The British Journal of Surgery Vol. 62 : No. 4 : April 1975 Br. J. Surg. Vol. 62 (1975) 253-258
The importance of environmental conditions, especially temperature, in the operating room and intensive care ward LORD BROCK* SUMMARY
Although most patients are essentially well enough to be able to resist or to adapt to unfavourable ambient conditions, this may not be so with an ill patient or one who is having or has had a serious operation. The climatic conditions necessary in the operating room to give an optimal environment are discussed. These are second in importance only to control of itlfectivity. Airconditioning in operating suites should be obligatory; there is even oficial acceptance of this. Earlier recommendations that the operating room should be heated to up to 80 " F (27.9"C)are obsolete. The temperature most Javoured by surgeons is 18.5-21 "C; some prefer a range of 21-22 "C. The critical ambient temperature desirable is 21 "C. For infants and children this may be increased up to 24 "C. It is dificult or impossible to achieve climatic conditions in the operating room that are acceptable to all. The needs of the patient are of special importance and are largely neglected; he alone is unable to speak for himself. The disposition of air inlets in the operating room is fully discussed. Climatic conditions in the intensive care unit are of great importance and are discussed. The need for full air-conditioning is absolute although this is often ignored. The delivery of conditioned air within the intensive care unit is also fully presented, especially the need to avoid direct chilling of the patient. The advantages oJ horizontal laminar air flow are presented. THEimportance of a study of central and peripheral temperatures in the recognition of hypovolaemia after open heart surgery was presented in the report of a case (Spitzer and Brock, 1968). A later article (Ross et al., 1969) on observations of central and peripheral body temperatures in the understanding and management of shock dealt with the valuable information that can be obtained essentially in regard to hypovolaemia as a major cause of shock. This work was based on the report of Ibsen (1967) on this subject. Prolonged experience with the study of central and peripheral temperatures and of the gradient between them has served to reinforce the statement (Ross et
18
al., 1969): 'we now feel unable to manage the care of a patient potentially or acutely ill without having information that temperature studies give'. It still remains true that 'few people are aware of such studies and we haveeven been told that all the information we are presenting is available by a simple touch of the hand on the nose or the feet of the patient.' Far from this information being of little value the present author remains convinced that much can be learned from it. Most patients are essentially well enough to be able to resist or to adapt satisfactorily to unfavourable conditions so that these often do not matter greatly. It is different with an ill patient or with one who is having or has had a serious operation. Let us first consider the significance of the climatic conditions in the operating room to which the patient and members of the operating team are exposed. Much has been written about this in recent years but the extent to which practical measures have been taken to achieve an optimal or even improved environment has varied considerably. It is important that the fullest consideration should be given to all the problems involved in view of the very large sums of money that are being spent on hospital construction and that will affect the comfort and recovery of patients and also the life and work of doctors, nurses and of many others for decades or even generations to come. Amongst the many publications on these matters attention is drawn to the Report of a Committee of the Royal College of Surgeons (1964) on 'design of operating theatre suites'. The most important factors relevant to the design of operating suites are those concerned with the avoidance or minimization of infection; clearly these are paramount. The transition from the old operating theatre through antiseptic to aseptic conditions was a brilliant and revolutionary achievement. Next in importance is the provision of
* Department of Surgical Sciences, Royal College of Surgeons, London.
253
Lord Brock suitable climatic conditions for all those within the operating suite, including the patient. It used to be taught that it was in the patient’s interest for the temperature in the operating room to be between 70 and 80°F. One well known and popular textbook of surgery states ‘The theatre . . . must be equipped with a heating system capable of maintaining a temperature of up to 80 O F . ’ That is 27 “C! Without air-conditioning the operating room can be uncomfortable and conditions may become intolerable. Operating room temperatures during the summer in the city of New York have reached the high 90’s with associated high humidity and consequent hyperpyrexia developing (Clark and Ravenstine, 1954). Such conditions are almost obsolete in the USA now that air-conditioning is used. In Great Britain the need for air-conditioning in operating suites is by no means generally accepted (Ministry of Health, 1967). Happily, reason is prevailing and there is wide, even official, acceptance of the absolute need for full airconditioning in most operating rooms (Medical Research Council and Department of Health, 1972). It is necessary to emphasize that air-conditioning must include control of temperature and humidity and does not mean just forced ventilation. Two other comments are appropriate at this point. The first is relative to the post-anaesthetic recovery area (that surely must be treated exactly as the operating room) and to the intensive care unit. The introduction of the intensive care unit is one of the most important and profound changes that has been seen in the clinical lifetime of most of us. Much of the organization of the intensive care unit is concerned with the measurement of parameters that give exact information about vital phenomena instead of relying on the observations and judgements of ‘good nursing’. The improvements in care that result are immense, as we understand more exactly and more deeply what is going wrong with the patient and what therapeutic adjustments are needed. However, the general neglect of deliberate consideration of the environmental conditions of the patient in the intensive care unit is surprising. For example, a recent authoritative article on ‘surgical intensive care’ (Walker, 1973) discusses thoroughly the various parameters that must be measured but makes no mention at all of the environmental conditions that may be important causes of undue extra stress. In a recently published special brochure devoted to intensive care Health and Social Service Journal, 1974) seventeen intensive care units are described and in only two is air-conditioning mentioned as being included in the primary design; in one other it was excluded on grounds of economy and later had to be added. In none of the other fourteen is it even mentioned. It is refreshing to read in an article on the organization and design of intensive care units (Verner, 1974) ‘Air-conditioning is essential in intensive care units.’ In the present author’s opinion the value of the various parameters can be greatly increased by 254
