[The concentration of carbon dioxide at the end of expiration as an index of hemodynamic status in open-heart operations]. / Kontsentratsiia uglekisloty v kontse vykhoda kak pokazatel' sostoianiia gemodinamiki pri operatsiiakh na otkrytom serdtse.

The interrelationship of the cardiac index (CI) and carbon dioxide concentration measured at the end of respiration (CO2ER) was studied in 258 patients, aged from 5 to 71 years, during operations on the open heart. Statistical analysis of the stage of revision of the left ventricular posterior wall showed that CO2ER decreases from 29.9 +/- 0.7 mm Hg to 24.9 +/- 1.4 mm Hg in parallel with reduction of CI from 2.81 +/- 0.19 l/min/m2 to 1.62 +/- 0.13 l/min/m2. At the end of this manipulation the CI and CO2ER were restored to the initial level. Marked parallel dynamics of CO and CO2ER was revealed in continuous appraisal of the cardiac output (CO), determined by the method of catheter flow measurement, at the stage of parallel circulation and blood pumping from the extracorporeal circulation apparatus before CO2ER stabilization. The correlation coefficient of these parameters varied in this stage in various patients from +0.73 to +0.96. Analysis of the mass of data (n = 161) collected in 14 patients showed that the CI--CO2ER relation was exponential in character and could be expressed by the equation CI (l/min/m2) = e (-0.99 + 0.065 x CO2ER); standard determination error +/- 0.42 l/min/m2. Analysis of the "CO2ER-venous pressure" relation in these 14 patients showed it to be similar to the "cardiac index-venous pressure" relation. The coefficients of correlation between CVD and CO2ER at this stage ranged in various patients from +0.74 to +0.96 and those between VP and CI from +0.58 to +0.97. Transition of the relations to the plateau occurred at equal CVP values.

[Different methods of determining the position on the oxyhemoglobin dissociation curve]. / Razlichnye metody opredeleniia polozheniia krivoi dissotsiatsii oksigemoglobina.

P50 values, as measured on DCA-1 analyzer and calculated according to Lichtman formula based on Hill equation, or calculated according to standard Severinghaus curve have been compared. No significant differences in P50 values have been observed. The method of direct oxyhemoglobin dissociation curve registration seems preferable, as it gives the idea not only of the position, but also of the form of curve changes. However, it cannot be widely recommended for clinical practice for lack of home-made equipment. Calculation methods are simpler, however, they depend on the accuracy of SO2 measurements and the necessity to use for calculations the results of blood pO2 measurements with SO2 in the range of 25-75%.