Minimally invasive heart surgery, for either coronary artery or valve surgery, has been evaluated for a few years. Surgeons and anaesthesiologists have encountered new challenges with these new techniques. There is no doubt that ‘minimally invasive’ surgery increases the technical difficulty for the surgeon and limits the exposure of the heart. Transoesophageal echocardiography (TOE), by giving complete and on-line anatomical and haemodynamic information, will obviously take a major place in this setting. It gives an instantaneous view of the filling of cavities and the contractility of both ventricles, in a situation where the heart is not exposed. It allows a more complete de-airing to be performed at the end of surgery. Mitral valve repair can be evaluated at the end of surgery, which is mandatory in a situation where surgical difficulties are increased. Other indications of TOE are also presented; some development might arise in the future since minimally invasive surgery is still evolving.
Most high-risk patients scheduled for surgery benefit from treatment designed to improve both their symptoms and their life expectancy. Cardiovascular treatments interfere with regulatory mechanisms of blood pressure and regional circulations, or they affect the cardiac electrophysiology and contractility. This explains why most peri-operative circulatory abnormalities are not due to the effect of anaesthetic agents on the circulation but to the interactions between cardiovascular and anaesthetic agents, both of which alter the functioning of several physiological systems. On the other hand, when given perioperatively, some treatments are effective in blunting the circulatory response to surgical stimulation and post-operative stress. In this chapter we describe the interactions between treatments chronically taken by high-risk patients and anaesthesia. This subject makes one look at-physiology and pharmacology and allows a better understanding of the compensatory mechanisms activated in response to the stress of surgery and anaesthesia.
Pre-operative cardiac interventions may be performed before a planned non-cardiac surgical procedure in order to optimize the patient's status and to reduce peri-operative morbidity and mortality (MM). The interventional procedures in patients with coronary artery disease are coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty, in patients with severe aortic stenosis, aortic valve replacement or aortic balloon valvuloplasty. These procedures can only be recommended if surgery without intervention would result in a higher peri-operative MM than the direct approach. Several aspects make the decision process difficult: lack of prospective randomized trials, specific indications for specific procedures, small cohorts of clinical studies, changing management in surgery, anaesthesiology and cardiology, and the influence on short- and long-term outcome. Excellent decision analysis models and guidelines of task forces, however, may help the clinician to obtain sufficient support for his or her pre-operative strategies. Finally, the local experience of the surgical, anaesthesiological and cardiological team has to be taken into consideration before the decision is made, if the individual patient is to benefit from the pre-operative interventional procedure.
When more than one drug is used at the same time, there is the potential for an interaction. If a muscle relaxant is being used, there must already be at least one other drug in use, the anaesthetic agent. It is common to use several drugs simultaneously during an anaesthetic, for example, systemic analgesics or antibiotics. In addition, the patient may be receiving therapy for a pre-existing medical disorder. As the number of drugs in use at a time increases, so does the potential for interactions and with the large and increasing number of drugs available on the market it is certain that this problem is set to rise rather than fall. This article examines many of the common interactions involving muscle relaxants which may be encountered during anaesthesia.
Transoesophageal echocardiography (TOE) is an important tool used to investigate closely all cardiac valves. With respect to cardiac valvular surgery, TOE has gained a most important place as an intraoperative diagnostic and monitoring technique. In this chapter, both mitral and aortic valvular disease with respect to intraoperative management will be discussed. Repair of the mitral valve is another important issue in modern cardiac surgery. Accurate and meticulous assessment of the mitral valve morphology and function by means of multiplane TOE provides a crucial asset for the cardiac surgeon during and after repair of the valve, improving outcome and reducing costs.
Transoesophageal echocardiography (TOE) is an outstanding tool for the clinical management of trauma patients. It provides valuable information on haemodynamic instability, diagnosis of myocardial contusion, traumatic valve dysfunction, traumatic aortic injuries, intrathoracic bleeding and systemic gas embolism related to pulmonary contusion. The accuracy of TOE in the diagnosis of traumatic aortic injuries is not perfectly determined: the main limitation is the operator dependency. Experience of trauma patients and specific signs of cardiovascular injuries are the keys to the extensive use of TOE in trauma centres. The main interest in TOE is the capability to perform TOE promptly upon admission, in the intensive care unit and in the operative room. In the case of delayed surgery of aortic injuries, TOE examination can participate in the decision-making process.
Different types of receptor-mediated mechanism play a key role in cellular transmembrane communication. The majority of plasma membrane receptors mediate the effects of neurotransmitters and hormones through activation of GTP-binding proteins (G-proteins). Coupling of the activated receptor to a G-protein initiates (occasionally inhibits) a cascade of enzyme-catalysed reactions leading to the production of one or more second messengers, eventually leading to the physiological response. The most commonly known cascades are the phosphoinositide and the cAMP route. This paper will describe the key concepts of G-protein-mediated signalling of both cascades and introduce the concept of ‘cross-talk’. Further, the effects of anaesthetics on the intracellular components of these signalling pathways will be reviewed.
