Traditional Chinese Medicine Tongue Examination for Acute Mountain Sickness in Healthy Women: A Pilot Study

Background: With increasing altitude, the barometric pressure falls, and the inspired partial pressure of oxygen decreases. Consequently, hypoxaemia develops, which may lead to impaired physical and mental performance as well as altitude-induced illnesses such as acute mountain sickness (AMS), characterized by headache, malaise, weakness, impaired postural control, and fatigue. Previous studies performed largely in healthy, young men have shown that 20–50% of workers and travelers develop AMS when staying overnight at altitudes between 2500 and 4000 m. Unfortunately, similar investigations have not been performed in women, and their susceptibility to altitude-related adverse health effects is therefore unknown. Methods: This prospective, non-randomized pilot study was conducted in healthy, non-smoking, premenopausal women (n = 19), aged 18 to 44 years, and living at altitudes <1000 m. Exclusion criteria were regular intake of headache medication, including painkillers, any pre-existing diseases, pregnancy or nursing. The study was performed at the National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyzstan (760 m), and the Kumtor Gold Mine operation facility (3600 m), Kumtor, Kyrgyzstan. At all locations, participants underwent clinical examinations, AMS symptom questionnaires (Lake Louise Score (LLS) and Environmental Symptoms Questionnaire (AMSc), cerebral score), and standardized tongue photography for subsequent blinded Traditional Chinese Medicine examination. Results: Upon arrival at 3600 m, peripheral oxygen saturation decreased significantly from 97.3 ± 0.6% to 86.3 ± 0.6% and heart rate increased from 76 ± 2 to 98 ± 2 bpm, with symptom scores peaking on Day 2 (LLS, 1.8 ± 0.3; AMSc, 0.36 ± 0.08; all p < 0.05). Using the 2018 Lake Louise criteria, AMS developed in 15.8% (3/19) on Day 1, 21.1% (4/19) on Day 2, and 5.6% (1/18) on Day 3. Tongue appearance ratings changed significantly from baseline (3.6 ± 0.2) to Day 2 (4.8 ± 0.2, p < 0.05) and declined toward baseline by Day 3 (3.9 ± 0.2); a similar temporal pattern was observed among the 11 participants who never met AMS criteria. However, tongue appearance was not significantly associated with AMS status (adjusted difference −0.11, 95% confidence interval (CI) −0.70 to 0.48; p = 0.72). The inter-rater agreement for this rating was moderate (Kendall’s W = 0.47). The most consistent feature-level change was a shift from thin coating (69.4% to 48.8% of ratings on Day 2, p = 0.016) towards thick coating (22.3% to 39.7%, p = 0.070). Most tongue features returned toward baseline by Day 3. Conclusions: This pilot study demonstrates that standardized tongue photographs can be acquired and assessed during high-altitude field research. Tongue appearance changed during acute high-altitude exposure, but these changes were not significantly associated with AMS status. Whether tongue characteristics have diagnostic or predictive value for hypoxic stress or AMS remains to be determined in larger, adequately powered studies.