The new Hybrid Cardiac Catheterisation Laboratory at Our Lady’s Children’s Hospital, Crumlin is the only fully equipped paediatric cardiology service on the island of Ireland to treat young children with heart defects. It is a new design build project by Clancy Construction delivered on time and within budget in 2016 through the use of building information modelling (BIM) by an interdisciplinary project team including RPS as mechanical and electrical consulting engineers. The project was recently awarded the Association of Consulting Engineers of Ireland Design Excellence Award 2017 for Mechanical & Electrical Projects (Medium). The new laboratory performs cardiac catheterisation to help diagnose heart problems in children, as well as correcting heart problems that once required open-heart surgery. The core equipment that the cardiologists and the team use is the specialist imaging equipment that allows for real-time imaging of the heart and its blood vessels. The design of the theatre suite also allows it to be rapidly turned into a cardiac theatre and thus permit more complex interventions than would have been previously possible on the island of Ireland. The laboratory is a new build at first-floor level, with a direct connection to the operating theatres by way of a link bridge. Equipment will be transferable to the new National Children’s Hospital when operational in the future, if required. The latest technology employed will facilitate open-heart surgery and uses both open heart and keyhole techniques in the same procedure to improve outcomes. It also allows immediate post-surgical cardiac catheter/angiography to confirm a satisfactory result.

Challenges of the building project

[caption id="attachment_36929" align="alignright" width="300"] Image 1: rendered BIM image at design stage[/caption] The project consisted of a three-storey development measuring 545 square metres of clinical space. The construction value was €4 million and the design/construction programme was 65 weeks. The building was designed with an undercroft area for car parking, and incorporated a hybrid catheterisation laboratory and orthopaedic theatre including an ultra-clean ventilation system. The third floor is an internal plantroom containing the mechanical and electrical equipment necessary to serve the building. Both the laboratory and the orthopaedic theatre are served by individual air handling units complete with high efficiency particulate air (HEPA) filtration to provide ultra-clean air to the spaces. All life-critical electrical systems are backed up with uninterruptible power supply (UPS) and isolated power supply (IPS) as required for medically used rooms. The Siemens Bi-Plane Cardiac scanner was supplied through a UPS system, which ensured the quality and resilience of the power supply. The scanner and its associated support system were carefully integrated into the lab and all associated services including electrical, ventilation and medical gas services. This project achieved all of the above through an innovative, highly efficient and collaborative approach by the design and construction teams and the hospital’s clinical staff. The key challenge on this project was the requirement for very detailed co-ordination of the mechanical and electrical services with the building and the end user equipment. To meet this challenge, the mechanical and electrical design was carried out in a Federated BIM Level 2 model using Autodesk Revit. The project team created a digital prototype of the building and thereby facilitated simultaneous rather than sequential integration of engineered systems (mechanical and electrical), structural and architectural disciplines resulting in great precision and efficiency and achieving successful compression of the construction window. BIM workshops convened at the outset of the design led to a project-specific BIM Protocol Manual that aligns as much as possible to the PAS 1192:2 Standard. Key members of the design and construction teams came together early in order to understand how each discipline intended to use 3D modelling on the project and to share experiences of BIM on past projects. On this project, the design and construction ensured that all activity was patient centric with site management integrating fully with the hospital-management team. The site-management team were uncompromising in implementing health and safety policy also using BIM to produce animations of site traffic and signage. Careful planning and consultation with all interested parties was required to achieve the tie-ins to the existing mechanical and electrical systems to ensure any interruption of life critical systems was minimised. Back-up systems were put in place to ensure continuity of service in critical patient care areas at all times during construction.

Complexity and volume of medical equipment

[caption id="attachment_36930" align="alignright" width="300"] Image 2[/caption] The complexity and volume of medical equipment to be installed in the catheterisation laboratory necessitated highly detailed design in both plan and elevation to ensure that the scanner rails, lighting and medical pendant positions, both in use and parked, would not interfere with the air distribution patterns. The air distribution pattern was critical to the hospital and its infection-control department. The velocity of the air at the operating table could not exceed 0.5 m/s. RPS demonstrated compliance with this requirement by producing data and test results for the proposed diffuser that had been factory tested for a previous project. Using the graphical representation of the velocities at measured distances from the centre of the diffuser, RPS was able to prove that the velocity in the operating zone would not exceed the requirements of the relevant Health Technical Memorandum (HTM 03-01). See graphical representation of the test results (Image 2). Placement of the air delivery diffusers in the ceiling was critical to achieving the required air distribution pattern and this was assisted greatly by the 3D modelling undertaken. The scanner equipment also required a number of access hatches in the ceiling to allow maintenance and future access which further complicated the ceiling design. The ultra-clean environment in the theatres does not allow the re-use of room air re-circulation and Fresh Air rates in excess of 25 air changes per hour (ACPH) were needed to meet the requirements of Health Technical Memorandum (HTM) 03-01: Specialised ventilation for HealthCare Premises. The reasons for the high air change rates are:
  • To remove, contain or dilute specific contaminants and fumes – for example (anaesthetic gases);
  • To preserve a desired air-flow path from a clean to a less clean area and maintain required pressure gradients between spaces;
  • To provide control of the cleanliness of the space;
  • To provide close control of temperature of the space;
  • To provide control of the humidity of the space.
In order to achieve a level of sustainability and reduce the running costs of the installation, the design of the air conditioning system provided for indirect heat recovery from air being discharged to the exterior. This was achieved through run around coils to recover heat energy from the extract air stream and use this heat energy to pre heat the fresh air intake air stream during periods of colder weather. Other methods of heat recovery, such as plate heat exchangers and thermal wheels, were examined during the design period but were ruled out due to space constraints within the plantroom.

Design conditions for the theatre

[caption id="attachment_36931" align="alignright" width="300"] L-r: Richard Crowe, ACEI president; Andrew Mulhall, RPS; Padraic Brennan, RPS; Sineád Hughes, MOLA Architecture; Ian Smillie, Clancy Construction and Niall Donohoe, RPS. Image: Colm Mahady[/caption] The design conditions for the theatre are 18-28 ±2°C and 40-60% relative humidity. The air-handling unit is equipped with a humidifier coil powered by clean steam to add moisture to the airstream during periods of cool dry weather. The chiller plant and cooling coil dehumidify the airstream during periods of warmer weather and the unit is fully controlled via the building management system (BMS) to control the space to the above conditions. A theatre control panel is installed in the theatre, which allows the clinical team to adjust the conditions within the space as required within pre-agreed limits. This panel is then in turn linked to the BMS, which controls the air handling unit and provides the conditions as specified by the clinical team. The LED surgical light pendant was also equipped with a high-definition camera, which was linked in turn to a full audio-visual system. This is controlled within the theatre and allows the team to transmit audio and video signals to other locations within the hospital and throughout the world of the procedures undertaken within the theatre. The project was executed by an integrated team under a design/build contract awarded to Clancy Construction. The adoption of BIM promoted ongoing value engineering of design solutions allowing the project to remain within cost limitations without impacting quality. This integration of design and construction encouraged a selfless team spirit that promoted co-operation as a basis for solutions, streamlined delivery and ultimately produced successful outcomes. The construction work was carried out in a live hospital campus adjacent to the existing operating theatres. The successful completion of this project on time and within budget through the design build process was a very efficient use of capital investment to create essential health infrastructure for the nation’s children. Author: Andrew Mulhall is a senior mechanical engineer with RPS with significant national and international experience. His projects include new build, facility expansion and retro-fit applications in the healthcare, medical devices, education and commercial sectors.