Alterations in haemoglobin are associated with increased risk of cardiovascular events not only in normal life but especially in the peri-operative setting. Anaemia as well as polycythaemia are symptoms of an underlying pathology and need further diagnostic evaluation for adequate treatment. Specific treatment of pre-operative anaemia is indicated, because simple transfusion of allogeneic blood does not necessarily reduce postoperative morbidity and mortality. Also, in patients with polycythaemia a reduction of elevated haemoglobin levels is essential to avoid complications due to hyperviscosity. In all patients the risk of allogeneic transfusion of blood products has to be calculated and alternative strategies should be taken into consideration. However, those methods have to be performed in a comprehensive multimodality programme adapted to the actual transfusion requirements, the patients' individual needs, the equipment available and the experience of the responsible physicians.
The context of the current outcome movement is discussed and different outcome measures are presented. One central issue is analysing the advantages and drawbacks of the various methods of assessing pain. However, relying solely on pain as an outcome measure is mostly inadequate in chronic conditions: the report of pain itself is already influenced by psychosocial factors, which, in turn, are themselves substantially related to outcome and are therefore considered to be important outcome variables. The impact of pain on psychological as well as work-related factors is emphasized, and appropriate ways of measuring improvement, and distinguishing statistically from clinically important change, are presented. Basic principles to develop and use good outcome assessment need to be observed.
The primary goal of pre-operative evaluation is to assess adequately the patient's preoperative condition and to diagnose and possibly to treat disturbances and diseases which may be of relevance to the course of anaesthesia, surgery and the post-operative period. A pertinent medical history and a physical examination by an experienced anaesthetist are compulsory. A minimal set of tests should be carried out in all patients. The results obtained from these tests were very abnormal in a variety of studies; the information was not always apparent from the history and the examination although it was of relevance to anaesthesia and the post-operative period. Further laboratory tests such as haematocrit and blood glucose and potassium (K+) concentrations should only be ordered if indicated on the basis of the history and the examination. This small set of tests seems to be justified for the following reasons:• to identify unexpected risk factors not apparent from the history and the examination;• to avoid additional costs resulting from deferring a case due to incomplete tests;• to avoid medicolegal consequences of a possibly incomplete pre-operative evaluation;• to protect patients from unnecessary invasive investigations. • to avoid additional costs resulting from deferring a case due to incomplete tests; • to avoid medicolegal consequences of a possibly incomplete pre-operative evaluation; • to protect patients from unnecessary invasive investigations.
The pre-operative examination is an indisputable duty of the anaesthesiologist. It can be performed in three different ways: the bed-side visit, the anaesthesiological consulting hour and the pre-operative clinic. The bed-side visit enables the anaesthesiologist scheduled for giving anaesthesia to introduce himself or herself to the patient. There is no additional cost for staff and equipment; however, the investigation is limited to a cursory interpretation of previous investigations and examinations. The best way to perform a pre-operative anaesthesiological examination is the pre-operative clinic. The staff of the pre-operative clinic comprises an anaesthesist, a nurse and a secretary. The examination is standardized and therefore easy to perform, easy to teach and easy to control. It includes an interview with the patient, a physical examination and the evaluation of several screening tests, if available (laboratory tests, chest X-ray, lung function and resting electrocardiogram). The complete examination enables the decision on whether the patient is fit for anaesthesia or not to be made. In a patient declared to be unfit the pre-operative condition has to be optimized and additional tests or consultants are required to rule out severe pre-operative diseases suspected on the basis of the pre-operative anaesthesiological investigation. If the suspicion is not confirmed, the patient proceeds to operation. If concomitant diseases are verified the surgical intervention is postponed until the patient's condition has been optimized. The costs of the pre-operative clinic are higher, mainly because of the need for additional anaesthesiological staff. However, as the pre-operative clinic enables a thorough and complete evaluation in most cases, it is the optimal presentation of the discipline anaesthesia. In our experience it plays a major role in quality management of patient care.
Transoesophageal echocardiography has rapidly become an important diagnostic modality for patients with aortic atherosclerosis or aortic dissection. Use of this modality can help direct patients to proper therapeutic modalities. This paper will review the role of transoesophageal echocardiography in these disease processes.
Interactions between intravenous anaesthetic agents can be either pharmacokinetic or pharmacodynamic. The clinical significance of a pharmacokinetic drug-drug interaction will depend on the magnitude of the change in the concentration of the drug at the site of pharmacological action. Intravenous anaesthetic agents can influence the distribution and elimination and/or the effect of other co-administered intravenous anaesthetic agents. Because of the larger pharmacodynamic variability (300–400%) compared to the pharmacokinetic variability (60–80%), pharmacodynamic interactions are more important clinically than pharmacokinetic interactions. Many pharmacodynamic interactions involving intravenous anaesthetics are synergistic, and this allows lower doses or concentrations to be used to achieve adequate depth of anaesthesia, with a corresponding reduction in the incidence of side-effects.
