Common Concerns and FAQs

I am due to have two anaesthetics within a very short time. Is there an increased risk in having two anaesthetics close together?
There is normally no increased risk in having two anaesthetics close together. This applies whether it is two general anaesthetics, two local or regional anaesthetics (such as epidurals or spinals), or a combination of general, regional and local anaesthetics. 

It is, however, important to tell your anaesthetist about any recent anaesthetics of any sort and to discuss with him or her the options for a second or subsequent anaesthetic. In discussion with your own medical advisers, it may be sensible to delay a second operation until you are fully mobile after surgery.

A relative recently developed a problem with breathing after an operation and was told that she had suxamethonium apnoea. What is this condition, is it inherited, and should we be tested for it?
Suxamethonium (Scoline™) is a muscle relaxant drug which is now uncommonly used by anaesthetists. However, there are some emergency situations where it is still the most appropriate choice.

A few people suffer from a condition known as ‘suxamethonium apnoea’. This is a rare, inherited condition, and if someone in your family is known to be affected, it may be wise for other members of the family to be screened for it by means of a blood test. Your GP should be able to arrange the blood test after discussion with the anaesthetic department at your local hospital.

When suxamethonium is used, the muscles are profoundly relaxed and the patient is unable to breathe for themselves. The effect usually lasts 3-4 minutes. In patients who have suxamethonium apnoea, the effect is prolonged for anything up to 4 hours. All trained anaesthetists are aware of the condition, and in the unlikely event that a patient develops it after being given suxamethonium , breathing is assisted by means of a mechanical ventilator until the drug wears off. The patient is usually sedated during this time because the experience may be frightening and unpleasant. However, there should be no long-lasting effects and recovery is complete.

How long do anaesthetics stay in the body?
Modern anaesthetic drugs are designed to be cleared from the body rapidly. The exact length of time depends on the nature and combination of the drugs used before, during and after the operation, and the nature and duration of the procedure itself. All patients differ slightly in their response to drugs and recovery after the operation will vary from patient to patient.

In general terms, although traces of the anaesthetic can be detected in the blood a few days later, most modern drugs have no noticeable effect after a few hours. Current advice is that it is not usually safe to drive or drink alcohol until at least 24 hours after a general anaesthetic.

Small quantities of anaesthetic drugs may be present in breast milk in breastfeeding mothers. In general, this does not cause a problem, but mothers should discuss the problem with their anaesthetists, who can then choose appropriate drugs and advise on the potential side-effects on the infant. It is usually possible to time surgery so as to minimise the effect, or to express breast milk for use in the immediate post-operative period.

Enquiries from patients – from the archive

There are persistent reports of holidaymakers being anaesthetised by the injection of ether into a caravan or motorhome, and then robbed. Is there any truth to this rumour? How much ether would be needed to make someone unconscious long enough to rob them, but without causing death?
It would not be possible to render someone unconscious with ether without their knowledge, even if they were sleeping at the time. Ether is an extremely pungent agent and a relatively weak anaesthetic by modern standards and has a very irritant affect on the air passages, causing coughing and sometimes vomiting. It takes some time to reach unconsciousness, even if given by direct application to the face on a cloth, and the concentration needed by some sort of spray into a room would be enormous. The smell hangs around for days and would be obvious to anyone the next day.

There are much more powerful agents around now, some of which are almost odourless. However these would be unlikely to be able to achieve this effect, and the cost would be huge enough to deter any thief unless he was after the crown jewels. Potential agents, such as the one used by the Russians in the Moscow siege are few in number and difficult to obtain.

Finally, unsupervised anaesthesia is very dangerous. In the Moscow siege about 20% of victims died from asphyxia, because their airways were unprotected. If the reports of holidaymakers being anaesthetized by injection of ether into a caravan or motorhome are true we would have expected a significant number of deaths or cases of serious brain damage to have been reported.
Issued February 2007

What is the currently quoted risk of death under general anaesthesia?
Data on this question are hard to find, especially from within the UK. There is evidence from several studies that mortality in adults increase with age and deteriorating physical status. ASA classification has been shown to be a good predictor of death after surgery in patients over 80 years old, though it cannot predict risk in individual cases. The three most recent reports of the UK Confidential Enquiries into Maternal deaths have reported four, eight and one death for the triennia 1988-90, 1991-93 and 1994-96 respectively. Since around 2 million deliveries occurred during each period, the overall mortality rate appears to have varied between 1:250,000 and 1:2 million, which could be described as 'minimal' or even 'negligible'.

Other studies have shown a higher risk, but it is difficult to separate purely anaesthetic risk from that due to surgical skill, postoperative care and other factors. Recent review articles on the subject make interesting reading:

1. Engelhardt T, Webster NR. Pulmonary aspiration of gastric contents in anaesthesia. Br J Anaes 1999;83:453-60.

2. Adams AM, Smith AF. Risk perception and communication: recent developments and implications for anaesthesia. Anaesth 2001;56:745-55.
Issued 2002