There have been many advancements in technology to provide protection from blast exposure, including limiting direct passage through the skull, compression of the torso causing a transfer of kinetic energy to the brain, and through protecting the chest and lungs to reduce hypoxia. [1]
Another potential site of blast overpressure transmission is through the ear canal. Researchers have designed a way to isolate blast overpressure to the ear, which has allowed them to study the ear’s role in blast injury. With this technology, they found that a single exposure to 50 PSI directly to the ear in rats resulted in immediate and permanent apnea, and ultimately death. Blasts above 30 PSI resulted in immediate decrease in blood pressure, while exposures less than 30 PSI had less pronounced blood pressure variations. [1]
This research demonstrates that the ear is vulnerable to blast overpressure, and blast overpressure through the ear can result in significant cardiorespiratory changes and death.
Even low-level blasts, which they defined as between 2-30 PSI, resulted in rapid and slow heart rate variabilities with a slow recovery.
Previously, the autonomic responses to blast exposures were attributed to the lungs. This study demonstrated the role the unprotected ear can have on the autonomic effects of blast exposure. It highlights the importance of developing ear protection that offers auditory, vestibular, and neurotrauma protection while maintaining hearing for situational awareness.
References:
- Sandlin, D. S., Yu, Y., Huang, J., Zhang, C., Arteaga, A. A., Lippincott, J. K., … & Zhou, W. (2018). Autonomic responses to blast overpressure can be elicited by exclusively exposing the ear in rats. Journal of Otology, 13(2), 44-53.