Barotrauma And Sipe In Freediving 2024 (SDCED/DAN WORKSHOP)
Authors: Peter Lindholm, Oliver Christen-Drew, Matías Nochetto, Frauke Tillmans, Elaine D. Yu, Richard E. Moon, Susan R. Hopkins, Benjamin A. Sebreros, Vitomir Maričić, Anna Lussier, Bradford J. Smith, Maria Hårdstedt, Gilbert E. Boswell, Andrew M. Luks, Peter Germonpré, Igor Barković, Claudia Seiler, John R. Fitz-Clarke, Fernando Silva, Alexander Patrician, Juan M. Valdivia-Valdivia
DOI / Source: UC San Diego / DAN
Date: 2024
Reading level: Advanced
Why This Matters for Freedivers
This proceedings volume is basically a safety upgrade: it makes it clear that “lung squeeze” isn’t one single thing, and that similar symptoms can come from different mechanisms that may need different responses. It also supports a more conservative culture: if you have pulmonary symptoms after diving (especially low SpO₂, breathlessness, or blood), you should treat it as a real medical/safety event with structured follow-up — not something to hide or normalize.
Synopsis
This document isn’t a single study — it’s a full workshop proceedings (UC San Diego Center of Excellence in Diving + DAN) focused on one of the biggest “grey areas” in freediving safety: what we casually call “lung squeeze”, and how it overlaps with SIPE/IPE (swimming/immersion-induced pulmonary edema). The editors bring together 21 papers plus panel discussions to summarize what’s known, what’s debated, and what needs better data — from competition medicine to underlying physiology and practical treatment decisions. 
A central theme is that several different injuries can look similar on the surface: cough, chest tightness, breathlessness, low oxygen, and sometimes blood. The proceedings explain two big buckets. One is immersion pulmonary edema, often framed as a pressure/flow problem where fluid is pushed from blood vessels into lung tissue (a “transcapillary pressure” issue influenced by arterial pressure, venous pressure, and lymph drainage). The other is barotrauma of descent, where mechanical stress and pressure changes can distort lung structures and lead to leaking or bleeding. Importantly, the workshop highlights that real life may involve mixed pictures (edema + bleeding + airway irritation), and risk factors may include things like cold water, heavy exertion, hypertension, and possibly infection/inflammation in some cases. 
The practical outcome is a push toward clearer terminology and better decision-making tools: the group discusses definitions, severity, screening (e.g., pulse oximetry and lung ultrasound), treatment options (including oxygen vs positive pressure), and the hardest question of all — when it’s safe to return to diving. A notable proposal coming out of the discussions is the umbrella term “Freediving-induced pulmonary syndrome (FIPS)”, acknowledging that current categories and severity grading are still limited by lack of reliable data.
Abstract
The San Diego Center of Excellence in Diving at UC San Diego and the Divers Alert Network convened the Barotrauma and SIPE in Freediving workshop on 27-28 October 2023 in San Diego, California to provide a synthetic overview of the current knowledge of barotrauma and swimming- induced immersion pulmonary edema (SIPE). This workshop was an international, interdisciplinary effort to examine the prevalent emerging issues with freediving and different types of swimming-, immersion- ,and altitude-related pulmonary edema. This volume presents 21 papers and panel discussions with particular focus on the definition, symptomatology, mechanics, prevention and treatment of SIPE and squeeze, a colloquial term amongst freedivers for lung barotrauma of descent. Immersion pulmonary edema is considered cardiogenic edema from increased transcapillary pressure. Fluid generated in the pulmonary interstitium or alveoli is dependent on inflow (arterial pressure); outflow (venous pressure); and, lymphatic drainage. Barotrauma of descent is coupled to a relative negative pressure in the airways and/or alveoli triggering anatomical distortion of lung parenchyma that presents as tears to the structures with bleeding. New data suggests that infection may be present providing permeability and inflammation as a contributing component. Mechanisms for individual sensitivity, influence of gender, and genetic predisposition are poorly known but hypertension has been identified as a factor. Workshop presentations spanned lung squeeze and DCI in freediving education, review of emergent freediving cases, current medical procedures at competitions, pathophysiology of SIPE, pulmonary capillary stress failure, infection as a risk factor, biomechanics of SIPE, sex and age difference prevalence, mechanisms of SIPE, pathophysiology and clinical course of HAPE (high-altitude pulmonary edema), patent foramen ovale in freediving, hemoptysis, diagnosis of SIPE in recreational swimmers, lung damage and long-term consequences of barotrauma. Finally, terminology, treatment, and return to freediving or swimming were addressed in a panel discussion format. A consensus was reached to introduce a new term to describe the multiple pulmonary injury types connected with freediving. Freediving-induced pulmonary syndrome (FIPS) was suggested, acknowledging that the classification of severity and recognizable symptoms of each subcategory of FIPS is not currently possible due to a lack of reliable data. Further discussion and collection of data is warranted from retrospective as well as prospective applied research. Workshop Proceedings can be downloaded at www.dan.org.