Lung Packing in Breath-Hold Diving, An Impressive Case of Pulmo-Cardiac Interaction
Authors: Jochen D. Schipke, Malte Kelm, Klaus Siegmund, Thomas Muth, Burkhard Sievers, Stephan Steiner
DOI / Source: https://doi.org/10.1016/j.rmcr.2015.09.007
Date: 14 September 2015
Reading level: Beginner
Why This Matters for Freedivers
Lung packing can make equalisation easier and add oxygen, but this case report shows a big downside: it can sharply reduce stroke volume and cardiac output by increasing pressure inside the chest and reducing blood return to the heart. In real life, that can mean dizziness, fainting risk, and less “circulation safety margin” right before a dive—so packing deserves respect, conservative use, and good supervision.
Synopsis
“Lung packing” (glossopharyngeal insufflation) is a technique some freedivers use to push lung volume above normal total lung capacity, mainly to improve equalisation at depth and increase the amount of oxygen carried in the lungs. But when you overfill the chest, you also change the mechanical relationship between lungs and heart. This short case report gives a vivid, real-world demonstration of that heart–lung interaction using cardiac MRI.
The subject was a healthy 40-year-old female competitive breath-hold diver. During a medical check-up, the team performed cardiac MRI at rest, then again after she did lung packing followed by a breath-hold (a 2-minute apnea after the glossopharyngeal insufflations). They also measured aortic blood flow to estimate stroke volume and cardiac output.
The effects were dramatic. Her heart rate rose from 50 to 66 beats/min during apnea, but her stroke volume fell from 92 mL (normal breathing) to 48 mL after packing and at the end of apnea. That means cardiac output dropped from about 4.6 L/min to 3.2 L/min—almost one third. MRI images showed both right and left ventricular volumes were reduced and the ventricular walls looked thicker, which the authors interpret as a result of reduced venous return plus increased intrapulmonary/intrathoracic pressure compressing the heart and limiting filling.
In the discussion, the authors connect this to practical freediving risks. Packing increases intrathoracic pressure, which can impede blood return to the heart and can cause hypotension symptoms ranging from dizziness to fainting, especially before a dive when someone is already calm, bradycardic, and sometimes standing or moving. Their conclusion is simple: the maneuver powerfully demonstrates heart–lung interaction, but it can have detrimental consequences because it reduces stroke volume and cardiac output—so caution is advised.
Abstract
There is a complex interaction between the heart and the lungs. We report on a healthy female who performs breath hold diving at a high, international level. In order to optimize pressure equalization during diving and to increase oxygen available, apneists employed a special breathing maneuver, so called “lung packing”. Based on cardiac MRI we could demonstrate impressive effects of this maneuver on left ventricular geometry and hemodynamics. Beyond the fact, that our findings support the concept of pulmonary–cardiac interrelationship, it should be emphasized, that the reported, extreme breathing maneuver could have detrimental consequences due to reduction of stroke volume and cardiac output.