Showing papers in "Baillière's clinical anaesthesiology in 1990"

Nosocomial pulmonary infections

Abstract: Summary Despite major advances in intensive care therapies and techniques, nosocomial pneumonia remains a frequent complication in hospitalized patients. It has been shown that bacterial colonization of the oropharynx and tracheobronchial tree plays a major role in the pathogenesis of nosocomial pulmonary infection, that the bacterial sources of colonization may be both environmental and exogenous, and that the critical illness alters patient's defences against colonization and infection. Severity of underlying disease, presence of impaired airway reflexes and the use of respiratory support devices have been recognized as the most important risk factors for development of nosocomial pneumonia. New and promising prophylactic strategies and sophisticated techniques of microbiological diagnosis have recently been developed. However, many areas of controversy still exist, concerning the definitions and the classification of nosocomial pulmonary infections, the feasibility of certain diagnostic procedures and the choice of prophylactic protocols. Further advances in the diagnosis, the prevention, and the treatment of this complication require new and carefully designed studies in well-defined populations of critically ill patients.

Pharmacokinetics and pharmacodynamics in the critically ill

Abstract: Summary Critically ill patients are frequently on drug treatment at the time of presentation,and usually receive additional drugs whilst in the intensive care unit. The necessity for each drug should be reviewed each day, risks weighed against benefits, and possible interactions borne in mind. Critically ill patients often have reduced functional reserves and adverse effects may be hard to detect. The use of a limited range of first-line drugs and of standard protocols developed with the aid of a designated pharmacist will minimize problems arising from inadequate stocks, incorrect storage, and errors in dispensing, dilution and administration. It has become fashionable to rationalize empirical dosing regimens on thebasis of systemic pharmacokinetic theory. However, this has contributed remarkably little to enhancing insight, or practices in the intensive care unit, as much of the available information is not relevant to critically ill patients, and because sudden changes in pathophysiology and blood concentrations cannot be accommodated by conventional pharmacokinetic analysis. There are also questions regarding the clinical relevance of drug blood concentrations, the influence of choice of site for blood sampling, the implications of the use of racemic mixtures, and of the effects of active metabolites. The use of physiological models and regional pharmacokinetics has the potential to provide the all-important ‘missing link’ between systemic pharmacokinetics and molecular pharmacology. However, much practical and theoretical work has yet to be done before this potential can be realized. For the moment, clinical practice should continue to be empirically based and reliance should be placed on the use of a few well-tried drugs and, whenever possible, on titrating dose against effect.

Recovery from day case anaesthesia

Abstract: Summary It is likely that almost 50% of all surgery will be performed as day cases in the near future. To provide safe discharge after longer and more extensive operations performed as day cases, we must carefully evaluate the patient's home readiness and instruct patients in such a way that they receive and understand all relevant information. Minimal criteria for safe discharge from the hospital are: stable vital signs for 1 hour, ability to walk without support, toleration of oral fluids, ability to void, none or minimal emesis, and no serious pain. If a patient does not have an escort home, the procedure should be cancelled or the patient should be admitted to the hospital. Recommendations not to drive after anaesthesia or sedation vary from between 24 and 48 hours, depending on the duration of anaesthesia. As the complexity of scheduled surgical procedures increases, patient safety and satisfaction will probably depend to an even greater degree upon the anaesthetist's medical skills and administrative abilities. The vast clinical experience has already proved that day surgery is as safe as inpatient surgery.

Psychological aspects of day care surgery for children

Abstract: Summary The psychological consequences of admitting children to hospital are summarized. Hospitalization stress has been assessed from measurements of physiological correlates of stress, from the observations of hospital and research staff, and primarily from questionnaires issued to parents. Long and short-term sequelae for both the child and the family are described and set in a historical context of the development of relevant psychological theories. Long-term effects are rare and specific to children from families in which adverse conditions exist and who suffer multiple admissions. Shortterm effects manifest in behavioural change are common, but are generally found to have dissipated 6 months after discharge. Psychological theories have emphasized the effects of separation of the child from parents, particularly at crucial stages of the child's development, children's interpretation of illness and hospital procedures, and the anxieties of parents about their child's admission. Children for whom adverse family circumstances prevail, such as discordant or broken home, those below the age of 6 years, and children or parents with high anxiety levels, are found to be particularly susceptible to the effects of hospital admission. It is for these children in particular that brief admissions, preferably for day care, are appropriate. Additional methods of reducing hospitalization stress by the provision of booklets, showing films, and making supportive nursing staff available are described. The authors conclude with a description of good practice and the optimum organization of day care units to minimize psychological trauma for both the child and family.

