Kasak, Alex

Background Whether lung fluid accumulates in acclimating individuals at high altitude (HA) remains controversial. Purpose To assess the effect of HA on lung fluid regulation. Methods/Results Systolic pulmonary artery pressure (sPAP) (echo), lung diffusing capacity for CO (DLCO), pulmonary capillary blood volume (Vc), alveolar‐capillary conductance (Dm) (single breath method), ultrasound lung comets (ULCs) and pulmonary function (PFTs) were assessed in 8 healthy adults at sea‐level and after 1 and 9 days at Mt. Everest Base Camp (EBC), Nepal (5150 m). Also, after 5 days at EBC, DLCO and PFTs were assessed in 5 subjects pre‐and post‐acute albuterol administration. EBC was reached after an 8 d hike at progressively increasing altitudes starting at 2800 m. Altitude exposure increased sPAP, had no effect on DLCO, increased Dm and decreased Vc with a subsequent increase in Dm/Vc, and decreased the number of ULCs (Table 1). There was no change in FVC or FEV 1 but an increase in MEF 50 . Albuterol administration increased PEF (11.85±1.52 vs. 12.40±1.45 L/s) and MEF 50 (4.85±0.77 vs. 6.00±1.30 L/s) but had no effect on DLCO, Dm or Dm/Vc. Conclusion These data suggest that lung fluid is decreased in acclimating healthy humans at high altitude. Funding: Mayo Clinic & The North Face.

BACKGROUND Psycho‐socio stressors may over time result in dominance of the sympathetic nervous system (SNS) over the parasympathetic nervous system (PNS). Reduced PNS control over cardiovascular processes has been associated with decreased health. Heart rate variability (HRV) has been proposed as a technique to quantify SNS and PNS interactions and thus might offer a noninvasive predictive index. OBJECTIVE To investigate the impact of real‐life stressors on HRV fluctuations in independent living elders (EL). METHODS For three months every two weeks EL (N=22; Age=75±9; M/F ratio=17/5) performed autonomic tests consisting of quiet breathing, paced breathing and hand grip. All did a questionnaire assessing depression, positive/negative live events, and isolation. RESULTS Negative events (r=0.36, p=.01) and isolation (r=0.35, p=0.02) are correlated with HR. Personal changes in HRV, SDNN (r=−0.43, p<0.005) and Poincare Width (r= −0.42, p<0.005), are correlated to negative life events. CONCULSION Negative life events reduce HRV which suggests either SNS activation and/or PNS withdrawal. Research was made possible by Healthy for Life, TNO, and the Center for Innovation, Mayo Clinic.

BACKGROUND Exposure to high altitude (HA) results in sympathetic nervous system (SNS) activation. This might interact with HA related illness. HRV is a technique to quantify SNS and parasympathetic nervous system (PNS) interactions and thus offers a noninvasive index in extreme environments. OBJECTIVE To quantify the changes in HRV in elite athletes (AT), acclimatized for 2 mo. at Everest base camp (BC) prior to summiting, relative to a control group (CT) (climbing and acclimatizing to BC in 3 wks). METHODS AT (N=4, Age=35±10 y, BMI=22±2, M/F ratio 2/2) and CT (N=8, Age=35±10 y, BMI=26±2, M/F ratio 8/0) performed autonomic tests consisting of quiet breathing, paced breathing prior to, mid‐way at BC and at 2 wks post expedition. RESULTS At BC, AT had (compared to CT) higher HR (p=0.07) and reduced HRV (SDNN, p=0.09). For AT and CT combined: measures of HRV were reduced at BC (SDNN, p=0.05, Poincare length, p=0.05) and remained below baseline 2 wks post climb (SDNN, p=0.01; PCL, p=0.01). CONCULSION HRV is reduced with HA exposure in both AT and CT and remains reduced 2 wks post exposure, suggesting either SNS activation and/or PNS withdrawal. FUNDING : Mayo Clinic & The North Face.