Non-invasive measurement of cardiac output using an iterative, respiration-based method
| Autor: | Vinzent N. Spetzler, James Duffin, Debashis Roy, Joseph A. Fisher, L. Minkovich, Markus Selzner, M. Klein, M. Machina, J.M. Knaak |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
medicine.medical_specialty
Cardiac output Swine Hemodynamic measurements Family suidae Thermodilution Oxygen Consumption Internal medicine Respiration Tidal Volume medicine Animals Cardiac Output Monitoring Physiologic Pulmonary Gas Exchange business.industry Non invasive Mathematical analysis Limits of agreement Reproducibility of Results Carbon Dioxide Anesthesiology and Pain Medicine Breath Tests Fully automated Background current Models Animal Cardiology Blood Gas Analysis business |
| Zdroj: | British Journal of Anaesthesia. 114:406-413 |
| ISSN: | 0007-0912 |
| Popis: | Current non-invasive respiratory-based methods of measuring cardiac output [Formula: see text] make doubtful assumptions and encounter significant technical difficulties. We present a new method using an iterative approach [Formula: see text], which overcomes limitations of previous methods.Sequential gas delivery (SGD) is used to control alveolar ventilation [Formula: see text] and CO2 elimination [Formula: see text] during a continuous series of iterative tests. Each test consists of four breaths where inspired CO2 [Formula: see text] is controlled; raising end-tidal Pco2 [Formula: see text] by about 1.33 kPa (10 mm Hg) for the first breath, and then maintaining [Formula: see text] constant for the next three breaths. The [Formula: see text] required to maintain [Formula: see text] constant is calculated using the differential Fick equation (DFE), where [Formula: see text] is the only unknown and is arbitrarily assumed for the first iteration. Each subsequent iteration generates measures used for calculating [Formula: see text] by the DFE, refining the assumption of [Formula: see text] for the next test and converging it to the true [Formula: see text] when [Formula: see text] remains constant during the four test breaths. We compared [Formula: see text] with [Formula: see text] measured by bolus pulmonary artery thermodilution [Formula: see text] in seven pigs undergoing liver transplantation.[Formula: see text] implementation and analysis was fully automated, and [Formula: see text] varied from 0.6 to 5.4 litre min(-1) through the experiments. The bias (between [Formula: see text] and [Formula: see text]) was 0.2 litre min(-1) with 95% limit of agreement from -1.1 to 0.7 litre min(-1) and percentage of error of 32%. During acute changes of [Formula: see text], convergence of [Formula: see text] to actual [Formula: see text] required only three subsequent iterations.[Formula: see text] measurement is capable of providing an automated semi-continuous non-invasive measure of [Formula: see text]. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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