Kathy A. O'Malley

Validation of a Simplified, Portable Cardiopulmonary Gas Exchange System for Submaximal Exercise Testing~!2009-10-25~!2010-01-09~!2010-03-17~!

Shape Medical Systems, Inc. has developed a new miniaturized, simplified system for non-invasive cardiopulmonary gas exchange quantification and has targeted their system for submaximal clinical exercise testing in order to abbreviate testing in an expanding clinical market during a climate of escalating health care costs. The focus of the present study was to compare this new device to a validated, standardized system for measures of cardiopulmonary gas exchange. Eighteen healthy adults (10 male/8 female, age 29±7 yr, BMI 23.8±2.4 kg/m 2 ) were brought to the laboratory and instrumented with both measurement systems via in-series pneumotachs. Additionally, the Shape system included a pulse oximeter for heart rate (HR) and oxygen saturation (SaO2), while the standard system included separate 12-lead ECG and oximetry devices. The protocol included 2-min resting breathing, followed by 3-min at each of 3 workloads (50, 70, 125 watts) on a cycle ergometer. Data were collected breath-by-breath and averaged the last 30-sec of each workload. After a 15-min rest period, the pneumotach order was reversed and the study repeated. Since gas exchange data were similar (p>0.05) within a given metabolic testing system between sessions the data were pooled for comparing the Shape and Standard systems. There were no differences (p>0.05) between the systems for oxygen consumption-VO2, carbon dioxide production-VCO2, ventilation-VE, end tidal CO2-PetCO2, tidal volume-VT, respiratory rate-fb, and HR at rest or any work load. SaO2 was slightly, but significantly lower using the Shape embedded oximeter (p 0.05). These data suggest that the new, simplified metabolic system developed by Shape Medical Systems, Inc. accurately quantifies key cardiopulmonary variables over a range of workloads, has a coefficient of variation similar to a well validated system and can be used with mouthpiece or mask.

Incidence and symptoms of high altitude illness in South Pole workers: Antarctic study of altitude physiology (ASAP)

Introduction Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to altitude), cold, and immediate exertion would increase altitude illness risk. Methods Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m2) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at altitude. Acetazolamide, while not mandatory, was used by 40% of participants. Results At SP, the barometric pressure resulted in physiological altitudes that approached 3400 m, while T °C averaged -42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1-2, yet in >20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less altitude experience, worse symptoms on previous exposures, and less SP experience. Conclusion The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar altitudes. Thus, the SP constitutes a more intense altitude exposure than might be expected considering physical altitude alone. Many symptoms persist, possibly due to extremely cold, arid conditions and the benefits of acetazolamide appeared negligible, though it may have prevented more severe symptoms in higher risk subjects.

Physiological variables associated with the development of acute mountain sickness at the South Pole

Exposure to altitudes >2500 m can result in acute mountain sickness (AMS), a mild and usually self-limiting condition. Research has attempted to identify factors associated with developing AMS without controlling important factors related to the ascent or collecting a comprehensive set of variables. Objectives The Antarctic Study of Altitude Physiology (ASAP) investigated variables associated with the development of AMS in adults experiencing rapid passive transport to altitude by airplane. Design Our prospective observational trial collected data, including personal history, anthropometrics, vital signs, blood samples and pulmonary function, at sea level and at altitude. Statistical analysis utilised independent sample t tests to investigate between-group differences (p<0.05) and a forward, step-wise binary logisitic regression analysis was performed. Participants Of 248 eligible ASAP participants, those who did not use acetazolamide (N=98) were included in the present analysis. Primary outcome measures The diagnosis of AMS using the Lake Louise Symptom Score. Results Analysis of participants not using acetazolamide (n=90) found 30 participants developed AMS and 60 participants did not. Estimated plasma volume decreased significantly at altitude (p=0.025) in the AMS group as compared with the No AMS group while body weight did not change (p=0.125). Serum sodium (p=0.045) and low-density lipoprotein (LDL) (p=0.049) levels were higher in the No AMS group. A logistic regression analysis emphasised the contributions of LDL and eosinophil levels in the development of AMS. Conclusions These results suggest that the body water regulation and inflammation are key factors in AMS development when all other factors such as the level of physical exertion during ascent, the rate and magnitude of ascent and the use of acetazolamide are controlled.

Oral contraceptive use and acute mountain sickness in South Pole workers.

INTRODUCTION Progesterone has a number of properties that could influence the development of acute mountain sickness (AMS), including anti-inflammation, respiratory smooth muscle relaxation, ventilatory stimulation, and antidiuretic characteristics. Oral contraceptive (OC) use decreases levels of circulating progesterone by preventing ovulation. We hypothesized rates of AMS development would be significantly higher in OC users as compared to Non-OC users in a population traveling rapidly to the South Pole. METHODS There were 50 female subjects (OC N = 13, no OC N = 37) who traveled by airplane from Sea Level (SL) to Altitude (ALTD) (-3200 m) in < 4 h and were monitored for the development of AMS. SL and ALTD measurements of anthropometrics, vital signs, hematologic variables, blood chemistries, electrolytes, endocrine responses, and pulmonary function were assessed with t-test and Chi-square analyses, P < 0.05. RESULTS As compared to Non-OC users, OC users had lower progesterone levels (ng x ml(-1)) at SL (0.7 +/- 0.5 vs. 3.2 +/- 4.6) and at ALTD (0.7 +/- 0.7 vs. 3.1 +/- 4.6). AMS was significantly more prevalent in OC users (85%) as compared to Non-OC users (51%). Acetazolamide prophylaxis was not protective, with a greater proportion of OC users (100%) developing AMS despite its use as compared to Non-OC users (50%). Blood pressure responses also differed significantly, with OC users displaying higher mean arterial pressures at ALTD vs. Non-OC users. CONCLUSION OC use at ALTD is associated with an increased risk for the development of AMS. Acetazolamide prophylaxis with OC use was also associated with an increased rate of AMS development.

Peripheral blood mononuclear cell gene expression in healthy adults rapidly transported to high altitude

License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on how to request permission may be found at: http://www.dovepress.com/permissions.php Advances in Genomics and Genetics 2015:5 1–9 Advances in Genomics and Genetics Dovepress