Ventilation―which mode?

Abstract: Choosing ventilation mode and settings IPPV remains the mainstay of ventilation therapy for patients with no spontaneous respiratory activity. These will be patients undergoing routine anaesthesia, comatose patients or sedated patients with respiratory failure. The use of PEEP is indicated when oxygenation is inadequate or in order to reduce high F iO 2 levels. The level of PEEP applied is chosen as a compromise between achieving satisfactory arterial blood gases and minimizing cardiovascular depression. Ventilator rates are adjusted during IPPV to achieve the required minute ventilation with given tidal volumes. Limiting factors include the absolute values of expiratory times in relation to the RC constant for the individual respiratory system, and the airway pressures produced with the given tidal volumes. In severe cases of asthma, controlled hypoventilation may be acceptable in order to allow full deflation of the lungs and avoid excessively high airway pressures. If full deflation of the lungs is not allowed, an ‘auto-PEEP' effect is produced as with the use of inverse ratio IPPV or with high ventilation frequencies as in HFV. Improved oxygenation in acute severe asthma with reduced hyperinflation and pleateau airway pressure, has been reported with the use of high inspiratory flows and low tidal volumes, in order to maximize expiratory times at a constant respiratory rate (Tuxen and Lane, 1987). Severe unilateral lung problems or mechanical mismatch may require the use of differential lung ventilation, possibly with mixed modes, in order to achieve satisfactory gas exchange. Such conditions include the occurrence of a unilateral bronchopleural fistula, a large unilateral bulla or severe unilateral collapse or consolidation. HFPPV or HFJV techniques in the past have been applied in extremecases of lung pathology where refractory hypoxaemia is a problem, or gross leaks from bronchopleural fistula have made IPPV ineffective. Certainly in cases of upper airway disruption the ability of HFJV to maintain ventilation in the absence of a sealed delivery circuit via a catheters makes it a technique of choice. The ability of HFJV to deliver high minute volumes also enables it to cope in the presence of large shunts. However, in cases of severe hypoxaemia, although HFV modes may offer improved oxygenation by promoting non-tidal mechanisms of gas transport at the higher frequencies (e.g. HFOV), or by taking advantage of grossly altered lung frequency responses, the consistent superiority of any one mode or combined mode has yet to be proven. Mixed spontaneous and mechanical modes of ventilation find their mainapplication in patients with spontaneous respiratory activity or in weaning from ventilation. IMV is commonly used in patients with an inadequate respiratory drive but who can generate adequate tidal volumes. While MMV may be more suitable for patients with variable respiratory drive, this mode still requires further evaluation. Pressure support appears to be more suitable for patients with adequate drive but poor respiratory effort, i.e. in conditions giving rise to low vital capacities and tidal volumes. During weaning from mechanical ventilation, the choice of mode and CPAP or sPEEP levels has to be made in a context that may not necessarily place P aO 2 or P aCO 2 level as the primary criteria. The mechanical ability of the patient to cope with the work of breathing may be a major problem and a compromise between gas exchange and work of breathing capability may have to be reached. Additional factors such as nutrition and patient psychology can also become important during prolonged weaning. CPAP and sPEEP techniques may also have a prophylactic role enabling patients with moderate respiratory dysfunction to avoid endotracheal intubation and/or mechanical ventilation. Accurate and adequate monitoring, including the measurement of respiratory mechanics, is essential for the optimum choice and adjustment of ventilation therapy.

