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Review Articles

Management of patients taking herbal medicines in the perioperative period: a survey of practice and policies within Anaesthetic Departments in the United Kingdom

Hogg, Lucy A; Foo, Irwin

Author Information
European Journal of Anaesthesiology: January 2010 - Volume 27 - Issue 1 - p 11-15
doi: 10.1097/EJA.0b013e32832f0878

Abstract

Introduction

Herbal medicine usage in the United Kingdom (UK) is increasing with recent estimates suggesting expenditure on herbal and alternative medicines to be around £1.6 billion pounds per year [1]. The WHO states that traditional medicine (which includes herbal medicines) may account for 80% of primary healthcare in some Asian and African countries [2]. The public generally associates ‘herbal’ with being ‘benign’ or ‘safe’. This trust may well be misplaced, as around a third of all modern conventional medicines are derived from plants, including some of our most toxic agents – such as vincristine (used as chemotherapy) – which is derived from the periwinkle plant. Various surveys have attempted to quantify the proportion of patients actually ingesting these remedies on presentation to hospital. Estimates vary along with the patient populations questioned, ranging from as low as 4.8% of adults presenting at a hospital in England for anaesthesia [3] to as high as 55% of adults undergoing cosmetic surgery in Los Angeles [4]. Otherwise healthy children (ASA I-II) surveyed on arrival for day surgery at a hospital in Ireland had a rate of herbal medicine use of 6.4% [5]. Whichever estimate most closely reflects UK patient groups, it accounts for a significant number of patients in most anaesthetists' day-to-day practice.

The most commonly used compounds include echinacea, ginseng, garlic, gingko and St John's Wort [3–6]. All of these have been reported to be pharmacologically active; however, the level of evidence varies from anecdotal case reports to more rigorous chemical and physiological analysis. Worryingly, some of the case reports credit herbal preparations with significant morbidity and mortality. Examples include bilateral subdural haematomas associated with Ginkgo [7], epidural haematoma related to excessive garlic ingestion [4], sudden death secondary to ephedrine toxicity [8] and a case series of acute renal failure in over 100 patients who had been taking Chinese herbal slimming pills [9]. There have also been attempts to formally study the pharmacological effects of herbal products which have provided evidence of organ rejection secondary to reduced bioavailability of immunosuppressants with concomitant St John's Wort administration [10] and immunosuppression and postoperative infections with long-term echinacea use [11]. There is still, however, limited evidence to demonstrate any benefits over and above placebo effects. Clinical and scientific studies are limited by a lack of statutory control over herbal products which may be marketed as food supplements or cosmetics. This allows exemption in the UK from the stringent product licensing as dictated by the Medicines Act 1968 [12]. As a result, studies have shown that some herbal products contain contaminants in addition to the herbal ingredients. This can be with other herbs, or more ominously with heavy metals or conventional western drugs [13]. Furthermore, a single herb may be made up of a complex mixture of compounds which may all have different pharmacological effects and a single batch of herbal medicine may contain varying amounts of each compound [14]. This limits the reliability of data collected, as adverse events and interactions may be the result of the herbs themselves or other, often unknown, contaminants. See Table 1[15] for a summary of commonly used herbal medicines and their known adverse effects.

Table 1
Table 1:
Summary of commonly used herbal medicines, known effects and perioperative recommendations as per British Association of Day Surgery guidelines[15]

Concerns for the anaesthetist lie with the unknown effects of these drugs, potential interactions with drugs given during the perioperative period and effects on patient physiology. For example, St John's Wort inhibits reuptake of serotonin and noradrenaline and is a potent inducer of liver enzymes. As a result, it can decrease the effect of commonly used anaesthetic drugs such as midazolam, alfentanil and lignocaine. It may also interact with sympathomimetics to induce exaggerated hypertension and arrhythmias [15]. A study [14] also demonstrated that patients taking traditional Chinese herbal medicines were more likely to have a preoperative event requiring correction (e.g. hypokalaemia) or a change in anaesthetic technique (e.g. epidural technique abandoned because of coagulopathy) than nonusers.

To compound the problem, patients often supplement their traditional therapies with herbal products but do not volunteer information regarding their use during history taking by healthcare professionals [16,17]. It has been shown that around half of patients will not disclose herbal medicine use unless specifically asked [16–18]. Ninety percent of anaesthetists admit to seldom or never specifically asking patients about the use of herbal medicine products [1].

