The Operating Theatre Environment

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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.

A modern operating theatre incorporates the following design features:

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 OPERATING THEATRE SUITE

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).

TABLE 20.1

Zones of Cleanliness in the Operating Theatre Suite

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

Transfer of Patient

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.

Anaesthetic Room

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.

image The patient’s anxiety may be reduced by avoiding the sights and sounds of the operating theatre. This is of special importance in children.

image 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.

image 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.

However, there are several disadvantages.

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.

Operating Room

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.

Temperature, Humidity and Ventilation

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).

Light

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.

Safety in the Operating Theatre

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.

TABLE 20.2

Potential Hazards in the Operating Theatre

Electricity

Liquids

Gases and vapours

Temperature

Humidity

Fire

Cables and tubes

Electrical Safety

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.

Explosions

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.

Fire is still a hazard if alcohol-based solutions are used by the surgeon to sterilize the skin; the usual ignition source is a spark from the diathermy probe, and paper drapes provide a fuel.

Atmospheric Pollution

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.

Anaesthetic gases are not the only source of environmental pollution in the operating theatre; volatile skin-cleaning fluids and aerosol sprays, e.g. iodine or plastic skin dressing, should be used sensibly, and inhalation of vapours should be avoided.

Infection

The most serious types of acquired infection in operating theatre staff are HIV and hepatitis, which may be contracted by contact with blood or body fluids from an infected patient. Several healthcare workers have been infected in this way, either by a needlestick injury or through cuts and abrasions. The risk of percutaneous transmission of HIV is believed to be low; the risk of acquiring HIV following needlestick injury is estimated to be around 1 in 300 needlestick injuries. The annual risk of HIV infection for anaesthetists is estimated at between 1 in 3100 and 1 in 80 000 in the US (depending upon the local HIV rate). High-risk fluids for HIV transmission include: CSF, pleural, peritoneal, synovial fluid and breast milk; vomit, urine, faeces and saliva are considered low-risk.

Two thousand cases of hepatitis B are reported each year in the UK, although the true incidence is probably very much higher. The prevalence of evidence of previous or current infection (antibodies to hepatitis B core antigen – anti-HBc) is around 1–2% in the UK; it is about 96% in parts of China and South Korea. Hepatitis B surface antigen persists for at least 6 months in 5–10% of infected individuals. Up to 20% of the population may have chronic hepatitis in South Asia, East Asia and sub-Saharan Africa. The virus is highly infectious, and minute amounts of blood may transmit the disease. The Association of Anaesthetists of Great Britain and Ireland (AAGBI) recommends that all anaesthetists should receive active immunization against hepatitis B and most hospitals in the UK insist that evidence of immunity to the virus is present in an anaesthetist’s serum before allowing employment to start. A single dose of hepatitis B immunoglobulin combined with active immunization is required immediately if an unprotected individual is inoculated with infected material.

Hepatitis C and D viruses are also blood-borne. Up to 50% of people infected with the hepatitis C virus develop chronic liver disease. Occupational transmission of this virus has been reported.

The prevalence of HIV infection in the community is increasing. Thus, anaesthetists are likely to be exposed to an increasing number of patients who may transmit HIV. Compulsory screening of hospital patients for HIV is regarded as unacceptable and impractical. Anaesthetists should therefore assume that all patients potentially carry blood-borne diseases and precautions should be taken with all patients.

The following precautions are recommended to reduce the risks of transmission of HIV and other blood-borne diseases. These precautions are largely the same as those for reducing the risk of hospital-acquired infections for the patient.

image Gloves must be worn during induction of anaesthesia, performance of venepuncture or insertion of any intravascular cannula, and during insertion or removal of airways and tracheal tubes; this should be a routine when dealing with any patient. A plastic apron, mask and eye protection should be worn if substantial spillage of blood is anticipated, e.g. during insertion of an arterial cannula. Gloves should normally be discarded on taking the patient into the operating theatre and a fresh pair donned when any of these procedures is carried out during or at the end of anaesthesia.

image Equipment, notes and other articles must not be handled with contaminated gloves.

image Needles which have been in contact with the patient must not be resheathed or handed from one person to another.

image Cuts or abrasions on the anaesthetist’s hands should be covered with a waterproof dressing. An anaesthetist with considerable skin lesions, such as eczema, chapping or several scratches, is particularly at risk of being infected.

image If a needlestick injury or contamination of a cut or abrasion occurs, bleeding should be encouraged and the skin washed thoroughly with soap and water.

image Advice should be obtained immediately from the hospital’s occupational health department if there is reason to believe that contamination has occurred. Post-exposure prophylaxis following potential HIV exposure should be started within one hour of injury.

image Disposable equipment should be used where possible. Non-disposable equipment should be decontaminated with 2% glutaraldehyde, washed with soap and water and left in glutaraldehyde for a further 3 h. Contaminated floors and surfaces should be washed with 1% hypochlorite solution. Gloves must be worn.