The application of scoring systems in adultintensive care

Abstract: Summary Severity of illness can be described for a single system (injury severity score) or for the whole disturbance (APACHE II, III). APACHE II uses the extent of abnormality of basic physiological variables to stratify acutely ill patients by risk of death. Such a system allows comparison of outcome in similar groups for alternative therapies or methods of delivery of care. A direct relationship exists between the severity score and risk of death but this can only be clearly defined if an accurate diagnosis is made. Trend analysis of serial APACHE scores with organ failure scoring is a recent development of APACHE II allowing prognosis to be related to the number of organs in failure. When response of organ function over time is assessed in this way the possibility of individual prediction of outcome becomes more realistic. Mortality prediction modelling uses a method of maximum likelihood toproduce a probability of hospital mortality. Whilst prediction with an outcome model alone could prove extremely valuable, it is response to treatment which may well determine the final outcome. In common with other systems, sensitivity is poor, limiting individual clinical decision-making. There are great difficulties in effecting accurate severity scoring. Data collection must be meticulous and clinicians involved must have a thorough understanding of the principles involved, in particular those related to scoring the neurological state of the patient. Nevertheless scoring provides essential statistics to audit and support our clinical practice and to rationalize the provision of intensive therapy worldwide.

RECALL—an integrated system for making, retrieving and analysing anaesthetic records

Abstract: Summary This chapter describes a computerized system that has been designed to increase the accuracy, accessibility and utility of anaesthesia records. The software has been designed to provide flexible and easy data entry by anaesthetists. The extensive use of personalized menus allows rapid entry of intraoperative comments and noting of drug administrations. A chronological summary is instantly available whenever required. Drug data include time, dose, elapsed time since the previous dose and cumulative dose. All comments are automatically time and date stamped, and where appropriate, entries are checked to ensure that they lie within a legitimate range. To provide maximum flexibility, hand-held computers can be used for data collection on the ward as well as in the theatre. The system features direct interfacing of patient monitors which allows sampling at much faster rates than is possible using manual methods. A unique modular interface provides the flexibility to use a wide range of monitors of different makes and types. There is a full-colour, real-time trend graph of vital signs in a familiar format, and other screens may be selected without interrupting the acquisition of data in real time. Printed anaesthetic records are available both during and after the operation. The standard file copy for general use is in A4 format and contains all important data presented in chronological order. It is possible to obtain more detailed output for specialized needs. All data are stored in an electronic database from which records can be retrieved within seconds whenever required. Internal coding makes use of the Read Clinical Classification enabling meaningful exchange of data with other systems. Individual work stations are intended to be linked in a local area network which allows access to the shared database from any work station. There is also the potential for direct communication with the hospital patient administration system (PAS). The system produces a number of routine reports relevant to departmental activity analysis and analysis of resource usage. The database is interfaced to statistics software which gives access to a wide range of powerful techniques in addition to providing presentation-quality tables and graphs. In summary, the RECALL system is designed to automate the task of anaesthetic record-keeping so far as this is practicable and to free the anaesthetist's time for patient-oriented activities. It incorporates many features of practical importance and has proved a useful contribution towards improved standards of patient care. It makes it easy to prepare and retrieve anaesthetic records and its capability to analyse recorded data offers valuable aid in medical audit and theatre administration.

Automated anaesthesia records

Abstract: Although the anaesthesia record was the normal method for keeping an account of the anaesthetist's interaction with the patient (Beecher, 1940), it was given a low priority in what has always been one of the more actionoriented medical specialties. For a long time, it was used as an aide-mOmoire for the anaesthetist. Today, the growing complexity of pharmacological interventions with the patient demand more sophisticated physiological monitoring, which has created the necessity for a legible, well-documented, complete and informative anaesthesia record. In recent times, there have been considerable advances in health-care delivery, especially in the postoperative period. This has made the anaesthetist's personal record even more important, as the record becomes 'common property' as a profile of the physiological state of the patient. This lays profound emphasis on the quality, clarity, accuracy and visual form of the presentation of the data in these records. If anaesthesia monitoring is compared to cockpit monitoring in an aircraft, the anaesthesia record can be considered as the black box--a vital source of information. This chapter presents an account of the purpose and clinical use of the automated anaesthesia record, its contribution to quality patient care, and the frequently debated issue of the merits and demerits of these records. To give an overview of a current automated anaesthesia recording system, we have provided a short technical description of an anaesthesia charting system developed in Erasmus University, which has been used in the Thorax Centre of the Academic Hospital, Rotterdam for more than ten years by every anaesthetist as an 'electronic secretary', taking down the minutes of the interaction between the anaesthetist and the patient.

