Side effects of anaesthesia: risks and complications

Anaesthesia is generally very safe. Complications are rare and are associated more with the patient's physical condition and the difficulty of the surgical procedure than with the anaesthesia itself.

Patients who smoke, are obese, have high blood pressure, have diabetes, regularly drink alcohol, or have heart, respiratory or kidney disease are more likely to develop complications.

The anesthesiologist will do a pre-anaesthetic assessment before the operation to evaluate potential risks for each patient due to their individual characteristics, in order to take these risks into account during the operation and minimise them.

General anaesthesia

Possible side effects

• Nausea and vomiting. This is a common side effect that can occur within the first few days post-operation.
• Sore throat. Caused by placing a tube in the trachea to maintain an open airway. Foreign objects in the trachea are very bothersome, as we have all experienced at one point or another, and having had a tube with a pressure-inflated cuff inserted can cause a sore throat.
• Confusion. The patient may be disoriented and confused when waking up from surgery. This happens especially in older patients and usually lasts for a few days.
• Muscle aches. Possible if medications were used to relax the muscles.
• Chills and hypothermia: Anaesthesia causes the patient's body temperature to drop, and chills and hypothermia can develop in the postoperative period.

Complications

Below we will specify complications that are possible, but which, as we mentioned, are highly unlikely.

• To keep the airway open, a tube is usually placed in the trachea, which can sometimes be difficult, depending on the patient’s physical characteristics. In these cases, traumatic injuries to the teeth, oesophagus or trachea may occur, and in extreme cases, a tracheotomy may be required.
• Even with fasting, digestive contents may pass into the lungs, leading to respiratory complications that can be severe.
• Cardiac alterations (arrhythmia, infarction, etc.) are another infrequent complication that is more associated with the patient's poor preexisting conditions.
• Malignant hyperthermia is a rise in temperature that is difficult to control.
• When cannulating veins, bruising or injury to nearby structures may occur. The substances administered may cause allergic reactions, although this is increasingly rare.

Local anaesthesia

Possible side effects

• Headache. In spinal anaesthesia, the dura mater is perforated and headaches can be caused by cerebrospinal fluid, which is connected to the brain, leaking through this hole. The risk is minimised with finer needles (smaller holes).
• Back pain at the site where the needle was inserted.
• Difficulty urinating, as the nerves that control urination are also affected.

Complications

• Some possible complications of local anaesthesia are caused by needles (haematomas, tearing of neighbouring structures).
• A rare complication, more related to personal factors, can be an infection at the injection site.

More severe, but rarer, complications are:

• Nerve damage. Nerves can be affected due to the toxicity of local anaesthetics.
• Injection of the anaesthetic into a blood vessel: The medication produces more intense hypotension and bradycardia effect and could in severe cases lead to arrhythmias and the excitation or depression of the central nervous system.

When a complication occurs, it is necessary to put the patient to sleep and perform general anaesthesia.

The risk of death from general anaesthesia is extraordinarily low, estimated at about 5 per 100,000 operations (the Christmas jackpot odds are 1 in 100,000).

www.mba.eu/blog/efectos-secundarios-anestesia/