[ad_1]
SYDNEY (BLOOMBERG) – Under green surgical drapes and a tangle of tubes, a healthy young sheep undergoes a heart-lung bypbad procedure to help answer one of many urgent questions relating to a pillar of the modern medicine: anesthesia.
Nearly two centuries after anesthesia has revolutionized surgery, more and more research is pointing to worrying side effects, ranging from delirium to immune suppression that leads to cancer.
Researchers knocked out a sheep last month at the University of Melbourne to try to understand why open-heart procedures result in acute kidney damage in nearly one-third of patients – as part of the study. a broader effort to study the impact of anesthesia on the immune system, brain and other major organs.
The results are already undermining decades of soothing messages about the safety of being put into a state of sleep.
"Anesthesiologists are now trying to say that it's not so safe," said Dr. Andrew Davidson, head of anesthesia research at the Murdoch Children's Research Institute in Melbourne. "You do not die on the table, but many of you do not come home."
Of the 200 million adults in the world who undergo noncardiac surgery each year, more than one million will die within 30 days. This risk increases to one in 20 for patients 70 years of age and older.
Within 1 mile of the Dr. Davidson Center of the Royal Children's Hospital & Melbourne, separate groups from the Florey Institute of Neuroscience and Mental Health and the Peter MacCallum Cancer Center Strive to understand if inhaled volatile gases such as isoflurane and sevoflurane are used by anesthetists. unconscious about 80% of patients – may be more harmful than intravenous agents, such as propofol and fentanyl.
With 313 million operations performed each year, the findings could have significant global economic and social implications and could herald a paradigm shift in surgical care, researchers say.
Science is contradictory and incomplete. A study by Dr. Davidson and colleagues, published Thursday, Feb. 14 in the Lancet medical journal, revealed that an hour of general anesthesia during early childhood had no lasting impact on the development of the human brain.
However, some operations may take longer and physicians at Mayo Clinic have discovered an badociation between anesthesia and attention deficit hyperactivity disorder in children.
The link with ADHD is "scientifically plausible, but the evidence is not strong," according to Dr. Davidson.
Sheep probe
On the fourth floor of a laboratory at the University of Melbourne, scientists at the Florey Institute use fiber optic probes to measure blood flow and oxygen levels in different regions of the merino sheep kidney two years of age undergoing open heart surgery.
The research, conducted by a team of clinicians and scientists in human surgical conditions, aims to track renal changes before, during and after the procedure, to identify the risks attributable to two types of anesthetic agents and to find ways to protect the blood. filtering organ.
According to Dr. Yugeesh Lankadeva, a researcher who studies the interaction, up to 30% of open-heart operated patients develop acute kidney injury that increases their risk of chronic kidney disease and death.
Dr. Lankadeva and his colleagues showed in an article published last month that volatile gas anesthesia was badociated with higher activity in a key nerve, which corresponded to a potentially damaging reduction in blood flow to the kidneys sheep during abdominal surgery. Intravenous anesthesia had less impact.
Dr. Lankadeva's current study aims to understand the mechanism in the context of heart-lung bypbad procedures – commonly used for heart transplants and valve replacements – when the kidney is likely to sustain further injury due to An influx of blood after normal resumption of circulation.
It is possible that nerve activation badociated with anesthesia, particularly the inhaled gaseous form, also alters the immune system, according to Dr. Clive May, head of the Florey's Preclinical Critical Care Unit. Institute, which has developed the renal probe technique.
"There is a well-known link between the nervous system and the immune system, and the activation of the nervous system can inhibit the immune system," said Dr. May.
This link is being explored across the street at the Peter MacCallum Cancer Center. This year, researchers from across the country will conduct an international clinical trial of 5,700 patients randomized to receive one or the other type of anesthesia for lung cancer or colorectal cancer surgery, followed for one year. five years to compare cancer recurrence and survival.
Information Directives
Laboratory research and clinical observations indicate that volatile gases can be harmful, said Dr. Bernhard Riedel, who is leading the study.
"But we really need a large randomized prospective study to examine the whole body of evidence on which we can change the guidelines."
Previous research suggests that inhaled anesthetics have a pro-inflammatory effect that can paralyze the immune system for about a week or so at the time of surgery, Dr. Riedel said. This could give opportunity to all the remaining cancer cells in the body to gain a foothold at the same time as gas anesthesia inadvertently encourages the growth of blood vessels to support emerging tumors.
Propofol, on the other hand, may have an anti-inflammatory effect, causing less immune disruption, he said.
With regard to the effects of anesthetic on the brain, both types of anesthesia appear to be involved in neuronal damage, basic work units of the organ, similar to those in the brain. 39, a concussion or a minor acute brain injury, according to Dr. Lis Evered, University. researcher in Melbourne.
Dr. Evered, a neuroscientist at St. Vincent Hospital in the city, and his colleagues have shown an increase in two biomarkers of neurological damage – neurofilament light and tau – in patients 60 years of age and older anesthesia on which blood samples were taken sequentially up to 48 hours after surgery.
Cognitive compromise
Studies in elderly patients also badociated a long duration of anesthesia with an increased risk of postoperative delirium – a transient complication badociated with poorer long-term neurocognitive function.
These raise questions about the benefit / risk ratio of certain operations in the elderly, said Dr. Evered.
"For 140 years, we were only concerned about security," she said. "Over the past 30 years, we have become a little more concerned about other types of impacts because people are living longer – we now want people to survive the procedure and have good quality. of life for the next 10 to 20 years. "
The findings of neurotoxicity also challenge conventional wisdom that general anesthesia "simply extinguishes the brain" for a period after which it will regain its pre-anesthesia state, said Dr. Davidson at the Institute. Murdoch Children's Research Center.
"Anesthesia is a very abnormal condition for the brain," he said. "So it makes sense that your brain circuits are no longer the same after anesthesia."
This is probably not important for young adult patients, he said.
"But if you're old or very young, then maybe that's starting to count."
[ad_2]
Source link
