Respiratory Services, Christchurch Hospital, Christchurch, New Zealand.
J Breath Res. 2010 Dec;4(4):046001. doi: 10.1088/1752-7155/4/4/046001. Epub 2010 Nov 15.
Using selected ion flow tube-mass spectrometry (SIFT-MS) for on-line analysis, we aimed to define the optimal single-exhalation breathing manoeuvre from which a measure of expired acetone concentration could be obtained. Using known acetone concentrations in vitro, we determined the instrument's accuracy, inter-measurement variability and dynamic response time. Further, we determined the effects of expiratory flow and volume on acetone concentration in the breath of 12 volunteers and calculated intra-individual coefficients of variation (CVs). At acetone concentrations of 600-3000 ppb on 30 days over 2 months there was an instrument measurement bias of 8% that did not change over time, inter-day and intra-day CVs were 5.6% and 0.0%, respectively, and the 10-90% response time was 500 ± 50 ms (mean ± SE). Acetone concentrations at exhalation flows of 193 ± 18 (mean ± SD) and 313 ± 32 ml s(-1) were 619 ± 1.83 (geometric mean ± logSD) and 618 ± 1.82 ppb in the fraction 70-85% by volume of exhaled vital capacity (V(70-85%)) and 636 ± 1.82 (geometric mean ± logSD) and 631 ± 1.83 ppb in V(85-100%). A difference was observed between acetone concentrations in the V(70-85%) and V(85-100%) fractions (p < 0.01), but flow had no effect. Median intra-individual CVs were 1.6-2.6%. On-line SIFT-MS measurement of acetone concentration in a single exhalation requires control of exhaled volume but not flow, and yields low intra-individual CVs and is potentially useful in approximating blood glucose and monitoring metabolic stress.
使用选择离子流管-质谱（SIFT-MS）进行在线分析，我们旨在定义最佳的单次呼气呼吸动作，从中可以获得呼出丙酮浓度的测量值。使用体外已知的丙酮浓度，我们确定了仪器的准确性、测量间变异性和动态响应时间。此外，我们还确定了呼气流量和体积对 12 名志愿者呼气中丙酮浓度的影响，并计算了个体内变异系数（CVs）。在 2 个月的 30 天内，丙酮浓度在 600-3000 ppb 之间，仪器测量存在 8%的偏差，且不会随时间变化，日间和日内 CVs 分别为 5.6%和 0.0%，10-90%的响应时间为 500±50ms（平均值±SE）。呼气流量为 193±18（平均值±SD）和 313±32ml s(-1)时，呼出肺活量（V(70-85%)）的 70-85%体积分数内的丙酮浓度分别为 619±1.83（几何平均值±logSD）和 618±1.82ppb，V(85-100%)内的丙酮浓度分别为 636±1.82（几何平均值±logSD）和 631±1.83ppb。在 V(70-85%)和 V(85-100%)部分之间观察到丙酮浓度存在差异（p<0.01），但流量没有影响。个体内中位数 CVs 为 1.6-2.6%。单次呼气中丙酮浓度的在线 SIFT-MS 测量需要控制呼出体积但不控制流量，且产生低个体内 CVs，可能有助于近似血糖并监测代谢应激。