Local anaesthesia for day stay surgery

Abstract: Summary Regional anaesthesia has an important role in anaesthesia for day case surgery, either alone or as part of a balanced anaesthetic technique combined with general anaesthesia. The principal advantage is the provision of first-class postoperative analgesia which can be prolonged well into the postoperative period without danger to the patient. Other advantages include reduced perioperative morbidity, particularly postoperative nausea and vomiting, dizziness and sedation, all of which may lead to unexpected hospital admission. These problems are encounted most often with ophthalmic surgery and gynaecological surgery, both of which are frequently suitable for regional anaesthetic techiques. The use of regional anaesthetic techniques does not delay recovery times or discharge from hospital. The disadvantages of regional anaesthetic techniques include a small but significant failure rate, prolonged time to perform, and the fact that certain skills are necessary for its performance. There are a few contraindications to the use of regional anaesthesia but the majority of patients are suitable. These techniques are particularly appropriate for day case surgery in children and are usually used in combination with a light general anaesthetic.

The medicolegal aspects of automated anaesthesia records

Abstract: This chapter examines the legal aspects of automated anaesthesia records. It is important to look first at why the process of automatically recording information, as opposed to manually recording the same information, should generate any additional legal concerns at all. There are radically disparate viewpoints on the matter. One leading commentator has concluded 'Thus, with the current generation of automated anesthesia records, the prime disadvantage is medicolegal' (Eichhorn, 1988); while another suggests that 'Anesthesiologists and their hospitals may be held liable for failing to acquire or use computers' (MacKenzie, 1984). It appears that we are damned if we do and damned if we don't. The only apparent choice is that we may choose our poison. I do not subscribe to either of these viewpoints. I do not believe that there are significant medicolegal obstacles to the use of automated records, and I do not believe that an anaesthetist will be successfully sued under existing tort law for negligently failing to use a computer. There are, however, issues that must be understood and addressed in order to distinguish an asset from a liability. There are also several issues arising from the database retrieval aspects of computerized records which are indeed distinct from manual systems. In order to sort out the issues, I will examine the role of records in the outcome of malpractice cases, the 'standards' for record-keeping in anaesthesiology practice, the interpretation of these standards from the point of view of an 'expert witness', the implication of artefacts, and the implication of electronic database management. It is important for the reader to keep in mind that the legal system discussed here is that of the USA, where specific malpractice laws vary from state to state within the overall context of an adversarial system that is quite distinct from most European legal systems. With this caveat in mind, we must first consider the 'rules of engagement' in the malpractice battle.

Newer drugs in intensive care

Abstract: Systems for monitoring the efficacy and safety of new drugs in the general population are now reasonably well-established, but it is only in the last few years that the pharmaceutical industry and the medical profession have recognized the need to assess drugs formally in critically ill patients, rather than making assumptions based on simple pharmacokinetic studies in patients with stable failure of single organ systems such as chronic renal failure or cirrhosis. Two examples have drawn attention to this problem: the hypnotic agent etomidate (Hypnomidate) and morphine-based opioids. Etomidate was used for infusion-sedation of critically ill patients by clinicians who assumed that its safety in anaesthetic practice would apply in intensive care; and it was not until Watt and Ledingham (1984) reported the association of such infusions with an increase in mortality in multiple trauma patients that the potent inhibitory effect of etomidate on adrenal cortical function was discovered (Lambert et al, 1983). Old drugs used in new surroundings are potentially even more hazardous, as they may escape the vetting procedures applied to new drugs: the accumulation of active morphine metabolites in renal failure (Osborne et al, 1986) is still not recognized by some clinicians. Some pharmaceutical companies are now applying for product licences specifically for intensive care, and this is a welcome development. In time it should be possible to develop a standardized approach to the investigation of new drugs in critically ill patients, but there are difficulties that need to be resolved. The assessment of drugs in patients with multiple organ failure (MOF) may be complicated by polypharmacy, changes in drug receptors, altered plasma protein and tissue binding, changes in regional blood flow and drug distribution, accumulation of either the parent compound or potentially active metabolites, and the effect of haemofiltration on drug clearance. Two particular difficulties include the measurement of tissue (as opposed to plasma) drug levels, and the absence of accurate non-invasive measures of hepatic blood flow and hepatocellular function. Pharmacodynamic studies, particularly those which use survival as an end-point, must stratify for severity of illness to reduce bias (Knaus et al, 1984). In this brief review, we have selected new drugs of relevance to intensive care practice, and have included some older compounds, which are either

