Effect of spinal immobilization devices on pulmonary function in the healthy, nonsmoking man

In the prehospital management of trauma, a variety of devices are used for immobilization of the spinal column during extrication and transport. Two of these commonly used immobilizers, the Zee Extrication Device and the long spinal board, use crisscrossing straps over the thorax to affix the patient to the device. Our study was designed to determine if these two devices alter pulmonary function in the healthy, nonsmoking man. We took 15 healthy, nonsmoking male volunteers and tested four pulmonary function parameters: forced vital capacity (FVC), forced expiratory volume in one second (FEV1), the ratio FEV1:FVC, and forced mid-expiratory flow (FEF 25%-75%). A Breon spirometer was used to test these functions both before and after the volunteers were strapped into the two devices. Three separate trials were given for each parameter and the best scores were used for data computation. Strap tension was controlled by placing a sphygmomanometer beneath each strap and adding tension to produce 10 mm Hg pressure. We found a significant difference (P less than .05) between prestrapping and poststrapping values for three of the four functions tested using the long spinal board: FVC (P = .0079), FEV1 (P = .0001), and FEF 25%-75% (P = .0252). Similarly significant differences were found for three of the four parameters using the Zee Extrication Device: FVC (P = .004), FEV1 (P = .0022), and FEF 25%-75% (P = .008). These differences reflect a marked pulmonary restrictive effect. The ratio FEV1:FVC can be normal or even slightly elevated with restrictive airway disease due to proportional reductions of each parameter. Correspondingly, we found no significant difference between prestrapping and poststrapping FEV1:FVC values (P greater than .05).(ABSTRACT TRUNCATED AT 250 WORDS)