ensuring that the patient is exposed to a standard controlled environment that shields him from unfavourable ambient influences. The improvements in physiological observation and care that are so important among the aims of the intensive care unit should surely be extended to physical environment. It should be axiom2tic that in planning the intensive care unit in every new hospital building provision should be made for full air-conditioning. When such a department is to be set up in an existing hospital it must necessarily be fashioned around or within existing accommodation and therefore shares the climatic disadvantages that the original wards or rooms may possess-disadvantages that may not be important in the original use of the quarters but may become extremely so in their new use. Experience reveals examples of this, especially in regard to the weather aspect. The main outlook may be south or south-west and this can lead to intolerable conditions at certain times of the day and during some seasons of the year. Conversely, an eastern or northern aspect can produce adverse conditions at the other extreme, particularly if the wind is in an unfavourable direction. An intensive care area often has a mixture of aspects of varying types but which have the one common factor that at certain times, either of the day or of the night, they each produce or contribute to an unfavourable environment for the patient. Much can be done to mitigate this in simple ways, such as by double glazing or efficient shading; proper care should always be directed to what are often obvious and simple measures to be taken but which are just not considered or are ignored. However, the basic essential requirement is full air-conditioning. The second comment that is inseparable from the issue arises directly from this, namely the type and design of air-conditioning to be used. The usual attitude to air-conditioning is that it is an entity like the provision of gas, water and electricity and can be requested and installed as such. This seems to be the conception of most surgeons, doctors or administrators when faced with the problem of the design of a new building or the conversion of an old one. The need to discuss with the engineers the type of airconditioning to be installed so as to secure the best conditions is far too little appreciated. Inevitably the engineer, in most instances, is likewise unlikely to be aware of just what is required. He will have full knowledge of the basic facts of ventilation, of control of temperature, humidity and filtration etc., that he can put at the disposal of his clients but he must or should be carefully informed of exactly what is required. The installation of the plant, the trunking and the outlets will be complex and expensive and will require conformity to or alteration of building design to accommodate them. The installation will inevitably be there for many years whether it is the right arrangement or not. Close cooperation between the doctors and the engineers is essential to ensure that it is known exactly what is needed. As the author is not an engineer the following suggestions may be incorrect, incomplete or
Importance of environmental conditions in intensive care
impractical but it is hoped they will serve as a basis for discussion. The suggestions now made are not meant to be complete or final or even fully reasoned. My team is embarking on a series of observations to try to introduce method to certain recommendations or suggestions. The securing of relevant information is time-consuming and is not easy. It is hoped to report in later articles on progress on various aspects of the problems that exist as information is gained. The basic design and function of the central plant and equipment must be the responsibility of the heating and ventilating engineers. The author is chiefly concerned with the mode of delivery of the conditioned air to the operating suite or to the intensive care unit and hence to the patient. Let us take the operating room first; apart from the anaesthetic room the requirements of the other rooms follow almost inevitably with the essential provision that the area of highest air pressure will be the operating room and the aseptic area in general, and the arrangement of doors, windows and other features will be such as to encourage the desired scheme of air circulation or air flow. While recognizing the prime need for attaining the highest standards of asepsis, of really clean air and the avoidance of contamination from any source, space does not permit a full consideration of these; in any case much has already been written about the control of infectivity. For example, environmental surveys of the operating suites at various RAF hospitals have been well reported by the Royal Air Force Institute of Health and Medical Training (1972a, b) at Halton under the overall direction of Group Captain I. A. McIntosh; a very high standard of infectivity control is achieved with consequent lessening of the incidence of postoperative infection. The present remarks will be confined essentially to the climatic factors involved. Mention has already been made of the modern readjustment of views on the temperature ranges desirable in the operating room and that the earlier recommendation of up to 80 O F (27 "C) is unacceptable. It should be realized, however, that it is not possible to provide the temperature conditions to suit the needs of all those working in the operating room. The surgeon, the anaesthetist, the scrub nurse, the other nursing assistants and the ancillary workers may all require different conditions. This has been well shown by the work of Wyon et al. (1968) on thermal comfort during surgical operations. The individual who is in danger of being overlooked is the patient and he, of course, is the one being who is unaware of and unable to take protective action if the climate to which he is exposed is uncomfortable, undesirable or even dangerous. It is important to recognize this difficulty or impossibility of achieving climatic conditions in the operating room that are acceptable to all. Wyon et al. (1968) found that most surgeons preferred temperatures around 66.5 "F(19 "C) at 50 per cent relative humidity and 25 ft/minute air movement, allowing for the average amount of thermal radiation from the operating room lamp. At this temperature nearly half
