June Anesthesiology Studies Show Promise for Alpha-2 Agonists to Reduce Opioid Use, Challenge Effectiveness of Simulator Manikins for Airway Training
(May 23, 2012)
A study from researchers at Geneva University Hospital, Geneva, Switzerland, provides evidence that use of alpha-2 agonists alongside opioids in surgical patients decreased opioid use by 25-30 percent. Even though opioid use was less, these patients reported slightly less pain after surgery.
Alpha-2 agonists are drugs that stimulate alpha-2 receptors in the brain and spinal cord, helping to reduce sensitivity to pain. Anesthesiologists have long sought drug regimens that reduce the need for opioids such as morphine.
“Combinations of strong opioids with non-opioid analgesics have become popular in anesthesia,” said lead study author Dr. Grégoire Blaudszun. “These multi-drug regimens aim to decrease postoperative pain, and also intra- and postoperative opioid requirements, and, subsequently, opioid-related adverse effects, such as increased sensitivity to pain and postoperative nausea.”
Dr. Blaudszun and his research group gathered data from 30 previous studies, which included a total of 1,792 patients, 933 of whom received the alpha-2 agonists clonidine or dexmedetomidine. At 24 hours after surgery, patients receiving clonidine consumed 25 percent less morphine, while those receiving dexmedetomidine consumed 30 percent less morphine. Both alpha-2 agonists lost their pain-relieving effects after 48 hours.
The study could not confirm the effect of alpha-2 agonists on chronic, as opposed to short-term, postsurgical pain.
Dr. Blaudszun said that further research on alpha-2 agonists is needed before they can be recommended for regular use by anesthesiologists and others:
“We have shown in our study that alpha-2 agonists decrease postoperative consumption of drugs related to morphine and that postoperative pain scores were lower when alpha-2-agonists were prescribed. We have also shown that the incidence of postoperative nausea, a typical opioid-related adverse effect, was decreased. However, because they can also affect blood pressure and heart rate, the systematic use of alpha-2 agonists cannot yet be recommended.”
How Real Are Airway-Training Manikins?
In the second study, a first-of-its-kind trial demonstrates that none of the widely used patient simulator manikins accurately reflect the anatomy of the human airway, casting doubt on the validity of prior studies on simulators that are used to teach airway management skills to physicians.
Lead study author Karl Schebesta, M.D., from the Medical University of Vienna, Austria, said that very little is known about how objectively “real” airway-training manikins are.
“This is the first trial that attempts to objectify the realism of airway training manikins and human patients simulators,” said Dr. Schebesta. “We clearly demonstrated that even the high-fidelity human patient simulators, which are thought to be very realistic, do not reflect the anatomy of the human upper airway.”
Airway management during anesthesia or for mechanical ventilation is a critical skill for anesthesiologists, as failure to keep the airway open can lead to devastating consequences. Human simulator manikins have been developed to allow those in training to practice certain airway skills repetitively without harming patients.
According to Dr. Schebesta, some in the field are calling for more clinical-based research with actual patients rather than simulator-based research, as it remains unclear whether research data collected on manikins can be successfully translated into clinical practice.
By using CT scans on 20 adult patients without injuries and comparing them to scans made of four patient simulators and two airway training devices, Dr. Schebesta and his research team found that, in particular, measurements of the pharyngeal airspace differed significantly between actual patients and all the simulators.
Differences were also found when comparing the size of the oral airspace, the horizontal diameter of the tongue and the distance from the epiglottis to the back of the pharyngeal wall.
“With the results of this trial, we show that none of the investigated manikins reflects the anatomic details of humans adequately,” said Dr. Schebesta. “Therefore, the conclusions drawn by others, who used these manikins as replacements for real patients, have to be questioned. In order to allow better airway training and research, the manikins should urgently be improved.”
For more information, visit the Anesthesiology website at www.anesthesiology.org.
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