Conference Lectures

ERGONOMICS IN ANAESTHETIC PRACTICE
Dr.R.S.Raghavendra Rao
Professor &HOD,
BMCRI,Bangalore
The anesthesia workplace can be regarded as a complex human-machine-system (HMS). In this information-intensive “cockpit” the operator has to handle several devices. Not only visual but also auditory cues have to be integrated in the action-control-loop. It´s obvious that in some stressful and complex situations, a perceptual and cognitive overloading of the anesthetist could occur and therefore inhibit an efficient and safe interaction. The design of the interfaces and the form of information presentation has a significant impact on these aspects.
Ergonomics is a discipline that investigates and applies information about human requirements, characteristics, abilities and limitations to the design, development, engineering, and testing of equipment, tools, systems and jobs. The objectives of ergonomists are to improve safety, performance, and well-being by optimizing the relationship between people and their work environment. The terms ergonomics, human factors, human engineering and usability engineering are often used interchangeably; however, the term ergonomics is used exclusively. 
Ergonomics in a literal sense would mean, “Scientific study of man at work”. The neglect of human errors in such working environment is very common, but often ignored.This thought of ergonomics is mainly applied to some useful industry and some branches and aspects of medical field in the last few decades. The word ‘ergonomics’ is derived from two Greek words i.e., ergo:-work and nomos: - base or foundation. It was coined byMurrel in 1949, who led a team of scientists in England during World War II. Those were mostly designed to war and weapons slowly started expanding into other fields of social upkeep. Then it started progressing as Human factor engineering. The growth has been enormous in the field of medicine more so concerned with intensive care, radiology, anesthesiology, monitors and laboratoryetc.,
The role of the application of ergonomics as an effective and useful method in the practice of anaesthesia in model such as,
Anaesthesiologist --(Ergonomics) -- Equipment -- (Bio-engineering) -- Patient
Here there are three elements viz., anaesthesiologist, equipment and patient.
There are two interfaces, ergonomics and bio-engineering.
The first interface, ergonomics which was much neglect of the past is now gets high importance in providing proper machine. The latter interface is concerned with the interaction between patient and technology.
The aspects to be concentrated in Ergonomics are: 
1. Equipment design.
2. Work-place layout.
3. Environmental conditions such as lighting and legibility.
4. Skill acquisition, productivity and safety.

• Equipment design:

            The equipment, its parts and design needs utmost research and implementation. The levers and handles should suit and be at the comfortable position to handle. Itshould be thick enough to be securely held and preferably possess feel grip. Its better they are made agent specific, as seen in flow control knobs of anaesthesia machines. They must be positioned such that its movement should not cause interference with knuckle and prevent excessive movement of elbow. There should not be sharp edges or high spots. There should be proper blocking of static charges and proper insulation. The evolution of anaesthesia machine to the present day anaesthesia workstation, which apart from having all safety features with visible, audible and programmable alarms and built in a composite manner with inbuilt monitor, ventilator and data recording feature as well. They have stand-by power back up option also. The design is well planned such that there is choice of the desired parameters to be chosen and an option for upgrading easily without replacing the whole equipment. The introduction of anesthetic scavenging system has reduced the operating room pollution and minimized the risk of exposure among permanent theatre personnel.

• Work-space layout:

            The arrangement and selection of inventory and furniture should be given proper thought with improvisation. One of the simplest and most basic measures to take a note in the operationtheatre is to replace the traditional fixed rotating stool at the head end of the operating table for anaesthesiologist. This to be replaced with good quality ergonomic designed height alterable seat with a provision of writing desk. A chair with castors, height adjustable with proper backrest and easy accessibility with maneuverability would be desirable. Today’s design of operating tables, anaesthesia machines, monitors and their controls suggests the ideal build of an anesthetist is something grotesque. The bulk of the soda-lime canisters on the side of a machine, drawers or other obstructions under what are meant as a work-surface and writing surface and the distance to operating table controls and lights are all instances of engineering which may be mechanically good but which ignore the dimensions of the human who is to operate them.
These examples and many more suggest it is worth reviewing all aspects of anaesthetic practice to find more effective ways to arrange equipment and other facilities optimally. The size of the operating theatre must allow sufficient room for the nurses and technical and helping staff to circulate. Preferably there must be a separate induction room and one for recovery with provision to attend to any complications if it ensues.

