Reutershan Jörg, Schmitt Andre, Dietz Klaus, Fretschner Reinhold
Department of Anaesthesiology and Intensive Care Medicine, University of Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany.
Clin Sci (Lond). 2004 Jan;106(1):3-10. doi: 10.1042/CS20030157.
In the daily clinical routine at the bedside, information on effective pulmonary blood flow (PBF) is limited and requires invasive monitoring, including a pulmonary artery catheter, to determine both cardiac output and intrapulmonary shunt. Therefore we evaluated a non-invasive method for the measurement of PBF in a clinical setting, including 12 patients with acute respiratory failure (acute respiratory distress syndrome) undergoing prone positioning. PBF was determined before (baseline), during and after prone positioning, by using a foreign gas rebreathing method with a new photoacoustic gas analyser. Values were compared with the cardiac output corrected for intrapulmonary shunt (COeff). Responders to prone positioning were defined according to the improvement of arterial oxygenation. A total of 84 measurements were performed. PBF values correlated well with COeff (R2=0.96; P<0.0001). Bias and limits of agreement (+/- 2 S.D.) for all measurements were -0.11 +/- 0.76 litre/min. At baseline, responders showed significantly lower PBF levels than non-responders (4.8 +/- 1.0 compared with. 6.4 +/- 1.2 litre/min; P=0.03). During prone positioning, PBF increased continuously in responders and remained high after patients had been returned to the supine position. PBF was unaffected in non-responders. Mean total increase in PBF was 1.2 +/- 0.2 litre/min in responders compared with -0.4 +/- 0.2 litre/min in non-responders (P<0.0001). In conclusion, the investigated rebreathing system allows for a non-invasive determination of PBF at the bedside. The accuracy of the measurements is comparable with the thermodilution method. It is able to reliably reflect changes in PBF induced by prone positioning. Moreover, measuring PBF might be a promising tool to identify responders to prone therapy.
在日常床边临床工作中，关于有效肺血流量（PBF）的信息有限，需要进行侵入性监测，包括使用肺动脉导管来确定心输出量和肺内分流。因此，我们评估了一种在临床环境中测量PBF的非侵入性方法，研究对象为12例接受俯卧位治疗的急性呼吸衰竭（急性呼吸窘迫综合征）患者。通过使用带有新型光声气体分析仪的外源性气体重呼吸法，在俯卧位之前（基线）、期间和之后测定PBF。将这些值与校正了肺内分流的心输出量（COeff）进行比较。根据动脉氧合的改善情况定义俯卧位治疗的反应者。总共进行了84次测量。PBF值与COeff相关性良好（R2 = 0.96；P < 0.0001）。所有测量的偏差和一致性界限（±2标准差）为-0.11±0.76升/分钟。在基线时，反应者的PBF水平显著低于无反应者（4.8±1.0与6.4±1.2升/分钟相比；P = 0.03）。在俯卧位期间，反应者的PBF持续增加，并且在患者恢复仰卧位后仍保持较高水平。无反应者的PBF未受影响。反应者的PBF平均总增加量为1.2±0.2升/分钟，而无反应者为-0.4±0.2升/分钟（P < 0.0001）。总之，所研究的重呼吸系统能够在床边非侵入性地测定PBF。测量的准确性与热稀释法相当。它能够可靠地反映俯卧位引起的PBF变化。此外，测量PBF可能是识别俯卧位治疗反应者的一种有前景的工具。
