial effect of non-absorbable disaccharides versus placebo/no intervention on mortality when including all RCTs with extractable data (RR 0.59, 95% CI 0.40 to 0.87; 1487 participants; 24 RCTs; I(2) = 0%; moderate quality evidence) and in the eight RCTs with a low risk of bias (RR 0.63, 95% CI 0.41 to 0.97; 705 participants). The Trial Sequential Analysis with the relative risk reduction (RRR) reduced to 30% confirmed the findings when including all RCTs, but not when including only RCTs with a low risk of bias or when we reduced the RRR to 22%. Compared with placebo/no intervention, the non-absorbable disaccharides were associated with beneficial effects on hepatic encephalopathy (RR 0.58, 95% CI 0.50 to 0.69; 1415 participants; 22 RCTs; I(2) = 32%; moderate quality evidence). Additional analyses showed that non-absorbable disaccharides can help to reduce serious adverse events associated with the underlying liver disease including liver failure, hepatorenal syndrome, and variceal bleeding (RR 0.47, 95% CI 0.36 to 0.60; 1487 participants; 24 RCTs; I(2) = 0%; moderate quality evidence). We confirmed the results in Trial Sequential Analysis. Tests for subgroup differences showed no statistical differences between RCTs evaluating prevention, overt, or minimal hepatic encephalopathy. The evaluation of secondary outcomes showed a potential beneficial effect of the non-absorbable disaccharides on quality of life, but we were not able to include the data in an overall meta-analysis (very low quality evidence). Non-absorbable disaccharides were associated with non-serious (mainly gastrointestinal) adverse events (very low quality evidence). None of the RCTs comparing lactulose versus lactitol evaluated quality of life. The review found no differences between lactulose and lactitol for the remaining outcomes (very low quality evidence).

AUTHORS' CONCLUSIONS

This review includes a large number of RCTs evaluating the prevention or treatment of hepatic encephalopathy. The analyses found evidence that non-absorbable disaccharides may be associated with a beneficial effect on clinically relevant outcomes compared with placebo/no intervention.

Impact of pretransplant hepatic encephalopathy on liver posttransplantation outcomes

Patients with cirrhosis commonly experience hepatic encephalopathy (HE), a condition associated with alterations in behavior, cognitive function, consciousness, and neuromuscular function of varying severity. HE occurring before liver transplant can have a substantial negative impact on posttransplant outcomes, and preoperative history of HE may be a predictor of posttransplant neurologic complications. Even with resolution of previous episodes of overt or minimal HE, some patients continue to experience cognitive deficits after transplant. Because HE is one of the most frequent pretransplant complications, improving patient HE status before transplant may improve outcomes. Current pharmacologic therapies for HE, whether for the treatment of minimal or overt HE or for prevention of HE relapse, are primarily directed at reducing cerebral exposure to systemic levels of gut-derived toxins (e.g., ammonia). The current mainstays of HE therapy are nonabsorbable disaccharides and antibiotics. The various impacts of adverse effects (such as diarrhea, abdominal distention, and dehydration) on patient's health and nutritional status should be taken into consideration when deciding the most appropriate HE management strategy in patients awaiting liver transplant. This paper reviews the potential consequences of pretransplant HE on posttransplant outcomes and therapeutic strategies for the pretransplant management of HE.

Considerations on the impact of hepatic encephalopathy treatments in the pretransplant setting

Hepatic encephalopathy (HE) is a common complication of acute and chronic liver disease associated with exposure of brain tissue to excessive levels of ammonia produced by intestinal bacteria. Clinical manifestations range from subtle neurologic abnormalities to coma. Because development of HE can reduce survival probability, guidelines for evaluating patients for liver transplantation suggest that patients who develop HE should be considered for transplantation. Various patient factors before transplantation, including the presence of HE and reduced nutritional status, may increase the risk of poor outcomes after transplantation. Therefore, effective management of HE before transplantation, while minimizing the potential impact of negative predictive factors, may improve transplantation outcomes. The most common HE treatments are directed toward reducing systemic ammonia levels, thereby reducing brain exposure to this neurotoxin. The administration of nonabsorbable disaccharides is considered as a first-line therapy for HE, and the antibiotics neomycin and metronidazole are frequently administered, despite a lack of clinical data supporting their efficacy. These agents are associated with adverse events that may reduce nutritional status in patients awaiting transplantation and could contribute to poor posttransplantation outcomes. The nonsystemic antibiotic rifaximin has demonstrated efficacy for the treatment of HE and has a favorable safety profile. Given these data, nonsystemic antibiotics may also provide a safe and effective option for treating HE in the pretransplant setting. This article reviews treatments for HE and the potential impact these treatments may have on pretransplantation status of patients awaiting liver transplantation and on posttransplantation outcomes.

