DIVE LOG Australasia

The problem with spontaneous pneumothorax is that there is almost always several of the anatomical defects that caused the event, and patients who suffer one, typically suffer repeat events. Let’s apply the 3 question analysis (above) to spontaneous pneumothorax. The answer to the first question is “yes”. Diving can most definitely “make the problem worse”. If a pneumothorax occurred spontaneously at depth, the ascent in diving would result in expansion of the gas in the pleural space, thus worsening the collapse and potentially causing a “so-called” tension pneumothorax in which the increasing pleural gas pressure pushes on the heart and prevents it working properly. A tension pneumothorax can become rapidly fatal. The answer to the second question is also “yes”. A pneumothorax can occur in diving even in normal lungs (if a diver holds their breath during ascent), and a pneumothorax is thus seen as a diving disorder. This would be much more likely in someone who has anatomic defects in the lung that might rupture with much smaller provocations than are usually required. Finally, the answer to the third question is yes. Clearly if a pneumothorax occurred in the water the diver could be unable to exercise or function adequately. Unfortunately, there is little that can be done to adequately mitigate the risk in diving implied by a previous spontaneous pneumothorax. Some sufferers undergo surgical procedures to stick the lung to the chest wall and prevent collapse, or even to remove segments of the lung that contain the anatomic defects (usually up near the top of the lung). Either procedure may reduce the risk of lung collapse but they don’t completely remove the hazard and they may, in fact, increase the risk of other consequences of lung barotrauma (such as arterial gas embolism). For these reasons, diving physicians (even relatively liberal ones like myself) continue to see previous spontaneous pneumothorax as a contraindication to diving. I am aware that some individuals have chosen to dive despite a history of spontaneous pneumothorax, but they do so at much greater risk, and are unlikely to have found a diving doctor who would endorse what they are doing. The medical community tries not to blindly adhere to old dogma on such issues, and periodically reviews its stance. This was done relatively recently in relation to spontaneous pneumothorax in a very considered and sensible review by colleagues from Duke University in the USA [1]. They were essentially looking for evidence that would support relaxation of our conservative stance on spontaneous pneumothorax but concluded that the current position is essentially sound. If any readers are interested in this article they can email me at sj.mitchell@auckland.ac.nz, and I will send it to them. Reference: 1. Alvarez Villela M, Dunworth S, Harlan NP, Moon RE. Can my patient dive after a first episode of primary spontaneous pneumothorax? A systematic review of the literature. Undersea Hyperb Med. 2018;45:199-208.

PROFESSOR SIMON MITCHELL MB ChB, PhD, DipOccMed, DipAdvDHM (ANZCA), FUHM, FANZCA Simon works as an anaesthesiologist at Auckland City Hospital and is Professor of Anaesthesiology at the University of Auckland. He provides on-call cover for the diving emergency service in New Zealand. He is widely published with two books and over 160 scientific journal papers or book chapters. He co authored the hyperbaric and diving medicine chapter for the last four editions of Harrison’s Principles of Internal Medicine. He has been Editor-in Chief of Diving and Hyperbaric Medicine Journal since 2019. He has twice been Vice President of the UHMS and in 2010 received the society’s Behnke Award for contributions to the science of diving. Simon has a long career in sport, scientific, commercial, and military diving. He was first to dive and identify Zealand, including one in 2002 which was the deepest wreck dive undertaken at the time. He was conferred Fellowship of the Explorers’ Club of New York in 2006, and was the Rolex Diver of the Year in 2015. His most recent expeditions were the Pearse Resurgence cave exploration (New Zealand) in 2020, a project to take arterial blood gas specimens from an elite freediver at 60m 2021, and hunted for a shipwreck in the sub-Antarctic in 2022. three historically significant deep shipwrecks in Australia and New

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DIVE LOG Australasia #408 - October ‘24