Zimová-Herknerová Magdalena, Plavka Richard
Division of Neonatology, Department of Obstetrics and Gynecology, General Faculty Hospital, First Faculty of Medicine, Charles University, Prague, Czech Republic.
Pediatr Pulmonol. 2006 May;41(5):428-33. doi: 10.1002/ppul.20367.
We sought to determine the normocapnic values of expiratory tidal volume measured by hot-wire anemometer, and to evaluate how often expiratory tidal volume exceeds estimated anatomical dead space during high-frequency oscillatory ventilation (HFOV) in preterm infants. We also sought to determine the relationship between expiratory tidal volume and other respiratory parameters. The neonatal respiration monitor SLE 2100 VPM, a hot-wire anemometer, was used to measure expired tidal volume (V(T,E)) in patients ventilated by the Sensormedics 3,100A during routine clinical use of HFOV. Two hundred and fourteen simultaneous measurements of PaCO(2), V(T,E), fraction of inspired oxygen (FiO(2)), continuous distending pressure (CDP), frequency, and amplitude were obtained from 28 patients. The median birth weight was 852 g (range, 435-3,450 g), and median gestational age was 27.2 weeks (range, 23.3-41.0 weeks). One hundred and eighteen (55%) normocapnic measurements, 42 (20%) hypocapnic measurements, and 54 (25%) hypercapnic measurements were recorded in which the median V(T,E) was 1.67 ml/kg (95% confidence interval (CI), 1.55-1.79), 1.94 ml/kg (95% CI, 1.74-2.14), and 1.54 ml/kg (95% CI, 1.42-1.66), respectively. The measured V(T,E) exceeded 2.0 ml/kg in 30 instances of normocapnic V(T,E) (14%) and 54 of all V(T,E) (25%), and 3 ml/kg only in 7 (3%) and 11 (5%) instances of normocapnic and all V(T,E). There was a significant difference in median normocapnic V(T,E) obtained when FiO(2) was between 0.21-0.35, compared to values obtained when FiO(2) was 0.36-1.0 (1.61 ml/kg (95% CI, 1.52-1.70) vs. 2.06 ml/kg (95% CI, 1.93-2.19), P < 0.002). The calculated values of PaCO(2) between 35-47, using the calculated regression equation for prediction of PaCO(2) (mmHg), correctly predicted normocapnic values in 60% of measurements. Values >47 should predict hypercapnia in 81% of cases. In conclusion, expired tidal volume measurement by heated double-wire anemometer sensor is feasible, provides useful real-time information about tidal volume changes, and may improve the clinical management of HFOV.
我们试图确定通过热线风速仪测量的呼气潮气量的正常碳酸血症值，并评估在早产儿高频振荡通气（HFOV）期间呼气潮气量超过估计解剖死腔的频率。我们还试图确定呼气潮气量与其他呼吸参数之间的关系。在HFOV的常规临床应用中，使用新生儿呼吸监测仪SLE 2100 VPM（一种热线风速仪）来测量由Sensormedics 3100A通气的患者的呼出潮气量（V(T,E)）。从28例患者中获得了214次同时测量的动脉血二氧化碳分压（PaCO(2)）、V(T,E)、吸入氧分数（FiO(2)）、持续扩张压力（CDP）、频率和振幅。中位出生体重为852克（范围435 - 3450克），中位胎龄为27.2周（范围23.3 - 41.0周）。记录了118次（55%）正常碳酸血症测量、42次（20%）低碳酸血症测量和54次（25%）高碳酸血症测量，其中V(T,E)的中位数分别为1.67毫升/千克（95%置信区间（CI），1.55 - 1.79）、1.94毫升/千克（95% CI，1.74 - 2.14）和1.54毫升/千克（95% CI，1.42 - 1.66）。在30例正常碳酸血症V(T,E)（14%）和所有V(T,E)的54例（25%）中，测量的V(T,E)超过2.0毫升/千克，仅在7例（3%）和1例（5%）正常碳酸血症和所有V(T,E)中超过3毫升/千克。当FiO(2)在0.21 - 0.35之间时获得的中位正常碳酸血症V(T,E)与FiO(2)为0.36 - 1.0时获得的值有显著差异（1.61毫升/千克（95% CI，1.52 - 1.70）对2.06毫升/千克（95% CI，1.93 - 2.19），P < 0.002）。使用预测PaCO(2)（mmHg）的计算回归方程，计算出的PaCO(2)在35 - 47之间的值在60%的测量中正确预测了正常碳酸血症值。值>47在81%的病例中应预测为高碳酸血症。总之，通过加热双丝风速仪传感器测量呼出潮气量是可行的，提供了有关潮气量变化的有用实时信息，并可能改善HFOV的临床管理。
