Cooling patients post cardiac arrest was introduced as a policy in 2002. Ice was the only method available for cooling these patients.

Ice proved to be a difficult cooling medium as large quantities of ice was often required and not available on campus. Serious hazards to both staff and patient safety were a recognised risk.

A trial to develop an effective, non-mechanical method of cooling these patients was explored.

In collaboration with an external company Arctic Heat a cooling kit was developed. The cooling kits are manufactured from polyester mesh fabric containing biodegradable non-toxic crystals which when soaked in water becomes a temperature retaining viscous gel. After initial cooling in a freezer the kit is placed on the patient allowing effective, indefinite cooling.

The kit eliminated ice related safety risks and has proven to be a portable, cost effective, efficient, safe and easy to use system.

To develop a method of cooling patients for long periods that is safe, portable, efficient, easy to use cost effective and complies with infection control standards.

Cooling post cardiac arrest was introduced in 2002 following published trials.  A patient’s core temperature must be lowered to between 32°C & 34°C and maintained for 12 to 24 hours. Ice was the only cooling method available to achieve these temperatures. Large quantities of ice were required which lead to sopping beds and dangerous puddles. This created OH&S issues relating to patient and staff safety. In addition, it proved distressing for relatives. In order to obtain enough ice to achieve lowered patient core temperatures, staff had to leave the campus to purchase ice from an outside source.

As funding was not available for the purchase of a commercial cooling machine, other methods for cooling patients were explored.

Published research indicated that by reducing core temperature to between 32°C and 34°C-post cardiac arrest, neurological outcomes were significantly improved. Cooling became policy in 2002. Cooling criteria was strict and the HKH Intensive Care Unit projected number of patients fulfilling these criteria was small (5-7) per year. Consequently funds were not made available for the purchase of a commercial cooling device. Ice was the only method of cooling available.

When the policy was introduced the Intensive Care Unit had 2 ice trays and access to an ice machine located on the other side of the campus.

In order to achieve the temperature reduction required, the patient had to be packed in ice for up to 24 hours.

ICU staff identified the following problems when using ice. The first was availability. As the hospital ice machine serviced the entire hospital there was never enough to cover the ICU needs. Whatever ice was available had to be carried across the campus in buckets, which, could weigh up to 10 kilos.To supplement supply staff had to leave the unit to purchase ice at the local service station, sometimes late at night, posing considerable OH&S & staffing issues.

Melting Ice was further problem. Nursing staff employed many methods to contain melting ice. However, water from melting ice managed to leak into the bed, the plastic draw sheets being the perfect conduit  onto the floor, creating electrical hazards and the risk of staff or visitors slipping. Bed linen had to be changed 2nd hourly requiring 3-4 staff members to carry out the procedure safely.

Finally, a significant increase in the risk of injury to patients was identified. Placing ice next to a patient’s skin can result in ice burns.  2nd hourly full linen changes pose risks to the maintenance of airway, lines and the potential for sudden deterioration in condition for critically ill patients on life support. The increased risk of immobile patients developing pressure sores is worsened by constantly wet beds.

The cooling vest has reduced patient shivering, which ultimately causes increased body core temperature when traditional ice cooling methods are used.

An article in Hospital & Health Care 2003 described the use of a cooling vest, which was utilised by surgeons.  The ICU CNC investigated the use of these cooling vests for post cardiac arrest patients in ICU.

Collaboration between the company Arctic Heat, distributors of the surgical cooling vests, and the HKHS ICU began in 2003. Initially the surgical cooling vest was sent to trial on ICU patients.  The vest design was difficult to use in the ICU environment. Arctic Heat agreed to work with the ICU CNC to redesign & develop a more practical cooling kit. Special temperature charts and staff evaluation sheets were used for each stage of development.

After 2 years and 15 patients the Hornsby Cooling Kit was developed. All items in the Kit are manufactured from polyester mesh impregnated with a non-toxic biodegradable crystals, which when activated in water become a viscous gel capable of retaining temperature for long periods.

The Kit consists of the following items:

• 2 x caps
• 2 x blankets (shoulder to thigh)
• 4 x groin pads
• 4 x axilla pads

After activation the kit is cooled in the freezer. The items are then rotated 2nd hourly from the freezer to the patient. At all times the patient has a cap, blanket, groin and axilla pads on while the other set is in the freezer. The Hornsby Cooling Kit allows for effective cooling over an indefinite period of time. 

The Cooling Kit

The cooling kit has reduced the burden of cooling enormously. Following its evaluation and approval by the Product Evaluation and Infection Control Committees, the kit is used in I.C.U. and Emergency and will soon be used in Theatres.

Staff evaluation has been positive. Patient core temperatures have been steadily maintained as opposed to variation of temperatures caused by the previous ice system utilised.

Kits are activated and stored in the freezer compartment of the units drug fridges. Care was taken during the design stage to ensure that the kit would fit into a standard freezer compartment as most areas have a drug fridge.

The kit is placed on the patient in Emergency thus preventing any delay in the cooling process. Application of the kit does not affect the action of monitoring equipment, it can remain in place during diagnostic tests such as angiograms or C.T. scanning. Should defibrillation or C.P.R. be required the blanket is moved to the legs.

Once in ICU the kit rotates from freezer to patient as required. Upon completion of treatment the kit is sanitized or soaked in a solution approved by infection control then replaced in the freezer for future use.

Patients need to be cooled both in and out of hospital for many reasons. Our kit has huge potential to improve patient outcomes as its portability will allow ambulance officers to initiate cooling in the field. Many hospitals continue to struggle with ice. The Australian Army is negotiating to have the kits in field hospitals and on manoeuvres. The Navy and Fire Brigade are also interested.It is the only re-usable, portable, cooling device in the world to-day. It costs under $400. The hospital will receive a percentage of every kit sold.

Bernard SA, Jones B.M. Horne M.K. Clinical Trial of induced hypothermia in comatose survivors of out-of-hospital cardiac arrest. Ann Emerg Med.1997; 30: 146–153.