A rebreathing method for estimating pulmonary Do2: Theory and measurements in dog lungs

Adaro, F; Scheid, P.; Teichmann, J.; Piiper, Johannes

doi:10.1016/0034-5687(73)90021-2

Cited by 41 publications

(8 citation statements)

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“…With the Fick method for oxy gen, the total cardiac output 'Q' is measured, whereas with the rebreathing method we determine the effective capillary pulmonary blood flow 'Qa'. 'Qa' differs from 'Q' by the size of the venous admixture; this value has been determined in our laboratory in anesthetized dogs at high ventilation [1] and was found to be 4% of the total cardiac output. Furthermore, any unequal distribution of Va to Q should produce lower estimations of the capillary blood flow, but would not affect the value of the cardiac output determined with the Fick method.…”

Section: Discussionmentioning

confidence: 99%

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Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

et al. 1974

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The rate of disappearance of acetylene or nitrous oxide from the alveolar gas during rebreathing was studied in dogs and in man. The subjects, hyperventilating in steady state, were connected at end-expiration to a re breathing bag for 30 sec. After the initial 2-4 breaths the alveolar inert gas concentration followed a single exponential course until the beginning of recirculation. From the slope and intercept of this exponential at zero time the capillary blood flow and the tissue volume of the lung were calculated. Simultaneous determinations of the cardiac output were made with direct Fick method for oxygen in dogs and indirect Fick method in man. A good correlation was found between both methods. A theory is represented which takes into consideration the effect of ventilation limitation upon inert gas transfer within the rebreathing system

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Section: Discussionmentioning

confidence: 99%

“…In these circumstances, there is some uncertainty in the determination of the rate of uptake *k\ The most satisfactory approach is the use of the volume-weighted averages of alveolar and bag gas concentrations [1], and with this procedure phase II could be extended by 3-4 sec.…”

Section: Discussionmentioning

confidence: 99%

Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

et al. 1974

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“…Experimental procedure and analytical methods are essentially the same as described earlier [Adaro et al, 1973;Scheid et al, in press] except for ventilation of the dogs in a body respirator. Blood clotting was prevented by intravenous adminis tration of heparin (7 mg/kg).…”

Section: Methodsmentioning

confidence: 99%

“…Rebreathing D o2, Do2rb, was calculated as recently described in full detail [Adaro et al, 1973;Scheid et al, in press). The following formula, which takes into account the ventilation limitation in the lung-rebreathing container system, has been used: where ko2 = rate constant of 0 2 equilibration during rebreathing; V L and VR = mean effective lung and rebreathing container volumes, respectively, determined by He dilution; Vefr = effective ventilation in the rebreathing container-lung system as determined from the mixing rate constant of He; Qc = pulmonary capillary blood flow (see below); /?b = slope of blood O2 dissociation curve in rebreathing conditions (see below); fig = capacitance coefficient for gas phase (for 37°C />g=0.0517 mmole ■ 1_1 • T orr-1).…”

Section: Calculationsmentioning

confidence: 99%

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Comparison of Rebreathing and Steady-State Pulmonary Do<sub>2</sub> in Dogs Ventilated by Body Respirator

Adaro¹,

Teichmann²,

Lüdtke-Handjery³

et al. 1974

Respiration

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Alveolar gas exchange was studied com-paratively in anaesthetised dogs during spontaneous breathing and during artificial ventilation produced by a body respirator. The pulmonary O₂ diffusing capac- ity, D O₂, in particular, was measured, employing two different methods: the conventional steady-state method, using ideal alveolar P O₂ (D O₂SS) and a rebreathing method (Do_2RB). A considerable decrease (by a factor of 3) in both D o_2SS and D_O2RB was observed on transition from spontaneous breathing to artificial ventilation. Distributional inhomogeneities were found to be considerably increased during artificial ventilation as indicated by increased values of both alveolar dead space ventilation and venous admixture. The increased inhomogeneity was probably due to considerably decreased end-expiratory lung volume during artificial ventilation at mean intrapulmonary pressure zero. The observed reduction in D_O2 should, at least in part, be attributed to the enhanced distributional inhomogeneity during artificial ventilation at low lung volume. Apparently, D_O2SS and D_O2RB are affected about equally by distributional inequalities in the lung

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Diffusion of Gases Across the Alveolar Membrane

Forster

1987

Comprehensive Physiology

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A rebreathing method for estimating pulmonary Do2: Theory and measurements in dog lungs

Cited by 41 publications

References 10 publications

Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

Determination of Pulmonary Blood Flow by Rebreathing of Soluble Inert Gases

Comparison of Rebreathing and Steady-State Pulmonary Do<sub>2</sub> in Dogs Ventilated by Body Respirator

Diffusion of Gases Across the Alveolar Membrane

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