Lung perfusion and chest wall configuration is altered by glossopharyngeal breathing

Abstract

Glossopharyngeal insufflation is used by competitive breath-hold divers to increase lung gas content above baseline total lung capacity (TLC) in order improve performance. Whilst glossopharyngeal insufflation is known to induce hypotension and tachycardia, little is known about the effects on the pulmonary circulation and structural integrity of the thorax.Six male breath-hold divers were studied. Exhaled lung volumes were measured before and after glossopharyngeal insufflation. On two study days, subjects were studied in the supine position at baseline TLC and after maximal glossopharyngeal insufflation above TLC. Tc 99 m labelled macro-aggregated albumin was injected and a computed tomography (CT) scan of the thorax was performed during breath-hold. Single photon emission CT images determined flow and regional deposition. Registered CT images determined change in the volume of the thorax.CT and perfusion comparisons were possible in four subjects. Lung perfusion was markedly diminished in areas of expanded lung. 69% of the increase in expired lung volume was via thoracic expansion with a caudal displacement of the diaphragm. One subject who was not proficient at glossopharyngeal insufflation had no change in CT appearance or lung perfusion.We have demonstrated areas of hyperexpanded, under perfused lung created by glossopharyngeal insufflation above TLC.KEYWORDS: Breath-hold diving, glossopharyngeal insufflation, hyperinflation, perfusion imaging, pulmonary perfusion B reath-hold diving, or freediving, is a highly organised, increasingly popular extreme sport. Many competitive breathhold divers perform glossopharyngeal breathing both as a training exercise and just prior to a dive or submersed breath-hold. Glossopharyngeal breathing, a pump-like action involving the glossopharyngeal structures and larynx that forces air into the airways [1], was originally developed as a therapeutic technique for neuromuscular patients to help expand tidal volume and cough effectiveness [2,3]. The increase in expired lung volume above baseline total lung capacity (TLC) using glossopharyngeal breathing is achieved by a combination of an increase in the Euclidian size of the lung and gas compression [4,5]. Participants refer to this technique as lung packing; however this is described in the literature as glossopharyngeal insufflation (GI) [1,5,6].In theory, GI above TLC has the potential to assist breath-hold diving performance by increasing available oxygen stores and providing a volume buffer against the compressive effects of hyperbaria. Improvements in both static apnoea duration and breath-hold diving performance have been shown [7]. The potential for adverse cardiocirculatory effects is also clear. The extremely high transpulmonary pressures achieved, of up to 80 cmH 2 O [5], are associated with tachycardia, hypotension and biventricular systolic dysfunction [8]. In keeping with these observations, adverse neurological symptoms (e.g. presyncopal episodes and light-headedness) have been associated with this manoe...

Cardiac Magnetic Resonance Imaging during Pulmonary Hyperinflation in Apnea Divers

“…The measured lung volutne may not completely reflect the real glossopharyngeal insufflation volume. At higher glossopharyngeal insufflation volumes, the transpulmonary pressure tnay increase without further changes in volume simply by compression and decreasing chest compliance (39). We did not measure transpulmonary pressure in our study.…”

Glossopharyngeal insufflation causes lung injury in trained breath‐hold divers

“…All subjects were required to be able to swim at least 100 m without fins on a single breath (dynamic distance), descend to a depth of 40 m without assistance (constant weight) and breath‐hold while submersed for at least 5 min (static apnoea). These subjects were recruited as part of a larger study and that data has been published elsewhere 5 . The Concord Hospital Human Research Ethics Committee approved the study and all subjects gave informed consent.…”

“…Expired lung volumes as high as 3 L above baseline TLC have been measured immediately following this manoeuvre, 3 and airway and transpulmonary pressures of 109 cmH 2 O and 80 cmH 2 O, respectively, have been recorded after GI 3 . Approximately two‐thirds of the additional air is accommodated by an increase in lung size, while the remainder is accounted for by intrathoracic compression of gas 3–5 . While it is likely that the pressure effect is evenly distributed, the increase in lung volume in subjects who perform GI while recumbent occurs preferentially in the inferior and anterior lung regions 5 …”

“…3 Approximately two-thirds of the additional air is accommodated by an increase in lung size, while the remainder is accounted for by intrathoracic compression of gas. [3][4][5] While it is likely that the pressure effect is evenly distributed, the increase in lung volume in subjects who perform GI while recumbent occurs preferentially in the inferior and anterior lung regions. 5 Under these extreme conditions barotrauma must be considered a real risk.…”

“…[3][4][5] While it is likely that the pressure effect is evenly distributed, the increase in lung volume in subjects who perform GI while recumbent occurs preferentially in the inferior and anterior lung regions. 5 Under these extreme conditions barotrauma must be considered a real risk. However, it is prima facie unlikely that pneumothorax occurs commonly, otherwise many adverse events would be expected to occur in the competitive setting.…”