Frey T M, Crapo R O, Jensen R L, Elliott C G
LDS Hospital, Pulmonary Division, Salt Lake City, UT 84143.
Am Rev Respir Dis. 1987 Dec;136(6):1381-4. doi: 10.1164/ajrccm/136.6.1381.
The single-breath diffusing capacity of the lung (DLCO) has been reported to decrease at a rate of 1.2 to 2.2% per hour during usual daytime hours. In an attempt to confirm these findings, we measured DLCO using both single-breath (DLCOs) and rebreathing techniques (DLCOR) in healthy, nonsmoking volunteers over the course of a day and again at different times on different days. Serial testing over a day showed a consistent fall (0.39%/h for DLCOS and 0.56%/h for DLCOR) in DLCO that was explained by increasing carboxyhemoglobin levels (COHb) and decreasing hemoglobin concentrations (Hb). When subjects were tested at different times on different days and compared using a paired t test, there was no change in DLCO over the time of day using either technique. We conclude that there is no diurnal variation in DLCO when adjusted for changes in Hb and COHb. The measurement of COHb levels and Hb concentrations for adjustment of DLCO results is important for correct interpretation of both individual and group studies of DLCO and should be performed whenever possible.
据报道，在白天正常时段，肺的单次呼吸弥散能力（DLCO）以每小时1.2%至2.2%的速率下降。为了证实这些发现，我们在一天的过程中以及在不同日期的不同时间，使用单次呼吸法（DLCOs）和重复呼吸技术（DLCOR）对健康、不吸烟的志愿者进行了DLCO测量。一天内的系列测试显示，DLCO持续下降（DLCOS为0.39%/小时，DLCOR为0.56%/小时），这可以通过羧基血红蛋白水平（COHb）升高和血红蛋白浓度（Hb）降低来解释。当在不同日期的不同时间对受试者进行测试并使用配对t检验进行比较时，无论使用哪种技术，一天内DLCO均无变化。我们得出结论，当针对Hb和COHb的变化进行调整后，DLCO不存在昼夜变化。测量COHb水平和Hb浓度以调整DLCO结果对于正确解释DLCO的个体和群体研究都很重要，应尽可能进行。
