UF Scientists discover new explanation for controversial
old patient-care technique
|GAINESVILLE, Fla. - You might not know what it's called, but if you've had general anesthesia before surgery, especially after an accident, it is likely you have received Sellick's maneuver. That's when fingers are pressed against a patient's throat to prevent regurgitation and spilling of stomach contents into the airway and lungs while anesthesia is being administered.
Such regurgitation could result in serious lung damage and even death.
The maneuver is a longstanding practice, first described in 1961 by British physician Brian Sellick. Performed dozens of times a day in hospitals, the procedure is accepted as "standard of care" and is a basic skill taught in all anesthesiology training programs. Anesthesiologists estimate conservatively that more than 100,000 people a year undergo the procedure.
But recently some physicians have begun to question the technique in the wake of a study challenging its effectiveness and ease of execution. And some have stopped using it altogether.
Now, researchers from University of Florida College of Medicine have used magnetic resonance imaging of the neck region to show that the maneuver works and that doubts about its effectiveness are based on a misunderstanding of what physical changes happen in the neck during the procedure.
"Sellick was right that the maneuver works - but he was a bit off on the anatomy," said UF anesthesiologist Mark J. Rice, M.D., who led the study now online and to be featured on the cover of the November edition of the journal Anesthesia & Analgesia. The journal will also include two editorials on the controversial topic side by side with the UF paper, which has been selected by the editorial board as this month's graduate medical education article for November.
Also called cricoid pressure, the eponymous maneuver has for decades been described as the pinching of the esophagus between the cricoid - a ring of cartilage that surrounds the trachea - and the neck vertebrae.
It is most often used in accident victims whose stomachs might not be empty before surgery, or in patients who have bowel obstructions or slowed emptying of the stomach because of certain drugs or medical conditions.
Some doctors say that the procedure is hard to get right, and that not applying enough pressure and at a proper angle would cancel out any benefit.
A 2003 paper further cast strong doubt on the procedure's effectiveness with a finding that in 90 percent of cases, the esophagus moves to the side during the procedure. It is generally thought that the procedure is effective only if done at the midline of the neck. So researchers concluded that such movement of the esophagus means the maneuver can't effectively prevent regurgitation.
The UF researchers used open MRI imaging of the neck while the procedure was administered to volunteers. That allowed the person performing the technique to do so unimpeded, and increased the chance of reproducing how the procedure is carried out in a clinical setting.
It turns out, the imaging studies show, that the esophagus does not exist at that point in the neck where the procedure is done. Instead, it is a structure called the hypopharynx - above the esophagus - that gets pinched between the cricoid and the bones of the neck. The esophagus exists only lower down, near the shoulders. So movement of the esophagus doesn't affect the procedure since it is not involved, Rice and co-authors Lori Deitte, M.D., Anthony Mancuso, M.D., Nikolaus Gravenstein, M.D., Charles Gibbs, M.D., and Timothy Morey, M.D. found.
"This is a major error that's been in the literature for 50 years," said Rice, who is chief of liver transplantation in UF's department of anesthesiology.
As for the sideways movement, the study showed that the hypopharynx and cricoid structures move together, so effective compression is achieved even if it is pushed to the side in the process.
"It turns out it doesn't matter," Rice said.
The new findings serve to reassure doctors that the procedure works, and that they don't have to do it "perfectly" for it to be effective.
"Astonishingly enough, our previous assumptions are totally wrong," said professor Scott Springman, M.D., director of ambulatory anesthesia at the University of Wisconsin-Madison. "Now I can explain to my residents more accurately why we're doing it. I will use it in more situations than I would if I still had grave doubts about its efficacy."
Although the study doesn't prove directly that Sellick's maneuver prevents regurgitation, that is reasonably inferred from the images.
"Because of Dr. Rice's study, Sellick's maneuver has again been shown to have anatomic efficacy, despite it occurring in a way that is different from the classic description," Springman said. "It also shows us that previous assumptions are not always correct, and that new technology can help us refine our hypotheses."
UF Researchers find triggers in cells' transition from colitis to cancer
GAINESVILLE, Fla. -- University of Florida researchers have grown tumors in mice using cells from inflamed but noncancerous colon tissue taken from human patients, a finding that sheds new light on colon cancer and how it might be prevented.
Scientists observed that cancer stem cells taken from the gastrointestinal system in patients with a chronic digestive disease called ulcerative colitis will transform into cancerous tumors in mice.
The finding, now online and to be featured on the cover of the Thursday (Oct. 15) issue of Cancer Research, may help explain why patients with colitis have up to a 30-fold risk of developing colon cancer compared with people without the disease.
New understanding of the link between colitis and cancer could lead to diagnostic tests that would evaluate tissue taken from patients with colitis for signs of cancer stem cell development, thereby identifying patients who may be at greater risk for cancer.
"Ultimately it would be great if we could prevent colitis or treat colitis so it never gets to the cancerous stage," said UF colorectal surgeon Emina Huang, M.D., who is a member of the Program in Stem Cell Biology and Regenerative Medicine at UF's McKnight Brain Institute and the UF College of Medicine.
Although colonoscopy is very effective in screening and preventing colon cancer for most people, for patients with colitis no diagnostic tests work well because the inflamed tissue makes identification of precancerous changes difficult.
According to the Crohn's and Colitis Foundation of America, approximately 700,000 people have colitis in the United States. The National Cancer Institute estimates that cancer of the colon and rectum will claim the lives of about 50,000 people this year.
UF scientists gathered colitic tissue from humans and chemically screened it for colon cancer stem cells, also called tumor initiating cells. These cells were then isolated and monitored in mice to see if tumors would grow.
Huang said these findings shed light on that fact that it may not be just the cancer "seed" cell, but the "soil" - in this case inflamed colon tissue - that plays a role in the development of cancer.
"Is it the seed, is it the soil or is it their interaction?" she said. "We think probably both, but now we have a new way to look at it and a new method of attack."
B. Mark Evers, M.D., a professor and vice chair of surgery at the University of Kentucky College of Medicine, said the study emphasizes the emerging role of the surrounding inflammatory tumor microenvironment on tumor growth and subsequent metastasis.
"Dr. Huang and her group have identified a potentially important mechanism to explain why long-standing inflammation of the colon predisposes patients to the development of cancer," said Evers, who is director of the Lucille P. Markey Cancer Center in Lexington, Ky.
To further understand the role of the "seed" and "soil" interaction, UF researchers paired colon cancer stem cells with normal, colitic and cancerous human cells taken from the scaffolding layer of the large intestine. The cells were implanted into mice to analyze growth rates. The combination of tumor cells and normal scaffolding tissue cells grew at the slowest rate. Tumor cells paired with cancerous tissue grew at an intermediate rate, and tumor cells paired with the colitic tissue grew at the fastest rate.
Huang said they found heightened levels of two immune system hormones called interleukin-6 and interleukin-8 in the cells from the colitic and cancerous tissues, which had the faster growth rates.
When UF researchers decreased the expression of these hormones within the cells, the tumor growth drastically decreased. When the hormones returned, the tumors began to grow again.
"We don't understand the transition at the molecular level so we are trying to figure out what we can target to interfere, intervene or inhibit that transformation of the benign colitic cells," she said. "The thought is if we can create a therapy to decrease function of these hormones, we may be able to prevent or inhibit cancer growth."
Clinical trials looking at the role of one of these hormones in humans are under way in England, Huang said.