Pulmonary hydraulic impedance responses to hypoxia and hypercapnia in newborn pigs
| Autor: | D. G. Crescenzo, K. L. Dyer, A. R. Analouei, Yining Wang, Patrick W. Domkowski, R. A. Hopkins, J. T. Cockerham, R. H. Messier, Peter A. Kot, R. B. Wallace |
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| Rok vydání: | 1994 |
| Předmět: |
Male
Pulmonary Circulation Swine Physiology Hemodynamics Hypercapnia Physiology (medical) Transducers Pressure medicine Animals Ketamine Normocapnia Thiopental Hypoxia Lung Thiopental Sodium business.industry Airway Resistance Azaperone Hypoxia (medical) Pulmonary Alveoli medicine.anatomical_structure Animals Newborn Anesthesia Vascular resistance Female Vascular Resistance Blood Gas Analysis medicine.symptom Energy Metabolism business medicine.drug |
| Zdroj: | Journal of Applied Physiology. 77:386-396 |
| ISSN: | 1522-1601 8750-7587 |
| DOI: | 10.1152/jappl.1994.77.1.386 |
| Popis: | The purpose of this study was to determine the cumulative effects of brief intervals of hypoxia and hypercapnia on the pulsatile characteristics of the pulmonary arterial circulation of 48-h-old compared with 2-wk-old open-chest Yorkshire pigs while using two different anesthetic regimens: 1) azaperone and ketamine (4 and 12 mg/kg im, respectively) and 2) thiopental sodium (25 mg/kg i.v.). Animals 48 h old were randomly allocated to undergo mild hypoxia (inspired O2 fraction = 0.15), severe hypoxia (inspired O2 fraction = 0.05), or hypercapnia (inspired CO2 fraction = 0.20), whereas animals 2 wk old underwent severe hypoxia or hypercapnia. With use of Fourier analysis, characteristic impedance (Zo), mean input impedance (Zm), impedance moduli, and phase angles were determined. In 48-h-old pigs anesthetized with azaperone-ketamine, neither mild nor severe hypoxia altered Zo, Zm, or pulmonary vascular resistance (PVR), whereas hypercapnia increased Zo by 22% (P < 0.001), which persisted despite a return to normocapnia. In 48-h-old animals anesthetized with thiopental, baseline control Zo and Zm were lower than those in same-age pigs anesthetized with azaperone-ketamine. In thiopental-anesthetized 48-h-old pigs, both severe hypoxia and hypercapnia increased Zm and PVR but Zo was unaltered. In 2-wk-old pigs anesthetized with thiopental, severe hypoxia but not hypercapnia elevated Zm and PVR, whereas Zo was not changed with either stress. Results indicate age- and anesthetic-dependent responses of Zo, Zm, and PVR to severe hypoxia and hypercapnia. The persistent elevation in Zo caused by hypercapnia indicates a prolonged decrease in arterial compliance or a reduction in effective proximal pulmonary arterial radius. |
| Databáze: | OpenAIRE |
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