English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

To the Editor, The recent review article by de Lima et al. delivers a well-written overview of the anesthesia-related aspects of interventional pulmonology. This includes a detailed section about access to the airway and ventilation. As jet ventilation is a widely used technique in this context, the authors dedicated a detailed portion of their review to this method. While much of what the authors state is factual and clear about many aspects of anesthesia for bronchologic interventions, the section about jet ventilation seems to be based more on information extracted from outdated literature and less from personal experience. As a result, some statements appear incorrect and/or are in opposition to actual practice—e.g., they state that ‘‘Based on the Venturi principle and other physical properties, the system achieves a high fraction of inspired oxygen (FIO2) by administering high-pressure gas through an open system’’. Their statement that jet ventilation depends on the Venturi principle, which would in turn enable a high FIO2, is a fundamental misconception and seems to reflect an uncritical repetition of phrases from inaccurate sources. In reality, the Venturi principle has no relevance for jet ventilation, and the closest effect that it resembles is ‘‘entrainment’’. This mechanism has a strong impact on jet ventilation, but instead of increasing FIO2 it decreases it by diluting the jet gas (which usually contains a high oxygen concentration) with ambient air. Nevertheless, there is also a benefit of entrainment. By increasing the injected gas volume into the airway and consequently enlarging tidal volumes, entrainment facilitates CO2 exhalation. The statement ‘‘technical settings (e.g., driving pressure and duration) of the jet ventilator can be adjusted according to intraoperative blood-gas analysis or based on the quantity of conventional ventilation periods required to achieve adequate SaO2’’ could also be modified to improve accuracy. The settings are not ‘‘driving pressure and duration’’, but rather ‘‘driving pressure and inspiratory duration’’ (or perhaps even better, the ‘‘I/E-ratio’’). While blood-gas analysis results as well as pulse oximetry are correctly stated, the notion that ventilation might be adjusted according to ‘‘the quantity of conventional ventilation periods required to achieve adequate SaO2’’ is at best vague and does not contain any applicable specific guiding information. The statement ‘‘recommendations to prevent barotrauma include maintaining a driving pressure around 1.5 bar (approximately 20 PSI) and limiting inspiration duration to 30-40% of the respiratory cycle’’ is arguably of little help either. For example, any level of driving pressure can cause barotrauma if the outflow of gas is hindered. Accordingly, it does not make any difference if the driving pressure was set at 2, 1, or even as low as 0.5 bar only. The real protection against barotrauma is continuous measurement of the airway pressure using a separate lumen and/or intermittently in the jet line. When using rigid bronchoscopy equipment, usually the pressure measurement can be done in the jet line alone. The essential safety feature in this context is an automatic shutdown of the ventilator if a user-set airway pressure limit has been surpassed. Furthermore, limiting the driving pressure to 1.5 bar would exclude a very large proportion This letter is accompanied by a reply. Please see Can J Anesth 2018; 65: this issue.

Comments on “Anesthesia for interventional pulmonology procedures: a review of advanced diagnostic and therapeutic bronchoscopy”