| In April 2003 Medicor, a consortium of companies that includes PB, was appointed under National Health Service (NHS) ProCure 21 to design and construct a new children’s specialist burns unit and education centre on the existing Birmingham Children’s Hospital site. PB is responsible for the mechanical, electrical design and civil and structural engineering designs.
NHS ProCure21 was launched in April 2000 in response to “Rethinking Construction,” a report undertaken in 1998 to review the UK construction industry, and HM Treasury’s “Achieving Excellence, a guide that reflects recent developments in construction procurement and focuses on optim izing cost and quality. NHS ProcCure21 is a standardised approach to the procurement of healthcare facilities that is based upon long-term relationships with carefully selected supply chains that have the ability to work with NHS clients across the whole life cycle of a scheme.
Project Overview
The existing hospital is located in the heart of Birmingham. The client expects a prestigious new centre of healthcare excellence that offers state-of-the-art specialist burns operations and treatment facilities whilst maintaining a caring, friendly, and fun environment for potentially seriously injured children.
The facility consists of a new four-storey extension, together with the adaptation of the existing 100-year-old four-storey building. The extension will provide new wards and outpatient accommodations, whilst the remodelled building will provide a specialist burns operating theatre suite, including a recovery area and high dependency bed unit. The remodelling presented the design team with a number of major challenges that had to be addressed in order to achieving the extreme environmental conditions required by the medical staff.
Incorporating a Helipad
Late in the design stage, the client asked the design team to investigate the possibility of adding a helipad to the new extension’s roof to facilitate the rapid transfer of burns patients in the UK. The requirement was that the helipad be designed for construction in the future in a “retro fit” phase of the development. This presented several challenges to PB’s engineering team.
It was first necessary, in conjunction with the aviation authority, to ascertain the size and position of the helipad to meet the authority’s stringent landing requirements. It was then necessary to agree to the maximum size of any helicopter that was to use the helipad and the physical dimensions of the pad itself. With these issues settled, we got on to the other challenges.
- Health and Safety. The design requirement that the helipad could be fitted retrospectively had significant health and safety implications because the hospital would be fully operational whilst the helipad was being installed. To minimise future health and safety risks, our design solution was to provide a solid concrete floor or roof between the future helipad and areas occupied by hospital staff and patients.
- Structural Impact. We used a proprietary bolt on platform with an aluminium deck on a steel frame to minimise structural impact on the buildings and minimise preparatory works. FEC Heliport from Cincinnati, Ohio, assisted PB’s design team with this aspect of the design.
The steel frame consisted of a bespoke design supplied as part of the future helipad installation. The interface between the helipad and the main structure was, therefore, clearly defined. Designated columns, structurally enhanced, were extended up though the roof finishes and weatherproofed. The tops of these columns can be exposed in the future and the steel frame bolted to them without any unnecessary disruptive structural works.
• Fuel Spillage. Petrol interceptors were included as an integral part of the helipad deck design to guard against future aviation fuel spillage. This feature kept the helipad as a self contained future works package and eliminated any need to fire protect the building’s internal drainage pipes at a later date.
• Stretcher Access. A major challenge was to provide stretcher access to and from the helipad. Aviation regulations stipulate that no obstructions can protrude above the deck during landing. Therefore, our team proposed a specialist scissor lift with retractable lift car housing. When not in use, the lift car housing can be retracted within the lift shaft, thereby sealing off the shaft and not protruding above the deck during helicopter landings.
Patient transfer from roof level to theatres will be by normal bed lift.
Defining Variable Environmental Conditions
The environmental requirements for conventional operating theatre facilities are well defined; however, there are no statutory regulation standards or NHS guidelines for environmental conditions for burns facilities. The client’s requirements for the burns operating theatre suite, recovery, and high dependency unit evolved during the concept design period. These conditions varied according to the different severities of the burns that had to be treated.
Figure 1: Birmingham Children's Hospial temperature/pressure regime. |
Our design team worked closely with the client, surgeons, consultants and clinicians to determine the required variable environmental conditions. The final agreement was to have a system that could provide an internal environment of 21ºC (70ºF)/50 percent relative humidity (RH) under normal conditions, and to adjust up to the highest level of 38ºC (100º F)/ 50 percent RH, which is the critical temperature when treating severely burned patients. Rest areas were also needed with a temperature of 28ºC (82º F) so staff could take short breaks from the extreme temperature when undertaking surgery or providing general care of the critically ill patients.
The clinicians viewed the high temperature of 38ºC (100º F)/ 50 percent RH as the most important issue because loss of body heat is considered to present the greatest risk to life during the treatment and recovery of burn patients. At the same time, our team needed to consider the spread of bacteria at extreme temperatures and humidity.
Maintaining High Heat and Avoiding Spread of Bacteria
Our team produced a simplified block diagram to indicate to the clinicians the variable temperature and air pressure regimes available to each area (Figure 1). Each area within the theatre suite (the operating theatre, high dependency unit beds, and recovery) would have independent temperature and humidity control. Humidity would be automatically controlled to maintain RH conditions at the increased temperature levels.
The extreme temperature condition and the need for rapid heat-up and control of humidity within the areas provided m ajor design challenges to the team. These requirements impacted the stringent air pressure and infection control requirements for the department as air movement has to cascade via pressure stabilisers from the operating theatre to the less clean areas; i.e., from a clean to dirty area. Temperature differentials between rooms must be kept below 2ºC (4º F).
The challenge presented to our design team regarding the requirement for rapid heat-up was to determine the optimum heat-up period in relation to realistic building insulation levels and avoidance of condensation. At the same time we had to meet the medical team’s expectation regarding use and availability.
Our design includes a high efficiency particulate air filter (HEPA), which is sometimes referred to as an absolute filter. The HEPA filter is designed to provide very high efficiency filtration of tiny particles in the sub-micron size range. It is located within an ultra clean canopy that will be installed into the theatre to prevent the spread of bacteria. Its construction will be refined so that the terminal HEPA filters will operate satisfactorily in the extreme environment. The unit will provide clean filtered air over the operating table, thus restricting bacterial contaminations in the remainder of the operating room from reaching the patient.
Preventing Condensation
Our design team had to carefully consider and examine internal building fabric details to ensure that condensation will not occur within the facility under the potential internal temperature and humidity levels. As part of our analysis, we determined an optimum heat-up period at which the required internal environmental temperature is reached and all internal building fabric is above the critical dew point value to avoid the occurrence of condensation.
Our analysis found that any internal building fabric below 26.5ºC (80º F) will give rise to condensation as it is below the dew point temperature of the environmental air. Our design solution included providing enhanced internal insulation to prevent the internal surface temperature of any component from dropping below that temperature when the outside temperature is -5ºC (23º F)—the recommended external health care design temperature—whilst the inside temperature is at its maximum high of 38ºC (100º F) with 50 percent RH.
The second part of our design solution was to develop a controls strategy that holds off the introduction of humidification until the required internal building fabric temperature level has been reached. Sensors will be provided in the fabric to monitor temperature levels and used to regulate and control the humidity levels accordingly.
Conclusion
The environmental conditions and operational needs for the patients and staff within this department are unique to this hospital. Temperatures at times will be severe, but these conditions for the staff are considered secondary to the need for the proper care and treatment of severely burned children. The new building is currently being constructed and the new facilities will be operational in March 2006
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