the anaesthetists would feel too cold; they mostly preferred temperatures around 71 O F (21.5 "C). The anaesthetist is for much of the time less active than the surgeon who bears the continuing burden of the anxiety and responsibility of the operation as well as having to work in a warmer area of the room. By contrast the anaesthetist may be sitting in such a position that he is directly exposed to the air inlets that may be immediately over his head. One simple answer to these differing personal requirements among the operating room team is that they should dress accordingly; the anaesthetist, for example, may need warmer clothing. This need for adaptation of the climatic requirements of each individual becomes most important when we consider the patient himself. It is unlikely that full control of the patient's requirements of heat loss or heat gain can be achieved by adjustment of the thermal environment of the operating room, and if we are to aim to provide what is best for the patient this can only be achieved by direct methods applied to him. It is not desirable to consider this important matter more fully in this paper; it must suffice to draw attention to it now and to deal with it more fully in another article. In addition to the varying factors that require differing conditions for the members of the operating room team we also have to face the individual preferences of the surgeon. Surgeons differ widely in what they require; many find that a comfortable working temperature is 18.5-21 "C, and it will be remembered that Wyon et a]. (1968) found that most surgeons were comfortable at temperatures around 66.5 O F (19 "C) in their survey of 30 operating suites and 85 operating rooms. Some surgeons do not like a low temperature and prefer a range of 21-22 "C. It should be remembered that unless the efficiency of the surgeon is impaired by environmental conditions which are uncomfortable for him it is the effect of the temperature and humidity of the operating room on the patient that is really important. The patient may be overheated, even as far as being exposed to hyperpyrexia, or he may be chilled. Paediatric surgeons are well aware of this and it is their practice to have the theatre warmer (22-24 "C) for infants or children, especially when the operation being done or the condition being treated (e.g. burns) involves exposure and produces excessive heat loss. Here it is necessary to consider what should be the critical ambient temperature. This has been considered and assessed by Morris and Wilkey (1970) and Morris (1971) as being 21 "C, and they recommend that to prevent intra-operative hypothermia the operating room temperature should be between 21 and 24 "C. If we accept 21 "C as the critical ambient temperature desirable for an adult this would have to be modified upwards for infants and children. Where an ambient temperature of as high as 24 "C could be accepted for the safer conduct of a high risk procedure on an ill child it would ordinarily be unacceptably warm and uncomfortable for an operating room team, even though temperatures as high or even higher than this are often inflicted on the occupants in 255
Lord Brock many operating rooms. Observations will be given in a later article that do not give support to the practice of increasing the ambient temperature to prevent heat loss. In fact the principle of the exeicise has been fully presented by Charles Lamb in his ‘dissertation on roast pork’. There should be wide general appreciation and awareness of the need for optimal climatic conditions in the operating room and it is suggested that it should be the proper duty and responsibility of the surgeon to make it a rule to acquaint himself with the exact conditions pertaining when he begins an operating session instead of paying little or no attention to them except to complain later that the room is too hot or too cold or too humid. For most routine operations and for short operations the climatic conditions that the patient undergoes do not matter greatly. Nature is prodigal in her endowments and patients can endure much without any great harm being done. However, if a long, complex and dangerous procedure is being undertaken, especially on an ill or a poor risk patient, then it should be incumbent upon the surgeon to acquaint himself clearly and fully with the environmental conditions in the operating room, just as he should know the relevant features of the patient’s clinical state such as pulse rate, blood pressure etc., and just as the captain of a ship must know the weather conditions, the state of the tides and the draught of water. Apart from the thermal and humidity levels it is necessary to consider the mode and site of the delivery of conditioned air into the operating room. The use of laminar air flow, whether vertical or horizontal, is at present predominantly used for control of infectivity and it would not be useful to discuss it more fully now. At the same time it must have considerable climatic significance apart from the control of infectivity and so discussion will be necessary later. The usual arrangement of air inlets is either by separate circular or square diffusers in the ceiling or by lateral inlets sited high up on one or more walls. The air escapes either via natural outlets such as doors, etc. or by planned outlet grilles or by pressurerelief flap valves. It is important that the delivery of air from the nlets should not be too violent or too concentrated, and that the inlets should be sufficient in number and size to ensure a gentle inflow. Their siting must also be considered carefully and should certainly not be left for the decision of the engineer on his own. Care should be taken that they are sited in the most ‘neutral’ part of the room and not directly over the heads of, for example, the anaesthetists. It is tempting to the engineer if an observation dome is present to avail himself of its circular form to carry the trunking and to position the inlets around the base of the dome. This will mean that all the team who are located under the periphery of the dome are exposed to a direct down draught. In general such ceiling inlets should be more peripherally sited. Careful thought must also be given to the size and siting of air inlets on the side 256
