The sitting position in anaesthesia

Editor, The sitting position, first introduced into clinical practice in the early twentieth century, had operations on the posterior fossa/upper cervical spine as textbook indications. Although risks are related to the use of the sitting position, it has enabled surgeons to perform operations, which otherwise could not have been done. United Kingdom surveys conducted in 1981 and 1991 show a gradual decline in the use of the sitting position.1,2 Our telephonic survey of neurosurgical centres in the UK listed on the Society of British Neurosurgeons website enquired about the current use of this position. Table 1 compares the results with historical data.3–6Table 1: Neurosurgical centres that use the sitting positionOnly 27% of UK centres offer the sitting position now, contrasting with countries on the continent. Interestingly, in the UK, the surgeon usually decides about patient positioning, whereas in Japan, with the lowest percentage of hospitals using the sitting position, it was the anaesthetists objecting to the sitting position in 31% of hospitals.3 We telephoned a Consultant Neuroanaesthetist in each of the 11 UK Hospitals using the sitting position in Neurosurgery, to enquire about monitoring used (Table 2). Although a degree of variation exists within departments, the view given is the one deemed to be a fair representation.Table 2: Monitoring used routinely for the sitting position in neurosurgeryPreoperative patent foramen ovale screening was routine in six out of 11 UK centres (55%). In Germany, 45% of centres screened patients preoperatively in 1998, and the percentage is likely to be higher today in line with recommendations. Central venous pressure monitoring is routine for the sitting position in nine out of 11 UK centres, in one centre not always, in a further centre not at all. Two of these centres advance the central venous pressure lines into the right atrium; a further centre uses a long central line to have the option to advance the line if needed. Transthoracic Doppler is used in two centres; in a further centre, most of the anaesthetists make use of this device. Transoesophageal echocardiography for intraoperative monitoring would be available for use in two out of 11 centres (18%), but is not part of the routine monitoring for the sitting position in the UK. Ventilation with a small amount of positive end-expiratory pressure (PEEP) is used in six centres; however, some variation exists within departments with regard to the use of PEEP. An antigravity device (military anti shock trousers) is applied in one centre (9%). Overall, there is a trend towards less invasive monitoring in the UK, contrasting with a different approach on the continent. The least invasive approach is chosen by one UK paediatric centre with no screening for patent foramen ovale; however, selection criteria for suitability are applied. This centre applies invasive arterial blood pressure monitoring, but does not routinely use central lines or Doppler/transoesophageal echocardiography monitoring. Although the use of the sitting position in neurosurgery in the UK is declining, it is still enjoying popularity in other surgical specialties. Shoulder surgery in the beach-chair position shows similar haemodynamic effects in response to the position, with hypotension and neurapraxia observed in up to 30% of patients, but major complications including spinal cord ischaemia, cerebral ischaemia and death are rare.7 Although in the early eighties about half of the anaesthetics for dental chair procedures in the UK used the sitting position with no evidence of increased risk, only a few years later, an emotional faint under general anaesthesia in the sitting position has been discussed as a common cause for morbidity and mortality in the dental chair.8 Revival of the sitting position for lumbar microdiscectomies under regional anaesthesia has been reported. The advantages are described to be good recreation of load conditions, with no major complications observed in this small group. The risk of a dural tear with subsequent cerebrospinal fluid leakage remains.9 In summary, positioning a patient for a neurosurgical procedure takes into consideration a list of factors; however, the importance of some of these has changed. The force of change has been the general advancement of science and technology. Tilting operating tables, neuronavigation, intraoperative haemostatic devices, and illuminated microscope, for example, made the importance of the sitting position less relevant. The shortcomings of not using a sitting position during surgery can usually be solved with technology and the recent introduction of robotics will help this further. As far as the monitoring for sitting patients in neuroanaesthesia is concerned, there is no common ground between different European countries. Although transoesophageal echocardiography is not used routinely for these procedures in the UK, it now appears to be the gold standard for monitoring these patients in Germany.6 The potential for major complication due to positioning, paralleled by fear of successful litigation for major complications of the use of the sitting position, has led to a substantial decline in the use of this position in neurosurgery in the UK.10 A review of the closed claims analysis for cervical injuries has been published by Hindman et al.11 Within all general anaesthesia claims between 1970 and 2007, cervical injury claims comprised under 1% of claims, but caused more permanent and disabling injuries. Most cervical injuries occurred in the absence of traumatic injury or instability, but cord injuries – as the most severe complications often resulting in quadriplegia – were observed with the sitting position in 24% of cases;11 however, a direct causative link was not established. It thus remains a matter of debate whether centres that offer operations on posterior fossa tumours or cervical spines in the sitting position should offer patients the alternative positioning option and whether the risk of sitting position should be included within the remit of consenting. This also implies that information on alternative services wherein alternative position choices are available would be part of informed consent; this is especially important for patients who are predisposed. The sitting position is still being used in neurosurgery and in other specialties. Lessons learnt from the past must not be forgotten. Prospective studies are required to evaluate further the outcome of these operations within the different approaches used by different countries. Acknowledgements relating to this article Assistance with the letter: we are very grateful for the willingness of all the neurosurgeons and anaesthetists in the neurosurgical centres to share their experience of the sitting position for neurosurgical patients with us. Without their help and participation, we could not have written this review. We also acknowledge the contribution of Dr Rickey Raja for conducting some of the telephonic interviews. Financial support and sponsorship: none. Conflict of interest: none.