Patients consciousness during surgery

 According to the NewScientists, anaesthesia wears off in about 0.02% of surgeries worldwide. In 2008, a study conducted by Washington University School of Medicine in St. Louis found that around 30,000 Americans a year awaken during surgical procedures, more often in children, sometimes experiencing intense pain and terror.

Researchers at the Massachusetts Institute of Technology (MIT) led by Emery Brown used an EEG cap with 64 electrodes to keep track of patients' brain activity across multiple brain regions as unconsciousness was induced using general anaesthetic. The team identified patterns related to consciousness and unconsciousness, and were thereby able to determine when a patient was waking up.

In the UK, about 2 % of hospitals do EEG monitoring during surgery, but only 3 or 4 electrodes are used. It only monitors one region of the brain, but the MIT team’s 64-electrode cap could bring new insight into patients’ levels of awareness during surgery, although it requires patients to shave their heads and EEG measurements are very sensitive to mechanical and electrical interference. The technique is not yet available in clinical settings.
Source: Consciousness signature warns of awareness during surgery. New Scientists, March 2013  　
Fewer patients awake during surgery

A new report published by the Royal College of Anaesthetists found that 153 cases of accidental awareness reported in 2011 across the UK, about 1 in every 15,000 general anaesthetics, a lot less than had been thought. Previous study found that about 1 in 500 patients were aware or awake under general anaesthetics. However, the leader of the new report, Professor Jaideep Pandit, says that under-reporting is possible partly because anaesthetists do not routinely see patients after an operation, so may not be aware of the awareness report. Sometimes patients do not report the incident.
Pandit says brain monitoring systems are available in about two-thirds of UK hospitals, but most anesthesiologists do not use them and there is a debate over how useful the monitors are. He is planning more research to focus on patient experience.

Source: Pandit JJ, Cook TM, Jonker WR, et al. A national survey of anaesthetists (NAP5 Baseline) to estimate an annual incidence of accidental awareness during general anaesthesia in the UK. British Journal of Anaesthesia. Published online March 13 2013

Risk of blood clots after surgery is higher and lasts longer than thought

Studies have shown that the risk of developing blood clot after major surgery is high but a new study pubished in BMJ Online First on 4 December found that this risk is higher and continues for up to 3 months after surgery.

The research was a large prospective study that tracked 947,454 women, average age 56, who were diagnosed with venous thromboembolism through the NHS breast screening programme between 1996 and 2001. The reserachers checked hospital admission and death records, followed for an average of 6.2 years and compared the risk of blood clots for those who did not have surgery with those who did have surgery.

The researchers found that within 6 weeks post operation, women who had day case surgery were 10 times more likely to have blood clots than those who had no surgery. The risk for those who had surgery in the hospital were nearly 70 times higher. At 7 to 12 weeks after surgery, the risk of blood clots was 6 times higher for the day case surgery group than the no surgery group and 20 times higher for the inpatient surgery group.

They also calculated different risks for different surgery and found that the incidence of blood clots in the 12 weeks after surgey :

• 1 in 45 had developed blood clots after hip or knee replacement;
• 1 in 85 after cancer surgery;
• 1 in 815 after day surgery;
• 1 in 6,200 women who did not have surgery

The researchers warn that the risk of developing blood clot after surgery is higher and lasts for longer than previously thought and suggest that doctors should extend the time that preventive measures such as blood thinning drugs or wearing stockings are used.

Critics say that despite the lack of data on how many of the participants were taking preventive measures, this study is important because it broadens our understanding to current evidence of the risk of potential fatal blood clot after surgery and the findings may have implications for prolonged prophylaxis after surgery.

Source:
Editorial : Cohen TA. Prevention of postoperative venous thromboembolism. BMJ 2009; 339: b4477 (f/t via Athens)
Sweetland S, Green J, Liu B. et al. Duration and magnitude of the postoperative risk of venous thromboembolism in middle aged women: prospective cohort study. BMJ 2009; 339: b4583 ( f/t via Athens)

Beta blockers cost more lives than they saved

For many years, beta blockers have been given routinely to patients undergoing surgery to reduce the risk of heart attcks after operations, but a new study, published in The Lancet, of more than 8000 patients in 23 countries who had surgery has found that those given the drugs double their risk of stroke and a third more likely to die within a month of surgery, the BBC reported.

The lead researcher said although beta blockers had benefits in lowering heart attacks, they were outweighed bythe increase of stroke and death. The study claimed that about 800,000 would have died as a result of doctors giving out the drugs without considering the side effects.

Source: "POISE Study Group. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomized controlled trial". Lancet 2008. DOI: 10.1016/S0140-6736(08) 60601-7. Ahead of print.