What’s a post-op delirium?
Postoperative delirium is an acute, mostly temporary state of confusion and is also known as a transitional syndrome or acute organic psychosyndrome. It occurs in 5-15% of all patients. At the same time, various functions of the brain are restricted.
There are changes in consciousness, thinking, moving, sleeping and feeling. It mainly affects elderly patients, can be very different in severity and changes in the course of the disease. From very restless and partly aggressive to very silent and hardly responsive patients, all variants of delirium are present.
The causes
The postoperative delirium cannot usually be traced back to a specific cause. It is usually a combination of various factors. In the course of a hospital stay and planning an operation, medication is often taken on or taken off.
These changes can trigger a postoperative delirium in the course of the operation. Lack of oxygen supply to the brain in ventilated patients, organ failure (lung, heart, liver, kidney), as well as underlying diseases such as severe infections are further causes. Changes in the electrolyte and acid-base balance must be closely monitored during an operation and corrected as quickly as possible.
Elderly patients with existing mental illnesses, e.g. dementia, often have difficulty adapting to new situations. Changes in the environment can worsen the state of confusion. Patients undergoing heart surgery often show postoperative delirium.
In some studies up to 46% of patients are reported to have this condition. Particularly during operations with heart–lung machines there are considerable changes in the circulatory system, which have to be compensated by the anaesthetist. Cardiac surgery patients often have a low ejection rate of the heart, which results in a lack of oxygen in the brain and low blood pressure.
Both risk factors for delirium. In addition, they show a higher serum cortisol due to stress reactions and increased inflammatory parameters due to the large and long surgical procedure. Due to the complex operations there is an increased incidence of postoperative complications.
Patients on intensive care units have serious, often life-threatening underlying diseases and often major operations behind them. The organ functions are often limited and are partly taken over by machines. This demands a lot of energy from the body, oxygen consumption is increased and the risk of a shortage and the formation of toxic substances in the body is significantly increased.
Pain therapy is a very important factor, especially with sedated patients it is often difficult to recognize pain. A lack of pain therapy is also a cause of delirium. A lack of sunlight (no window seat in the intensive care room) and disturbing noises from machines, fellow patients or staff disturb the ability to fall asleep and sleep through the night or the entire day-night rhythm, which promotes the development of delirium.
The majority of patients who develop a postoperative delirium are >60 years old. The reason for this is the presence of several risk factors that promote delirium. In addition to age, these include visual/hearing impairment, underlying diseases such as diabetes, high blood pressure, stroke, atrial fibrillation or mental limitations such as dementia.
Older patients often take several drugs (polypharmacy). During/after anaesthesia, drugs which can have a dilirant effect, such as opiates and benzodiazepines, are also administered. Elderly patients tend to have low blood pressure, low blood sugar and low sodium during general anaesthesia. It is therefore important, especially for elderly people, to keep the duration of anaesthesia as short as possible or to use regional anaesthesia if possible.
