engleski

Analysis of involuntary diaphragmatic movement in elite breath-hold divers - MRI study

Maximum voluntary apnea is divided into two phases: the first or the easy going phase of apnea and the second phase or the struggle phase of apnea where a person resists the increasing urge to breath. In the second phase of maximal apnea involuntary breathing movements (IBM) appear and represent the physiological compensational mechanism for extending the duration of apnea. The purpose of the study is to determine and quantify involuntary contractions of the diaphragm within IBM, during apnea, using dynamic magnetic resonance imaging (MRI). The purpose is also to determine does the intensity of the contractions of diaphragm depend on the lung capacity and are analysed parts of the diaphragm equally involved in active contractions. Eight male elite breath-hold divers (21-29 years) were studied with MRI. Examinations consist of two parts: TLC (total lung capacity) and FRC (functional residual capacity) apnea. We have performed a continuous scanning of the right hemidiaphragm during the whole TLC and FRC apnea and we have measured lung volumes and the physiological parameters: heart rate (HR), arterial oxygen saturation (SpO2), end tidal partial pressure of oxygen (ETO2), end tidal partial pressure of carbon dioxide (ETCO2). Results indicate the occurrence of diaphragmatic contractions whose intensity increases towards the end of TLC and FRC apnea. The intensity of involuntary diaphragmatic contraction does not depend on the lung volume and with involuntary contraction diaphragm does not function as a single entity. Significant changes in physiological parameters are occurring during TLC and FRC apnea. The study has confirmed that the diaphragm participates in involuntary breathing movements which occur in later stages of apnea in divers. We have established differences in the mobility of diaphragm segments during the contraction.

apnea ; involuntary breathing movements ; quantify involuntary contractions ; dynamic magnetic resonance imaging

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