The sensitivity of pneumothorax diagnosis via handheld ultrasound is low, and there is no equipment suitable for use with life-threatening tension pneumothorax in a prehospital setting. This study proposes a novel technology involving optical fibers and near-infrared spectroscopy to assist in needle thoracostomy decompression. The proposed system via the optical fibers emitted dual wavelengths of 690 and 850 nm, allowing distinction among different layers of tissue in vivo. The fundamental principle is the modified Beer–Lambert law (MBLL) which is the basis of near-infrared tissue spectroscopy. Changes in optical density corresponding to different wavelengths (690 and 850 nm) and hemoglobin parameters (levels of Hb and HbO2) were examined. The Kruskal–Wallis H test was used to compare the differences in parameter estimates among tissue layers; all p-values were < 0.001 relevant to 690 nm and 850 nm. In comparisons of Hb and HbO2 levels relative to those observed in the vein and artery, all p-values were also < 0.001. This study proposes a new optical probe to assist needle thoracostomy in a swine model. Different types of tissue can be identified by changes in optical density and hemoglobin parameters. The aid of the proposed system may yield fewer complications and a higher success rate in needle thoracostomy procedures.