Pulmonary effects of ‘lung packing’ by buccal pumping in an elite breath-hold diver.

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Pulmonary effects of ‘lung packing’ by buccal pumping in an elite breath-hold diver.

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Title: Pulmonary effects of ‘lung packing’ by buccal pumping in an elite breath-hold diver.
Author: Simpson, G; Ferns, J; Murat, S
Abstract: Buccal pumping is a technique used by breath-hold divers to increase lung capacity above normal total lung capacity (TLC) and thus increase depth capability. Concern has been expressed that hyperinflating the lungs using the pharyngeal muscles could itself produce pulmonary barotrauma, but transpulmonary pressures after buccal pumping have not previously been measured. We studied a breath-hold diver (SM) using whole-body plethysmography and oesophageal balloon manometry. Spirometry demonstrated that vital capacity could be increased from 7.48 to 9.22 l by buccal pumping. TLC increased from 9.28 to 11.02 l, calculated by assuming a constant residual volume of 1.8 l. At normal TLC, mean maximal pulmonary relaxation pressure measured at the mouth was 8.9 cm H2O. This rose to 86 cm H2O following buccal pumping to ‘super’ TLC. Mean transpulmonary pressure (mouth pressure minus oesophageal balloon pressure) at normal TLC was 31.6 cm H2O and at super TLC was very similar at 29.3 cm H2O. There did not seem to be a dramatic alteration in pulmonary compliance at higher lung volumes, although this was technically difficult to measure. These data suggest that buccal pumping itself does not carry a risk of pulmonary barotrauma. We postulate that the lack of rise in transpulmonary pressure relates to increased elastic recoil of the chest wall at volumes greater than normal TLC giving a positive intrapleural pressure and preventing pulmonary over-distension. Splinting of the chest wall has been shown experimentally to reduce the risk of pulmonary barotrauma in anaesthetised animals and fresh human cadavers, probably by a similar mechanism.
Description: Journal of the South Pacific Underwater Medicine Society
URI: http://archive.rubicon-foundation.org/10026
Date: 2003

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