walls; they should be large enough and so placed that a stream of turbulent air is avoided. It is now possible to be supplied with air diffusers that do not blow down directly upon those underneath, but can direct the air inflow horizontally or in a lateral direction (Fig. 1). This is a simple but important consideration. Enough has been said already to make it mandatory to provide fully conditioned air for the intensive care unit. The mode of its provision demands as much thought as in the operating room. First of all it is necessary to emphasize that the intensive care unit may need much more planned protection from harmful or unfavourable external environmental influences than does the operating room. The main weather aspect should be deliberately considered and it should not be overlooked whether it is, for example, south or north. Also any differences within the unit of the various weather aspects must be considered and protection be provided, where needed, either by appropriate shading or by double glazing. This alone can produce great benefits. If the unit contains separate or individual rooms these will need special consideration. A common form of air inlet provided is a circular or square diffuser in the ceiling sited immediately over the patient’s bed (Fig. 1). It is scarcely necessary to do more than draw attention to such a gross error. Similarly, in a larger ward housing several patients the siting of ceiling diffusers can be equally objectionable, not only for the patients but also for the nurses. It has already been pointed out that air diffusers can now be supplied that deliver a stream horizontal to the ceiling and not directly downwards. The views and experiences of the nurses are often not consulted in assessing the good or bad points of the construction of such a ward, but if asked they may be immediately forthcoming about the nuisance and drawbacks of ill-placed ceiling inlet diffusers. It will be discovered that they often find it necessary to move the patient’s bed so that he may not be exposed directly to a downward air stream. The nurse may complain bitterly of this and can find it especially unwelcome if she is sitting or standing beside the bed under a downward air stream. For reasons such as these it is necessary that the temperature controls should be conveniently adjustable in the ward and in the individual rooms. One objection often raised is that this is undesirable as nurses and others are liable to tinker with and disturb the setting. Nevertheless if the controls are inaccessible an engineer has to be summoned to alter them and this may entail much delay, especially at night. Lateral grilles in the side walls may be unwelcome unless carefully sited. A form of laterally placed inlet that is often more satisfactory is a long slit across the whole length of one wall. If used in a single room and placed high on the wall above the patient’s head it can direct the air stream in an arching fashion that passes completely over the patient and spares him from any direct discomfort while at the same time the room is efficiently ventilated.
Importance of environmental conditions in intensive care
Fig. 1. Diagrammatic representation of a room with a direct down draught of incoming air and how this can and should be prevented by an inlet that gives a horizontal direction to the air flow.
Fig. 2. Diagram showing a room air-conditioned by horizontal laminar flow.
257
Lord Brock The method that should be especially considered in the intensive care unit is laminar flow. This can be vertical or horizontal but the horizontal flow is likely to be more practical. This is possibly the best means of air-conditioning the intensive care unit (Fig. 2). The availability of commercial equipment designed for clean air industrial rooms means that the experience and production methods are available and that the cost need not be excessive. Careful thought should be given to the provision of laminar flow equipment. Many problems may be avoided if early thought is given to its provision while designing or modifying rooms and extra care in design can avoid any undue noise if the fans and humidifiers are carefully sited.
Acknowledgements I wish to acknowledge the great help that 1 have received from Miss P. Archer and Mr Patrick Elliott of the Department of Medical Illustration at Guy’s Hospital for their preparation of the two illustrations. References and RAVENSTINE E. A. (1954) Body temperature studies in anaesthetised man. JAMA 154, 311-3 19. HEALTH AND SOCIAL SERVICE JOURNAL (1974) Intensive care. Pp. 14, 37, 58. IBSEN B. (1967) Treatment of shock with vasodilators measuring skin temperature. Dis. Chest 52, 425429. CLARK R. E.
MEDICAL RESEARCH COUNCIL AND HEALTH (1972) Report by Joint
DEPARTMENT OF
Working Party on Ventilation in Operation Suites. London, MRC and DHHS.
258
(1967, reprinted 1972) Hospital Building Note No. 26; The Operating Department. London, HMSO. MORRIS R. H. (1971) Influence of ambient temperature on patient temperature during abdominal surgery. Ann. Surg. 173, 230-233. MORRIS R. H. and WILKEY B. R. (1970) The effects O f ambient temperature during surgery not involving body cavities. Anaesthesiology 31, 102-107. ROSS B. A., BROCK, LORD and AYNSLEY-GREEN A. (1969) Observations on central and peripheral temperatures in the understanding and management of shock. Br. J. Surg. 56, 877-882.
MINISTRY OF HEALTH
ROYAL AIR FORCE INSTITUTE OF HEALTH AND MEDICAL TRAINING (1972a) Report IMHT No. 19/72. An
Environmental Survey of the Operating Suite at Wegberg. ROYAL AIR FORCE INSTITUTE OF HEALTH AND MEDICAL TRAINING (1972b) Report IMHT No. 27/72. An
Environmental Survey of the Operating Suite at Cambridge Military Hospital, Aldershot. ROYAL COLLEGE OF SURGEONS OF ENGLAND (1964) Report on design of operating theatre suites. Ann. R. Coll. Surg. Engl. 34, 217-288. SPITZER A. G. and BROCK, LORD (1968) The recognition of hypovolaemia after open heart surgery. Guy’s Hosp. Rep. 117, 131-138. VERNER I. R. (1974) The organization, design and staffing of intensive therapy units. Br. J. Hosp. Med. 11, 828-830. WALKER w. F. (1973) Surgical intensive care. Ann. R. CON.Surg. Engl. 53, 50-56. WYON D. P., LIDWELL 0. M. and WILLIAMS R. E. 0. (1 968) Thermal comfort during surgical operations. J. Hyg. (Camb.) 66, 229-248.
