Purpose: To determine the cooling effect of generic insulated shipping containers in ambient and high-temperature environments.
Methods: Twenty-seven shipping containers were packed with wet ice according to industry standards. The ice in each container was weighed. Ambient temperatures were recorded by data loggers affixed to the exterior. Internal temperatures were recorded by data loggers packed inside the containers, for as long as the data loggers remained at ≤8°C. The cooling effect, or minutes per gram of ice a data logger maintained a temperature of ≤8°C, was calculated using linear regression; 8 similar containers were subjected to elevated summer temperatures.
Results: Small, medium, and large containers held mean masses of wet ice of 685, 1929, and 4439 g, respectively. The linear regression equation for grams of ice to duration of time at ≤8°C was y = 0.1994x + 385.13 for small containers, y = 0.1854x + 1273.3 for medium, and y = 0.5892x + 1410.3 for large containers, resulting in a cooling effect of 25.1 hours for small, 58.9 hours for medium, and 85.7 hours for large containers at ambient temperature. The duration of cooling effect in the summer profile group was consistent with that of the ambient temperature group.
Conclusions: All of the container sizes successfully maintained proper cooling when packed with the appropriate grams of wet ice for the needed time interval. This study validates current practice for the shipment of corneal tissue in inexpensive, generic containers that can maintain effective cooling for the duration required for local, national, and international shipment.
*SightLife, Seattle WA
†Group Health Cooperative, Bellevue, WA
‡Department of Ophthalmology, University of Washington Medical Center, Seattle, WA
§Vision Share, Apex, NC.
Reprints: Thomas D. Miller, Director of Clinical Services and Regulatory Affairs, SightLife, 221 Yale Avenue N, Suite 450, Seattle, WA 98109 (e-mail: firstname.lastname@example.org).
Supported by SightLife and Vision Share, the nonprofit organizations with which the authors are associated as employees (T.D.M., A.J.M., J.R.) or Medical Director (T.D.L.).
The authors state that they have no proprietary interest in the products named in this article.
Editorial assistance in the drafting of this manuscript was provided by Jan Beiting, Wordsmith Consulting.
Received November 14, 2011
Accepted July 3, 2012