Delirium – an under-recognised risk factor

The medical condition and age of the patient as well as the type of surgery undergone are contributing factors. Patients affected by delirium are at increased risk of being left with longer-term cognitive impairment. Delirium is a particularly common co-morbidity in the context of hospital treatment. The causes of delirium are manifold and many patients recover only slowly. Some of the terms still commonly used such as ‘transition syndrome’, ‘OBS’ (Organic Brain Syndrome) or ‘ICU psychosis’ trivialise the clinical picture, as they don’t do justice to the high rate of complications, the European Delirium Association emphasises: ‘Waiting for the transition syndrome to pass amounts to medical malpractice.’

The mortality rate is also increased and the condition always necessitates intensive care. As yet there is no real treatment available to shorten the duration of delirium, and even just recognising the symptoms requires a lot of experience from anaesthetists and other medical and nursing staff.

In a recent randomised, controlled study, Professor Claudia Spies MD and her colleagues at Berlin’s Charité University Hospital showed that the incidence of postoperative delirium can be lowered significantly – by around 22.9% -– by neuromonitoring the depth of anaesthesia with EEG. The brain’s electrical activity is measured by recording frequency fluctuations on the scalp.

1,155 patients over aged 60 were split into two groups. In the intervention group (n=575) the anaesthetists monitored the depth of anaesthesia during surgery with an EEG. In the control group (n=580) monitoring was blinded. ‘The EEG shows the effect of the anaesthetic on the brain. It allows us to administer anaesthetic more precisely, to detect changes in the patient during the anaesthetic and to react to them,’ the professor explains. 16.7% of patients in the intervention group were found to have postoperative delirium after surgery, but the proportion in the control group was 21.4%. The results of the study were published in the British Journal of Anaesthesia.

‘As there are only a few therapeutic procedures available for the treatment of postoperative delirium this type of prevention is the best option,’ said Professor Christian Werner MD, president of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI) commenting on the significance of the study.

Prevention is of utmost importance

Bearing in mind that postoperative delirium goes hand in hand with an increased risk of cognitive dysfunction and mortality, and the treatment options available are not satisfactory, the prevention of the problem with the help of monitoring during anaesthesia is a priority.

The question arises whether or not postoperative delirium may not also be a sign of a pre-existing impairment of mental function. This would explain its greater incidence in line with increasing age of the patients, as well as the increased incidence of long-term cognitive deficits following delirium. Very deep phases of anaesthesia thus correlate with postoperative delirium.

It is up to the anaesthetist’s skill to determine the correct depth of anaesthetic and not only to adapt it depending on the surgery phase but also to the patient’s individual need for anaesthetic. Monitoring would also help to avoid the dreaded intra-operative awareness reported by some patients, or would at least help to make it become evident.

Nurses’ obligations

The causes of delirium can be infections, pain or psychological and physical strain, such as experienced after surgery. Delirium can also be caused by undesired side effects of medication, and patients taking a large number of different drugs are at particular risk due to the confusing medicinal interactions.

In addition, nurses on surgical units are not always sufficiently trained to prepare patients for surgery in the best possible way. This mainly concerns pre-operative warming, premedication and infection prevention and control guidelines, as reported by a nurse.

The Canadian Hospital Elder Life Programme (HELP)

Non-medicinal strategies to prevent delirium are helpful. Anne Pizzacalla and her team from Hamilton, Canada, have been working with the HELP since 2004. This was developed at Yale Medical School to prevent delirium in older hospital patients. ‘The care process is of utmost importance for the prevention of delirium. This also includes supposed trivialities, such as ensuring that patients are given enough fluids and wear their glasses or hearing aids,’ she emphasises. HELP is used in Canada, the USA and now – for the first time in Europe – in Bielefeld, Germany.
 

30.04.2013

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