A 12-lead electrocardiogram (ECG) allows the recognition of cardiac diseases that may have evolved without causing subjective disturbances. ST changes, bundle branch blocks or left ventricular hypertrophy as well as arrhythmias or premature ectopies are the most important findings. In younger patients the detection of a pre-excitation syndrome (especially Wolff-Parkinson-White) is essential, as it does require special therapeutic management. At our pre-operative clinic a resting ECG is part of the screening programme. The data of 18 939 patients were evaluated over a 3 year period, divided into two categories, with (category I) or without (category II) previous cardiac disturbances in their history. In comparison the resting ECGs of 10 523 healthy firemen (category III) were evaluated. The percentage of pathological ECG findings in the patients scheduled for noncardiac surgery was high. Depending on the decade of their life, 9.5–45.2% of subjects in category I (without any previous cardiac disturbances) and 13.2–80.2% in category II had a pathological ECG. In contrast, only 1.6–4.2% of subjects in category III had pathological ECG findings. The statement that the percentage of relevant pathological findings is increasing with age can be emphasized although a threshold cannot actually be defined: there is no difference in the incidence of changes in the age groups from 40 to 60 years. On the other hand, surgical patients without any cardiac history showed an incidence of pathological findings of 7.6%. The ECG is an inexpensive, easy-to-perform non-invasive procedure. In combination with an exact physical examination and a careful judgement of the impact of the findings on anaesthesia it allows a reliable pre-operative evaluation.
The incidence of pulmonary aspiration of gastric content according to prospective and retrospective studies lies between 1.4 and 4.7 aspirations per 10 000 operations. Mortality has decreased to 1/71 829 anaesthesias. Reasons for an increased incidence of aspiration are higher American Society of Anesthetists status, emergency surgery, pregnancy and intestinal obstruction. New guidelines for elective surgical patients include no solid food for 6–8 hours but clear fluids up to 2 hours before operation. Acid antagonists and gastrokinetics should be given to patients with increased risk.
Advances in transoesophageal echocardiography (TOE) have made this modality a powerful diagnostic tool in the critical care unit. TOE in combination with stress (atrial pacing, pharmacological stress) provides important information about myocardial ischaemia and myocardial viability. Recent progress in transducer technology and computerized image processing brings three-dimensional and contrast-enhanced TOE closer to the critical care unit. Finally, miniaturization of probes and automated contour detection techniques make TOE a sensitive and continuous monitor of global and segmental left ventricular function.
Pre-anaesthetic evaluation serves the purposes of maximizing both anaesthetic safety and efficiency of healthcare delivery. With the advent of outpatient care, the pre-anaesthetic evaluation clinic has become common. In the emerging American model, computerized records speed the gathering of patient records and the assessment of patient condition. Physician entry of patient evaluation is moving from dictation to direct physician entry, which will accelerate as handwriting and voice recognition systems mature. Purchasers of such systems should consider the security of the system, including authentication, authorization, encryption and storage systems utilized.
Chronic pain is difficult to treat successfully. The lack of satisfactory outcome from the traditional medical, pharmacological and surgical approaches was an impetus to the development of specialty treatment facilities—multidisciplinary pain centers (MPCs). With health-care costs continuing to rise, the clinical efficacy and cost-effectiveness of MPCs have recently been challenged. In this chapter, it is argued that the efficacy of treatment for chronic pain should be evaluated on multiple criteria: reduction in pain, use of analgesic medication and utilization of the health-care services. Increases in functional activity, return to work and closure of disability claims should also be considered. The published results for MPCs are reviewed in comparison with alternative treatment methods. The results suggest that MPCs are more effective than alternative monodisciplinary approaches. Furthermore, it is concluded that MPCs can produce saving of billions of dollars in terms of health-care expenditure and indemnity costs.
Several recent guidelines have been published to codify the pre-operative evaluation of the cardiac patient undergoing non-cardiac surgery. Considering the lack of any randomized clinical trials in this area, they have incorporated information from both prospective cohort studies and the experience from the general care of the cardiac patient. The decision to perform testing is based on the clinical risk factors, exercise tolerance and surgical procedure. Testing should not be performed unless the results will actually change practice. Among the interventions advocated to reduce peri-operative risk, the decision to perform coronary revascularization before non-cardiac surgery must include issues related to local rates of morbidity and mortality for each of the procedures and potential long-term benefits.
Anaesthetists are occupied with the possibility of complications during the peri-operative period. All previously published proposals have attempted to estimate the pre-operative state of the patient in order to be able to judge the risk of the impending anaesthetic treatment more reliably. In this chapter we describe the predictive value of the most common anaesthetic classification systems. The prediction of the ASA grade, the Goldman cardiac risk index, the Mannheim checklist and the Munich checklist for peri-operative complications are analysed. Furthermore, we give an overview of the extensive literature of the risk classification in anaesthesia in the different medicine compartments with a special view on ambulatory patients.
