Blood pressure regulation in neurally intact human vs. acutely injured paraplegic and tetraplegic patients during passive tilt
| Autor: | Kevin D. Donohue, Sevda C. Aslan, Abhijit Patwardhan, Charles F. Knapp, David C. Randall, Susan M. McDowell, Joyce M. Evans, Robert F. Taylor |
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| Rok vydání: | 2007 |
| Předmět: |
Adult
Male Time Factors Physiology Posture Hemodynamics Blood Pressure Baroreflex Autonomic Nervous System Quadriplegia Tilt table test Heart Rate Tilt-Table Test Physiology (medical) Heart rate Humans Medicine cardiovascular diseases Spinal cord injury Paraplegia medicine.diagnostic_test business.industry Middle Aged medicine.disease Spinal cord Blood pressure medicine.anatomical_structure Case-Control Studies Anesthesia Female business circulatory and respiratory physiology |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 292:R1146-R1157 |
| ISSN: | 1522-1490 0363-6119 |
| Popis: | We investigated autonomic control of cardiovascular function in able-bodied (AB), paraplegic (PARA), and tetraplegic (TETRA) subjects in response to head-up tilt following spinal cord injury. We evaluated spectral power of blood pressure (BP), baroreflex sensitivity (BRS), baroreflex effectiveness index (BEI), occurrence of systolic blood pressure (SBP) ramps, baroreflex sequences, and cross-correlation of SBP with heart rate (HR) in low (0.04–0.15 Hz)- and high (0.15–0.4 Hz)-frequency regions. During tilt, AB and PARA effectively regulated BP and HR, but TETRA did not. The numbers of SBP ramps and percentages of heartbeats involved in SBP ramps and baroreflex sequences increased in AB, were unchanged in PARA, and declined in TETRA. BRS was lowest in PARA and declined with tilt in all groups. BEI was greatest in AB and declined with tilt in all groups. Low-frequency power of BP and the peak of the SBP/HR cross-correlation magnitude were greatest in AB, increased during tilt in AB, remained unchanged in PARA, and declined in TETRA. The peak cross-correlation magnitude in HF decreased with tilt in all groups. Our data indicate that spinal cord injury results in decreased stimulation of arterial baroreceptors and less engagement of feedback control as demonstrated by lower 1) spectral power of BP, 2) number (and percentages) of SBP ramps and barosequences, 3) cross-correlation magnitude of SBP/HR, 4) BEI, and 5) changes in delay between SBP/HR. Diminished vasomotion and impaired baroreflex regulation may be major contributors to decreased orthostatic tolerance following injury. |
| Databáze: | OpenAIRE |
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