Smallpox and its control in Canada.

Edward Jenner's first treatise in 1798 described how he used cowpox material to provide immunity to the related smallpox virus. He sent this treatise and some cowpox material to his classmate John Clinch in Trinity, Nfld., who gave the first smallpox vaccinations in North America. Dissemination of the new technique, despite violent criticism, was rapid throughout Europe and the United States. Within a few years of its discovery, vaccination was instrumental in controlling smallpox epidemics among aboriginal people at remote trading posts of the Hudson's Bay Company. Arm-to-arm transfer at 8-day intervals was common through most of the 19th century. Vaccination and quarantine eliminated endemic smallpox throughout Canada by 1946. The last case, in Toronto in 1962, came from Brazil.

Evolution of 20th century attitudes to prophylaxis of pulmonary aspiration during anaesthesia.

PURPOSE: To describe the evolution of aspiration risk identification and prophylactic management during general anaesthesia as presented in the United Kingdom (UK) anaesthesia textbooks published 1900-1998. METHODS: The Cumulated Index Medicus, 1900-1997, was searched under the headings: anaesthesia, aspiration, and pneumonia for relevant articles. A classification of features was created using key words and phrases: fasting guidelines, gastric emptying, intestinal obstruction and peritonitis, gastro-oesophageal function, upper oesophageal sphincter, raised intra abdominal pressure, pregnancy, posture and difficult tracheal intubation. Finally, 46 20th century UK anaesthesia text books were studied for the presence or absence of these features. RESULTS: Throughout the century, intestinal obstruction was a recognized risk factor. Only in the 1940s did some authors mention many of the now known risk factors. Hazards for the pregnant patient were described and in the 1960s the importance of the cricopharyngeus muscle was identified. Prophylactic measures included food and water restriction recommendations, especially in the latter half of the century and gastric lavage and drainage were mentioned throughout the century, as was posture at induction. In the 1950s tracheal intubation began to be routinely recommended. In the 1960s, cricoid pressure appeared and then a burgeoning interest in pharmacological control of gastric content character. Awake tracheal intubation is not always mentioned in 1990-96 textbooks. CONCLUSION: The consensus of information in textbooks since 1970 was lacking in the previous part of the century. Current textbooks are fewer and are published less frequently. Their role in contemporary anaesthesia education and update merits review.

Stethoscopy during anaesthesia.

PURPOSE: First, to determine when, following the description of stethoscopy by Laennec, it was used by anaesthetists in an operating room and, second, to describe the developing possibilities for stethoscopic monitoring. METHODS: A manual search of the medical literature based on Index Medicus and relevant publications were obtained and analyzed. Textbooks randomly available were also read. PRINCIPAL FINDINGS: Stethoscopy was first described early in the 20th century but was not widely recommended for anaesthesia until the 1950s. The change in attitude to stethoscopy during anaesthesia was probably due to alterations in anaesthesia delivery; increasing difficulty in employing direct human sensing. However the complexity of practice often makes traditional stethoscopy ergonomically unsatisfactory. Substantial research in the sensing and analysis of lung sounds support the contention that cheap visual displays of information from suitably designed sensors could be made available for anaesthetists. CONCLUSION: Current advances in sensing, analysis, and display of lung sounds could be used to create a simple and cheap device helpful for monitoring in the operating room.

Oropharyngeal and nasopharyngeal airways: I (1880-1995).

PURPOSE: During the past decade the laryngeal mask airway (LMA) has dominated literature about airways for use during general anaesthesia. The LMA addresses clearly defined clinical objectives. The purpose of this study is to determine whether those objectives were described collectively with reference to earlier airway designs. METHODS: The anaesthesia sections of Index Medicus 1880-1995 were read and publications in the English language about airways were obtained and analysed. Secondary information sources were references to causes of respiratory obstruction. This was supplemented by random reference to available textbooks. RESULTS: The multiple objectives, as least partially, satisfied by the LMA were not described collectively at the time of Hewitt's presentation of an oropharyngeal airway in 1908 and largely were neglected until the present time. CONCLUSION: The design of airways has been based on clinical circumstances and perceived requirements of the time. In contemporary anaesthetic practice, distinct clinical situations still occur and there is a role for different device designs. Currently for supraglottic airway management during general anaesthesia, four types of airway should be available: a Guedel airway, nasopharyngeal airway, a laryngeal mask airway, and an airway specifically designed to facilitate blind tracheal intubation.

Implication of anaesthesiologists' varying location during surgery.

Anecdote indicates anaesthesiologists in the operating room are not invariably at the head of the operating table beside their equipment. The validity of this was investigated by a nationally distributed questionnaire. The results support the anecdotal evidence. The behaviour can be justified so supports a recommendation for appropriate visibility of information displays. Whether such action would improve patient safety is debatable.

Anaesthesia monitoring: the human factors component of technology transfer.

Resistance to change in monitoring practices from within the anaesthesiology community is a formidable obstacle, and coercive and exhortatory solutions are likely to be unsuccessful in some situations. An analysis of publications about technology transfer and professional obsolescence, and application of this data to the practice of anaesthesia, reveals various stresses that technology transfer from research areas to the work-place may induce in vulnerable anaesthesiologists and account for their attitudes. It is suggested that the invaluable pronouncements of high profile anaesthesiologist groups must be supplemented by supportive behaviour by physicians and administrators at an institutional level. The human factors issues to be addressed include: (i) Monitored data acquisition skills. (ii) Possibility of acting on monitored data. (iii) Assistance for personal insight into attitudinal difficulties that may be encountered. (iv) Data supporting the value of the device. (v) Ergonomically effective integration of the monitor into the work station. Alternatively the perceptions of potential users may accurately reflect changes in their status in the new work situation created by monitors, and decision making aids that may or may not be derived from them. Thus, plans to present job satisfaction in related clinical areas or to associate the proposed new system with evaluation of its effect on patient outcome will be necessary. In this way the clinician becomes involved in clinical research, a quality of personal and quality care development.