There have been a number of instances in which items of disposable equipment, e.g. angle-pieces and catheter mounts, have been re-used, but in which the lumen has become obstructed, probably accidentally, by other items of equipment kept in the anaesthetic room. Equipment intended for single use must be discarded after use; re-usable equipment should be checked carefully to ensure that it is functioning correctly.

It is standard practice that a bacterial filter should be placed between the tracheal tube or airway and the anaesthetic breathing system in all patients to prevent cross-infection from a patient with undiagnosed infection.

In some countries, and particularly the UK, there has been increasing concern in recent years about the possibility of transmission of the prion responsible for the development of variant Creutzfeldt-Jakob disease (vCJD), attributed to infection from cows affected by bovine spongiform encephalitis (BSE). In infected patients, the prion is believed to be present in high concentrations in the tonsils. It is resistant to conventional methods of cleaning or sterilizing equipment. Consequently, hospitals in the UK have taken steps to stop the use of non-disposable items of equipment which could come in contact with structures in the pharynx. These items include laryngoscopes, bougies and laryngeal mask airways, and single-use devices have been introduced.

Prevention of Hospital-Acquired Infection

Anaesthetists are responsible for patients when they are at significant risk of hospital-acquired infection both at the operative site and through invasive procedures. There is some evidence linking better outcomes for patients with improved hand hygiene practice amongst anaesthetists.

Effective hand hygiene is the single most important measure to reduce the risk of infection of patients. All anaesthetic rooms and operating theatres should have ready access to hand-washing sinks, antiseptic hand-rubs and clean gloves. The anaesthetist has a responsibility to comply with hand hygiene policies in their work place. Typically these include the following:

A good handwashing technique is a key component. The six-stage technique is recommended due to the frequency with which areas are missed with less rigorous handwashing.

The anaesthetist should also wear clean, disposable gloves for all procedures where he/she is exposed to body fluids (e.g. cannulation, airway management). This is mainly for the protection of the anaesthetist. It is important that these gloves are removed promptly to avoid cross-contamination.

There is some evidence that drugs drawn up and administered by anaesthetists may not be sterile by the time they reach the patient. This break in sterility may occur at any point in the preparation, storage and administration process. Anaesthetists must therefore ensure that they have a process which actively avoids inadvertent contamination of syringes and their contents.

Noise

Noise in the operating theatre should be kept to a minimum. Patients in the anaesthetic room before induction of anaesthesia may be made more anxious by boisterous laughter or loud conversation coming from the operating theatre. Similarly, as patients recover consciousness after the operation, undue noise is undesirable.

Surgeons and operating theatre staff may enjoy listening to music during surgery, and it is not uncommon for sound systems to be installed in operating theatres. The anaesthetist must ensure that sounds from the monitoring system, e.g. the tone indicating arterial oxygen saturation and the sounds of alarms, can be heard, either by turning up the volume of tones from the monitoring system or turning down the volume of the sound system.

The evidence regarding beneficial or detrimental effects of music in theatre is mixed. There are clearly times when it may hinder the ability of staff to concentrate or monitor the patient. Conversely, there may be times when it is an aid to concentration.

Equipment Checks

Anaesthetic equipment should be up to date, maintained regularly and the instruction manuals should be available and accessible. Monitoring apparatus should be in accordance with contemporary guidelines. Appropriate alarm limits must be set, and alarms must not be permanently disabled. An equipment check must be performed before an operating theatre session begins because a frequent cause of misadventure is the use of a machine which has not been checked properly, and which malfunctions. An adequate check of anaesthetic apparatus is an integral part of good practice; failure to check the anaesthetic equipment properly may amount to malpractice.