• Environmental conditions such as lighting and legibility:

            Proper lighting, visibility, legibility (readability) are the most desirable features in indoor engineering. In the past only surgical lighting was given importance. As we progressed it’s more emphasised for the team and theatre as whole. The light should be good enough to appreciate colour changes in the operating field cyanosis /pallor should be distinctly observed and identified. Monitor display also to be viewed with atmost clarity. The problems faced with routine top lights to present day shadow free, non-glare able, non-heat producing lights are appreciable. There is provision to adjust these lights directly by the operating team or independently manually or by remote. These lights have almost nullified the problem of glare.
Numbers and letters should both be legible at a distance of 30cm. the ratio of the height to distance should be 1:200. There must be protocol for the style of print and font which makes them easiest to read as well as wording placed on the equipment.Mistakes occur from parallax, pointers hiding numerals, scales whose direction of increase contradict the user's expectation, polycarbonate plastic covers which reflect light and scratch easily may better be avoided or modified to suitable alternatives.
Displays should be grouped according to function, follow a logical sequence from top to bottom and left to right, and have an obvious relation in space to the controls which alter them. Non-urgent information, such as the maker's name and model and serial numbers of equipment, should not be on the front face. Controls and displays for maintenance should be shielded, while controls which are critical to life should be handiest and protected against accidental activation or de-activation.
The design of displays is a large subject on its own, with needs for simple, legible, and standard presentation of data. Information presented to the anesthetist may be of measured quantities or of status. Different grades of system status are best shown by indicator lights coded green, amber, red, or red flashing 3 to 5 times per second as visible alarms’ along with audible warnings to be used. Even low-level noise disturbs good working rhythm and may mask necessary conversation or audible signals. Distracting chatter, noisy equipment, and inappropriate impromptu lectures may all be intrusive.
Apart from lighting and vision there are other environmental factors which can affect theatre staff adversely, as well as the patient. Temperature and humidity obviously need control, and there should be simple gauges for these in operating theatres, together with an efficient hospital engineering service to maintain them in good working conditions.Apart from impairing efficiency of work, factors in the environment can be downright dangerous but this very danger has meant earlier recognition and control of such threats as anaesthetic gas pollution, electric shock and radiation. Some attention also has to be paid towards the work load of hospital staff in terms of lack of sleep and efficiency and stress of all kinds has to be considered in planning the working environment of operating rooms. Physical problems include back injuries and tripping.

• Skill acquisition, productivity and safety:

            To illustrate an example of the skill, “thread a needle”. This is a skillful task for two hands together to remain steady by abolishing normal hand tremor till the completion of the task. Such skills are learnt very fast. Someone who has found it difficult to thread a needle will find this lesson lasts a life time. Few anaesthetic procedures have been analysed in terms of their elements. In many skills, it is the accuracy of feel rather than the accuracy of movement that is important. A budding anesthetist is likely to learn the resistance of vein wall through a run of hematomas. Analogies suggest learning is quicker with better feedback and if simulators are   used for teaching. Understanding the forces involved, and the details of the common pattern of hand posture used by experts is very essential.
The psychological analysis of how skills are acquired can be carried further, defining stages of learning. The first of these is the coding of individual movements, especially hand and body posture. An example of this is been given earlier in Environmental conditions. The later stages are arranging coded elements of movement into a sequence, which eventually becomes an unconscious act like the sub-routine of a computer program.
A basic implication of ergonomics for anaesthesia is to have a fresh look at the requirement of the infrastructure and the work of the anesthetist to define his activities in a logical and detailed way. The ergonomics of controls and displays has special relevance as anaesthetic technology became more complex and advanced. It is even more important as acquiring of skills in certain aspects of work so they are carried out by specially trained technician and nurses under the supervision of the anaesthesiologists instead of directly by them. The introductions of least exposure radiology equipment (CRM), use of ultrasound and echo in the areas of monitoring has made features noninvasive and more reliable adding to better patient safety.
Components of ergonomics: To optimise system performance while maximising human wellbeing and operational effectiveness, ergonomics embraces a range of human centered issues relevant to equipment or systems design and training, including:

• Body size (anthropometry), motion, and strength capabilities (biomechanics)
• Sensory-motor capabilities—vision, hearing, haptics (force and touch), dexterity
• Cognitive processes and memory (including situational awareness)
• Training and current knowledge relating to equipment, systems, and practices
• Training and current knowledge of medical conditions (including emergency conditions)
• Expectations and cultural stereotypes relating to the operation of equipment
• General health, age, motivation, stress levels, mental fatigue and performance

Implications for action:Anesthesiologists forum have to be pursued with fact that the foregoing analysis is valid and significant, the following practical steps are better and to be taken for discussion:

• Organizations’ such as the Society of Anaesthetists should formally acknowledge the relevance of ergonomics to anaesthetic equipment and work-place design and also towards training and analysis of skills used.
• Organizations’ of anesthetists should have an ad hoc committee and designated resource persons to relate ergonomics to anaesthesia.
• Ergonomics should be incorporated into standards for anaesthetic equipment, a protocol of recommended design for work areas including operating theatres, recovery and intensive care areas, routine procedures and for training.
• Research on ergonomics and anaesthesia should be encouraged by the suitable choice of projects for senior trainees and others likely to seek new areas for investigation.

Summary:
Understanding human limitations early in the development of medical devices can reduce errors and avoid performance problems exacerbated by stress and fatigue.Using ergonomics in a design process can reduce the costs of procuring and maintaining products.Ergonomics can minimise the incidence of injury or longer term malaise from poor working environments.An ergonomics task analysis can help identify key components of surgical skill, ensuring that students have affordable, appropriate, valid and reliable training.The way of visualizing and documenting the interaction data with the help of the i-Flow Chart showed assets in communication at the interdisciplinary debriefing.Potential ergonomic benefits associated with the use of ultrasound-guided regional anesthesia. Prospective studies are needed to quantify the ergonomic or other benefits, to explore additional applications of this technology in the training and practice of ultrasound-guided procedures.
References:
1. Albus, J. S. et al.: A Proposal for a Decade of the Mind Initiative. Science 317, 2007
2. Brull R, Macfarlane AJ, Parrington SJ, Koshkin A, Chan VW. Is circumferential injection advantageous for ultrasound-guided popliteal sciatic nerve block? A proof-of-concept study. Reg Anesth Pain Med 2011; 36:266–270.
3. Endsley, M. R. et al.: Cognitive Engineering and Decision Making: An Overview and Future Course. Journal of Cognitive Engineering and Decision Making
4. Grandjean E.(1980).Fitting the Task to the Man: An Ergonomic Approach. Taylor & Francis, London.
5. Grantcharov TP, Rosenberg J, Pahle E, Fuch-Jensen P. Virtual reality computer simulation: an objective method or evaluation of laparoscopic surgical skills. Surg Endosc 2001;15: 242-4. [PubMed]
6. Kohn L, Corrigan J, Donaldson M, eds. To err is human: building a safer health system. Committee on Quality of Health Care in America, Institute of Medicine, Washington, DC: National Academy Press, 1999.
7. M.B. Weinger M. Wiklund D. Gardner-Bonneau Human factors in medical device design: a handbook for designers. 2011 CRC Press/Taylor & Francis Boca Raton
8. Michel Patkin FRCS website:Ergonomics and anaesthesia, presented to annual general meeting of Australian society of anaesthetists, Melbourne 1981
9.P. Carayon Handbook of human factors and ergonomics in health care and patient safety. 2012 CRC Press Boca Raton
10. Pollard, Brian J (1972) A Chair of Anaesthesia. Anaesth. Intens. Care, 1, 161-162 
11. Sites BD, Spence BC, Gallagher JD, Wiley CW, Bertrand ML, Blike GT. Characterizing novice behavior associated with learning ultrasoundguided peripheral regional anesthesia. Reg Anesth Pain Med 2007; 32:107–115.