The need for guidance for both the general public and clinicians would appear clear. However, having determined a patient is taking a herbal medicine, little in the way of protocols exists at a national or international level. Neither the Royal College of Anaesthetists (RcoA) nor the Association of Anaesthetists of Great Britain and Ireland (AAGBI) has published a national guideline outlining management of herbal medicines in the perioperative period. However, they do recommended full disclosure by patients in information leaflets and specific questioning by anaesthetists in guidelines about preoperative assessment [19–21]. Internationally, the WHO acknowledges the paucity of national policies but does not itself have a guideline [2]. The American Society of Anaesthesiologists publishes an information brochure regarding herbal medicines in which they also encourage full disclosure by patients and for physicians to actively seek a history of herbal medicine use. They state that the public and medical community should be aware that herbal products could pose serious health risks if taken prior to surgery. They have not made a formal statement of policy or issued a standard of care specific to phytopharmaceuticals [17]. A booklet published by the British Association of Day Surgery (BADS) does offer clear advice regarding continuation or cessation of herbal medicines perioperatively. Their recommendations for commonly used products are shown in Table 1[15].

We conducted a national survey to ascertain whether the information and guidance available were being translated into local policies and clinical practice or whether many patients were potentially being exposed to harm by undergoing surgery and anaesthesia without full disclosure of their drug history to their team.

Methods

A questionnaire survey (see Fig. 1) was sent to all UK hospitals with an Anaesthetic Department, as identified from the Directory of Operating Theatres & Departments of Surgery 2006 [22]. If a clinical lead or department head was identified within the listing, the letter was addressed to that individual. If no such individual was singled out, a doctor was selected at random from the list of clinicians within the department. Enclosed with the questionnaire were a stamped addressed reply envelope and a covering letter. A reminder letter was sent to those who did not initially respond after 4 months. This again included a copy of the questionnaire and a stamped addressed return envelope.

Fig. 1
Fig. 1

We designed a survey to determine whether or not it was commonplace for herbal medicines to be considered by anaesthetic departments in the preparation for surgery. Was this reflected in departmental documentation? Did departments have a perioperative herbal medicine policy to guide clinicians and other staff involved in advising patients in the perioperative period? Was advice given consistent across the country and congruent with current guidance?

Results

A total of 176 replies were initially received from the 321 questionnaires sent. A further three questionnaires were returned, as the doctors no longer worked in the relevant departments. This was an overall response rate of 55.7%. Following the reminder letter, replies were obtained from a further 57 doctors. This gave a final response rate of 72.6%. The questionnaires were completed predominantly by Consultant Anaesthetists – 209 (90%). The remainder were completed by three trainees (two SHO, one SpR), one SAS Grade doctor and 20 respondents did not specify their grade on the returned form.

Of the 233 departments that replied, 17 (7.3%) currently had a perioperative herbal medicine policy and five did not know whether a policy existed within their department. Of the 211 that did not have guidelines in place, six stated that there were plans to develop one. One hundred and sixty-five departments definitely did not plan to develop one and 40 were uncertain. Five respondents missed out this question. In response to question 4, which was ‘Does your anaesthetic chart provide space for documenting herbal medicine use specifically? (i.e. not just a ‘Drug’ section for kardex drugs)’, 229 (98.3%) respondents did not have a specific space on their anaesthetic chart, in addition to a general section for ‘drugs’, to document herbal medicine use.

The majority – 216 (92.7%) – of departments have pre-assessment clinics for elective surgical patients. Of these, 34 specifically ask patients attending about herbal medicine use. Of the remainder, 152 did not make specific enquires about herbal medicines and 31 respondents did not know what questions patients were asked at pre-assessment. See Table 2 for a summary of results.

Table 2
Table 2:
Summary of results

The 17 departments that did have perioperative herbal medicine policies in place were asked what advice they gave to patients regarding discontinuation of herbal medicines in the perioperative period. Four recommended stopping 1 week before surgery, 10 recommended stopping 2 weeks before surgery, three said it depended on the herb in question and that there were local guidelines which could be referred to and one department reported that they discussed each case on an individual basis. Interestingly, of the 17 departments that had a policy, only 13 specifically asked about herbal medicines at their pre-assessment clinics.