Operating theatre staff usually carry out checks when setting up an operating theatre for use, or after apparatus has been serviced or repaired, but the ultimate responsibility for ensuring that the apparatus is safe for its intended use rests with the anaesthetist. Sophisticated tests may have been performed after major servicing, but key control settings may have been altered and it is essential that the anaesthetist checks that the equipment is in proper working order and ready for clinical use. The final pre-use check is the sole responsibility of the anaesthetist who is to use the machine. It cannot be delegated to any other person.

There is no justification for proceeding with an anaesthetic when faults have been identified in the equipment. If there is no record of an adequate preoperative check of equipment and a problem occurs as a result of equipment failure, it is very difficult to defend an allegation of negligence.

At its most basic, the function of an anaesthetic machine is to enable the anaesthetist to administer to a patient oxygen under pressure without leaks. If all else fails, this allows the anaesthetist to preserve life.

Anaesthetic apparatus should be checked before the start of each operating session in a logical sequence as recommended in the AAGBI checklist shown in Tables 20.4 and 20.5. Further checks shown in Table 20.6 should be undertaken between cases. The primary intention of the check of the anaesthetic machine is to ensure that it is safe to use and to deliver gases under pressure without leaks. These checklists are available as laminated cards, intended to be attached to all anaesthetic machines in the UK and Ireland.

TABLE 20.6

The Association of Anaesthetists of Great Britain and Ireland Checklist for Checking Anaesthetic Equipment between Cases

image

Adapted from Checking Anaesthetic Equipment 2012, with permission.

In most industries in which complex equipment is used, full training is provided for users. It is not acceptable for anaesthetists to assume that they intuitively understand an anaesthetic machine which they have not used before. Those new to the speciality require detailed instruction and training in the use of anaesthetic equipment, but even experienced anaesthetists need tuition in the use of new equipment.

Power Supply

The anaesthetic workstation and relevant ancillary equipment must be connected to the mains electrical supply (where appropriate) and switched on. The anaesthetic workstation should be connected directly to the mains electrical supply, and only correctly rated equipment connected to its electrical outlets. Multisocket extension leads must not be plugged into the anaesthetic machine outlets or used to connect the anaesthetic machine to the mains supply.

Hospitals should have back-up generators and many operating theatres have their own back-up system. Anaesthetists should know what is available where they are working. Back-up batteries for anaesthetic machines and other equipment should be charged.

Switch on the gas supply master switch (if one is fitted).

Check that the system clock (if fitted) is set correctly.

Gas Supplies and Suction

On some workstations, it is necessary to disconnect the oxygen pipeline in order to check the correct function of the oxygen failure alarm, although on machines with a gas supply master switch, the alarm may be operated by turning the master switch off. Repeated disconnection of gas hoses may lead to premature failure of the Schrader socket and probe, and current guidelines recommend that the regular pre-session check of equipment includes a ‘tug test’ to confirm correct insertion of each pipeline into the appropriate socket. It is also recommended that the oxygen failure alarm is checked once a week by disconnecting the oxygen pipeline with the oxygen flowmeter turned on. The alarm must sound for at least 7 s. Oxygen failure warning devices are also linked to a gas shut-off device. Anaesthetists must be aware of both the tone of the alarm and also which gases will continue to flow on the anaesthetic machine in use.

Medical Gas Supplies

Identify the gases which are being supplied by pipeline, confirming with a ‘tug test’ that each pipeline is correctly inserted into the appropriate gas supply terminal. Only gentle force is required; excessive force during a ‘tug test’ may damage the pipeline or gas supply terminal.

It is essential to check that the anaesthetic machine is connected to a supply of oxygen and that an adequate reserve supply of oxygen is available from a spare cylinder. It is also necessary to check that adequate supplies of any other gases intended for use are available and connected. All cylinders should be securely seated and turned off after checking their contents.

Carbon dioxide cylinders should not be present on the anaesthetic machine. If a blanking plug is supplied, it should be fitted to any empty cylinder yoke.

All pressure gauges for pipelines connected to the anaesthetic machine should indicate a pressure of 400–500 kPa.