Role of nutrition in liver transplantation for end-stage chronic liver disease

Patients with end-stage liver disease often reveal significant protein-energy malnutrition, which may deteriorate after listing for transplantation. Since malnutrition affects post-transplant survival, precise assessment must be an integral part of pre- and post-surgical management. While there is wide agreement that aggressive treatment of nutritional deficiencies is required, strong scientific evidence supporting nutritional therapy is sparse. In practice, oral nutritional supplements are preferred over parenteral nutrition, but enteral tube feeding may be necessary to maintain adequate calorie intake. Protein restriction should be avoided and administration of branched-chain amino acids may help yield a sufficient protein supply. Specific problems such as micronutrient deficiency, fluid balance, cholestasis, encephalopathy, and comorbid conditions need attention in order to optimize patient outcome.

Magnetic resonance colonography without bowel cleansing using oral and rectal stool softeners (fecal cracking)—a feasibility study

The aim of our study was to assess the effect of oral and rectal stool softeners on dark-lumen magnetic resonance (MR) colonography without bowel cleansing. Ten volunteers underwent MR colonography without colonic cleansing. A baseline examination was performed without oral or rectal administration of stool softeners. In a second set, volunteers ingested 60 ml of lactulose 24 h prior to MR examination. In a third examination, water as a rectal enema was replaced by a solution of 0.5%-docusate sodium (DS). A fourth MR examination was performed, in conjunction with both oral administration of lactulose and rectal application of DS. A T1-weighted data set was acquired at scanning times of 0, 5 and 10 min after colonic filling. A fourth data set was acquired 75 s after i.v. injection of contrast agent. Signal intensity of stool was calculated for all colonic segments. Without oral ingestion of lactulose or rectal enema with DS stool signal intensity was high and did not decrease over time. However, lactulose and DS caused a decrease in stool signal intensity. Both substances together led to a decreasing signal intensity of feces. Combination of lactulose and DS provided the lowest signal intensity of stool. Thus, feces could hardly be distinguished from dark rectal enema allowing for the assessment of the colonic wall.

Effect of sugar alcohols on gut function and body composition in normal and cecectomized rats

The effects of two sugar alcohols on feed utilization, digesta retention, gut fermentation and serum lipid profiles were compared in normal and cecectomized rats to examine the possibility of the cecectomized rat as an experimental animal with relevance to humans. Semi-purified diets containing no sugar alcohol, 7% sorbitol or 7% lactitol were fed to normal and cecectomized rats for 16 days. The digestibility of the crude fat and the compositions of the carcass dry matter and crude fat were significantly decreased by feeding sugar alcohols in both groups, but the effects were relatively higher in the cecectomized rats than in the normal rats. Diarrhea, faster transit times and shorter retention times of digesta were noted in the cecectomized rats fed sugar alcohols, while the inverse results were observed in the normal rats fed similar diets. The concentration of cecal organic acids was increased in the normal rats, whereas the concentration of colonic organic acids was decreased in the cecectomized rats fed sugar alcohols, compared with their corresponding control groups. The concentration of serum total cholesterol was decreased in both the normal and cecectomized rats fed diets containing sugar alcohols. The tendencies for diarrhea, faster digesta transit and reduced body fat induced by the fermentable materials in the cecectomized rat have good relevance to the parallel effects of fermentable materials in humans, suggesting the possibility of using the cecectomized rat as a model to study some of the physiological effects of sugar alcohols in humans.

