Developing Pulmonary Vasculopathy in Systemic Sclerosis, Detected with Non-Invasive Cardiopulmonary Exercise Testing

BACKGROUND: Patients with systemic sclerosis (SSc) may develop exercise intolerance due to musculoskeletal involvement, restrictive lung disease, left ventricular dysfunction, or pulmonary vasculopathy (PV). The latter is particularly important since it may lead to lethal pulmonary arterial hypertension (PAH). We hypothesized that abnormalities during cardiopulmonary exercise testing (CPET) in patients with SSc can identify PV leading to overt PAH. METHODS: Thirty SSc patients from the Harbor-UCLA Rheumatology clinic, not clinically suspected of having significant pulmonary vascular disease, were referred for this prospective study. Resting pulmonary function and exercise gas exchange were assessed, including peakVO2, anaerobic threshold (AT), heart rate-VO2 relationship (O2-pulse), exercise breathing reserve and parameters of ventilation-perfusion mismatching, as evidenced by elevated ventilatory equivalent for CO2 (VE/VCO2) and reduced end-tidal pCO2 (PETCO2) at the AT. RESULTS: Gas exchange patterns were abnormal in 16 pts with specific cardiopulmonary disease physiology: Eleven patients had findings consistent with PV, while five had findings consistent with left-ventricular dysfunction (LVD). Although both groups had low peak VO2 and AT, a higher VE/VCO2 at AT and decreasing PETCO2 during early exercise distinguished PV from LVD. CONCLUSIONS: Previously undiagnosed exercise impairments due to LVD or PV were common in our SSc patients. Cardiopulmonary exercise testing may help to differentiate and detect these disorders early in patients with SSc

Planck pre-launch status : The Planck mission

Peer reviewe

Changes in breath ^(13)CO_2/^(12)CO_2 consequent to exercise and hypoxia

Because the natural enrichment of carbohydrate with ^(13)C is greater than that of lipid, we hypothesized that the natural enrichment of exhaled CO_2 with ^(13)C (E_N) could be used to gauge endogenous substrate utilization in exercising human subjects. To test this, E_N and the respiratory exchange ratio (R) which equals the respiratory quotient (RQ) in the steady state, were measured simultaneously in seven subjects. Rest and exercise protocols, performed under conditions of room air (sea level) and hypoxic (inspired O_2 fraction = 0.15) breathing, were chosen to cause a variety of patterns of oxidative substrate utilization. Work rates were performed both below and above the subject's lactate threshold (LT). Work above the LT was expected to cause the greatest increase in E_N reflecting greater utilization of glucose. There was significant intersubject (P < 0.05) but not intrasubject variability in resting E_N. By 40 min of exercise, E_N increased significantly (P < 0.05) over resting values in all exercise protocols during both room air and hypoxia conditions. In the room air studies, we found no difference in E_N during the below-LT work, even though there were significant increases in O_2 uptake (VO_2). In contrast, above-LT work resulted in significantly greater increases in E_N by 20 and 40 min of exercise (P < 0.05). Contrary to our expectations, we observed no separate effect by hypoxia on the E_N during exercise. Both E_N and R tended to increase from rest to exercise, but during exercise there was no overall correlation between R and the E_N. E_N reflects changes in endogenous substrate utilization over relatively long periods of time such as at rest, but delays in the appearance of ^(13)CO_2 at the mouth due to dilution in body CO_2 pools, and possibly isotopic fractionation, preclude the usefulness of E_N as an indicator of endogenous fuel mix during short-term exercise

Adapting forest health assessments to changing perspectives on threats – a case example from Sweden

A revised Swedish forest health assessment system is presented. The assessment system is composed of several interacting components which target information needs for strategic and operational decision making and accommodate a continuously expanding knowledge base. The main motivation for separating information for strategic and operational decision making is that major damage outbreaks are often scattered throughout the landscape. Generally, large-scale inventories (such as national forest inventories) cannot provide adequate information for mitigation measures. In addition to broad monitoring programs that provide time-series information on known damaging agents and their effects, there is also a need for local and regional inventories adapted to specific damage events. While information for decision making is the major focus of the health assessment system, the system also contributes to expanding the knowledge base of forest conditions. For example, the integrated monitoring programs provide a better understanding of ecological processes linked to forest health. The new health assessment system should be able to respond to the need for quick and reliable information and thus will be an important part of the future monitoring of Swedish forests