The importance of environmental conditions, especially temperature, in the operating room and intensive care ward LORD BROCK* SUMMARY
Although most patients are essentially well enough to be able to resist or to adapt to unfavourable ambient conditions, this may not be so with an ill patient or one who is having or has had a serious operation. The climatic conditions necessary in the operating room to give an optimal environment are discussed. These are second in importance only to control of itlfectivity. Airconditioning in operating suites should be obligatory; there is even oficial acceptance of this. Earlier recommendations that the operating room should be heated to up to 80 " F (27.9"C)are obsolete. The temperature most Javoured by surgeons is 18.5-21 "C; some prefer a range of 21-22 "C. The critical ambient temperature desirable is 21 "C. For infants and children this may be increased up to 24 "C. It is dificult or impossible to achieve climatic conditions in the operating room that are acceptable to all. The needs of the patient are of special importance and are largely neglected; he alone is unable to speak for himself. The disposition of air inlets in the operating room is fully discussed. Climatic conditions in the intensive care unit are of great importance and are discussed. The need for full air-conditioning is absolute although this is often ignored. The delivery of conditioned air within the intensive care unit is also fully presented, especially the need to avoid direct chilling of the patient. The advantages oJ horizontal laminar air flow are presented. THEimportance of a study of central and peripheral temperatures in the recognition of hypovolaemia after open heart surgery was presented in the report of a case (Spitzer and Brock, 1968). A later article (Ross et al., 1969) on observations of central and peripheral body temperatures in the understanding and management of shock dealt with the valuable information that can be obtained essentially in regard to hypovolaemia as a major cause of shock. This work was based on the report of Ibsen (1967) on this subject. Prolonged experience with the study of central and peripheral temperatures and of the gradient between them has served to reinforce the statement (Ross et
18
al., 1969): 'we now feel unable to manage the care of a patient potentially or acutely ill without having information that temperature studies give'. It still remains true that 'few people are aware of such studies and we haveeven been told that all the information we are presenting is available by a simple touch of the hand on the nose or the feet of the patient.' Far from this information being of little value the present author remains convinced that much can be learned from it. Most patients are essentially well enough to be able to resist or to adapt satisfactorily to unfavourable conditions so that these often do not matter greatly. It is different with an ill patient or with one who is having or has had a serious operation. Let us first consider the significance of the climatic conditions in the operating room to which the patient and members of the operating team are exposed. Much has been written about this in recent years but the extent to which practical measures have been taken to achieve an optimal or even improved environment has varied considerably. It is important that the fullest consideration should be given to all the problems involved in view of the very large sums of money that are being spent on hospital construction and that will affect the comfort and recovery of patients and also the life and work of doctors, nurses and of many others for decades or even generations to come. Amongst the many publications on these matters attention is drawn to the Report of a Committee of the Royal College of Surgeons (1964) on 'design of operating theatre suites'. The most important factors relevant to the design of operating suites are those concerned with the avoidance or minimization of infection; clearly these are paramount. The transition from the old operating theatre through antiseptic to aseptic conditions was a brilliant and revolutionary achievement. Next in importance is the provision of
* Department of Surgical Sciences, Royal College of Surgeons, London.
253
Lord Brock suitable climatic conditions for all those within the operating suite, including the patient. It used to be taught that it was in the patient’s interest for the temperature in the operating room to be between 70 and 80°F. One well known and popular textbook of surgery states ‘The theatre . . . must be equipped with a heating system capable of maintaining a temperature of up to 80 O F . ’ That is 27 “C! Without air-conditioning the operating room can be uncomfortable and conditions may become intolerable. Operating room temperatures during the summer in the city of New York have reached the high 90’s with associated high humidity and consequent hyperpyrexia developing (Clark and Ravenstine, 1954). Such conditions are almost obsolete in the USA now that air-conditioning is used. In Great Britain the need for air-conditioning in operating suites is by no means generally accepted (Ministry of Health, 1967). Happily, reason is prevailing and there is wide, even official, acceptance of the absolute need for full airconditioning in most operating rooms (Medical Research Council and Department of Health, 1972). It is necessary to emphasize that air-conditioning must include control of temperature and humidity and does not mean just forced ventilation. Two other comments are appropriate at this point. The first is relative to the post-anaesthetic recovery area (that surely must be treated exactly as the operating room) and to the intensive care unit. The introduction of the intensive care unit is one of the most important and profound changes that has been seen in the clinical lifetime of most of us. Much of the organization of the intensive care unit is concerned with the measurement of parameters that give exact information about vital phenomena instead of relying on the observations and judgements of ‘good nursing’. The improvements in care that result are immense, as we understand more exactly and more deeply what is going wrong with the patient and what therapeutic adjustments are needed. However, the general neglect of deliberate consideration of the environmental conditions of the patient in the intensive care unit is surprising. For example, a recent authoritative article on ‘surgical intensive care’ (Walker, 1973) discusses thoroughly the various parameters that must be measured but makes no mention at all of the environmental conditions that may be important causes of undue extra stress. In a recently published special brochure devoted to intensive care Health and Social Service Journal, 1974) seventeen intensive care units are described and in only two is air-conditioning mentioned as being included in the primary design; in one other it was excluded on grounds of economy and later had to be added. In none of the other fourteen is it even mentioned. It is refreshing to read in an article on the organization and design of intensive care units (Verner, 1974) ‘Air-conditioning is essential in intensive care units.’ In the present author’s opinion the value of the various parameters can be greatly increased by 254
