What is the purpose of the air bubble test in bronchoscopy (Bronchoscopy)?

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Last updated: April 19, 2025View editorial policy

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From the Guidelines

The air bubble test is not a recommended technique in bronchoscopy as there is no recent or high-quality evidence to support its use, and it may not be directly relevant to the provided guideline evidence. When considering the use of diagnostic techniques in bronchoscopy, it is essential to prioritize methods that are evidence-based and directly relevant to patient care. The provided guideline evidence [ 1 ] focuses on the British Thoracic Society guidelines on diagnostic flexible bronchoscopy, particularly in the context of intensive care units. This guideline highlights the importance of flexible bronchoscopy in inspecting the upper airways and bronchial tree in critically ill patients but does not mention the air bubble test.

Key points to consider in bronchoscopy include:

  • The selection of an appropriate bronchoscope for the specific clinical setting, such as the intensive care unit, where the internal diameter of the endotracheal tube may restrict the size of the bronchoscope [ 1 ].
  • The importance of efficient suctioning, which requires a larger bronchoscope with a wide suction channel.
  • The risks associated with bronchoscopy in non-intubated patients, as outlined in the section on complications.

Given the lack of recent, high-quality evidence supporting the air bubble test in bronchoscopy, and considering the provided guideline evidence [ 1 ], the focus should be on established, evidence-based diagnostic techniques that prioritize patient safety and effective care. In real-life clinical practice, it is crucial to rely on methods that have a strong evidence base to ensure the best possible outcomes in terms of morbidity, mortality, and quality of life.

From the Research

Bronchoscopic Sampling Techniques

  • The air bubble test is not explicitly mentioned in the provided studies, however, bronchoscopic sampling techniques are discussed in several studies 2, 3, 4.
  • Bronchoscopic sampling of bronchoalveolar fluid (BAL) should be safe and effective, and the Ambu Bronchosampler with aScope 4 has been evaluated as an alternative integrated sampling solution 2.
  • The study found that the Ambu Bronchosampler remained upright in all procedures with no loss or spillage of sample, and obtaining a sample was much easier in 60% of procedures 2.

Diagnostic Accuracy of Bronchoscopy Procedures

  • The diagnostic accuracy of bronchoscopy procedures is discussed in a methodological review, which outlines standard measures of diagnostic accuracy and highlights how these differ from "diagnostic yield" 4.
  • The review draws examples from the interventional bronchoscopy literature to illustrate key concepts and potential pitfalls, but does not mention the air bubble test specifically 4.

Therapeutic Bronchoscopy

  • Therapeutic bronchoscopy has been established as the main therapeutic means for central airway diseases of both benign and malignant aetiology 5, 6.
  • Techniques applied to regain patency of the central airways include mechanical debulking, thermal ablation, and cryo-surgery, but the air bubble test is not mentioned in these studies 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Diagnostic Accuracy of Bronchoscopy Procedures: Definitions, Pearls, and Pitfalls.

Journal of bronchology & interventional pulmonology, 2022

Research

Recent advances in therapeutic bronchoscopy.

Swiss medical weekly, 2012

Research

Therapeutic bronchoscopy for central airway diseases.

European respiratory review : an official journal of the European Respiratory Society, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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