What is general anaesthesia?

General anaesthesia puts our body into a sleep-like state. Our consciousness and sense of touch and pain are completely shut off and muscles are relaxed. Operations can therefore be performed without pain and fear. Important bodily functions like breathing, the heart beating and the circulation of blood are monitored at all times.

Risks of general anaesthesia

Before any general anaesthesia is applied, there is a conversation with the anaesthetist (FHM title anaesthesia). Pre-existing conditions, allergies and medications are discussed and the patient’s general state of health is reviewed. Particular attention is paid to cardiac and pulmonary functions.

The anaesthesia discussion serves to detect potential risks so that the anaesthesia can be adjusted or prepared accordingly.

Depending on the operation, an adjustment of medications may be necessary. For instance, anticoagulants will be stopped or reduced before the operation.

Side effects and potential complications

General anaesthesia is never completely free of risk. General and mild side effects like hoarseness, sore throat, nausea and vomiting can occur after general anaesthesia. In very rare cases, mild pneumonia may occur due to stomach contents being inhaled (aspiration) during anaesthesia.

Other complications, like cardiovascular issues or breathing problems depend, in particular, on the individual’s state of health.  By clarifying these individual risks, the anaesthesia team is prepared for an increased risk and can adjust the anaesthesia accordingly.  Serious complications have therefore become very rare today and general anaesthesia can also be safely used for patients with pre-existing conditions.



Fasting, both food and fluids, before anaesthesia serves especially to reduce the risk of aspiration (see above). The rule of not eating starting six hours before an operation applies. Up to two hours before the administration of anaesthesia, clear fluids like tea or juice without pulp, alcohol or fat can be consumed in small amounts.

Smokers must refrain from smoking on the day on which they are to received anaesthesia. Jewellery, contact lenses, hearing aids, artificial hair pieces, etc. will be removed for hygiene reasons and patients should not wear make-up. To prevent airways from shifting, dental prostheses must also be removed.

Pre-op room

First, we go to the pre-op room. There, the most important information is reviewed again using a checklist. The anaesthesia team will insert an intravenous line so the anaesthesia medication, fluid and, if needed, additional medications can be administered directly into the bloodstream if needed. In general, we also receive a tranquillizer or sedative in the pre-op room.

Operating rooms

The anaesthetist will administer the anaesthesia medication (anaesthetic) in the operating room via the intravenous line and, in general, also via a breathing mask to control the general anaesthesia throughout the entire operation. The anaesthetic consists of sedatives, analgesics and muscle relaxants. Because they also limit respiratory function, as soon as we fall asleep, a hose will be placed in the trachea via the mouth (intubation) to support breathing during anaesthesia. Our swallowing and coughing reflexes are also suspended during anaesthesia. That is why fasting before general anaesthesia is so important so that stomach contents cannot get into the respiratory tracts. 

What happens to the body during general anaesthesia

Our body is in a deep sleep-like state. The depth of the anaesthesia can vary depending on the operation, but is always continuously monitored so we remain in the desired state throughout the entire operation. The deep sleep-like state is induced by the anaesthetic which impacts the electrical signals in the brain and puts the brain into a state of unconsciousness.

Cardiovascular system

During anaesthesia, important functions like cardiac activity (EKG), blood pressure, respiration, oxygen supply and core body temperature are monitored with the help of several monitoring devices. Sometimes, during major operations and special operations, brain waves are also monitored (EEG). The anaesthesia team can detect disruptions in these bodily functions during general anaesthesia immediately and correct them accordingly when needed.

Bowel and bladder function

Our digestive organs and bladder are also “shut down” (anaesthetised) during general anaesthesia. Therefore, after waking up, it can take some time before these organs function properly again.

Even though digestion and urine production continue normally during an operation, this practically never poses a problem. During longer operations, help is provided by measures such as inserting a urinary catheter.

Involuntary urine or stool excretion is so rare that you need not be concerned about this. It is still necessary that you empty your bladder before the operation.

Waking up in the recovery room

After the operation is completed, the administration of the anaesthetic is stopped and we wake up within a few minutes. However, it can take even longer for us to fully regain consciousness and be fully aware of our surroundings.  After first waking up, falling asleep again is completely normal.  During this time, the wake-up phase and bodily functions like blood pressure and heart rate are monitored for a while in the recovery room before we are transferred back to the ward.

Recovery time after general anaesthesia

After the operation, it takes some time before all bodily functions are restored and the anaesthetic is completely broken down by our body. Wait until your digestive organs are active again before drinking or eating. In general, we can consume small amounts of fluid around 30 minutes after waking up and a light meal after one to two hours. However, after major operations in the abdominal or chest area, it may be somewhat longer.

Complaints after anaesthesia

Sometimes, nausea and vomiting may occur after anaesthesia. With medications, so-called anti-emetics, these symptoms can be prevented prior to anaesthesia.

The irritation of the throat due to the intubation hose may present itself as hoarseness and a sore throat after waking up. These symptoms pass relatively quickly, however.

Our nervous system function is still inhibited for quite some time after general anaesthesia. During the first 24 hours after anaesthesia, actively participating in road traffic or operating machinery is therefore not recommended. On occasion, there can be a temporary loss of memory, reduced concentration and mental ability may be slightly reduced after general anaesthesia. This phenomenon can last between several hours to days and include a certain amount of confusion.

Depending on the operation, the patient may need to receive powerful analgesics which can further reduce the ability to pay attention and concentration.

In general, the patient recovers from general anaesthesia completely within a few days. The further recovery process then depends primarily on the type of operation and not the anaesthesia.

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