ensuring that the patient is exposed to a standard controlled environment that shields him from unfavourable ambient influences. The improvements in physiological observation and care that are so important among the aims of the intensive care unit should surely be extended to physical environment. It should be axiom2tic that in planning the intensive care unit in every new hospital building provision should be made for full air-conditioning. When such a department is to be set up in an existing hospital it must necessarily be fashioned around or within existing accommodation and therefore shares the climatic disadvantages that the original wards or rooms may possess-disadvantages that may not be important in the original use of the quarters but may become extremely so in their new use. Experience reveals examples of this, especially in regard to the weather aspect. The main outlook may be south or south-west and this can lead to intolerable conditions at certain times of the day and during some seasons of the year. Conversely, an eastern or northern aspect can produce adverse conditions at the other extreme, particularly if the wind is in an unfavourable direction. An intensive care area often has a mixture of aspects of varying types but which have the one common factor that at certain times, either of the day or of the night, they each produce or contribute to an unfavourable environment for the patient. Much can be done to mitigate this in simple ways, such as by double glazing or efficient shading; proper care should always be directed to what are often obvious and simple measures to be taken but which are just not considered or are ignored. However, the basic essential requirement is full air-conditioning. The second comment that is inseparable from the issue arises directly from this, namely the type and design of air-conditioning to be used. The usual attitude to air-conditioning is that it is an entity like the provision of gas, water and electricity and can be requested and installed as such. This seems to be the conception of most surgeons, doctors or administrators when faced with the problem of the design of a new building or the conversion of an old one. The need to discuss with the engineers the type of airconditioning to be installed so as to secure the best conditions is far too little appreciated. Inevitably the engineer, in most instances, is likewise unlikely to be aware of just what is required. He will have full knowledge of the basic facts of ventilation, of control of temperature, humidity and filtration etc., that he can put at the disposal of his clients but he must or should be carefully informed of exactly what is required. The installation of the plant, the trunking and the outlets will be complex and expensive and will require conformity to or alteration of building design to accommodate them. The installation will inevitably be there for many years whether it is the right arrangement or not. Close cooperation between the doctors and the engineers is essential to ensure that it is known exactly what is needed. As the author is not an engineer the following suggestions may be incorrect, incomplete or
Importance of environmental conditions in intensive care
impractical but it is hoped they will serve as a basis for discussion. The suggestions now made are not meant to be complete or final or even fully reasoned. My team is embarking on a series of observations to try to introduce method to certain recommendations or suggestions. The securing of relevant information is time-consuming and is not easy. It is hoped to report in later articles on progress on various aspects of the problems that exist as information is gained. The basic design and function of the central plant and equipment must be the responsibility of the heating and ventilating engineers. The author is chiefly concerned with the mode of delivery of the conditioned air to the operating suite or to the intensive care unit and hence to the patient. Let us take the operating room first; apart from the anaesthetic room the requirements of the other rooms follow almost inevitably with the essential provision that the area of highest air pressure will be the operating room and the aseptic area in general, and the arrangement of doors, windows and other features will be such as to encourage the desired scheme of air circulation or air flow. While recognizing the prime need for attaining the highest standards of asepsis, of really clean air and the avoidance of contamination from any source, space does not permit a full consideration of these; in any case much has already been written about the control of infectivity. For example, environmental surveys of the operating suites at various RAF hospitals have been well reported by the Royal Air Force Institute of Health and Medical Training (1972a, b) at Halton under the overall direction of Group Captain I. A. McIntosh; a very high standard of infectivity control is achieved with consequent lessening of the incidence of postoperative infection. The present remarks will be confined essentially to the climatic factors involved. Mention has already been made of the modern readjustment of views on the temperature ranges desirable in the operating room and that the earlier recommendation of up to 80 O F (27 "C) is unacceptable. It should be realized, however, that it is not possible to provide the temperature conditions to suit the needs of all those working in the operating room. The surgeon, the anaesthetist, the scrub nurse, the other nursing assistants and the ancillary workers may all require different conditions. This has been well shown by the work of Wyon et al. (1968) on thermal comfort during surgical operations. The individual who is in danger of being overlooked is the patient and he, of course, is the one being who is unaware of and unable to take protective action if the climate to which he is exposed is uncomfortable, undesirable or even dangerous. It is important to recognize this difficulty or impossibility of achieving climatic conditions in the operating room that are acceptable to all. Wyon et al. (1968) found that most surgeons preferred temperatures around 66.5 "F(19 "C) at 50 per cent relative humidity and 25 ft/minute air movement, allowing for the average amount of thermal radiation from the operating room lamp. At this temperature nearly half
