To determine whether the M40 protective chemical gas mask (M40 mask) increases bronchial airway hyperreactivity in military active duty soldiers with exercise induced bronchospasm (EIB). The point of prevalence of EIB in the US Army is 7% and many of these soldiers are capable of performing their exertional military duties. However, it is unclear how soldiers with EIB will perform when they are required to use the M40 mask for prolonged periods. Furthermore, there are anecdotal concerns of increased EIB exacerbations when these individuals wear the M40 mask.
Active duty soldiers were screened in the Pulmonary clinic for EIB. Diagnostic criteria for EIB included a history of exertional dyspnea, normal baseline spirometry and a positive methacholine challenge test ≤ 4mg/ml. Subjects who participated in the study completed exercise spirometry breathing room air. A repeat exercise spirometry was performed two days later with the subject wearing a full face M40 mask. A matched number of participants with no history of EIB or other pulmonary disorders were included in the control group. The FEV1 post exercise challenge testing (ECT) with and without the M40 mask was compared in both subject and control groups.
Nine subjects with EIB and 3 controls were evaluated. Both the subjects and controls underwent baseline (ECT) with and without the M40 mask. The FEV1 post ECT was compared and there was no statistical difference in both groups with or without the M40 mask. One of the nine subjects with EIB had a positive ECT while wearing the M40 mask.
Our pilot study revealed that soldiers with EIB who exercised wearing the M40 mask infrequently had bronchospasm exacerbations.
Our results support the US Army retention standards of soldiers with EIB. Because one subject did have a positive ECT while wearing the M40 mask we recommend screening ECT while the protective mask is worn in soldiers with EIB retained on active duty.
Pedro Lucero, None.