If flowmeters are present, their function should be checked, ensuring that each control valve operates smoothly and that the bobbin moves freely throughout its range without sticking. If nitrous oxide is to be used, the anti-hypoxia device should be tested by first turning on the nitrous oxide flow and ensuring that at least 25% oxygen also flows. The oxygen flow should then be turned off to check that the nitrous oxide flow also stops. The oxygen flow should be turned back on, the nitrous oxide flow should be turned off and a check should be made that the oxygen analyser display approaches 100%. Turn off all flow control valves. Machines fitted with a gas supply master switch will continue to deliver a basal flow of oxygen.

The emergency oxygen bypass control should be operated to ensure that flow occurs from the gas outlet without a significant decrease in the pipeline supply pressure. It is important to ensure that the emergency oxygen bypass control ceases to operate when released; there is a risk of awareness if it continues to operate.

Breathing System and Vaporizers

All breathing systems which are to be used must be checked and a ‘two-bag test’ performed before use (Table 20.5). Breathing systems should be inspected visually for correct configuration and assembly. All connections within the system and to the anaesthetic machine should be checked to ensure that they are secured by ‘push and twist’. Ensure that there are no leaks or obstructions in the reservoir bags or breathing system and that they are not obstructed by foreign material. A pressure leak test (between 20 and 60 cmH2O) should be performed on the breathing system by occluding the patient end and compressing the reservoir bag.

Manual leak testing of vaporizers was previously recommended routinely. It should only be performed on basic ‘Boyle’ machines because it may be harmful to modern anaesthetic workstations. Refer to the manufacturer’s recommendation before performing a manual test.

Check that vaporizers for the required volatile agents are fitted correctly to the anaesthetic machine, that any locking mechanism is fully engaged and that the control knobs rotate fully through the full ranges. Check that the vaporizers are adequately filled but not overfilled, and that the filling port is tightly closed. Vaporizers must always be kept upright. Tilting a vaporizer can result in delivery of dangerously high concentrations of vapour.

All vaporizers must be turned off after they have been checked.

Manual Leak Test of Vaporizer: A flow rate of oxygen of 5 L min− 1 should be set and, with the vaporizer turned off, the common gas outlet should be temporarily occluded. There should be no leak from any part of the vaporizer, and the flowmeter bobbin (if present) should dip.

If more than one vaporizer is present, turn each one on in turn and repeat this test. After the tests, ensure that the vaporizers and flowmeters are turned off.

It may be necessary to change a vaporizer during use although this should be avoided if at all possible. If a change is necessary, repeat the leak test because failure to do so is a common cause of critical incidents. Some anaesthetic workstations automatically test the integrity of vaporizers.

It is only necessary to remove a vaporizer from a machine to refill it if the manufacturer recommends this.

Two-Bag Test

A two-bag test should be performed after the breathing system, vaporizers and ventilator have been checked individually (see Table 20.5). Breathing systems should be protected with a test lung or bag when not in use to prevent intrusion of foreign bodies.

Airway Equipment

This includes bacterial filters, catheter mounts, connectors and tracheal tubes, laryngeal mask airways, etc. These should all be available in the appropriate sizes for patients on the operating list and must be checked for patency.

A new, single-use bacterial filter and angle piece/catheter mount must be used for each patient. It is important that these are checked for patency and flow, both visually and by ensuring that gas flows through the whole assembly when connected to the breathing system. This check must occur whenever new airway equipment is provided, and is a standard part of the WHO checklist for every patient.

Appropriate laryngoscopes must be available and checked to ensure that they function reliably. Equipment for the management of the anticipated or unexpected difficult airway must be available and checked regularly in accordance with departmental policies. The anaesthetist and anaesthetic assistant should both be aware of the location of the nearest ‘difficult airway’ trolley.

Total Intravenous Anaesthesia (TIVA)

When TIVA is used, there must be a continuous intravenous infusion of anaesthetic agent or agents; interruption from whatever cause may result in awareness. A thorough equipment check is therefore the most important step in minimizing the incidence of awareness. Anaesthetists using TIVA must be familiar with the drugs, the technique and all equipment and disposables being used.

The following recommendations have been made to minimize the risks of awareness during TIVA.

Recovery Room/Post-Anaesthesia Care Unit

A recovery room or ward is an essential requirement in the operating theatre. All patients require close surveillance in the immediate postoperative period and, after major surgery or in vulnerable patients, for up to 24 h.