the anaesthetists would feel too cold; they mostly preferred temperatures around 71 O F (21.5 "C). The anaesthetist is for much of the time less active than the surgeon who bears the continuing burden of the anxiety and responsibility of the operation as well as having to work in a warmer area of the room. By contrast the anaesthetist may be sitting in such a position that he is directly exposed to the air inlets that may be immediately over his head. One simple answer to these differing personal requirements among the operating room team is that they should dress accordingly; the anaesthetist, for example, may need warmer clothing. This need for adaptation of the climatic requirements of each individual becomes most important when we consider the patient himself. It is unlikely that full control of the patient's requirements of heat loss or heat gain can be achieved by adjustment of the thermal environment of the operating room, and if we are to aim to provide what is best for the patient this can only be achieved by direct methods applied to him. It is not desirable to consider this important matter more fully in this paper; it must suffice to draw attention to it now and to deal with it more fully in another article. In addition to the varying factors that require differing conditions for the members of the operating room team we also have to face the individual preferences of the surgeon. Surgeons differ widely in what they require; many find that a comfortable working temperature is 18.5-21 "C, and it will be remembered that Wyon et a]. (1968) found that most surgeons were comfortable at temperatures around 66.5 O F (19 "C) in their survey of 30 operating suites and 85 operating rooms. Some surgeons do not like a low temperature and prefer a range of 21-22 "C. It should be remembered that unless the efficiency of the surgeon is impaired by environmental conditions which are uncomfortable for him it is the effect of the temperature and humidity of the operating room on the patient that is really important. The patient may be overheated, even as far as being exposed to hyperpyrexia, or he may be chilled. Paediatric surgeons are well aware of this and it is their practice to have the theatre warmer (22-24 "C) for infants or children, especially when the operation being done or the condition being treated (e.g. burns) involves exposure and produces excessive heat loss. Here it is necessary to consider what should be the critical ambient temperature. This has been considered and assessed by Morris and Wilkey (1970) and Morris (1971) as being 21 "C, and they recommend that to prevent intra-operative hypothermia the operating room temperature should be between 21 and 24 "C. If we accept 21 "C as the critical ambient temperature desirable for an adult this would have to be modified upwards for infants and children. Where an ambient temperature of as high as 24 "C could be accepted for the safer conduct of a high risk procedure on an ill child it would ordinarily be unacceptably warm and uncomfortable for an operating room team, even though temperatures as high or even higher than this are often inflicted on the occupants in 255
Lord Brock many operating rooms. Observations will be given in a later article that do not give support to the practice of increasing the ambient temperature to prevent heat loss. In fact the principle of the exeicise has been fully presented by Charles Lamb in his ‘dissertation on roast pork’. There should be wide general appreciation and awareness of the need for optimal climatic conditions in the operating room and it is suggested that it should be the proper duty and responsibility of the surgeon to make it a rule to acquaint himself with the exact conditions pertaining when he begins an operating session instead of paying little or no attention to them except to complain later that the room is too hot or too cold or too humid. For most routine operations and for short operations the climatic conditions that the patient undergoes do not matter greatly. Nature is prodigal in her endowments and patients can endure much without any great harm being done. However, if a long, complex and dangerous procedure is being undertaken, especially on an ill or a poor risk patient, then it should be incumbent upon the surgeon to acquaint himself clearly and fully with the environmental conditions in the operating room, just as he should know the relevant features of the patient’s clinical state such as pulse rate, blood pressure etc., and just as the captain of a ship must know the weather conditions, the state of the tides and the draught of water. Apart from the thermal and humidity levels it is necessary to consider the mode and site of the delivery of conditioned air into the operating room. The use of laminar air flow, whether vertical or horizontal, is at present predominantly used for control of infectivity and it would not be useful to discuss it more fully now. At the same time it must have considerable climatic significance apart from the control of infectivity and so discussion will be necessary later. The usual arrangement of air inlets is either by separate circular or square diffusers in the ceiling or by lateral inlets sited high up on one or more walls. The air escapes either via natural outlets such as doors, etc. or by planned outlet grilles or by pressurerelief flap valves. It is important that the delivery of air from the nlets should not be too violent or too concentrated, and that the inlets should be sufficient in number and size to ensure a gentle inflow. Their siting must also be considered carefully and should certainly not be left for the decision of the engineer on his own. Care should be taken that they are sited in the most ‘neutral’ part of the room and not directly over the heads of, for example, the anaesthetists. It is tempting to the engineer if an observation dome is present to avail himself of its circular form to carry the trunking and to position the inlets around the base of the dome. This will mean that all the team who are located under the periphery of the dome are exposed to a direct down draught. In general such ceiling inlets should be more peripherally sited. Careful thought must also be given to the size and siting of air inlets on the side 256
