labor epidural accident - risk of obstetric anesthesia for childbirth
Epidural-accident

Epidural Accident

Date: May 11th, 2011


In July last year 37-year old woman became the victim of drug administration error in one of the large academic hospitals in Sydney. Instead of normal saline, anesthetist administering labor epidural filled loss of resistance syringe with chlorhexidine in alcohol, highly toxic antiseptic solution used to sterilize the skin. As the result, it was injected into the patient’s epidural space. The clinical consequences of this mistake are devastating: the patient developed acute inflammatory condition of important neural structures that required surgery and has developed severe neurological symptoms, including paraplegia. The story has been reported by leading Australian newspapers and has been hotly discussed on several Internet forums and blogs. One version of it can be read here:

http://www.theage.com.au/national/toxic-epidural-ravages-mother-20100820-1390i.html

The case is currently under investigation, and it inappropriate to discuss the details of this clinical accident until the official review is completed. In the meantime the number of requests for epidurals in many Sydney hospitals fell sharply in the weeks that followed. This reaction is understandable and predictable, though not rational. In the months following September 11 attack on the Trade Center in New York in 2001 the sales of airline tickets fell sharply, as many people were afraid to travel by air and chose other ways of transportations, often driving in their cars. As the result, the traffic on highways became more congested, and the number of road fatalities significantly increased, to the point that it exceeded the number of fatalities related to the 9/11 attack. Emotional decision – rejecting travelling by air – actually resulted in taking more risk.

The perspective of becoming disabled is terrifying, and every woman considering labor epidural has the right to ask a question: how likely is such accident to happen to me? The answer is not straightforward.

Statistics of medical errors

At first glance the statistics of medical errors are not very reassuring. Medical errors are relatively common, and taking into account huge number of patients that are admitted to the hospital system even rare mistakes may lead to considerable number of victims. An article published in 2000 in the Journal of American Medical Association revealed that every year in the USA an estimated 44,000 to 98,000 patients die as the result of medical mistakes, 7,000 of which are caused by medication errors in hospitals.

Another study from the UK that analysed data from 19 hospitals reported that consultants made prescription errors in about every 5 out of 100 medication orders, while for junior doctors this number was as high as 10.3 per 100 orders! The majority of these errors were relatively innocent and not dangerous, such as prescribing insufficient dosage or not prescribing patient’s regular medication on admission to hospital. However about 1.7% of errors were potentially lethal, however they were detected and corrected by the nurses, doctors and pharmacists. The latter is also the testimony to well organized risk management practices in hospitals.

The statistics above reflects overall hospital practices which encompass various medical disciplines: internal medicine, surgical specialities and other areas of clinical practice. However women considering labor epidural would be more interested in more specific numbers relating to the risks of such errors while administering epidurals. At least theoretically, epidurals errors should be less likely. Epidurals are always administered by doctors, anaesthetists, and the choice of drugs in anaesthesiology is more limited compared to general hospital practice. Unfortunately, there is no data specifically addressing epidurals. However, recent review published in the British Journal of Anaesthesia addresses the incidence of errors among anesthetists, and this data is useful for the purposes of current discussion.

Drug errors in anesthesia

The review refers to two recently conducted prospective studies on anaesthetic errors, one from New Zealand and one from South Africa. According to the studies the incidence of medication errors was 1 in 133 in New Zealand and 1 in 274 anaesthetics in South African study. Substitution errors – the type that lead to epidural accident described at the beginning of this article – constituted between one and two thirds of all mishaps. In spite of relative large incidence of mistakes, after doing some math the numbers are reassuring.

Based on the numbers above, when having attended by an anesthetist for whatever reason you have between 1 in 133 to 1 in 274 chance of getting a wrong drug during the encounter. The highest proportion of substitution errors, including administering wrong medication, was 60%, which translates to the chance of that happening to between 1:200 and 1:456. Though no error should be dismissed, most of such mistakes are relatively harmless, and several earlier studies demonstrated that only 1% of all drug errors lead to injury. This means that when attended by anesthetist, your chance of being seriously injured ranges from 1:200,000 to 1:450,000. For comparison consider this fact: if you live in the USA you run annual chance of dying in traffic accident of 1:10,000, or about 20 to 40 times higher.

Looking at the numbers from another perspective, the incidence of an error of 1 in 133 cases means that during the course of the year a busy anaesthetist will make on the average 7 drug errors. If 1% of these errors were thought to result in injury then each anaesthetist would expect to harm 2 patients in the course of a 30 year career by any cause, while the chance of serious harm by making a substitution error is even lower.

