Klein U, Gottschall R, Hannemann U, Kämpf R, Knebel F G, Schönherr V
Klinik für Anästhesiologie und Intensivtherapie, Friedrich-Schiller-Universität Jena.
Anasthesiol Intensivmed Notfallmed Schmerzther. 1995 Aug;30(5):276-82. doi: 10.1055/s-2007-996492.
Rapid bronchoscopy in general anaesthesia still has its precise indications, where the high frequency jet ventilation technique offers several advantages. The monitoring of ventilation, however, has been rather unsatisfactory up to date. We therefore studied capnography in 60 bronchoscopies during HFJV (rate: 100/min; I:E = 0.33; driving pressure: 0.08-0.14 MPa) using a rigid bronchoscope with a distally located sampling port. Continuous capnograms were recorded. End-tidal partial pressures of carbon dioxide (petCO2), however, were obtained from 2-3 single breaths by intermittently reducing the jet-frequency to 10-12/min. After 6 min (MP1: whole group; n = 60) and 18 min of HFJV (MP2: n = 34 of this group) petCO2 values were regularly obtained and compared to pCO2 in synchronously drawn capillary blood samples (pcCO2). The jet driving pressure initially adjusted to body weight, however, was only corrected according to petCO2, aiming at 34 mmHg.
During HFJV, sinusoidal capnograms permitted the identification of every single jet impulse. With instruments being passed through the bronchoscope, however, these curves were substantially distorted. Mean pcCO2 at MP1 (37.8 +/- 6.7 mmHg) and MP2 (37.2 +/- 6.7 mmHg) demonstrated normal ventilation to light hyperventilation. Differences from mean petCO2 obtained during low frequency breathing were 3.3 mmHg at MP1 and 4.4 mmHg at MP2 (p < 0.05). There were strong correlations between the individual pairs of pcCO2 and petCO2 from MP1 (r = 0.80) and MP2 (r = 0.75) as well as between the pairs of dpcCO2 and dpetCO2 from both MPs (r = 0.77). The accuracy of the ventilator setting according to petCO2 with reference to pcCO2 was 73% for MP1 and 74% for MP2 (sensitivity: 75%/79%; specificity: 72%/67%).
Capnography in rigid bronchoscopy during HFJV proved a clinically applicable addition to monitoring. Its routine use is strongly recommended in interventional bronchoscopy. The true petCO2 values obtained by intermittent single low frequency jet breathing permit estimates of gas exchange sufficiently exact for clinical purposes and for adjustment of the ventilator setting. Wave forms of the continuously recorded capnogram during HFJV are a warning of impeded ventilation or airway obstruction and, thus, of the danger of barotrauma or hypoventilation. Besides contributing to patient safety, this monitoring method might improve the acceptance of HFJV for bronchoscopy. Furthermore, it can also be applied to rigid bronchoscopy with common ventilation.
全身麻醉下的快速支气管镜检查仍有其确切的适应证，高频喷射通气技术具有诸多优势。然而，迄今为止通气监测一直不尽人意。因此，我们在60例使用带有远端采样口的硬支气管镜进行高频喷射通气（频率：100次/分钟；吸呼比：0.33；驱动压力：0.08 - 0.14兆帕）的支气管镜检查中研究了二氧化碳波形图。记录连续的二氧化碳波形图。然而，通过间歇性地将喷射频率降至10 - 12次/分钟，从2 - 3次单次呼吸中获取呼气末二氧化碳分压（petCO2）。在高频喷射通气6分钟后（MP1：全组；n = 60）以及18分钟后（MP2：该组中的n = 34），定期获取petCO2值，并与同步采集的毛细血管血样中的pCO2（pcCO2）进行比较。最初根据体重调整的喷射驱动压力仅根据petCO2进行校正，目标值为34毫米汞柱。
在高频喷射通气期间，正弦波形的二氧化碳波形图能够识别每一个喷射脉冲。然而，当器械通过支气管镜时，这些曲线会严重变形。MP1时的平均pcCO2（37.8 ± 6.7毫米汞柱）和MP2时的平均pcCO2（37.2 ± 6.7毫米汞柱）显示通气正常至轻度通气过度。与低频呼吸期间获得的平均petCO2的差异在MP1时为3.3毫米汞柱，在MP2时为4.4毫米汞柱（p < 0.05）。MP1时pcCO2与petCO2的各个配对之间（r = 0.80）以及MP2时（r = 0.75），以及两个MP时dpcCO2与dpetCO2的配对之间（r = 0.77）存在很强的相关性。根据petCO2相对于pcCO2进行通气机设置的准确性在MP1时为73%，在MP2时为74%（敏感性：75%/79%；特异性：72%/67%）。
高频喷射通气期间硬支气管镜检查中的二氧化碳波形图被证明是监测的一种临床适用补充方法。强烈建议在介入性支气管镜检查中常规使用。通过间歇性单次低频喷射呼吸获得的真实petCO2值允许对气体交换进行足够精确的估计，以用于临床目的和通气机设置的调整。高频喷射通气期间连续记录的二氧化碳波形图的波形是通气受阻或气道阻塞的警示信号，因此也是气压伤或通气不足危险的警示信号。除了有助于患者安全外，这种监测方法可能会提高高频喷射通气在支气管镜检查中的接受度。此外，它也可应用于普通通气的硬支气管镜检查。