The recovery room should be an integral part of the operating theatre suite and should be located within the clean area. Department of Health guidelines suggest that there should be 1.5 places in the recovery area for each operating theatre, although a greater number may be required for surgery with a high turnover, e.g. gynaecology or day-case surgery. Each place requires a minimum floor area of approximately 10 m2, and there must be sufficient space to move a patient without disturbing the others in the room.

It is appropriate for many patients to lie on a trolley in the recovery room, but beds should be available for those who are likely to stay for more than 30–45 min, e.g. patients who have undergone major surgery, or ASA (American Society of Anesthesiologists) grade III or IV patients who may require prolonged observation even after minor surgery. Each place should have piped oxygen and suction outlets on the wall, with an oxygen flowmeter and suction apparatus attached to a wall rail. Lighting should conform to the same standards as apply to the operating theatre, and additional spotlights should be provided. It is not common practice in the UK to monitor the electrocardiogram in all patients in the recovery ward, but oxygen saturation and blood pressure should be monitored routinely and the facility to monitor ECG and invasive arterial blood pressure should be available. Most large recovery areas have two or three places which are fully equipped with piped nitrous oxide, a mechanical ventilator and complete cardiovascular monitoring facilities.

An anaesthetic machine, a defibrillator, and equipment and drugs for resuscitation must be available in the recovery room. Oxygen is usually administered by disposable face mask, but each place should have a self-inflating resuscitation bag and anaesthetic mask.

Drug cupboards and storage space for equipment should be provided as well as dedicated telephones. Nursing staff spend most of their time with the patient, but require a nursing station at which notes may be written and from which wards can be contacted by telephone. At least one nurse is required for each three bed spaces. At present, specific training in the UK for recovery room nurses is somewhat haphazard. Student nurses may receive as little as 1 week of training in this area.

In many hospitals, it is possible to provide supervision of patients in the recovery ward for up to 24 h after major surgery, although it is now usual for patients who require close supervision for more than a few hours to be transferred to a high-dependency unit.

Clinical aspects of recovery room care are discussed in Chapter 40.

High-Dependency Unit

A high-dependency unit is an area for patients who require more invasive observation, treatment and nursing care than can be provided on a general ward. It would not normally accept patients requiring mechanical ventilation, but could manage those who require invasive monitoring. A survey conducted by the AAGBI in the 1990s indicated that many intensive care units admitted patients who could have been managed appropriately in a high-dependency unit. An unknown number of patients return from the recovery area to a general ward requiring monitoring or an intensity of nursing or medical care which cannot be provided safely in that location.

The facilities required to provide high-dependency care vary. Essential features are a high nurse-to-patient ratio, provision of piped oxygen and suction at every bed, and appropriate monitoring equipment. Protocols must be in place for admission and discharge criteria, and medical staffing must be clearly defined. In large hospitals, several units may be desirable, each dedicated to the care of specific groups of patients; in smaller hospitals, a single, multi-user unit may be more appropriate.

Other Accommodation

Storage space is required for large items of equipment. In most modern operating theatre suites, instruments are sterilized in a separate department, which is not always on-site.

Near-patient testing of a variety of blood tests is now available and most theatre suites provide these in a single location. Arterial blood gas analysis and measurement of serum electrolyte concentrations is essential, especially if major surgery is to be undertaken, and if the equipment is not available in theatre then it should be readily available in an adjacent ITU.

The theatre coordinator needs adequate facilities for the smooth administration of theatres which should be accessible to non-theatre staff for the booking of cases and discussion of requirements.

Staff accommodation includes changing rooms and rest rooms. There should be facilities for staff to take their breaks. Theatre team leaders need office accommodation for their non-clinical time. Ideally, there should be a tutorial or seminar room for staff training. Some theatre suites incorporate offices for the anaesthetic department.

Other Anaesthetizing Locations

The anaesthetist is often required to work in areas outside the operating theatre suite. Many hospitals have peripheral theatres for some types of surgery, e.g. a self-contained day-case unit or treatment centre. In addition, patients may require anaesthesia in the emergency department, the radiology and radiotherapy departments or, in some instances (e.g. paediatric oncology), the side room of a ward. In these circumstances, where conditions are frequently not ideal, it is essential that the same precautions are taken as in the operating theatre suite to ensure that the identity of the patient and the nature of the proposed procedure are checked, that equipment is functioning correctly, that skilled help for the anaesthetist is available and that recovery facilities and staff are satisfactory. It is wise to avoid sending junior and inexperienced anaesthetists to these remote locations without direct senior supervision.

