3D Printed Liver Makes Surgery Safer

3D Printed Liver Makes Surgery Safer

 

By Tia Ghose, Staff Writer 

A new method of 3D printing an anatomically accurate replica of the human liver is now helping to guide surgeons during tricky procedures.

The 3D-printed replicas, which are made of transparent material threaded with colored arteries and veins, could help surgeons prevent complications when performing liver transplants or removing cancerous tumors, researchers said.

"We provide the surgeons with a physical model that is 100 percent identical to what they will encounter in surgery when they operate," said Dr. Nizar Zein, the chief of hepatology at the Cleveland Clinic in Ohio. "It takes away some of the potential surprises that will be found at the time of surgery."

The new liver replica could also be used to train medical students in the techniques needed for surgery, Zein said.

View Slideshow Of 3D images 

Anatomically accurate

While reading a newspaper article about 3D printing, Zein realized that the technique could help make surgeries simpler. Before complicated liver surgeries, doctors usually look at a magnetic resonance image (MRI) or a computed tomography (CT) scan to visualize the liver and plan the operation.

A new, anatomically accurate replica of a liver could make surgeries safer.

But these 2D images don't provide true visual guidance during surgery. There are three main veins in the liver, and doctors often go into surgery unsure exactly where these blood vessels are located. Inadvertently cutting them can lead to "a disaster outcome," Zein told Live Science.

To create the artificial livers, the researchers combine the MRI and CT scans that patients have already undergone, and then recreate the 3D shape of the organ. A study published last month in the journal Liver Transplantation confirmed that the models are anatomically accurate in terms of volume and location of vessels in the liver.

Using these models, the team creates the 3D-printed organs using a transparent polymer, then dyes the main blood vessels and the bile ducts.

Complications avoided

So far, the team has used such livers in about 30 cases. In a few operations so far, surgeons changed their plan for the surgery based on the simulated organs, for instance, after realizing that cancerous liver tumors were too close to certain veins to completely cut the growths out.

"We believe we actually avoided some complications this way," Zein said.

The researchers are now developing similar methods to guide complicated surgeries, such as hand and face transplants, and pancreatic tumor removals, Zein said.

They are also investigating a way to integrate organ models into the global positioning systems (GPS) that currently guide surgeries. These GPS tools determine the exact location to cut and the safe margins for a surgery. By improving the models of the organs that these systems use, the hope is that the GPS will become even more accurate, Zein said.

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Low-calorie diet before liver surgery may reduce blood loss

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Low-calorie diet before liver surgery may reduce blood loss

Last Updated: 2013-07-12 18:37:23 -0400 (Reuters Health)

By Gabriel Miller

NEW YORK (Reuters Health) - Restricting patients to a low-calorie diet for the week before hepatic resection reduces the amount of fat in the liver and blood loss during the procedure, a retrospective study suggests.

Researchers looked for signs of steatosis and steatohepatitis in tissue taken from patients' livers, both of which have been associated with worse outcomes and death following surgery. It included 111 patients, more than 90% of whom were having surgery for cancer.

The study, published June 27 in Surgery, wasn't rigorously designed: the first 60 patients were not given any preoperative dietary restrictions, while the final 51 were given dietary instructions comprised of meal options providing 900 kcal/day, primarily fats and carbohydrates. When asked on the day of surgery, all of the patients in the restricted diet group said they adhered to the instructions.

The groups were generally well-balanced, although the control group had a significantly higher rate of diabetes and the diet-restricted group had a higher rate of preoperative chemotherapy treatment. Mean body mass was 27.2, and was similar in the two groups; 32% overall had a body mass index of 30 or more.

A gastrointestinal pathologist blinded to the origin of the samples found that compared to patients who ate normally before their operations, those who followed the diet had significantly less steatosis (15.7% vs 25.5% of hepatocytes containing fat, p=0.05) and less steatohepatitis (15% vs 27%, p=0.02).

Patients who dieted also had a lower mean intraoperative blood loss (600 vs 906 mL, p=.002).

The study was done by surgeons at Dartmouth-Hitchcock Medical Center, who took the diet from the bariatric surgery group at their institution. All patients undergoing laparoscopic gastric bypass at that hospital submit to a two-week pre-operative diet.

Two major limitations of the study were that it was non-randomized and that compliance with the diet in the experimental arm was self-reported by patients. But the investigators, led by Dr. Richard Barth, think it's unlikely that factors other than diet affected the results because univariate and multivariate analyses each showed that diet and BMI were associated with lower rates of steatosis, and BMI was similar in both groups.

"This intervention is easily instituted, so it is clinically feasible," the authors said, adding that "many studies" by other groups have shown that patients with less steatosis have fewer perioperative complications and fewer infections complications after liver resection.

The authors did not respond to a request for comment.

SOURCE: http://bit.ly/18epdxD

Surgery 2013.

Blood tests predict mortality following liver resection

Simple blood tests predict mortality following liver resection

Last Updated: 2010-11-23 13:35:26 -0400 (Reuters Health)

By Gabriel Miller

NEW YORK (Reuters Health) - A set of three simple preoperative tests may predict in-hospital death following hepatectomy, according to a study published in the November issue of Archives of Surgery.

Many previous studies have identified factors postoperatively that contribute to death after liver resection, the investigators say. However, their study has identified a set of tests done before surgery that predict mortality and can be used to decide who should -- and should not -- have the operation immediately.

