![]() ResultsĮighty-one infants with a median (range) gestational age of 28.7 (22.4–41.9) weeks were recruited. Alveolar ventilation ( V A) was also calculated. Volumetric capnograms were constructed to calculate the dead space using the modified Bohr–Enghoff equation. Expiratory tidal volume and carbon dioxide levels were measured. MethodsĪ prospective study of mechanically ventilated infants was undertaken. We determined if there were differences in dead space and alveolar ventilation in ventilated infants with pulmonary disease or no respiratory morbidity. Their major advantage is facilitating and speeding up computer-aided on-line determinations of VD.Dead space is the volume not taking part in gas exchange and, if increased, could affect alveolar ventilation if there is too low a delivered volume. The derived equations were tested in experimental situations, showing equality between values of dead space determined by using the algebraic solution and the graphical method. The formulas exactly represent Fowler's graphical method and can be applied to all gases which are applicable in dead space determination. We obtained two algebraic equations for both possible conditions, nonsloping and sloping alveolar plateau, and, as the main result, an even more general third equation that includes both Bohr's and Fowler's solution. Whereas Fowler visually partitioned phase II into two equal areas bordered by F(V), R(V), and VD, in the present paper the area between F(V) and R(V) is set equal to the area of a trapezoid, one side of which is the unknown VD to be determined. ![]() According to Fowler's method, anatomical dead space (VD) can be determined graphically or computer-aided by iteration procedures by which phase III of a fraction-volume expirogram F(V) is back-extrapolated by a straight line R(V). ![]()
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