EFFECT OF EXTREME COLD ON MULTITASK PERFORMANCE DURING EXPOSURE TO MODERATE AND SEVERE NORMOBARIC HYPOXIA

INTRODUCTION: This study compared the physiologic and cognitive response to moderate (5486m, MH) and severe (7620m, SH) normobaric hypoxia while under ambient and cold conditions. METHODS: Six males (39 (plus-or-minus sign) 7yr, 1 78 (plus-or-minus sign) 6cm, 86 (plus-or-minus sign) 7kg) gave their informed consent and continually performed multiple cognitive tasks while exposed to a simulated altitude profile using a Reduced Oxygen Breathing Device (5min at sea level (SL), 10min at 3048m, 20min at plateau (MH), and 10 min recovery at SL, then following a rest, repeat sequence with a SH plateau) once at 21 degree C (W) and again at -21 degree C (C) on a separate day. Subjects trained on SYNWIN (Ver. 1.2.39, Chula Vista, CA) until achieving proficiency in short term memory (STM), math (M), visual (VM) and auditory (AM) monitoring tasks. A composite score (CS), individual task scores and reaction times (RT) were determined every 20s and %change from SL calculated. ANOVA (Tukey-Kramer post-hoc) were used to determine performance differences based on temperature (p=0.05). SpO2 at the finger (SpO2(f)) and forehead (Nonin model 9847, SpO2(h)), respiratory rate (Equivital(registered trademark), RR), heart rate, core, finger and toe temperatures were monitored. 7620m exposures were terminated and 100% O2 administered at SpO2(f)= 60%. RESULTS: Drop in SpO2(h) (2; 4%) and RR rise (18; 54%) was greater in C vs. W (MH; SH, respectively). To relate cognitive with physiologic responses, changes in task performance were calculated when the SpO2 dropped between 70 and 80% (a) and between 60 and 70% (b). While SpO2(h) fell below 80% more rapidly in the cold at MH (69 (plus-or-minus sign) 45s (C) vs. 83 (plus-or-minus sign) 27s (W)), during SH it took longer (45 (plus-or-minus sign) 43s (C) vs. 37 (plus-or-minus sign) 27s (W)). Under SH at (a), CS performance was worse in W(-13 (plus-or-minus sign) 31% (C) vs. -17 (plus-or-minus sign) 19% (W)), while STM score was lower and RT slower in C (-33 (plus-or-minus sign) 37% (C) vs. 2 (plus-or-minus sign) 5% (W); (28 (plus-or-minus sign) 70% (C) vs. 16 (plus-or-minus sign) 14% (W), respectively). Whereas under MH at (a), STM score was higher and RT faster in C (8 (plus-or-minus sign) 22% (C) vs. -17 (plus-or-minus sign) 34% (W); (21 (plus-or-minus sign) 15% (C) vs. 30 (plus-or-minus sign) 33% (W), respectively). Similar trends were found in (b). However, these differences were not significant. DISCUSSION: The impact of cold on per