Peri-operative TOE is associated with a 0.08% incidence of major complications and 0.03% mortality, emphasizing the importance of informed consent, careful risk-benefit assessment, and safe training practices.
Peri-operative transoesophageal echocardiography (TOE) during cardiac surgery has become routine clinical practice throughout much of the developed world. In some situations, such as during mitral valve surgery, it would be considered negligent if TOE were not used. In 2015, 35,158 cardiac surgical procedures were performed in the UK and > 50% of these had a ‘Class-1’ indication for TOE (http://www.bluebook.scts.org/#ActivityRates). As well as heart valve surgery, TOE is recommended in some circumstances during coronary artery bypass graft surgery. The European Board of Echocardiography and the European Association of Cardiothoracic Anaesthesiology go further and recommend its use for all patients undergoing all types of cardiac surgery 1. Transoesophageal echocardiography has emerging roles in other circumstances such as non-cardiac surgery, procedures in the cardiology catheter laboratory and to guide management in the critical care environment. There are many guidelines on the use of TOE 1-3, but there is little evidence to suggest a treatment effect associated with it. However, a randomised controlled trial would be regarded by many as unethical, because TOE has become an integral part of peri-operative practice. In our institution, TOE is always used during cardiac surgery unless there are contra-indications. This month in Anaesthesia, Ramalingam et al. report results from the largest prospective multicentre study of morbidity and mortality associated with peri-operative TOE examinations to date 4. The incidence of major complications and mortality was 0.08% and 0.03%, respectively. This is higher than previously reported, which may cause great alarm to many. The authors should be congratulated, as it is difficult to co-ordinate such a large study that included 28 centres. However, they acknowledge several limitations, including underestimation of the total number of TOE examinations performed, as 6 out of 34 (18%) UK centres did not contribute and the private sector was excluded. Examinations in critical care and the cardiac catheter laboratory may have also been underestimated, which makes the suspected higher incidence of complications in the cardiac catheter laboratory of great concern. The question is, should we restrict the use of peri-operative TOE to certain operations or patient groups or personnel until we better understand strategies for the prevention of peri-operative TOE-related complications? Intra-operative TOE has previously been shown to modify the planned surgical operation in 15% of cardiac surgical procedures 5. Most cardiac anaesthetists will recall cases such as a patient scheduled for an aortic valve replacement for aortic stenosis when the intra-operative TOE examination before median sternotomy finds no evidence of aortic stenosis. Furthermore, Skinner et al. investigated differences between pre-operative transthoracic echocardiography (TTE) and intra-operative TOE and found that intra-operative TOE revealed unexpected findings in 6% of cases necessitating a change to the procedure in 4% 6. In these cases, the pre-operative TTE was inaccurate in 44% of cases either by omission, inaccuracy or disease progression. We would argue that, although a pre-operative TTE has the advantage of being non-invasive, it cannot replace intra-operative TOE. In our opinion, there is sufficient evidence to demonstrate that the benefits of intra-operative TOE outweigh the risks, even if these risks are now greater than previously thought 4. Ramalingam et al. explore the issue of informed consent, which is of crucial relevance given the higher than expected risk of major complications and death from a procedure many may consider to be benign. Modern healthcare has moved from the traditional paternalistic approach to a patient-centred approach incorporating informed consent and shared decision making 7, 8. In 2011, The Kings Fund defined the process by which clinicians and patients should work together to select tests, treatments, management strategies or support packages based on clinical evidence and the patient's informed preferences 9. Clearly, TOE, as an investigation, with its known risks and benefits, should come under this definition. At the same time, it is not a requirement to obtain signed consent for anaesthetic procedures that facilitate another treatment, such as surgery 10. Although there is no requirement for a separate signed consent form, we remain duty bound to document the verbal consent process including discussions and questions around it. Failure to do so may lead to negative sequelae, including litigation. We recently reviewed our local peri-operative TOE consent process following two major complications. Our department reached a consensus that when TOE is performed as part of a surgical procedure, there is no requirement to obtain written consent. We do, however, document verbal consent, as we would for any invasive procedure such as central neuraxial blockade or central line insertion, and we feel this is sufficient. There is no question that TOE is a vital monitoring and diagnostic tool in many areas of medicine. Due to its increasing popularity, there is also an increase in the requirement for training. As with any practical skill, this should be done in a safe and patient-focused way 11. Transoesophageal echocardiography is a technical skill which requires both theoretical knowledge as well as the acquisition of practical skills through ‘hands-on’ training. Some skills can be obtained through increasingly available simulation programmes, but many feel there is no substitute for ‘hands-on’ training in the operating theatre 12. Simulation is well validated as an educational tool within the field of medicine 13 and rapidly gaining popularity for training in TOE 12. In fact, one small study demonstrated that TOE simulator training was superior to ‘hands-on’ theatre teaching with the simulation group having a better understanding of anatomy and pathology resulting in improved trainee satisfaction 12. The accepted standard for informed consent is to provide information that ‘a