Adjustment of DLCO for hemoglobin concentration.

Abstract

The equation proposed by Cotes and coworkers is currently considered as the most acceptable to correct carbon monoxide diffusing capacity (DLCO) for hemoglobin concentration [Hb] by both the American Thoracic Society (ATS) and the European Respiratory Society (ERS) guidelines for standardization of DLCO. In a previous study on 24 anemic patients undergoing bone marrow transplantation (1), we found that DLCO is underestimated using the equation of Cotes and coworkers. To further explore this finding, 28 anemic patients ([Hb] = 8.2 +/- 1.0 (SD) g/dl) with chronic renal failure were prospectively studied during the recovery period of anemia (5.4 +/- 3.5 mo). In all 28 subjects, the slope deltaDLCO/delta[Hb] computed as ratio of overall change in DLCO to overall change in [Hb] throughout the study period was 1.40 +/- 0.72 ml CO/min/mm Hg/g/dl. The individual relationship between measured DLCO and [Hb] closely fitted a simple linear regression. The resulting equations for adjustment of DLCO (DLCOadj) to a standard [Hb] of 14.6 g/dl for men and 13.4 g/dl for women are: [equations: see text]. The present adjustment function for DLCO is linear and independent of the observed DLCO values, whereas the formulas previously proposed are curvilinear, DLCO correction varying with the measured DLCO values. For a measured DLCO of 15 ml CO/min/mm Hg and [Hb] ranging from 7 to 12 g/dl, the present DLCO adjustment is higher (by 2.7 ml CO/min/mm Hg, on average) than that proposed by Cotes and coworkers. This difference appears to be relevant for a precise interpretation of DLCO in patients with normocytic anemia in different clinical conditions.

Standardisation of the single-breath determination of carbon monoxide uptake in the lung

“…Since CO-Hb binding is such an important factor in CO transfer, DL,CO changes can be substantial as a function of Hb concentration [93][94][95][96][97]. The empirical change in DL,CO with Hb change closely matches what is expected from a theoretical approach using the relationship in equation 2, with h assumed to be proportional to the Hb, DM/hVc is assumed to be 0.7 [96], and the ''standard'' Hb value is assumed to be 14.6 g?dL -1 (9 mmol?l The equation for adjusting predicted DL,CO in children ,15 yrs of age and females is: DL,CO,predicted for Hb~DL,CO,predicted|(1:7 Hb=(9:38zHb)) ð14Þ…”

“…Results from a more recent study in patients with a wide range of Hb abnormalities [97] showed a slightly greater and more In these calculations, room temperature (T) is measured in Celsius and gas pressures are measured in mmHg. In all four cases, the inspired volume (VI) is the measured volume of inhaled dry gas and, thus, is considered under ambient temperature, ambient pressure, and dry (ATPD) conditions.…”

Haemodynamic response to dynamic exercise after heart-lung transplantation

“…The patients' chest radiographs and standard pulmonary function tests were within normal limits, except for a slight reduction in carbon monoxide diffusing capacity which averaged 78.5% of predicted after adjustment for haemoglobin concentration [15]. Their electrocardiogram, echocardiogram, and radionuclide ejection fraction were all consistent with a normal systolic function of the allograft.…”

Reference Values for the Diffusing Capacity Determined by the Single-Breath Technique at Different Altitudes: The Latin American Single-Breath Diffusing Capacity Reference Project

“…[3][4][5][6][8][9][10]14,16,18 This study was done with current equipment and procedures and good test quality, giving comparable results across several cities of Latin America with substantial advantages over previous studies. Reference equations in use were obtained many years ago with varied equipment, procedures, and populations and according to our data give results with systematic bias for single-breath D LCO and also with coefficients that do not adjust properly to changes with age, altitude, and height.…”