Anaesthesia




Concern raised over how few anaesthesiologists monitor cardiac output during high-risk surgery

 

In a European and US study, that will be of interest to anaesthesiologists in the Middle East, it was found that only 35% of anaesthesiologists are carrying out a simple procedure during high-risk surgery that can make a significant impact on how well patients recover from their operations. Middle East Health reports.

Research presented to the European Anaesthesiology Congress in Amsterdam last year showed via a survey of 463 randomly selected European and US anaesthesiologists that although more than 95% of them knew that it was of major importance that enough oxygen reached all parts of the body during an operation and that this was determined by how well the heart was pumping blood around the body, 65% of them were failing to monitor the amount of blood the heart was pumping – a procedure known as cardiac output monitoring.

As a result of their findings, the authors of the study, led by Dr Maxime Cannesson, an Associate Professor of Anaesthesiology at the University of California, Irvine (USA), are calling for action at national and international level to ensure that cardiac output monitoring is carried out for all high-risk surgical operations.

The numbers of operations affected are significant. High-risk surgery represents about 10-14% of all the 240 million surgeries performed each year worldwide, meaning that about 30 million patients in the world are undergoing high-risk surgery every year. Examples of high-risk surgery include operations on the liver, pancreas, aorta, most cancer surgery, and orthopaedic surgery, for instance on the spine or for hip fractures.

Dr Cannesson said: “Several studies have shown that when anaesthesiologists measure and then set goals for cardiac output during high-risk surgery, their patients will have fewer postoperative complications, a shorter stay in the hospital after the surgery, and fewer of them will die in the postoperative period. The idea is very simple: since oxygen is of major importance to the body when it is experiencing stress, as in the case of highrisk surgery, it seems logical that setting goals for maximising the delivery of oxygen to the tissues would improve patients’ care. Oxygen is used by the cells in order to produce energy and to fight the stress. If the cells and tissues do not receive oxygen during the surgery, they are going to produce toxins, which will eventually worsen the situation and increase postoperative complications such as infection, kidney failure, pneumonia, and so forth. It’s like running a marathon at high altitudes where there is very little oxygen: you get short of breath very quickly and soon you’ll develop chest pain and expose your body to high risk if you do not stop running.”

There are three main parameters that anaesthesiologists measure to check on oxygen delivery: levels of haemoglobin (the iron-containing, oxygen-carrying protein in red blood cells), oxygen saturation (how much oxygen the blood is carrying), and the cardiac output. Haemoglobin levels are usually checked regularly during high-risk surgery; continuous measuring of oxygen saturation is compulsory during anaesthesia in all European countries; but, as this study shows, cardiac output monitoring does not happen on a regular basis. “Yet, if cardiac output is not measured there is no way to know whether oxygen is delivered appropriately to the tissues or not,” said Dr Cannesson.

“Our study shows that there is a need for action by national and international professional societies to ensure that cardiac output monitoring is used in clinical practice for these patients. There should be a European and US task force that comes up with recommendations regarding all haemodynamic monitoring [monitoring of blood flow] during surgery in order to improve the care of patients,” he said.

The main reasons given for not monitoring cardiac output were: the cardiac output monitors were too invasive; anaesthesiologists were using a surrogate for cardiac output monitoring such as checking variations in pulse pressure; and 30% of respondents believed that cardiac monitoring did not provide important information.

Dr Cannesson said: “The last reason is interesting given that nearly all of them say that they know that oxygen delivery is of major importance and that cardiac output is involved in oxygen delivery.”

He said that current cardiac output monitoring was no longer as invasive as it used to be when it involved a catheter inserted into the pulmonary artery. Nowadays, there were several, minimally invasive ways of doing it. Furthermore, using surrogates such as pulse pressure variations, could not substitute for cardiac output measurements. “They have not been shown to improve patients’ outcome and can only be used in 40% of patients under anaesthesia. They are excellent adjuncts to cardiac output monitoring, and should be included in the clinical management wherever possible, but they should not replace it,” he said.

Now Dr Cannesson and colleagues are running a multi-centre study in California focusing on the impact on patient care and postoperative outcome of the implementation of guidelines and checklists for monitoring blood flow during high-risk surgery. “Medical researchers are very good at finding the mechanisms underlying various conditions and developing research programmes aimed at developing better treatments. But our research shows that a crucial aspect of this is lacking: the delivery to the patient. Researchers and international professional societies should also be focusing on ensuring that when a treatment is appropriate for a condition or a situation, that this treatment is actually applied to the patient.”
 

