The Operating Theatre Environment
Until the middle of the nineteenth century, surgery was carried out in any convenient room, frequently one which was used for other purposes. Although the introduction of antisepsis resulted in the washing of instruments and the operating table, the operating room itself was ignored as a source of infection. Operating rooms were designed with tiers of wooden benches around the operating table for spectators; thus the term operating theatre was introduced. During the early part of the twentieth century, large windows were incorporated, as artificial light was relatively ineffective, and high ceilings were introduced to improve ventilation. Additional facilities became necessary for preparing and anaesthetizing the patient, for sterilization of instruments and for the surgeon and other theatre staff to change clothes and scrub up. In addition, the design of operating theatres changed, and smaller theatres were introduced to facilitate frequent cleaning.
In addition, provision should be made immediately adjacent to the operating theatre for preparing instruments, cleaning dirty instruments and for the surgeon to scrub up. Traditional practice in the UK has been to have a separate room for anaesthetizing the patient. Many countries around the world do not use separate anaesthetic rooms and some operating theatres are now designed with shared or no anaesthetic rooms. Procedure rooms are becoming more common where aspects of perioperative care can be carried out such as regional anaesthesia and insertion of central venous catheters. There should also be separate areas for reception and recovery of patients. It is the usual practice for each hospital to have a suite of theatres, rather than operating theatres close to each of the surgical wards, which was formerly a common feature. The use of theatre suites permits more flexible and efficient use of staff and resources.
The number of operating theatres required is difficult to calculate, but approximates in most British cities to one for every 40 000 of the population served. Ideally, the operating theatre suite should be close to the surgical wards, and adjacent to, and on the same floor as, the accident and emergency department, intensive care unit, X-ray department, day-case ward and sterile supplies unit. It is logical for the anaesthetic department to be immediately adjacent to, or an integral part of, the operating theatre suite, although this seldom occurs in practice.
The main purpose of the operating theatre environment is to provide a safe environment for patients and staff. A key component of this is to minimize the risk of transmission of infection to the patient from the air, the building or the staff. The operating theatre suite contains four zones of increasing degree of cleanliness (Table 20.1).
Outer zone – hospital areas up to and including the reception area
Clean zone – the circulation area used by staff after they have changed, and the route taken by patients from the transfer bay to the anaesthetic room
Aseptic zone – scrub-up and gowning area, anaesthetic room, theatre preparation room, operation room, exit bay
Disposal zone – disposal area for waste products and soiled or used equipment and supplies
There is some evidence that anxiety in the surgical patient peaks as transfer from the ward to the operating theatre begins, and it is important that facilities for transfer minimize stress. A member of staff from the ward usually accompanies the patient, but it is customary for the ward staff to leave adult patients before anaesthesia has been induced. In paediatric practice, it is the normal routine that a ward nurse or play therapist and parent remain with the child during induction of anaesthesia.
On arrival at the reception area, the patient’s identity and surgical procedure are checked. In a theatre suite, it may be necessary for patients to wait for some time in the reception area to prevent delays in the operating schedules. Consequently, adequate space should be provided for several beds, and there should be screens for patients who wish privacy. The staff in the reception area should include nurses. The décor should be cheerful, and the lighting subdued.
Transport should involve the minimum number of changes of trolley. A trolley is used frequently to transfer the patient to the operating theatre suite, and changes of trolley may be required to enter the clean area and also for transfer to the operating table after anaesthesia has been induced. Because sedative premedication is now unusual, patients not infrequently walk to the operating theatre suite and climb on to a trolley on arrival.
Alternatively, the patient’s own bed may be taken to the operating theatre suite. If the patient is infirm or in severe pain, the bed may be taken to the anaesthetic room and transfer delayed until after induction of anaesthesia, but this is appropriate only if the bed has the facility to be tipped head-down if necessary. In some hospitals, a single transfer is effected by transporting the patient to the theatre suite in bed, where the patient is moved on to the operating theatre table-top, which is mounted on a wheeled frame. After induction of anaesthesia, the table-top is wheeled into the theatre and the top attached to a fixed base, which allows it to be positioned for surgery.
There is increasing awareness of the risk of injury to operating theatre personnel as a result of lifting patients, and thus an increasing tendency to install transfer systems which do not require great physical effort. There are also risks to patients arising from transfer to and from trolleys, operating tables and beds, including physical injury, disconnection of intravenous infusions or intravascular catheters, displacement of a tracheal tube and disconnection of monitoring apparatus. The anaesthetist is responsible for ensuring the safety of the patient and of themselves during transfer. There is no universal method of transferring patients from one trolley to another. All hospitals should provide training on safe transfer techniques.
All trolleys in the operating theatre suite should be equipped with oxygen, and this should be administered routinely to patients during transfer from theatre to the recovery room at the end of the procedure if general anaesthesia has been used or if there is any other clinical indication.
