Study of intrapulmonary gas mixing in man by simultaneous wash-out of helium and sulfur hexafluoride

Kawashiro, Takeo; Sikand, Rajinder S.; Adaro, F; Takahashi, Hiroshi; Piiper, Johannes

doi:10.1016/0034-5687(76)90044-x

Cited by 21 publications

(8 citation statements)

References 20 publications

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“…Care has to be taken to maintain constant condi tions for ventilation and especially tidal vol ume during experimental demonstration of stratification, as change of breathing pattern is known to influence the effect of diffusive gas transport \Lacquet, 1976; Kawashiro et al, 1976;v. Nieding et al, 1976], In this study, comparable conditions have been es tablished in the control and isoproterenol experiments, thus experimental errors could be avoided.…”

Section: Discussionmentioning

confidence: 99%

Use of Isoproterenol Infusion to Study Intrapulmonary Gas Mixing in Man

Löllgen¹,

Nieding²

1978

Respiration

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In the present investigation, the effect of an increased cardiac output on intrapulmonary gas mixing was studied in healthy male subjects. Increase of heart rate and cardiac minute output was induced by infusion of isoproterenol, intrapulmonary gas mixing was analyzed by simultaneous washout of inert gases widely differing in molecular weight (helium and sulfur hexafluoride). Parameters, appropriate to indicate quality of gas mixing, have been crossover point (COP) and separation index (SI). During isoproterenol-induced tachycardia, the COP occurred earlier and the SI decreased. Both changes then demonstrate an improved gas intrapulmonary mixing. The movement of the heart reduces stratified inhomogeneity.

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Section: Discussionmentioning

confidence: 99%

Use of Isoproterenol Infusion to Study Intrapulmonary Gas Mixing in Man

Löllgen¹,

Nieding²

1978

Respiration

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“…Thus, in the case of diffusive mixing, He will approach its partial pressure equilibri um 2.8 times faster than CO. Sikand et al [1976] and Kawashiro et al [1976] have shown that even in healthy subjects intrapulmonary gas concentration gradients are best explained by the existence of stratified inhomogeneities. Magnussen et al [1976] and v. Nieding et al [1978] could demon strate that in patients with emphysema, stra tification is of main importance in limiting intrapulmonary gas mixing.…”

Section: Interpretation Of the Kinetics Of Dcomentioning

confidence: 99%

D<sub>CO</sub> at Various Breath-Holding Times: Comparison in Patients with Chronic Bronchial Asthma and Emphysema

Magnussen¹,

J²,

Hartmann³

et al. 1979

Respiration

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Measurement of D_CO is known to be dependent upon functional inhomogeneities. Because different types of inhomogeneities are operative in patients with bronchial asthma and patients with emphysema, different changes of D_CO with increasing breath-holding time, t_A, are to be expected. We studied the change of Dco with increasing breath-holding time in healthy subjects, patients with asthma bronchiale and patients with emphysema. In the patients the severity of airway obstruction was about the same. The following results were obtained: (a) in healthy subjects and in the asthmatics D_CO decreased with t_A, in a similar manner, approaching a value (ml·min^-1·Terror^-1) of 34.7 and 31.6 at 10 sec, respectively, and (b) in patients with emphysema D_CO increased with t_A, yielding negative values at small t_A: 1.5 sec-23.4; 10 sec: 11.7.From these results we suggest that in healthy subjects and in patients with bronchial asthma parallel inhomogeneities influence the course of D_CO. In emphysema the time course of D_CO is best explained with a faster intrapulmonary mixing of He compared to CO. This behavior indicates that in emphysema low D_CO values can be mainly attributed to large diffusional resistances (stratification) within the lungs.

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“…Kawashiro et al (1976) have measured the sizes of Fowler dead spaces in the washout of He and SF6 in breathing frequencies 4/min-34/min, in order to eliminate the effect of dead space in the study of intrapulmonary gas mixing due to diffusion. In such analysis, if appropriate correction is not performed, there is a possibility to produce a serious misinterpretation on the assessment of incomplete gas mixing due to gaseous diffusion.…”

Section: Delaymentioning

confidence: 99%

“…Since there is generally a time delay involved in the response of the gas analyzer, precise correction must be made for the determination of volume-concentration relationships to calculate the anatomical dead space. Especially, it is important in the study of diffusive gas mixing when more than two different species of gas, such as He and SFs, are used for comparative measurement of the dead space (Kawashiro et al 1976; Von Nieding et al 1977). Since the response time of the gas analyzer generally differs according to the varieties of gases, discussion concerning the difference in dead space found with various species of gas cannot be made unless corrections are accurately made.…”

mentioning

confidence: 99%

“…Among those reports, there are examples of no correction of the delay time (Fowler 1948; Roos et al 1955; Hensley et al 1978), correction of the lag time from signal input until the beginning of the response (Engel et al 1973), the lag time plus 50% response time (Kawashiro et al 1976), 90% response time (Bashoff et al 1967) and 95% response time (Shepard et al, 1957, Nunn et al 1959Hart et al 1963). Furthermore, Bartels et al (1954) selected a 0.09 sec correction for the 0.06 sec lag time and the 0.06 sec 90% response time of the mass spectrometer.…”

mentioning

confidence: 99%

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