Management of multiple organ donors

Abstract: Summary Multiple organ donation from a beating heart donor is an efficient way ofproviding organs for transplantation. Surgical expertise is such that 1 year allograft survival in adults is greater than 60% for renal, heart, heart/lung, single lung and hepatic transplantation. The major obstacle to improving the waiting lists for transplantation is the supply of donor organs. Medical staff on the intensive care units must be able to recognize potential donors as early as possible and to obtain consent for organ donation. Once consent is obtained the intensive care unit must provide aggressive management of the donor to ensure optimum organ function before organ retrieval. For successful organ procurement and subsequent successful transplantation there must be good cooperation between the medical staff caring for the donor, the transplant coordinator and the transplant teams who perform the retrieval operation. Further education of both public and medical staff will ensure maximal awareness of the transplant programmes and so help reduce the current shortfall of donor organs required to meet present demands.

Paediatric day case anaesthesia

Abstract: Summary In the past 30 years there have been significant advances in anaesthetic and surgical techniques, equipment and pharmacology. These, together with the better understanding of the psychological effects of hospitalization on children, and encouraged by escalating health care costs, have stimulated a worldwide expansion in paediatric day stay surgery. Good preoperative preparation of both parents and child is vitally important to ensure that the surgery involves minimal emotional disturbance. Increasingly, attention is being given to parental involvement in anaesthetic induction and the use of oral or rectal medication where possible. This approach is best achieved in a self-contained day surgery facility with a team of dedicated and caring personnel. Anaesthesia for day surgery must include all the technical facilities and skill that would normally be applied to inpatients. In addition, the anaesthetist must be involved in establishing protocols for selection, preparation and discharge of patients. Important aspects of the perioperative anaesthetic care include efforts to minimize fasting and provision of adequate postoperative pain relief with minimal nausea and vomiting, with regional anaesthesia playing a major role. Follow-up of patients after discharge is also an important means of assessing and improving the quality of day surgical care.

Automated anaesthesia records: economic aspects

Abstract: Many types of system for automating anaesthesia records are under development, both commercially and as a result of purely professional or scientific endeavour. They have diverse aims, ranging from the collection of simple descriptive management data, to systems that collect clinical data on-line, prepare a record for the notes, and retain data for other purposes. The widely differing systems of medical practice found in Europe result in engrained attitudes which are barely appreciated and which influence the priorities of anaesthetists in different countries. However, many anaesthetists fail to consider the real costs of the available systems, or the time value of the result. Everything has a cost and everything has a value, which must be considered by those who have to take the decisions on what to purchase, and who may be less committed to automation than some of the potential users. There can be no doubt that enormous sums are involved. Fully automated systems involve sums running into thousands of pounds for each anaesthetizing location, without including the cost of off-line printers and of maintaining the systems. Simple arithmetic reveals that millions of pounds are involved, even in only one country; but will it be worth it?