Thirty-four departments responded to say they specifically asked patients attending pre-assessment clinics about herbal medicine use. Thirteen of these were departments with herbal medicine policies as outlined above. Of the remaining 21 departments that did not have policies, information was requested regarding what advice they gave patients who disclosed that they were currently using a herbal product. The variety of answers given are shown in Table 3. One department did not answer the question.

Table 3
Table 3:
Advice given at pre-assessment clinics to patients taking herbal medicines

Discussion

To improve our survey, we could have attempted to increase our overall response rate to give a more accurate picture of the current UK situation. This could have been achieved with further telephone follow-up. It was also unclear from the directory [11], and so assumed, that all departmental heads were clinical anaesthetists. We may have received different results by specifically contacting clinicians within departments. Lastly, we did not request a copy of the policies from the respondents who identified that they had one in place. This may have given more information about the nature of the advice given, as a number of those questioned indicated that the advice depended on the herbal medicine in question and one department reported ‘discussion on an individual basis’ which would suggest that no formal written policy existed.

What is clear from our survey is that the one piece of consistent advice we are being given by the RcoA and AAGBI – elicit a herbal drug history from preoperative patients [19–21] – is not being adopted as usual practice at local level. Most UK anaesthetic departments do not currently have a perioperative herbal medicine policy for staff to reference. Our survey also showed that most have no plans to develop one in the near future. This is also reflected in the departmental paperwork and clinics that patients attend. There is very little targeted questioning at pre-assessment clinics and the anaesthetic charts lack the vital prompts (in the form of specific areas to document herbal medicine use) for staff to positively seek a herbal medicine history. Even within the departments that did have a herbal medicine policy, not all of them (82%) actively questioned patients at pre-assessment clinics. As we know that anaesthetists do not make specific enquiries and a great number of patients do not volunteer herbal medicine use [1,16–18], it is likely that a significant proportion of patients undergo surgical and anaesthetic procedures with their respective teams unaware of their full drug history. This results in unnecessary potential for adverse drug interactions and complications. There may be a number of reasons for this: anaesthetists may not prioritise it as clinically relevant and this was reflected in comments on the respondents' forms such as ‘this is a nonissue’. It is also not a subject currently given much emphasis within medical school or exam curricula. A second reason that clinicians may be reluctant to ask about herbal medicines is that having determined that patients are consuming a herbal medicine, there is little coherent advice about what to do. The 17 departments that had a policy gave varying advice to patients. At the 34 pre-assessment clinics where a history of herbal medicine use was sought, different advice was given to their patients, as 62% did not have a policy to refer to. As can be seen by comparing the advice given in Table 3 with the recommendations in Table 1, evidence-based practice is not being observed. That most departments would stop all or most herbal preparations would suggest that the advice given is not inherently dangerous, but also appears to reflect a lack of regard for the products as pharmacologically active. In the minority of cases (e.g. valerian which should not be discontinued abruptly as it poses a risk of withdrawal syndrome [13]), this may prove to be incorrect and potentially harmful advice. It may also be the case that a number of unexplained episodes of perioperative morbidity could be related to herbal medicine use but go undetected, thus the true scale of the problem remains unknown.

It would seem clear that education at medical student and postgraduate levels is required. In spite of the need for more definitive studies into these products, there is enough evidence to show that these are pharmacologically active agents which affect many physiological processes pertinent to all doctors but particularly anaesthetists who administer and prescribe several different drugs in the perioperative period. A number of review articles that outline perioperative herbal medicine interactions and their management are available to reference [11,16] and guidelines have been published by smaller organizations [15], but a definitive statement or guideline from a national body would highlight the issue and raise awareness of the potential risks. It would also provide the information required to make sensible and safe decisions about continuation or cessation of these products. This would reduce confusion for both staff and patients alike and produce uniformity between hospitals and regions. It may also be the impetus required to generate interest within departments to develop strategies or adopt national guidelines into daily practice.

References

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Keywords:

herbal medicine; herbalism; medicine herbal; perioperative care; policy analysis; policy making

© 2010 European Society of Anaesthesiology