Effect of insulin-like growth factor-I on nitrogen balance and intestinal galactose transport in rats with moderate liver cirrhosis

The malnutrition caused by liver cirrhosis (LC) often worsens the course of the disease. Patients affected by LC often have a low bioavailability of the anabolic liver peptide insulin-like growth factor (IGF)-I. The present study was undertaken to investigate the effect of low doses of IGF-I on the nutritional status and in vivo jejunal transport of D-galactose in anatomically, pathologically and biochemically confirmed moderate, non-ascitic, cirrhotic rats. LC was experimentally induced in growing rats by inhalation of CCl4 and addition of phenobarbital to drinking water. Both the nutritional status, as evaluated by N balance, and in vivo intestinal transport of D-galactose, were significantly impaired in cirrhotic rats. As compared with healthy rats, administration of 20 microg human recombinant IGF-I/kg body weight for 14 d to cirrhotic rats significantly improved N balance variables and restored in vivo intestinal transport of the sugar. However, IGF-I had no effect on the steatorrhoea associated with LC. These results suggest that low doses of IGF-I may have beneficial effects on the malnutrition associated with moderate LC.

Nonabsorbable disaccharides for hepatic encephalopathy

BACKGROUND

Nonabsorbable disaccharides (lactulose or lactitol) are considered the treatment of choice for hepatic encephalopathy.

OBJECTIVES

To assess the beneficial and harmful effects of nonabsorbable disaccharides for patients with hepatic encephalopathy.

SEARCH STRATEGY

Trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register (March 2003), The Cochrane Central Register of Controlled Trials (Issue 1, 2003), MEDLINE (1966 to 2003/03), EMBASE (1980 to 2003/03), manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing lactulose or lactitol versus no intervention, placebo, or antibiotics and trials comparing lactulose versus lactitol for hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

The primary outcome measures included no improvement of hepatic encephalopathy and all-cause mortality. Binary outcomes are reported as relative risks (RR) based on a random effects model. Subgroup analyses were performed with regard to methodological quality and form of hepatic encephalopathy.

MAIN RESULTS

Thirty trials assessed nonabsorbable disaccharides versus placebo, no intervention, or antibiotics or assessed lactulose versus lactitol. We could not extract data from all trials. Compared with placebo or no intervention, nonabsorbable disaccharides had no statistically significant effect on mortality (RR 0.41, 95% CI 0.02 to 8.68, four trials), but appeared to reduce the risk of no improvement of hepatic encephalopathy (RR 0.62, 95% CI 0.46 to 0.84, six trials). However, this result may reflect bias due to low methodological quality of the majority of included trials. Trials of high methodological quality found no significant effect of nonabsorbable disaccharides on the risk of no improvement (RR 0.92, 95% CI 0.42 to 2.04, two trials). We found no statistically significant difference between lactulose and lactitol on mortality (two trials) or risk of no improvement (four trials). However, our meta-analyses were underpowered to establish whether these treatments have comparable effect. Nonabsorbable disaccharides appeared to be inferior to antibiotics on reducing the risk of no improvement (RR 1.24, 95% CI 1.02 to 1.50, 10 trials).

REVIEWERS' CONCLUSIONS

This systematic review questions the beneficial effects of nonabsorbable disaccharides and highlights that there is insufficient high-quality evidence to support this treatment. We found that antibiotics appeared to be superior to nonabsorbable disaccharides in improving hepatic encephalopathy, but it is unclear whether this difference in treatment effect is clinically important to patients. Nonabsorbable disaccharides should not serve as comparator in randomised trials on hepatic encephalopathy.

Malnutrition is not related to alterations in energy balance in patients with stable liver cirrhosis

BACKGROUND AND AIMS

Little information are available on the relationship between energy balance and the alterations in nutritional status occurring in cirrhotic patients. The aim of the present study was to evaluate the daily energy balance in clinically stable cirrhotic patients with or without malnutrition.

PATIENTS

Seventy-four consecutive cirrhotic patients and nine healthy controls were studied.