"Our experience showed that preoperative liver function tests and coagulation as well as evaluation of liver capacity predict the mortality rate in patients requiring right-sided major or an extended major liver resection with extra-hepatic bile duct resection," lead author Dr. Elie Housseau-Oussoultzoglou at Hautepierre University Hospital in Strasburg, France told Reuters Health in an email. "All these biological parameters are easily available and measurable preoperatively in a simple blood sample."

Though the study found several pre-operative measures that were predictive of mortality, hepatic resections are extremely complicated procedures in a widely varying patient population. Considering the high mortality rate already established with these operations, it 's not surprising that a retrospective review would uncover a few significant measures, said Dr. William Jarnagin, chief of the Hepatopancreatobiliary Service at Memorial Sloan-Kettering Cancer Center in New York City.

"These are big operations and they're performed on patients with advanced cancers so there is a lot of morbidity," said Dr. Jarnagin, who was not involved in the study. "It's complicated to analyze (and) there are a lot of factors, so to pick one or two things, even though they might be significant, is not a simple thing at all."

Dr. Jarnagin added that several of the pre-operative tests the authors suggest are already done on a routine basis by many clinicians.

The study retrospectively reviewed the preoperative evaluation of 67 patients without cirrhosis undergoing liver resection of at least four contiguous liver segments.

More than half of the patients (n=35) had co-morbidities prior to their operation, most commonly hypertension and cardiovascular disease.

The main outcome measure was postoperative mortality, which included intraoperative death, death within 90 days after surgery and in-hospital death.

In the series, all of the postoperative deaths (7%) were related to liver failure, which was mainly associated with the extent of liver resection and the inability of the liver to regenerate, the investigators report`.

On univariate analysis, five factors were associated with higher postoperative mortality: serum alanine aminotransferase (ALT) level > 40 U/L, preoperative prothrombin (PT) ratio less than 70%, a preoperative indocyanine green retention rate at 15 minutes (ICGR-15) greater than 15%, preoperative biliary drainage, and extrahepatic bile duct resection.

Based on the results of their multivariate analysis, the authors propose that patients who have two or more risk factors based on ICGR-15, PT ratio, and ALT level should not have surgery. Surgery can proceed in patients with one risk factor, they suggest, although mortality rates will be higher than 5%.

"In patients with altered preoperative liver tests and function, the initially planned surgery should be postponed, until full recovery of the biological parameters," Dr. Elie Housseau-Oussoultzoglou said. "During this interval a palliative anti-tumoral therapy is administered to avoid disease progression.

"Considering the high expected risk of lethal liver failure it would be preferable to survive few months with a chronic disease instead (of dying) within a thirty-day hospital stay," Dr. Housseau-Oussoultzoglou added.

SOURCE: http://link.reuters.com/tab86q

Arch Surg 2010;145:1075-1081

More fat around internal organs may mean more complications after liver surgery

More fat around internal organs may mean more complications after liver surgery

The amount of intra-abdominal fat appears to be associated with the risk of complications following major liver surgery, according to a report in the November issue of Archives of Surgery, one of the JAMA/Archives journals. However, appearing overweight or having a high body mass index (BMI) were not associated with increased post-surgical risks.

About 65 percent of the U.S. population is currently overweight, with half of those qualifying as obese, according to background information in the article. The increased incidence of obesity "requires surgeons to examine more critically the effect of overweight and obesity on their patients," the authors write. "The literature currently presents mixed findings on the effect of overweight and obesity on various surgical populations, with different measures of obesity being used in these studies."

Katherine Morris, M.D., and colleagues at Memorial Sloan-Kettering Cancer Center, New York, studied 349 patients undergoing surgical removal of part of the liver between June 1996 and November 2001. Computed tomographic (CT) scans taken before surgery were used to assess the amount of perinephric fat, a measure of fat around the kidneys, which was used as a surrogate for intra-abdominal fat. In addition, the patients' BMI was calculated using height and weight data. The authors also used CT scans to measure outer abdominal fat. Complications were tracked through the cancer center's database.

Following the major liver operations, 230 patients (65.9 percent) had complications and nine patients (2.6 percent) died. The average length of hospital stay was 10.8 days.

As assessed by the amount of fat surrounding the kidney, patients with more intra-abdominal fat were more likely to have complications, including severe complications, had longer lengths of hospital stay and were more likely to die within 30 days than patients with less fat. Patients with a higher body mass index (BMI) had procedures that took longer; however, BMI and measures of outer abdominal fat were not associated with the rate of complications, occurrence of severe complications, length of stay or risk of death within 30 days.

BMI seems be a poor measure of the type of obesity that places abdominal surgery patients at risk, the authors note. "As defined by a simple, single surrogate measurement of perinephric fat, intra-abdominal fat was able to be used to risk stratify the patients for mortality, complication rate, severity of complications and increasing length of stay," they write.

"This should help surgeons be better able to identify high-risk patients and, conversely, not refuse an operation based on the presumed high risk of someone with external obesity. Now that most of our patients being considered for a major upper abdominal resection will have a preoperative computed tomography scan, the information provided by looking at levels of perinephric fat is easily determined and should not be ignored."


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(Arch Surg. 2010;145[11]:1069-1073. Available pre-embargo to the media at www.jamamedia.org .)

Editor's Note: This study was supported in part by a grant from the Flight Attendant Medical Research Institute. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

For more information, contact JAMA/Archives Media Relations at 312/464-JAMA (5262) or e-mail mediarelations@jama-archives.org .