reasonable patient’ would want and need to know to make an informed decision. Although we are all familiar with this process, relatively little information is given to the patient about training. The Association of Anaesthetists consent guidelines state that “the risks and benefits of each procedure and its components, both to the patient concerned and to society in general, must be considered” 10. This supports training, as it is of benefit to society. Porta et al. investigated whether the routine disclosure of trainee surgeon participation during affected the consent process 14. Most patients appreciated the importance of teaching and trainee surgeon participation, with 94% consenting to trainee participation. Unsurprisingly, this willingness to participate decreased if trainees were less experienced and if informed that trainees would perform the procedure with direct or distant supervision. The study also demonstrated that most patients wished to receive information about trainee participation in their surgical procedure. Whether or not full disclosure is feasible or risks a reduction in the number of patients providing consent has no easy answer 8. Porta et al. argue any reduction may be offset by a more detailed explanation of the benefits of teaching. In our institution, the consent forms states that “I understand that you cannot give me a guarantee that a particular person will perform the procedure. The person will, however, have appropriate experience”. We do not feel that patients need to be specifically informed that a trainee will be involved in the anaesthetic, including the TOE, as they will either be directly supervised or fully competent . We do, however, run a ‘hands-on’ TOE course twice a year and we are in the process of reviewing our policy to consent patients who would potentially participate in the TOE course. We do not believe that the incidence of complications precludes ‘hands-on’ TOE courses if patients are properly consented and the patient is to have a TOE as part of their operation. Steps can be taken to mitigate risks, such as avoiding multiple examinations and probe insertion performed only by the course instructor and observed by trainees. For ‘hands-on’ training courses, we advise separate written consent as the patient is likely to be subject to more probe manipulations than normal 10, 15, 16. Clinicians should always undertake a risk vs. benefit assessment on each patient for each clinical procedure. The identification of patient- and procedure-specific risk factors is vital if we are to reduce TOE-related complications. These risk factors have not been identified by Ramalingam et al., and in patients undergoing cardiac surgery, we assume these risk factors may include: co-existing gastro-intestinal pathology, such as a hiatus hernia; systemic anticoagulation; prolonged probe insertion; periods of low cardiac output; periods of non-pulsatile flow; increased frailty; musculoskeletal disorders and the use of antiplatelet agents or steroids. Our patients are increasingly elderly and frail, which will undoubtedly increase the risk of these complications. It is not yet clear where the balance lies with regard to the decision to not undertake a TOE examination and decision making is likely a function of a large number of patient, anaesthetic and surgical factors. This national audit is similar in concept, although smaller in scale, to the series of National Audit Projects (NAP) undertaken by the Royal College of Anaesthetists. The scale of the NAP projects would be impossible to match for the investigation of TOE-related complications, as the denominator in the NAP projects is every anaesthetic given in the UK in one calendar year, which is over 3 million. Although the study by Ramalingam et al. may inform the incidence of complications and the risk of death relating to TOE, it was not large enough to inform us as to which patients are at risk of these complications. Unfortunately, it would be impractical to undertake a study like a NAP project, as to achieve the number of examinations needed would take approximately 133 years. We feel that the development of a national registry or a yellow card system would be a more practical solution. We hope this study will also open the door to funding to enable the collecting of more detailed prospective observation data for all patients undergoing TOE examinations in the UK. The majority of TOE examinations occur in patients undergoing or following cardiac surgery or Interventions in the cardiology catheter laboratory. The National Institute for Cardiovascular Outcomes Research (NICOR) collects clinical information on all patients undergoing adult cardiac surgery and interventional cardiology into secure registries aiming to improve clinical practice and patient care. There are also a number of organisations such as the Healthcare Quality Improvement Partnership (HQIP) which supports national audit and clinical outcome programmes. We suggest that collaboration with NICOR or HQIP would be worth exploring as much of the infrastructure is already in place. In conclusion, it is not easy to set out a list of national implementable practice recommendations resulting from observations of rare events, no matter how catastrophic they are 17. However, there are sensible measures that may reduce the risk of major complications, such as: the use of laryngoscope for probe insertion 18-20; including safety aspects of TOE probe use in TOE clinical training and courses; reviewing consent and procedures around ‘hands-on’ training courses and making careful benefit vs. risk judgements on a case-by-case basis for all patients. That said, there is an urgent need for prospectively funded studies to better understand the mechanisms of TOE-related complications and how they might be prevented. For now, it is our view that peri-operative TOE will continue to be a vital part of the armamentarium of the cardiac anaesthetist, and increasingly, the general anaesthetist or intensivist. Until further information is available, we recommend gentle probe insertion, ideally by an experienced operator and with an insertion aid, and for the number of probe manipulations to be limited as much as feasibly possible. No competing interests declared.
Ashworth et al. (2019) studied this question.