Trapezius muscle metabolism measured with NIRS in helicopter pilots flying a simulator
Harrison, M.F.; Neary, J.Patrick.; Albert, W.J.; Veillette, D.W.; McKenzie, N.P.; Croll, J.C.
Aviation Space and Environmental Medicine 78(2): 110-116
2007
ISSN/ISBN: 0095-6562 PMID: 17310881 Document Number: 612380
Introduction: This study examined metabolic and hemodynamic responses during night vision goggle (NVG) induced neck strain among military helicopter pilots. We hypothesized that near infrared spectroscopy (NIRS) would be capable of identifying metabolic differences in the trapezius muscles of pilots between simulated flights with and without NVG. Methods: There were 33 pilots who were monitored on consecutive days during Day and NVG flight simulator missions. NIRS probes were attached bilaterally to the trapezius muscles at the C7 level to record total oxygenation index (TOI, %), total hemoglobin (tHb), oxyhemoglobin (HbO(2)), and deoxyhemoglobin (HHb). Results: Significant differences in tHb were found between Day (0.51 +/- 2.31 mu mol center dot cm(-1)) and NVG (4.14 +/- 2.74 mu mol center dot cm(-1)) missions, and for HbO(2) (Dayend 2.63 +/- 1.64 mu mol center dot cm(-1); NVGend 5.77 +/- 1.98 mu mol center dot cm(-1)). Significant left and right side differences between Day and NVG were found for tHb (NVGleft -1.83 +/- 2.55; NVGright 10.45 +/- 2.86 mu mol center dot cm(-1)), HbO(2) (NVGleft 1.77 +/- 1.90; NVGright 9.95 +/- 2.07 mu mol center dot cm(-1)), and HHb (Dayleft -1.84 +/- 0.95; Dayright -2.32 +/- 0.87 mu mol center dot cm(-1); NVGleft -3.60 +/- 1.05 mu mol center dot cm(-1); NVGright 0.49 +/- 1.16 mu mol center dot cm(-1)). Discussion: These results support NIRS's utility in assessing the significant metabolic and hemodynamic effects of NVG on neck musculature during real-time missions for 1) left and right side differences; and 2) Day vs. NVG missions. The additional mass of the NVG equipment does increase the metabolic stress of these muscles during simulated missions.