Can we use normal saline stored under stress conditions? A simulated prehospital emergency medical setting

Data on stability and suitability to use normal saline stored under stress conditions in ambulances is lacking.

We aimed to study the impact of exposure to extreme temperature variations on normal saline stability and compatibility with its packaging.

Normal saline in 96 polyolefin bags were exposed to continuous temperature of 22, 50, and 70 °C or to a cyclic temperature of 70 °C per 8 h and 22 °C per 16 h. The bags were sampled at 12, 24, 48 and 72 h and at 1, 2, 3, and 4 weeks in the short- and long-term experiments, respectively. Solution inside the bags was evaluated for any evidence of crystallization, discoloration, turbidity, or pH changes. A sample of normal saline was withdrawn from each bag to analyze sodium and chloride levels.

Precipitation, discoloration, or turbidity were not observed in the solution inside normal saline bags. The average pH was 5.59 at 22 °C, 5.73 at 50 °C, 5.86 at 70 °C and 5.79 at cyclic exposure. In the short- and long-term experiments, sodium and chloride concentrations were within 100.2-111.27% and 99.04-110.95%, respectively. Leaching of the plastic components in the polyolefin bag into the normal saline solution was not detected.

Sodium and chloride levels of normal saline were stable and compatible with polyolefin bags stored in simulated continuous and cyclic extreme temperatures for around one month. The effect of storage in the cabinet of operational ambulance vehicles during different seasons in arid countries is yet to be evaluated in real-world conditions, to further confirm our results.