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Determination of regional pulmonary blood flow with systemically injected nonentrapped microspheres
M Kleen1, B Zwissler, R Schosser
1Institute for Surgical Research, University of Munich, Germany.
Abstract:
Radioactive microspheres (MS) injected into the systemic circulation shunt to the venous side of the circulation and are trapped in the lung vasculature. We hypothesized that regional pulmonary perfusion could be determined by using systemically injected shunted MS. In seven anesthetized mechanically ventilated foxhounds, regional pulmonary perfusion was measured at baseline and during experimental acute respiratory distress syndrome with MS injected into both the right and left atrium (protocol 1). Methodological error of the MS technique was assessed by simultaneous injection of two different batches of MS into the right atrium (protocol 2). Measurement of perfusion during baseline and during experimental acute respiratory distress syndrome with shunted MS had a mean bias of 0.8 and 5.6% and mean precision of 19.2 and 34.7% (r = 0.94 and r = 0.95), respectively, compared with data from nonshunted MS. Simultaneous perfusion measurements displayed bias of -2.7 and 6% and precision of 8.2 and 5.3% (r = 0.98 and r = 0.99), respectively. Systemic shunt should be high for this method to prevent bronchial circulation from imposing significant error. We conclude that systemically injected MS can be used for simultaneous measurement of regional systemic and regional pulmonary perfusion, provided that MS that shunted in the first pass are measured in lung tissue.
Insights
Systemically injected radioactive microspheres (MS) can measure regional pulmonary perfusion. This method accurately assesses blood flow in the lungs, even during acute respiratory distress syndrome.
Area of Science:
- Physiology
- Medical Imaging
- Cardiopulmonary Research
Background:
- Pulmonary perfusion measurement is crucial for understanding lung function.
- Existing methods for assessing regional pulmonary perfusion can be invasive or limited in scope.
Purpose of the Study:
- To evaluate the efficacy of systemically injected radioactive microspheres (MS) for measuring regional pulmonary perfusion.
- To determine if MS can accurately assess perfusion during both baseline and acute respiratory distress syndrome (ARDS) conditions.
Main Methods:
- Radioactive MS were injected into the systemic circulation of anesthetized foxhounds.
- Regional pulmonary perfusion was measured at baseline and during experimentally induced ARDS.
- Methodological error was assessed via simultaneous injection of different MS batches.
Main Results:
- Systemically injected shunted MS showed good correlation (r=0.94-0.95) with nonshunted MS for perfusion measurement during baseline and ARDS.
- The technique demonstrated acceptable bias (0.8-5.6%) and precision (19.2-34.7%) in measuring regional pulmonary perfusion.
- Simultaneous MS injections yielded high precision (8.2-5.3%) and low bias (-2.7-6%), indicating methodological reliability.
Conclusions:
- Systemically injected MS can be utilized for simultaneous measurement of regional systemic and pulmonary perfusion.
- Accurate assessment requires ensuring that first-pass shunted MS are quantified in lung tissue.
- This method offers a viable approach for studying pulmonary perfusion dynamics, particularly in critical care settings.