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Intermittent capnography during high‐frequency jet ventilation for prolonged rigid bronchoscopy
Author(s) -
Frietsch T.,
Krafft P.,
Becker H. D.,
Buelzebruck H.,
Wiedemann K.
Publication year - 2000
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.2000.440406.x
Subject(s) - capnography , medicine , anesthesia , arterial blood , discontinuation , ventilation (architecture) , arterial ph , blood sampling , surgery , mechanical engineering , engineering
Background: Gas exchange during high‐frequency jet ventilation (HFJV) for prolonged rigid bronchoscopy (RBS) is usually monitored by arterial blood gas analysis. Capnography of expired gases during brief HFJV discontinuation may be a reliable and noninvasive supplemental method. Capnography can be performed either for single breaths or with respiratory rate (RR) reduced to 10 · min −1 . The aim of this study was to demonstrate that capnography during short periods of HFJV discontinuation represents a reliable measure of PaCO 2 during prolonged RBS. Methods: We prospectively investigated 100 consecutive patients (75 male and 25 female) undergoing HFJV for RBS. HFJV was delivered through the rigid bronchoscope at the following settings: working pressure 1.2 bar, rate 100 · min −1 , F I O 2 0.99, t i /t tot 0.6. The light guiding channel ending at the distal tip of the rigid bronchoscope was used for gas sampling. Capnograms were assessed at 5 min intervals and compared to PaCO 2 from arterial blood samples drawn simultaneously. The accuracy of single breath CO 2 sampling was compared with sampling at RR=10 · min −1 . Results: Mean duration of RBS was 30±21 min. A significant correlation between capnography (PetCO 2 ) and arterial blood gas analysis (PaCO 2 ) was observed, being r=0.90 for the RR=10 · min −1 method and r=0.91 for the single breath method. Mean difference between PaCO 2 and PetCO 2 was 0.37±0.2 kPa throughout the entire study period. No significant differences between single breath sampling or sampling at RR=10 · min −1 were observed. Conclusion: Capnography performed during short periods of HFJV discontinuation reliably and noninvasively reflects PaCO 2 during prolonged endoscopic procedures. Capnography during HFJV for RBS may reduce the frequency of arterial blood gas sampling, the duration of unmonitored intervals and costs.