Perioperative myocardial ischaemia and infarction in non-cardiac surgical patients

Abstract: Summary Cardiovascular morbidity and mortality associated with non-cardiac surgery increase with the probability and severity of coronary artery disease in the surgical population. In the absence of coronary artery disease, the risk of a perioperative cardiac event is negligible. Preoperative evaluation of patients should always include a thorough history and clinical examination but specific investigations should be individualized as false-positive results are common when the incidence of coronary artery disease is low. Recent myocardial infarction, symptoms suggestive of unstable angina and the presence of heart failure are powerful predictors of perioperative cardiovascular morbidity. A routine 12-lead electrocardiogram should be obtained for all men over 40 years and for all women over 55 years as well as for all patients with a history suggestive of heart disease. Stress testing, with or without thallium, is useful for patients with peripheral vascular disease, and dipyridamole-thallium imaging may be of value in risk stratification for those patients in whom adequate exercise levels cannot be achieved. The risk of a cardiovascular event during surgery can be stratified using a ‘risk index’. Coronary angiography allows precise definition of the coronary anatomy and accurate assessment of left ventricular function but this is usually reserved for patients with severe symptoms or for those found to be at high risk as a result of provocative testing, where it is felt that revascularization of the myocardium may be indicated before the proposed surgery. Every effort should be made to treat any reversible risk factors that arepresent (unstable angina, heart failure, etc.) before surgery, with the aim of decreasing perioperative morbidity and mortality. In general, all cardiac medications should be continued throughout the perioperative period unless specific complications occur necessitating their withdrawal. Throughout the stress of the perioperative period myocardial oxygen delivery must be maintained while myocardial oxygen consumption should be kept at a low level. Myocardial ischaemia is common in patients with coronary artery disease during anaesthetic inducation and perioperative infarction occurs largely in those patients who develop significant tachycardia, hypotension or hypertension during surgery, the risk of infarction being increased three-fold when perioperative ischaemia occurs. Monitoring of the cardiac rhythm, arterial pressure, ST segment changes and, in high-risk patients, more sophisticated parameters of cardiac function, will allow for the early diagnosis of myocardial ischaemia and allow therapy to be monitored. Anaesthetic risk cannot be eliminated but can be minimized. The anaestheticagents and technique can be tailored to a patient's cardiovascular status but much will also depend on the anaesthetist's experience and expertise. Even with the best management there will be circumstances when myocardial ischaemia and infarction will occur and successful management will depend upon recognition and treatment. Careful monitoring can help diagnose myocardial ischaemia but infarction may be difficult to diagnose unless there is a high index of suspicion. It is often not possible to obtain a history and the standard investigations such as the 12-lead electrocardiogram and cardiac enzymes can be difficult to interpret. Radionuclide techniques and echocardiography can be helpful. The initial treatment of myocardial ischaemia and infarction in the perioperative period is identical, with nitrates, β-blocking drugs, aspirin and calcium antagonists being used. Thrombolytic therapy is contraindicated during and immediately after surgery. A combination of improved anaesthetic agents and techniques, togetherwith advances in the treatment of coronary artery disease, appear to be making surgery safer for patients with heart disease.

Peroperative anaesthetic audit

Abstract: The need for audit of operating theatre work is clear, both from an ethical and a medicolegal standpoint--'in-house quality control is an important aspect of clinical practice' (Lunn and Devlin, 1987). The problem is to know what to record, and how to record it so that it will be both acceptable and worthwhile to working anaesthetists. The first report of the audit committee of the College of Anaesthetists (November 1989) suggested the use of logbooks to make a personal record for all anaesthetists, together with a record of departmental theatre service load, work in other areas such as the intensive care unit, morbidity and mortality audit, a critical incident register and education audit. We have been recording departmental and individual theatre service load for three years. At first, we attempted to record every fact about the anaesthetic to form a complete anaesthetic record so that no data would be lost. There are many variations on this theme: Cardiff (Lunn and Vickers, 1982), Glasgow (Todd et al, 1983), Harvard (McPeek, 1980) and others have collected large databases and distilled essential information from them. For example, at Cardiff (Farrow et al, 1984) and Cleveland (Schneider et al, 1979) it has been shown how one could begin to predict anaesthetic risk factors and hospital morbidity. This sort of work, however, requires substantial resources of manpower and funds which are seldom available. Moreover, when these data were considered more closely, the vast majority was of little use to a district hospital, where it is not generally necessary to collect information about drug and disease type during anaesthesia since this information is already available as part of the patient administration system or from the pharmacy computer. Computerizing the anaesthetic record was not part of our task. We had thus to define our requirement more clearly. It was to develop a system that could be used by an anaesthetic department to provide the peroperative data needed for audit and management on a daily routine basis. Information should be derived that would provide answers to the sorts of questions being asked by the College Visitors when reviewing a department, or by managers looking at working patterns. There should be in addition some record of the complications arising during anaesthesia. The system should use a standard software package, running on standard equipment that can be bought 'off the shelf', so that both can be used by the department for other purposes during the time that it is not processing data,

