Oxygen tensions and oxyhemoglobin saturations in the assessment of pulmonary gas exchange
| Autor: | Kenneth Oates, Jukka Räsänen, John B. Downs, Donald J. Malec |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
medicine.medical_specialty
chemistry.chemical_element Critical Care and Intensive Care Medicine Oxygen Alveolar gas equation Internal medicine medicine Ventilation-Perfusion Ratio Humans Oximetry Oxygen content Monitoring Physiologic Lung business.industry Pulmonary Gas Exchange Oxygenation Oxygen uptake Oxygen tension medicine.anatomical_structure chemistry Anesthesia Oxyhemoglobins Cardiology Arterial blood business Mathematics |
| Zdroj: | Critical care medicine. 15(11) |
| ISSN: | 0090-3493 |
| Popis: | We studied the theoretical basis for continuous monitoring of pulmonary gas exchange using arterial and mixed venous oximetry by examining the mathematical relationships between the calculated venous admixture (Qsp/Qt) and the ventilation-perfusion index, which is derived from oxyhemoglobin saturations. We compared this relationship with that between Qsp/Qt and its commonly used estimates: inspired oxygen concentration to arterial blood oxygen tension ratio, arterial to alveolar oxygen tension ratio, and alveolar-arterial oxygen tension difference. The relationship between Qsp/Qt and the oxygen tension-based indices is nonlinear and substantially influenced by changes in inspired oxygen concentration and arteriovenous oxygen content difference. Therefore, it is inaccurate within the clinically acceptable range of arterial blood oxygenation. In contrast, calculation of ventilation-perfusion index from arterial and mixed venous blood oxyhemoglobin saturations provides a linear estimate of Qsp/Qt that is minimally affected by alterations in inspired oxygen concentration or oxygen uptake and, therefore, will allow accurate continuous assessment of pulmonary gas exchange. |
| Databáze: | OpenAIRE |
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