Even more, the numbers in the review include all errors in anaesthetic practice, and it is important to emphasize that the largest part of it is general anesthesia. Its practice may vary considerably from patient to patient and involves the use of large number of drugs. Labor epidural, on the other hand, is considerably more specialized and more standardized procedure that involves the use of limited number of medication: a local anesthetic, an opioid, sterilizing solution and normal saline for loss of resistance technique. Variations in technique also limited. This makes the chance of drug substitution error lower than in general anesthetic practice.

Safety systems

Substitution errors are often the result of inadequate system of procedures. In civil aviation it has been recognized years ago, and all procedures in that industry are governed by protocols and check lists that ensure that nothing is missed or misunderstood. It is impossible to fully replicate such approach in clinical medicine; however some elements of system safety have been introduced in hospitals as well. Some errors may be eliminated by simple rules. For example, standard chlorhexidine solution is transparent and looks similar to normal saline, so that it is easy to confuse one liquid with another. For some reason this fact escaped the attention of epidural practitioners.

After the incident primary investigation came up with several recommendations in order to reduce the probability of such error happening in the future. Currently used solution of chlorhexidine is painted bright purple and is virtually impossible to mistake with normal saline or any other fluid. To further improve safety the procedure of sterilizing the skin is now performed separately from epidural: skin area where epidural needle is going to be inserted is prepped with chlorhexidine, and the tray containing the sterilizing solution is discarded; only then are syringes filled with drugs used for epidural. Finally, the incident has drawn tremendous attention to substitution errors in general, and has been discussed in virtually every anesthetic department in the country. As the result anesthetists are conscious of the possibility of errors. All these measures are likely to reduce the likelihood of already rare event to even lower level.

Air or saline?

As a sideline, another debate has been re-awakened among anesthetists, on advantages and disadvantages of using air or saline for loss of resistance. There is some data that by using saline for loss of resistance the number of non-functioning epidurals is reduced. Some anesthetists will argue that failures happen with either air or saline, and at the end of the day the technique with which the anesthetist is most familiar and experienced will work best. The fact is that by using air for loss of resistance the possibility of injecting wrong substance is completely eliminated. At the end of the day the technique with which the anesthetist is most familiar is the safest, as long as measures are taken to avoid substitution errors.

Safety record

Overall safety record of labor epidural is very good, and serious complications are in fact rare. Statistically, the risk of severe neurological injury as the result of epidural complication is very low, between 1 in 100,000 and 1 in 200,000, and probably only a fraction of these is caused by errors.

Unfortunately, everything comes at a price. Epidural is the most effective and reliable way to eliminate the pain of childbirth. However, like every invasive medical procedure it will always have the list of complications. It is also unlikely that human error will ever be completely eliminated. After all, human error is still one of the leading causes of accidents in civil aviation, industry that deals with machines that behave in much more predictable manner than human bodies.

Childbirth itself is not a risk-free endeavor: according to the UN databases maternal mortality was 24 per 100,000 live births in 2008 (8 per 100,000 in Australia for the same year), way higher than severe neurological damage from epidural. For comparison, in Congo it was 580, Dominican Republic 100 and 1200 per 100,000 live births in Somalia! The reason it is so much lower in the developed countries is well developed medical infrastructure, with access to obstetric help that also includes epidurals.

Chlorhexidine is one of the most used antiseptics in the world and hundreds thousands of epidurals are performed every year. Yet there is only one case, besides that described at the beginning of this article where the use of chlorhexidine has caused severe neurological damage during labor epidural. Mind you, the circumstances of that case are much less clear cut, and chlorhexidine was determined as the cause of injury by exclusion, simply because there was no other possible explanation of paralysis.

It is unlikely that complications will ever be eliminated from the practice of obstetric anesthesia. Severe neurologic damage as the consequence of labor epidural is very low, considerably lower than the average statistical risk of serious car accident or serious consequence of childbirth itself. Accidents like the one described at the beginning are devastating. However they are unlikely. The acceptance of risk, on the other hand, is a personal matter, and different people will always perceive the risk differently. The most important point is that in order to accept risk the person needs to be presented with reliable statistical data. Presenting comprehensive data – good or bad – relevant to pain relief during childbirth is the goal of this website.

Reference: 

1. Glavin RJ. Drug errors: consequences, mechanisms, and avoidance. British Journal of Anaesthesia. 105 (1): 76–82 (2010)

2. http://unstats.un.org/unsd/mdg/SeriesDetail.aspx?srid=553

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Dr. Eugene Smetannikov is a practicing anesthesiologist with the interest in obstetric anesthesia. He is the author of the most comprehensive book on the subject, The Truth About Labor Epidural

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