Awake

Out of every 1000 patients, two at most wake up during their operation. Unintended awareness in the patient is thus classified as an occasional complication of anesthesia – but being aware of things happening during the operation, and being able to recall them later, can leave a patient with long-term psychological trauma. How to avoid such awareness events, and what treatment is available for a patient who does experience awareness, is the subject of a report by Petra Bischoff of the Ruhr University in Bochum and Ingrid Rundshagen of the Charité Berlin published in Deutsches Ärzteblatt International (Dtsch Arztebl Int 2011; 108(1-2): 1-7).

The usual culprit in cases of unintended awareness during an operation is an inadequate depth of anesthesia. In addition, several risk factors exist that promote awareness events. For example, children have eight to ten times the risk of being aware under anesthesia. Longterm use of painkillers or misuse of medication can also make patients more liable to this kind of experience. The nature of the operation and the surrounding circumstances can also play a part: cesarean sections and emergency operations carry a higher risk of awareness than other kinds of surgery, and operations at night a higher risk than those carried out during the day.

For prevention of awareness during anesthesia, the authors recommend taking into account the risk factors that have been mentioned and raising the level of vigilance among medical personnel for awareness phenomena by regular training sessions. Premedication with benzodiazepines and not using muscle relaxants are also worthwhile measures. Additionally, it is important to measure the anesthetic gas concentrations regularly and monitor brain electrical activity by EEG. If possible, the patient should be given hearing protection. If a post-traumatic stress disorder does occur, the prognosis is good if professional treatment is started without delay.

Awareness under anesthesia http://tinyurl.com/8ywyyvz
 


 

Is anaesthesia dangerous?

In pure numerical terms, anaesthesiaassociated mortality has risen again. The reasons for this are the disproportionate increase in the numbers of older and multimorbid patients and surgical procedures that would have been unthinkable in the past. This is the result of a selective literature review of André Gottschalk’s working group at the Bochum University Hospital published in Deutsches Ärzteblatt International (Dtsch Arztebl Int 2011; 108[27]: 469-74).

In the 1940s, anaesthesia-related mortality was 6.4/10,000. By introducing safety standards such as pulse oximetry and capnometry, the rate was reduced to 0.4/100,000 by the late 1980s. This value still applies for patients without relevant systemic disease. However, mortality has risen in patients with relevant comorbidities (0.69/100,000). Such comorbidities include heart failure, angina pectoris, chronic renal failure, or severe malignant hypertension. Because of improved safety standards such patients can have surgery nowadays – something that would have been unthinkable in the past owing to their multimorbidity. Another factor explaining anaesthesia-related mortality is the fact that the proportion of patients who are older than 65 rose in Germany from 28.8% in 2005 to 40.9% in 2009.

Is anesthesia dangerous? http://tinyurl.com/7o35c54
 


 

Researchers show benefits of local anaesthesia after knee replacement surgery

Researchers at the Rothman Institute at Jefferson University in the United States have shown that local anaesthesia delivered through a catheter in the joint, intraarticularly, may be more beneficial than traditional opioids such as morphine and Oxycontin for pain management following total knee replacement surgery.

Their research was recognized with the Knee Society Award for the best work on a surgical technique at the American Academy of Orthopedic Surgeons annual meeting, in February in San Francisco.

The randomized, double-blind trial administered either bupivacaine, a common analgesic, or normal saline intraoperatively through a catheter in the joint to 150 primary, unilateral knee replacement patients.

The catheters released fluid continually over two postoperative days. Patients were asked to complete questionnaires at 5pm on the day of surgery and 8am and 5pm each day until discharge, as well as at a four-week follow-up visit.

Patients who received bupivacaine reported receiving the least pain and the lowest narcotic consumption. There was also no significant different in postoperative complications.

The study concludes that knee replacement patients may positively benefit from intraarticular delivery of a local analgesic to decrease overall pain levels and reduce the need for opioids following surgery. With no noted increase in infection risk, intraarticular delivery may also provide an effective alternative for pain relief in the immediate postoperative time period without the disadvantages encountered with epidural anaesthesia, regional nerve blockade and patient controlled analgesia pumps.

“This study opens up a potential new option for better pain management postsurgery for our knee replacement patients. Though further study is needed, these initial results are promising,” says Nitin Goyal, MD, of the Rothman Institute at Jefferson, an author on the study.
 


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ate of upload: 24th Mar 2012

 

                                  
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