The critically ill child

Abstract: Summary The purpose of this chapter is to review common paediatric emergencies,their management in a general intensive care unit, and the indications for transfer to a specialist paediatric teaching hospital. Neonatal conditions are not discussed. There are many differences between sick children and adults that affect assessment, treatment and outcome. These are mentioned in the appropriate sections.

The value of anaesthetic records for morbidity and mortality studies

Abstract: Summary At the Karolinska Hospital in Stockholm computerized anaesthetic record-keeping has been used for more than twenty years. The results show that anaesthetic records are valuable for morbidity and mortality studies. The value of anaesthetic records for studies is dependent upon many factors. First of all it has to be realized that nothing can be found that has not been previously recorded, and that every study has to be carefully planned. Secondly, the record system itself, if it is to be used for studies, has to be carefully constructed with due consideration given to the interests of all active participants. The key factor is the medical personnel, who generate the data. If a frequent, medically relevant feedback to this group is not produced the value of the records quickly diminishes. It is also of great importance that the record system is managed by clinically active physicians, and that the decision-making positions are held by doctors. Of paramount importance to the value of studies based on records is the use of unambiguous words, and therefore all types of international standardization and collaboration are to be actively supported. There are problems of anaesthetic records that have not been satisfactorily solved, such as what to do with the enormous amount of data generated by modern monitors, and the question of averaging and redundancy. Computerized anaesthetic record-keeping is a promising field for scientific work.

Automatic data capture in anaesthesia

Abstract: Automatic data capture in anaesthesia implies the automatic transfer of data from a biomedical monitor, to a microcomputer or to a printer, with no manual input or manipulation of that data being required. The arrival of inexpensive microcomputers has made automatic data capture in anaesthesia an achievable reality. Additionally, more manufacturers of medical equip- ment are now providing the necessary hardware outputs on their products to allow automatic transfer of data. The advantages of on-line data capture to produce an automatic anaes- thetic record are many. The number of patient monitors present in the operating theatre is growing, and it is becoming increasingly laborious to transcribe the data they produce on to the anaesthetic record at regular intervals. During an intraoperative crisis, the anaesthetist will probably only have time to write down some of the figures immediately, filling the rest in from memory later or, worse still, not at all. Also, various studies have shown that anaesthetists tend to bias handwritten records towards more normal values (Zollinger et al, 1977; Logas et al, 1987; Lerou et al, 1988; Whitcher, 1988). The absence of a properly documented anaesthetic record may be a disadvantage to the anaesthetist if such a case should end in litigation (Gravenstein and Feldman, 1989). An automatic record-keeping system will continuously record all data such as heart rate, blood pressure and oxygen saturation, allowing the anaesthetist to concentrate on the patient. A further benefit is that the resulting anaesthetic record is legible. Another area of interest is in the manipulation, storage and retrieval of information. Data that are too complicated or are produced too rapidly to analyse in real time can be stored for later analysis. Parameters that are not available from a particular monitor's digital display may be derived in real time, for example automatic measurement of pulmonary capillary wedge pressure or rate-pressure product. Automatic data capture is essential in the use of closed-loop control systems of blood pressure, neuromuscular blockade or depth of anaesthesia (Ty Smith et al, 1984). For example, in the closed-loop control of blood pressure with a vasodilating agent such as sodium nitroprusside (SNP), the system is designed to maintain the patient's blood pressure (BP) around a preset value (Colvin and Kenny, 1989). Blood pressure is continuously measured from an intra-arterial cannula; the analogue waveform is collected