Zeballos R J, Weisman I M, Connery S M
Department of Clinical Investigation, William Beaumont Army Medical Center, El Paso 79920-5001, USA.
Chest. 1998 Mar;113(3):602-11. doi: 10.1378/chest.113.3.602.
To compare arterial blood gas (ABG) and pulmonary gas exchange variables (alveolar-arterial oxygen pressure difference [P(A-a)O2] and physiologic dead space to tidal volume ratio [VD/VT]) measured during incremental exercise test (IET) and constant work (CW) exercise at a matched oxygen uptake (VO2).
A comparison of IET and CW variables was accomplished using patient data from clinical referrals for cardiopulmonary exercise testing and control data not reported from a previous study.
El Paso, Tex, located at an altitude of 1,270 m (barometric pressure, 656 mm Hg).
Sixteen patients with dyspnea on exertion/exercise intolerance and nine normal subjects were evaluated above the anaerobic threshold (AT); seven patients were also studied below the AT.
Participants had a maximal IET followed in 1 h by a 5-min CW test. Arterial blood samples were obtained from a radial catheter every other minute during IET and during minute 5 of CW. Cardiopulmonary measurements were obtained using an automated system in a breath-by-breath fashion (60-s averaging).
Above the AT, no differences were observed in normal subjects between IET and CW at a matched VO2 in the following: PaO2 (79 vs 79 mm Hg); arterial oxygen saturation (SaO2) (94% vs 94%); P(A-a)O2 (16 vs 16 mm Hg); and VD/VT (0.09 vs 0.09) (mean values). Similarly, no differences were observed in patients above the AT in PaO2 (69 vs 68), SaO2 (90 vs 90), and VD/VT (0.24 vs 0.23). PaCO2 was 2 mm Hg higher (36 vs 34) in normal subjects and in patients (34 vs 32) during IET. A significant (p<0.05), albeit clinically unimportant, difference was also observed in P(A-a)O2 (28 vs 29) in patients. No statistically significant differences were observed below the AT between IET and CW for any of the variables measured.
These data demonstrate the reliability of ABG and pulmonary gas exchange variables measured during 1-min IET for clinical use in patients and normal subjects. However, PaCO2 tends to be slightly higher during IET vs CW.
比较在递增运动试验（IET）和恒定负荷（CW）运动期间，在匹配的摄氧量（VO₂）下测量的动脉血气（ABG）和肺气体交换变量（肺泡-动脉氧分压差[P(A-a)O₂]和生理死腔与潮气量比值[VD/VT]）。
使用来自心肺运动试验临床转诊的患者数据和先前研究未报告的对照数据，对IET和CW变量进行比较。
得克萨斯州埃尔帕索，海拔1270米（气压656毫米汞柱）。
16例运动时呼吸困难/运动不耐受患者和9名正常受试者在无氧阈（AT）以上进行评估；7例患者也在AT以下进行研究。
参与者先进行最大IET，1小时后进行5分钟CW测试。在IET期间每隔1分钟以及CW的第5分钟，从桡动脉导管采集动脉血样。使用自动系统以逐次呼吸方式（60秒平均）进行心肺测量。
在AT以上时，在匹配的VO₂下，正常受试者在IET和CW之间，以下各项未观察到差异：动脉血氧分压（PaO₂）（79对79毫米汞柱）；动脉血氧饱和度（SaO₂）（94%对94%）；P(A-a)O₂（16对16毫米汞柱）；以及VD/VT（0.09对0.09）（平均值）。同样，AT以上的患者在PaO₂（69对68）、SaO₂（90对90）和VD/VT（0.24对0.23）方面也未观察到差异。在IET期间，正常受试者和患者的动脉血二氧化碳分压（PaCO₂）分别高2毫米汞柱（36对34）和（34对32）。在患者中，P(A-a)O₂也观察到显著（p<0.05）但临床上不重要的差异（28对29）。在AT以下，IET和CW之间测量的任何变量均未观察到统计学上的显著差异。
这些数据证明了在1分钟IET期间测量的ABG和肺气体交换变量在患者和正常受试者临床应用中的可靠性。然而，IET期间的PaCO₂往往比CW期间略高。
