Bailliere's clinical anaesthesiology最新文献

Over the last decade, transoesophageal echocardiography combined with Doppler modalities has evolved into the single most comprehensive diagnostic method in clinical cardiology. The multiplane transducer systems provide a higher yield of diagnostic quality images than mono- and biplane systems in less time. It is therefore the ideal modality for the intraoperative refinement of surgically relevant echocardiographic decision-making and monitoring. It is an essential tool in the evaluation and treatment of critically ill patients who often present with a diagnostic dilemma in the emergency department and in the intensive care environment, especially in mechanically ventilated patients. Further miniaturization of transducers will allow continuous monitoring of cardiac function of conditions in which the clinical status may rapidly change.

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.

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.

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.

The preoperative period means for the majority of patients a distressing situation, which is characterized by anxiety and fear. This is not only uncomfortable for the patient, but the simultaneously occurring activation of the sympathetic nervous system is potentially dangerous for a predisposed patient. Therefore, the primary goal for the patients preoperatively is to reduce anxiety and to induce sedation. Furthermore, if indicated, premedication should minimize the risk of an aspiration syndrome, prevent postoperative nausea and vomiting (PONV), provide analgesia, reduce secretions and control infections.

Besides fear and anxiety, stress may even cause an adaptation syndrome or depression. Physiological reactions of all organ systems to epinephrine and norepinephrine result from the stimulation of the sympathetic nervous system. To quantify these effects physiological and biochemical parameters are used. Fears may be recognized consciously or may be masked; for anxiety there is a differentiation between trait-anxiety and state-anxiety, which are of differing importance. It can be stated that the perioperative anxiety influences the patient's outcome.

For the preoperative medication both the individual patient, due to the physical and psychological status and to their history, and the desired goals have to be considered. The most commonly used ways of administration are oral, rectal or intranasal. We can choose our pharmaceutical premedication for anxiolysis and sedation from different substance classes as benzodiazepine, barbiturates, α-2-agonists, being aware of specific effects and side effects and also the possibility of antagonization. On the other hand, the anaesthesiologist has to know the meaning of the psychological premedication too.

Other unpleasant experiences for patients postoperatively are nausea and vomiting, which are to be treated prophylactically in patients with a known history of PONV. Anticholinergics are no longer routinely used for premedication, and from a legal point of view this is no longer recommended.

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.

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.

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.