Ancillary Staff

Skilled and dedicated help should be available to the anaesthetist at all times. In the majority of hospitals in the UK, this is provided by operating department practitioners (ODPs), who undergo a 2-year training programme in recognized institutions and are required to sit examinations. In some hospitals, anaesthetic nurses assist the anaesthetist. It is important to differentiate between anaesthetic nurses and the nurse anaesthetists who are trained to deliver anaesthesia in some countries (e.g. CRNAs in the USA). The anaesthetic nurse performs essentially the same functions as the ODP. These include the following:

image Preparation and preliminary checking of equipment. It should be stressed that this does not absolve the anaesthetist from the responsibility of checking the equipment fully before an operating list is started.

image Alleviation of anxiety by reassurance and constant communication with the patient while awaiting anaesthesia.

image Checking the correct identity of the patient and participating in the WHO checklist procedures. It is the responsibility of the surgeon to ensure that the appropriate procedure is undertaken on the correct patient, but the anaesthetist must also confirm the identity of the patient and, as far as is possible, confirm that the surgeon is performing the correct operation. This is one of the many reasons why the anaesthetist must see every patient preoperatively.

image Preparation of intravenous infusions, cardiovascular monitoring transducers, etc.

image Assistance during anaesthesia, particularly during induction, when special manoeuvres such as cricoid pressure may be required, and after transfer to the operating theatre to assist in re-establishment of monitoring.

image Assistance in positioning the patient for local or regional blocks.

image Assistance in obtaining drugs or equipment if complications arise during anaesthesia.

image Assistance in the immediate postoperative period before the patient is transferred to the recovery room.

The ODP or anaesthetic nurse should never be left alone with an anaesthetized patient unless a dire emergency requires the anaesthetist’s presence elsewhere.

Physicians’ Assistants (Anaesthesia)

Physicians’ assistants (anaesthesia) (PA(A)s) are fully trained professionals who have completed a specific postgraduate diploma. They work under the direction and supervision of a consultant anaesthetist at all times, often in a 2:1 model where one consultant supervises two theatres with a trainee and a PA(A) or two PA(A)s. They are allowed to provide anaesthesia without an anaesthetist present but overall responsibility for the care of the patient remains with the supervising consultant anaesthetist. Their role is to improve theatre utilization through reductions in theatre downtime, assisting with preoperative assessment and regional anaesthesia. However, for every case, the supervising consultant anaesthetist must:

Individual departments of anaesthesia are responsible for precise details of the scope of practice for PA(A)s. At present, they are not allowed to prescribe drugs but may administer drugs using locally developed patient-specific tools. At qualification, PA(A)s are not qualified to undertake regional anaesthesia, obstetric or paediatric practice or initial airway assessment/management of the acutely unwell or injured patient unless they are the first team members to arrive. Following extended training, PA(A)s have taken on some of these roles safely.

FURTHER READING

Association of Anaesthetists of Great Britain and Ireland. Immediate postanaesthetic recovery. London: AAGBI, 2013.

Association of Anaesthetists of Great Britain and Ireland. Infection control and anaesthesia 2. London: AAGBI, 2008.

Association of Anaesthetists of Great Britain and Ireland. Checking anaesthetic equipment 2012. London: AAGBI, 2012.

Boumphrey, S., Langton, J.A. Electrical safety in the operating theatre. BJA CEPD Reviews. 2003;3:10.

Johnston I.D.A., Hunter A.R., eds. The design and utilization of operating theatres. London: Edward Arnold, 1984.

Royal College of Anaesthetists, 2011. PA(A) supervision and limitation of scope of practice (May 2011 revision). http://www.rcoa.ac.uk/node/1927

Spence, A.A. Environmental pollution by inhalation of anaesthetics. Br. J. Anaesth. 1987;59:96.

Taylor T.H., Major E., eds. Hazards and complications of anaesthesia, second ed., Edinburgh: Churchill Livingstone, 1994.

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Anaesthesia for ENT, Maxillofacial and Dental Surgery Complications During Anaesthesia Drugs Acting on the Cardiovascular System Basic Physics for the Anaesthetist Management of the Difficult Airway Anaesthesia Outside the Operating Theatre