In several countries, the anaesthetic room has developed from a small annexe to the theatre to an integral part of the operating theatre suite. However, this is not universal, and in many parts of the world anaesthesia is induced in the operating theatre after the patient has been transferred onto the operating table. The following are the main advantages of the anaesthetic room.
The equipment which may be necessary during induction of anaesthesia can be stored in an uncluttered manner, with each item readily available and its location obvious, in contrast to the cramped ‘cart’ which is usually employed to provide equipment and drugs when anaesthesia is induced in the operating theatre.
Time is saved by inducing anaesthesia while surgery is being completed on another patient. This is useful particularly if preparation is prolonged, e.g. performance of local anaesthetic blocks or establishment of invasive cardiovascular monitoring, but is safe only if at least two anaesthetists and two trained assistants are present.
Even in countries where anaesthetic rooms are used, it is customary to induce anaesthesia in the high-risk patient on the operating table, as the delay between onset of unconsciousness and the start of surgery must be kept to a minimum, e.g. for emergency caesarean section or severe haemorrhage.
The design of the anaesthetic room should allow easy access all round the patient’s trolley, and should provide space for anaesthetic and monitoring equipment, and storage cupboards and shelves. The minimum floor area recommended by the Department of Health in the UK is 17 m2, but this is inadequate. A floor area of 21 m2 is more appropriate. Piped gases and suction, and electrical sockets, are required near the head of the trolley. An anaesthetic machine, mechanical ventilator and monitoring system are also necessary. Cupboards must be available to store equipment and drugs, and worktops must be of sufficient size to allow syringes, needles, cannulae and drugs to be prepared. There should be a clock with a second hand.
The layout of the anaesthetic room has an impact on both safety and efficiency of operating lists. Clear labelling, prioritization of commonly used items and avoidance of overstocking are important factors. Anaesthetists commonly work in several different theatres and a consistent layout between anaesthetic rooms may facilitate safe and smooth working.
The operating room is designed around its centrally situated operating table with overhead lighting and ventilation systems. The ideal shape for the operating room is circular, but this is inefficient and most operating rooms are square or nearly square. The Royal College of Surgeons of England has suggested that the floor should be 625 ft2 (approximately 58 m2) in area, and no smaller than 484 ft2 (approximately 45 m2). Theatres for specialized surgery may require a larger area to accommodate bulky equipment.
Outlets for piped gases and electrical sockets must be positioned close to the head of the operating table; they are provided most conveniently by a boom or stalactite system. Electrical cables should not lie across the floor. The operating room should be of sufficient size to allow all types of surgery without moving the position of the head of the table; this location should be reached easily and without complex manoeuvres as the patient enters the theatre from the anaesthetic room.
The temperature in the operating theatre and anaesthetic room should be sufficiently high to minimize the risk of inducing hypothermia in the patient, but must be comfortable for theatre staff. The patient may develop hypothermia at an ambient temperature of less than 21 °C. Temperatures of 22–24 °C are usually acceptable in the operating room, with a relative humidity of 50–60%; a higher environmental temperature is required during surgery in the neonate or infant. Slightly lower temperature and humidity are acceptable in other parts of the theatre suite. Controls for temperature and humidity should be located within the operating theatre so that adjustments can be made by theatre staff. The theatre temperature is less of a concern when patient warming devices are used, but anaesthetists should be aware that there are often significant periods when the patient is exposed without warming. A cold theatre will put the patient at greater risk of inadvertent hypothermia.
Heating and humidity are controlled usually by an air-conditioning and ventilation system, which provides an ambient pressure inside the operating room slightly higher than atmospheric. In general, air is introduced directly over the operating table, and leaves at the periphery through ducts positioned near floor level. In the area of the table, 400 air changes per hour are required to minimize the risk of airborne transmission of infection. More effective systems of ventilation, involving radial exponential air flow away from the operating table, or laminar flow, are used in some centres for some types of surgery, e.g. joint replacement, in which infection is especially undesirable. High-flow systems may accelerate cooling of the patient (and staff).
Daylight is not necessary in the operating theatre, although it is more pleasant for staff if there are windows in the theatre suite, e.g. in corridors and common rooms. A high level of illumination is required over the operating table, and ceiling-mounted lamps are standard; it is preferable if they can be positioned directly by the surgeon.
The intensity and colour temperature of general lighting are very important to the anaesthetist, as appreciation of skin colour is affected by the spectrum of the source of illumination. The spectrum provided by lighting tubes should be similar to that of daylight, with an emission temperature of 4000–5000 K. The colour of the décor should be neutral and uniform. The intensity of general illumination should be up to 325 lm m−2 in the operating theatre, and it should be diffuse to avoid glare. In the anaesthetic room and recovery area, a light intensity of approximately 220 lm m−2 is acceptable, but a spotlight should be available if increased illumination is required for specific procedures.