METHODS

Basal energy expenditure was measured by indirect calorimetry and adjusted according to the patients' physical activity to estimate the daily energy expenditure. Food intake was evaluated based on a 3-day dietary diary. Nutritional status and body composition were assessed using skinfold anthropometry and dual energy X-ray absorptiometry, respectively.

RESULTS

Thirty-two patients in the cirrhotic group were classified as severely malnourished according to anthropometric parameters. Two different patterns of soft-tissue loss were observed in the malnourished cirrhotic group: a significant reduction in fat mass and in fat-free mass was observed in males, whereas, females showed a significant reduction in fat mass only. Basal energy expenditure was similar in all groups, while the non-protein respiratory quotient was lower in cirrhotics notwithstanding their nutritional status. This suggests that lipids were the preferred oxidized fuel in the post-absorptive state in these patients. No difference in the estimated daily energy expenditure and energy intake was observed among groups. Lipid content of the diet was significantly lower in malnourished cirrhotics than in controls (33.1+/-1% vs 37.8+/-1%, P=0.02).

CONCLUSIONS

Cirrhotic patients in stable clinical condition with malnutrition show a normal energy balance.

Malnutrition is a risk factor in cirrhotic patients undergoing surgery

Cirrhotic patients may become candidates for elective and emergency surgery. This may be due to conditions requiring operations such as cholecystectomy, herniotomy, or gastrointestinal malignancies, more common in cirrhotics when compared with the general population, or to complications of the liver disease such as resectable hepatocellular carcinomas or surgical portosystemic shunts to treat portal hypertension. It has been estimated that 10% of cirrhotics undergo at least one operative procedure during the final 2 y of their lives. Many studies have documented a high risk of morbidity and mortality associated with surgical procedures in these patients, and several factors influencing the postoperative outcome have been identified. Malnutrition, which is frequently encountered in cirrhotic patients, has been shown to have an important impact on the surgical risk. A poor nutrition status also has been associated with a higher risk of complications and mortality in patients undergoing liver transplantation. Few data are available concerning the perioperative nutrition support in surgical cirrhotic patients. The results of these studies are sometimes encouraging in reporting that the nutrition therapy may improve the clinical outcome in cirrhotic patients undergoing general surgery and/or liver transplantation. The limited number of patients and their heterogeneity, however, do not allow definitive conclusions, and more research on this issue is needed.

Effect of lactitol on blood ammonia response to oral glutamine challenge in cirrhotic patients: evidence for an effect of nonabsorbable disaccharides on small intestine ammonia generation

OBJECTIVE

Nonabsorbable disaccharides are widely used to decrease blood ammonia concentration. Their principal mode of action is the modification of pH and bacterial flora in the colon. The aim of the present study was to test the hypothesis that these drugs may also reduce small intestine ammonia generation.

METHODS

Eight male cirrhotics without overt hepatic encephalopathy received 20 g of glutamine in 100 ml of water. Venous samples for whole blood ammonia were taken before, 30 and 60 min after the load. Immediately after the last blood sample the patients were submitted to the following psychometric tests: number connection test, Posner's attention test, and Sternberg paradigm. After the first glutamine load, patients were started on lactitol (initial dose 20 g, three times a day). Once two bowel movements/day were obtained and maintained for at least 5 days, oral glutamine challenge and psychometric tests were repeated.

RESULTS

Ammonia increased significantly after the glutamine load (from 83 +/- 13 to 164 +/- 30 microg/dl at 30 min and 210 +/- 29 microg/dl at 60 min; mean +/- SE; p = 0.006 analysis of variance) but not after glutamine load after lactitol treatment (from 77 +/- 17 to 111 +/- 21 microg/dl and 142 +/- 24 microg/dl; p = not significant). The peak increment (127 +/- 24 vs 65 +/- 18 microg/dl; p = 0.008) of ammonia elevation was significantly smaller during lactitol administration. The patients' psychometric performance after the glutamine load did not differ significantly after lactitol treatment.

CONCLUSIONS

Lactitol reduces the elevation in blood ammonia that follows oral glutamine challenge. Because enterally administered glutamine is efficiently absorbed in the jejunum and, in part, metabolized to ammonia we suggest that lactitol affects small intestine ammonia generation probably by shortening the residence time of intestinal contents.