Acute mountain sickness and retinal evaluation by optical coherence tomography.

PURPOSE: Acute mountain sickness (AMS), the commonest form of altitude illness, might represent early-stage high altitude cerebral edema (HACE). Optical coherence tomography (OCT) was used to evaluate optic nerve head (ONH) consequences following a sojourn to extreme altitude. METHODS: This prospective study included 4 high-altitude expeditions in Himalayas. Twenty-four eyes of 12 healthy male climbers underwent baseline and postexpedition complete ophthalmic evaluation, including OCT to measure the peripapillary retinal nerve fiber layer (RNFL) thickness, ONH parameters, and macular thickness and volume. Lake Louise Scoring (LLS) self-report questionnaire was used to estimate AMS severity. RESULTS: All mountaineers experienced symptoms of AMS (LLS: 5.1±1.1, range 4.0-7.0). Average peripapillary RNFL thickness showed a significant increase in postexpedition examination (94±23 µm, 47-115), compared with baseline values (89±19 µm, range 45-114) (p=0.034). Superior (p=0.036) and temporal (p=0.010) quadrants also showed an increased RNFL thickness following exposure to high altitude. Vertical integrated rim area (VIRA) was significantly higher in postexpedition examination (0.71±0.43 mm(3), 0.14-1.50) than in baseline examination (0.51±0.26 mm(3), 0.11-1.00) (p=0.002). Horizontal integrated rim width was significantly higher in postexpedition examination (1.90±0.32 mm(2), range 1.37-2.34) than in baseline examination (1.77±0.27 mm(2), 1.27-2.08) (p=0.004). There was no correlation between LLS and OCT parameters (p>0.05). CONCLUSIONS: In climbers with AMS, OCT was able to detect subtle increases in the peripapillary RNFL thickness and in some ONH measurements, even in absence of HACE and papilledema. These changes might be a sensitive parameter in physiologic acclimatization and in the pathogenesis of AMS.

Skin coverage in frostbite injuries: experimental study.

OBJECTIVE: Dermal grafting after secondary wound healing constitutes the mainstay of management in cold injury tissue defects, displacing the use of local flaps. We present an experimental study in which the following treatments for frostbite defects are compared: guided wound healing, partial-thickness skin grafts and cutaneous flaps, which by definition posses an independent vascular supply. MATERIAL AND METHODS: A dorsal defect in the rabbit leg was created using a cold injury model. The animals were separated in three different sets, each with a specific treatment for the defect. In the first group, the defect was left to heal by secondary intention. In the second group, a dermal graft was used. In the third group, the defect was covered with a flap. The surface area lacking cutaneous cover at day 7 (SCp7) and the healing time (TC) were analysed. RESULTS: The cases in which flaps were employed presented a SCp7 of 62mm2, and a healing time of 11.6 days. When grafts were used, the SCp7 was 130mm2, and the healing time 15.9 days. The group which healed by secondary intention presented a SCp7 of 225mm2 and a healing time of 20.1 days. CONCLUSIONS: Compared to grafts, flaps provide a better skin cover both in quality and quantity. Their own vascularity makes them nondependent of the characteristics of the recipient bed. Due to this and to the radioisotopic and resonance imaging studies, which determine the ultimate level of tissue damage demarcation in a few days, an early treatment for these injuries is possible, with no need to achieve a favourable recipient site.