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Abstract

We would like to thank Drs Tetzlaff and Eichhorn for their useful comment on our study.1de Bakker H.M. Tijsterman M. de Bakker-Teunissen O.J.G. Soerdjbalie-Maikoe V. van Hulst R.A. de Bakker B.S. Prevalence of pulmonary bullae and blebs in postmortem CT imaging with potential implications for diving medicine.Chest. 2020; 157: 916-923Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar We agree with the authors that, based on literature, divers with bullae and blebs in the lungs have a potential risk on pulmonary barotrauma and subsequent cerebral air embolism. As mentioned in our study, there is a lack of information on the incidence of bullae and blebs in the healthy population, and performing prospective trials on this topic is indeed unethical. Most case reports or case series of divers with pulmonary barotrauma and a CT of the thorax showing abnormalities such as bullae, blebs, or air trapping suggest a causal relationship between these lung abnormalities and pulmonary barotrauma. Two arguments can be posed to refute that causality. First, when no CT scans are available from the patients before the accident, it cannot be ruled out that these abnormalities are actually the result of the barotrauma in these divers. Second, because we found an incidence of small bullae and/or blebs in one-third of the general population without underlying lung disease,1de Bakker H.M. Tijsterman M. de Bakker-Teunissen O.J.G. Soerdjbalie-Maikoe V. van Hulst R.A. de Bakker B.S. Prevalence of pulmonary bullae and blebs in postmortem CT imaging with potential implications for diving medicine.Chest. 2020; 157: 916-923Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar it can be expected that these abnormalities are also found in a large number of divers that suffered pulmonary barotrauma, not necessarily being the cause or lead point of the pneumothorax. The authors are right that a small bulla/bleb theoretically can lead to a cerebral air embolism when changes in intrapulmonary pressure related to ambient pressure are rapid, for example during a fast ascent by a diver breathing compressed air. With an incidence of bullae/blebs in one-third of the general population, many more incidents would have been expected. In the most recent guidelines from The Health and Safety Executive of the UK government,2The medical examination and assessment of commercial divers (MA1/rev 4, 2015). Health and Safety Executive. http://www.hse.gov.uk/pubns/ma1.htm. Accessed January 24, 2020.Google Scholar it is, however, stated that “there is no evidence to exclude anyone from diving in the presence of small blebs and bullae. With the presence of large bullae or cysts, the person is regarded unfit to dive. Further research is needed to define the term large.” The question is when this last question will be answered. In conclusion, decisions regarding fitness to dive and diving profiles in divers with bullae or blebs on CT scan need to be taken in a shared decision-making process with the individual diver and his or her diving physician, discussing the risk and benefits of continuing diving and the diving profile. Prevalence of Pulmonary Bullae and Blebs in Postmortem CT Imaging With Potential Implications for Diving MedicineCHESTVol. 157Issue 4PreviewPulmonary bullae and blebs can result in a pneumothorax. Their prevalence in the normal population is currently unknown. Postmortem CT (PMCT) images from a forensic database were used to determine the prevalence of pulmonary bullae/blebs in the normal Dutch adult population and its consequence for diving medicine, as bullae and blebs are often considered a contraindication for diving. Full-Text PDF Risk of Barotrauma When Diving With Pulmonary BullaeCHESTVol. 158Issue 4PreviewIn a previous issue of CHEST (April 2020), de Bakker et al1 should be congratulated for providing data on the prevalence of lung bullae and blebs in a general adult population. Although in normal life, these anomalies may not cause any harm, they can predispose to life-threatening injury under conditions of rapidly changing ambient pressure. Expanding gas in enlarged pulmonary airspaces may be trapped during ascent from a scuba dive or during commercial air travel, eventually causing pulmonary barotrauma. Full-Text PDF