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Critical dependence of acetate thermal mattress on gel activation temperature
  1. A Carmichael,
  2. S McCullough,
  3. S T Kempley
  1. Neonatal Transfer Service for London, Barts and the London NHS Trust, London, UK
  1. Correspondence to:
    S T Kempley
    Royal London Hospital, Whitechapel, London E1 1BB, UK;steve.kempley{at}


Background: Sodium acetate gel mattresses provide an active method of warming patients through release of latent heat of crystallisation. They can be used as an adjunct to incubator care or as an exclusive heat source.

Objective: To determine activation temperatures of the Transwarmer mattress needed to achieve plateau temperatures of 38–42°C.

Design and setting: In vitro testing of mattress temperature.

Methods and outcome measures: Transwarmer mattresses were activated at initial temperatures ranging from 5 to 40°C. Mattress temperature was recorded up to 4 h to determine peak and plateau temperatures. Peak and plateau temperatures achieved by the mattress were related to the initial starting temperature.

Results: The starting temperature of the mattress was strongly correlated with peak and plateau temperature (r = 0.99, p<0.001). To achieve the target temperature of 38–42°C, the Transwarmer mattress requires activation between 19.2°C and 28.3°C. A temperature of 37°C could be generated by activation at 17°C.

Conclusions: Safe use of this device is critically dependent on gel temperature at the point of activation. To ensure warming of a hypothermic neonatal patient without running any risk of burns, the mattress should be activated with a gel temperature between 19°C and 28°C.

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  • Published Online First 28 July 2006

  • Competing interests: None.

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