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Does pulse contour analysis provide a valid estimate of cardiac output during spaceflight?
Author(s) -
Yee Nicholas J,
Zuj Kathryn A,
Greaves Danielle K,
Hughson Richard L
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.762.2
Subject(s) - spaceflight , photoplethysmogram , cardiac output , cardiac function curve , pulse wave analysis , medicine , cardiology , arterial stiffness , biomedical engineering , simulation , hemodynamics , computer science , blood pressure , engineering , aerospace engineering , heart failure , filter (signal processing) , computer vision
Model flow is a pulse contour analysis method that provides non‐invasive ambulatory cardiac output, which can characterize potential degradation of cardiovascular function due to long‐duration spaceflight. However, the model flow algorithm has not been tested in altered gravitational environments. The purpose of this study was to use a standard rebreathing measure of cardiac output (COre) to validate the model flow cardiac output (COmf) and to detect potential changes in cardiovascular physiology during spaceflight using the stiffness index, model flow Aortic Age (AGEmf). Data were collected from nine male astronauts (45 ± 7 years old) who were aboard the International Space Station for 6 months. Testing occurred pre‐flight and inflight approximately 3 weeks before returning to Earth. Rebreathing cardiac output was collected using the Pulmonary Function System. The arterial pressure waveform was collected using finger photoplethysmography for the determination of COmf and AGEmf. Changes in COmf with spaceflight did not match changes in COre (p < 0.001). COre increased from pre‐flight to inflight (4.8 ± 0.7 L/min and 7.0 ± 1.4 L/min, respectively; p < 0.01) while COmf remained constant with spaceflight (pre‐flight: 6.2 ± 1.4 L/min and inflight: 5.8 ± 1.1 L/min, respectively; p > 0.05). The model flow algorithm assumes central arterial properties based on age but as changes in COmf were not similar to COre with spaceflight, this assumption appears to have been violated. As well, the stiffness index AGEmf decreased with spaceflight (pre‐flight: 68 ± 16 years old and inflight: 41 ± 9 years old; p < 0.01). These results suggest changes in cardiac function and in arterial properties that invalidate pulse contour analysis during spaceflight. Support or Funding Information The research was supported by the Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, and the American Physiological Society.