Department of Anaesthesia and Pain Management, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
E-mail: rmacpherson{at}doh.health.nsw.gov.au
Accepted for publication May 17, 2004.
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Abstract |
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Methods. We developed an eight-item questionnaire that can be administered before admission to assess patient suitability for surgery under LA. In a prospective study over a 9-month period, 128 patients were seen in a pre-admission clinic, and according to the responses to the questionnaire administered by junior medical staff, 123 were deemed suitable for surgery under LA, and five under general anaesthetic (GA).
Results. All 123 patients went on to have surgery successfully performed under LA. A further two patients from the GA group were determined by the attending anaesthetist to be suitable for surgery under LA.
Conclusion. This assessment instrument has been shown to be a highly specific means of selecting patients for surgery under LA, and can be administered by medical or nursing staff.
Keywords: anaesthetic techniques, regional, peribulbar ; anaesthetic techniques, regional, retrobulbar ; assessment, pre-anaesthetic ; eye, cataract ; screening ; surgery, cataract
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Introduction |
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This investigation proposed to design and test a simple questionnaire that would enable non-anaesthetists to accurately select patients to undergo surgery under LA.
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Methods |
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Questionnaire development
Senior medical staff who were currently providing anaesthetic services for the ophthalmic surgery lists were consulted. After discussion and a review of available literature, a consensus was reached upon a set of criteria that would need to be met before a patient was considered a suitable candidate for surgery under local anaesthesia. The criteria are listed below. Since the questionnaire would be administered by non-anaesthetic staff, some further explanatory notes were provided where needed.
Study design
A prospective study was designed to assess the validity of this assessment tool. Patients who were seen in the pre-admission clinic had the eight-point questionnaire administered by the admitting medical staff who was either the resident medical officer from the surgical team or the clinic medical officer. If all points were answered appropriately, the patient was to undergo surgery under LA. Patients were not seen by an anaesthetist. A sticker was attached to the anaesthesia chart with answers to the eight questions. Other data that were recorded included whether the patient had either insulin- or non-insulin-dependent diabetes or were taking oral anticoagulants.
Only patients who failed to answer all questions appropriately were to be seen by an anaesthetist to either determine if they were appropriate for surgery under LA or assessed them for fitness for general anaesthesia.
In keeping with contemporary practice,1 4 patients selected for surgery under LA had no formal medical history taken, no physical examination performed, and no pathology tests ordered. The only investigation routinely undertaken was an ECG.
At the time of operation, the attending anaesthetist recorded the type of anaesthesia used, its success or failure, whether there were any attendant complications, and the use and dose of any adjunctive sedative agents.
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Results |
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With respect to ECG analysis, the majority of patients (n=90) were in sinus rhythm. The most common abnormalities were heart block (n=22), atrial fibrillation (n=6), and evidence of previous myocardial infarction (n=6). Patient characteristics and the prevalence of diabetes or anticoagulant use are shown in Table 1.
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Of the 128 patients presenting for surgery, 125 proceeded to have the procedure performed under LA. This included all of the patients (123) selected for LA at the clinic appointment and two patients from the GA group. These two, after assessment on the day by the attending anaesthetist, were considered suitable for LA.
All local anaesthetic procedures were successfully completed. There were no complications and no requirement for any of the procedures to be converted to GA. On occasion (n=53), either midazolam (13 mg) or propofol (1030 mg) was used to provide light sedation whilst the block was performed. The types of block used included peribulbar (n=100), retrobulbar (n=17), and topical anaesthesia (n=8). Topical anaesthetic was used in those patients taking anticoagulant medications.
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Discussion |
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First, the conclusions from a number of studies suggest that LA is the preferred method of anaesthesia,5 6 accepting that there may be local variation depending on surgeon preference and practice setting.7 8
Secondly, patients undergoing cataract extraction are drawn primarily from an elderly population with a high incidence of co-morbidities,1 9 the most common being diabetes mellitus, rheumatoid and osteoarthritis, hypertension and previous cerebrovascular accident.10 However, despite this rather gloomy picture, patients generally tolerate the procedure and associated anaesthesia very well with low rates of mortality and morbidity.1113
Lastly, with the exception of an ECG, banks of pathology tests and radiology examinations can be avoided.14 15 When such tests are ordered they more often than not simply reflect the specialty of the individual16 and have been shown to be of no benefit in either predicting patients liable to suffer perioperative complication or in lowering operative risk.1520
Various professional groups have proposed guidelines to help select patients for cataract surgery under LA. The document produced by the Royal Colleges of Anaesthetists and Ophthalmologists5 suggests that in adult patients, LA is contraindicated in patients who decline it; in those who are unable to communicate; in patients with tremor; or who cannot be positioned correctly. Other guidelines have suggested that performing the procedure under LA would be difficult in patients with deformities such as kyphoscoliosis21 or in uncooperative patients.2 However, all of these suggestions seem to have been made on the basis of assumption rather than by actual testing. This study appears to be the first attempt test and extend these varied guidelines.
There are often logistical problems in patient selection for cataract surgery. The patient will be seen initially by the ophthalmologist, usually with the assumption that the surgery will be performed under LA. Should the patient later be found to be an unsuitable candidate for LA, this might result in surgery either being either cancelled or delayed. This screening tool, which has demonstrated a sensitivity of 98.4% and a specificity of 100% in this sample, allows the ophthalmologist, nursing, or pre-admission clinic staff to quickly identify patients who might require a more detailed assessment or who may not be candidates for LA. In addition to simply providing simple screening statements to select patients, it was found that adding a short explanatory background note for each of the eight points gave added guidance for the interviewer. For example, the presence of a tremor per se need not be a contraindication to LA provided it does not involve the head and neck.
In this study there were some cases where either propofol or midazolam was used by the attending anaesthetist in addition to LA. Doses were low and the medications were given for the purpose of facilitating the placement of the block injection, a common practice.22 23
The assessment tool used in this study does not take the place of a preoperative visit by the attending anaesthetist. However in today's hospital setting, where so many patients are seen in pre-admission centres, and frequently by non-anaesthetic personnel24 25 and attend hospital only on the day of surgery, this instrument has proved to be an accurate means to allow non-anaesthetists to quickly determine suitability for surgery under local anaesthesia.
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Acknowledgments |
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References |
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