Self-perception of the ability to work in the cold.

Accumulating evidence of beneficial effects from physical exertion must be balanced against increased risk of cardiac arrest during performance. There is evidence that, by using such cues as heart rate, individuals can monitor their level of exertion perceptually. We undertook experiments to discover whether temperature and heart rate interact to affect self-perception when the effective temperature is moved downard from the comfort zone. In the first pilot study, 36 males practiced a new game, SwedeBall, for a period of 20 minutes. Twelve were randomly assigned to play at a temperature of 22 degrees C, another 12 to play at 0 degrees C, and the remaining 12 to play at -7 degrees C. The players showed tendencies toward an overall improvement in self-evaluations after brief practice, with more favorable responses when the temperatures were lower. In a second experiment on different days, 8 men pedaled a standard bicycle mounted as a wind trainer in a controlled environment chamber where the effective temperature was set at 26 degrees C, 8 degrees C, or -10 degrees C. The first 5-minute ride at each temperature was at a heart rate of 120 beats per minute (bpm), the second at 140 bpm, and a third at 160 bpm. We measured ratings of perceived effort (RPE), thermal impression, discomfort, perceived rate of speed, and projected endurance. The result confirmed that RPE was lowered by temperature when heart rate was constant. The data also showed that the lowered temperatures uniformly produced more favorable self-perceptions on the other four scales. The outcome is related to physiological problems that might arise when temperature depresses heart rate and reduces the experience of effort.

A unified approach to providing general anaesthesia monitoring with special reference to developing countries.

Information concerning general anaesthesia, monitoring and ergonomics has been assembled to present a plan for the introduction of necessary monitors into a department of anaesthesia. This includes reference to: (i) The need for instrumental monitors; (ii) Division of tasks between anaesthetist and monitor; (iii) User education; (iv) Anaesthetist/monitor interface; (v) Hospital infrastructure. Emphasis is placed on the continued need for anaesthetists to employ their own senses for monitoring in the traditional manner and the essential role instrumental monitors should play in helping trainees to refine and calibrate their clinical skills. It is suggested that in situations where neither mechanical ventilators are available nor instrumental monitors necessary to refine the conduct of general anaesthesia a transitional stage in evolution could be the presence of two persons with clearly defined responsibilities for all the anaesthesia tasks necessary during a safely conducted case.

Monitoring regional anaesthesia.

Monitoring patients under regional anaesthesia is more challenging than patients under general anaesthesia but it has been somewhat neglected in anaesthesia literature. The fundamental differences are that during regional anaesthesia. 1. The patient is often awake. 2. Respiration is more difficult to measure. 3. Autonomic changes influence information obtained by pulse oximetry. 4. Monitoring personnel are at a greater risk of vigilance decrement. A review of reported complications during regional anaesthesia enabled conclusions to be reached regarding monitoring policies in an institution. These include particular reference to spontaneous respiration and cerebral function. The need for an appropriately skilled person monitoring the patient in the operating room at all times is emphasized, as is the necessity for education appropriate for the skills they may have to exercise even on rare occasions. Specific instruction in vigilance decrement avoidance should be part of that curriculum.

Application of automated human voice delivery to warning devices in an intensive care unit: a laboratory study.

Environmental concerns about the delivery of warning messages in intensive care units exist in the belief that conventional non-verbal alarm signals are perceived to be threatening by some patients. There is also a significant opportunity for error in interpretation by fatigued or anxious personnel. A laboratory study was undertaken to determine whether human subjects made fewer errors when messages regarding ICU related tasks were delivered by tape recorded human voice than by the non-verbal signals derived from devices in the ICU. Results demonstrated a statistically significant superiority of human voice messages over non-verbal signals. It is concluded that taped human voice messages merit field trials in intensive care units.

Laryngoscope design and the difficult adult tracheal intubation.

Clinical examination of a patient is very likely to reveal the factors making tracheal intubation difficult and thus increasing the likelihood of a traumatized temporo-mandibular joint or mouth. Although laryngoscopes and bronchoscopes incorporating fiberoptic visual devices are invaluable they are usually only employed for extremely difficult patients. Other laryngoscopes exist in a variety of designs and can be categorised according to the particular problem they address: (i) prominent sternal region, (ii) narrow space between the incisors, (iii) reduced intraoral space and, (iv) the anteriorly positioned larynx. An atraumatic tracheal intubation will be assisted if the laryngoscope blade to be used is selected on the basis of the anatomic difficulties prescribed by the patient. The Miller, Jackson-Wisconsin, Macintosh, Soper, Bizarri-Guffrida, and Bainton blades together with appropriate handles and fittings comprise a group from which selection can be made.

Affective responses to commercial and experimental auditory alarm signals for anaesthesia delivery and physiological monitoring equipment.

The affective response of subjects to the sounds of commercial and experimental auditory alarm signals was tested using a standard experimental protocol for measuring mood states and changes. Both types of signal evoked affective response. The commercial signals, however, evoked more response than the experimental signals, and that response was more negative in affect. A subset of the experimental signals, distinguished by specific acoustic characteristics, evoked particularly low levels of affect. The implications of low-affect alarms for the operating room are discussed.