Trailing electrical wires, gas supply hoses, ventilator tubing, intravenous tubing and monitoring cables represent a hazard to both staff and patients in the operating theatre. Staff may trip and suffer injury, and it is easy to disconnect the electrical supply to vital equipment. If the power to modern anaesthetic machines is disconnected, monitoring, ventilation and gas supplies may fail simultaneously. In addition, there may be a risk to staff from pollution of the atmosphere with anaesthetic gases and vapours, and of contracting infection, particularly human immunodeficiency virus (HIV) or hepatitis, from infected patients. Potential hazards in the operating theatre are shown in Table 20.2.
Gases and vapours
Cables and tubes
Although some mention is made of electrical hazards in the operating theatre in Chapter 14, a detailed description is beyond the scope of this book, and the reader is referred to the article by Boumphrey and Langton (2003) in the further reading list. The electrical supply to the operating theatre and all electrical equipment connected to the patient incorporate design features which minimize the risk of electrical currents being transmitted through the patient to earth.
However the theatre is designed, there will always be some electrical connection between the anaesthetic machine and the wall or ceiling sockets. Anaesthetists should develop a system which minimizes the risk of disconnection and trip hazard from these cables. Stopping staff from walking behind the anaesthetic machine is a simple but effective approach.
Explosive anaesthetic gases and vapours (diethyl ether, cyclopropane, ethyl chloride) are no longer used in developed countries. However, diethyl ether is still used occasionally in some countries. Ether burns in air, but forms an explosive mixture with oxygen. An explosion may be initiated by a spark of very low energy (< 1 μJ) or by contact with a temperature of 300 °C or higher. The risk of explosion is highest within and close to the anaesthetic breathing system because of the presence of a high oxygen concentration. Beyond a distance of 10 cm from the breathing system, the oxygen concentration diminishes and the risk is reduced. Ethyl chloride is used in some centres to generate a cold stimulus when testing the extent of regional or local anaesthetic blocks, and the risk of fire or explosion should not be forgotten.
The construction of anaesthetic apparatus is designed to minimize explosion hazards from generation of sparks caused by accumulation of static electricity. All rubber is conductive, so that electrical charges leak to earth, and non-conductive substances are treated with antistatic material. In most operating theatres more than 15–20 years old, the floor has a high but finite resistance, so that static charges leak to earth but electrocution risks are minimized. Until recently, theatre footwear was also designed to earth static charges. Sparks may be generated by clothing made of synthetic materials such as nylon. The risk of accumulation of static electricity on walls and equipment is reduced if the environment humidity exceeds 70%.
Diathermy must not be used if flammable or explosive anaesthetics are employed. However, because the use of these agents has ceased in developed countries, many of the precautions against generation of sparks, and the use of expensive antistatic flooring, have become unnecessary.
There has been considerable controversy regarding the risk to theatre staff from atmospheric pollution by anaesthetic gases and vapours. Earlier investigations suggested that theatre staff are more likely than other hospital personnel to suffer from hepatic and renal disease, to have non-specific neurological symptoms and for their children to have an increased risk of congenital abnormality. However, none of these problems has been substantiated.
There was more convincing evidence from some studies that female staff who worked in the operating theatre during the early months of pregnancy suffered an increased incidence of spontaneous abortion, and there is experimental evidence to suggest that constant exposure of rats to a concentration of more than 1000 ppm of nitrous oxide produces adverse results on their reproduction. However, the most recent, comprehensive and only randomized prospective investigation of operating theatre staff failed to demonstrate any increased health risk.
Trace concentrations of anaesthetic gases have been implicated in another area of concern – impairment of professional performance. Motor and intellectual performance were shown in an early laboratory study in volunteers to deteriorate in the presence of concentrations of nitrous oxide of 500 ppm, with or without halothane 15 ppm. However, subsequent studies failed to confirm these findings, and the consensus of several studies is that concentrations of 8–12% nitrous oxide are required before significant impairment of performance occurs. Such concentrations might be inhaled if the anaesthetist is close to an unscavenged expiratory valve, or during inhalation induction of anaesthesia, but exceed those present in other areas of an adequately ventilated operating theatre.
Nevertheless, it is sensible to minimize atmospheric pollution in the operating theatre, and hospital regulations in both western Europe and North America require the installation of anaesthetic gas-scavenging systems in all areas where anaesthesia is administered. In the USA, the National Institute of Occupational Safety and Hygiene (a federal regulatory body) dictates that environmental concentrations of anaesthetic gases should not exceed a value of 25 ppm of nitrous oxide and 2 ppm of volatile agent. In the UK, the Health and Safety Executive introduced maximum limits of exposure to anaesthetic agents in January 1996; these are shown in Table 20.3. Scavenging systems are described in Chapter 15.
|Agent||Maximum Concentration (ppm)|