walls; they should be large enough and so placed that a stream of turbulent air is avoided. It is now possible to be supplied with air diffusers that do not blow down directly upon those underneath, but can direct the air inflow horizontally or in a lateral direction (Fig. 1). This is a simple but important consideration. Enough has been said already to make it mandatory to provide fully conditioned air for the intensive care unit. The mode of its provision demands as much thought as in the operating room. First of all it is necessary to emphasize that the intensive care unit may need much more planned protection from harmful or unfavourable external environmental influences than does the operating room. The main weather aspect should be deliberately considered and it should not be overlooked whether it is, for example, south or north. Also any differences within the unit of the various weather aspects must be considered and protection be provided, where needed, either by appropriate shading or by double glazing. This alone can produce great benefits. If the unit contains separate or individual rooms these will need special consideration. A common form of air inlet provided is a circular or square diffuser in the ceiling sited immediately over the patient’s bed (Fig. 1). It is scarcely necessary to do more than draw attention to such a gross error. Similarly, in a larger ward housing several patients the siting of ceiling diffusers can be equally objectionable, not only for the patients but also for the nurses. It has already been pointed out that air diffusers can now be supplied that deliver a stream horizontal to the ceiling and not directly downwards. The views and experiences of the nurses are often not consulted in assessing the good or bad points of the construction of such a ward, but if asked they may be immediately forthcoming about the nuisance and drawbacks of ill-placed ceiling inlet diffusers. It will be discovered that they often find it necessary to move the patient’s bed so that he may not be exposed directly to a downward air stream. The nurse may complain bitterly of this and can find it especially unwelcome if she is sitting or standing beside the bed under a downward air stream. For reasons such as these it is necessary that the temperature controls should be conveniently adjustable in the ward and in the individual rooms. One objection often raised is that this is undesirable as nurses and others are liable to tinker with and disturb the setting. Nevertheless if the controls are inaccessible an engineer has to be summoned to alter them and this may entail much delay, especially at night. Lateral grilles in the side walls may be unwelcome unless carefully sited. A form of laterally placed inlet that is often more satisfactory is a long slit across the whole length of one wall. If used in a single room and placed high on the wall above the patient’s head it can direct the air stream in an arching fashion that passes completely over the patient and spares him from any direct discomfort while at the same time the room is efficiently ventilated.
Importance of environmental conditions in intensive care
Fig. 1. Diagrammatic representation of a room with a direct down draught of incoming air and how this can and should be prevented by an inlet that gives a horizontal direction to the air flow.
Fig. 2. Diagram showing a room air-conditioned by horizontal laminar flow.
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Lord Brock The method that should be especially considered in the intensive care unit is laminar flow. This can be vertical or horizontal but the horizontal flow is likely to be more practical. This is possibly the best means of air-conditioning the intensive care unit (Fig. 2). The availability of commercial equipment designed for clean air industrial rooms means that the experience and production methods are available and that the cost need not be excessive. Careful thought should be given to the provision of laminar flow equipment. Many problems may be avoided if early thought is given to its provision while designing or modifying rooms and extra care in design can avoid any undue noise if the fans and humidifiers are carefully sited.
Acknowledgements I wish to acknowledge the great help that 1 have received from Miss P. Archer and Mr Patrick Elliott of the Department of Medical Illustration at Guy’s Hospital for their preparation of the two illustrations. References and RAVENSTINE E. A. (1954) Body temperature studies in anaesthetised man. JAMA 154, 311-3 19. HEALTH AND SOCIAL SERVICE JOURNAL (1974) Intensive care. Pp. 14, 37, 58. IBSEN B. (1967) Treatment of shock with vasodilators measuring skin temperature. Dis. Chest 52, 425429. CLARK R. E.
MEDICAL RESEARCH COUNCIL AND HEALTH (1972) Report by Joint
DEPARTMENT OF
Working Party on Ventilation in Operation Suites. London, MRC and DHHS.
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(1967, reprinted 1972) Hospital Building Note No. 26; The Operating Department. London, HMSO. MORRIS R. H. (1971) Influence of ambient temperature on patient temperature during abdominal surgery. Ann. Surg. 173, 230-233. MORRIS R. H. and WILKEY B. R. (1970) The effects O f ambient temperature during surgery not involving body cavities. Anaesthesiology 31, 102-107. ROSS B. A., BROCK, LORD and AYNSLEY-GREEN A. (1969) Observations on central and peripheral temperatures in the understanding and management of shock. Br. J. Surg. 56, 877-882.
MINISTRY OF HEALTH
ROYAL AIR FORCE INSTITUTE OF HEALTH AND MEDICAL TRAINING (1972a) Report IMHT No. 19/72. An
Environmental Survey of the Operating Suite at Wegberg. ROYAL AIR FORCE INSTITUTE OF HEALTH AND MEDICAL TRAINING (1972b) Report IMHT No. 27/72. An
Environmental Survey of the Operating Suite at Cambridge Military Hospital, Aldershot. ROYAL COLLEGE OF SURGEONS OF ENGLAND (1964) Report on design of operating theatre suites. Ann. R. Coll. Surg. Engl. 34, 217-288. SPITZER A. G. and BROCK, LORD (1968) The recognition of hypovolaemia after open heart surgery. Guy’s Hosp. Rep. 117, 131-138. VERNER I. R. (1974) The organization, design and staffing of intensive therapy units. Br. J. Hosp. Med. 11, 828-830. WALKER w. F. (1973) Surgical intensive care. Ann. R. CON.Surg. Engl. 53, 50-56. WYON D. P., LIDWELL 0. M. and WILLIAMS R. E. 0. (1 968) Thermal comfort during surgical operations. J. Hyg. (Camb.) 66, 229-248.
