The gases diffuse across the barrier following pressure gradients. Gas exchange occurs via simple diffusion across the blood-air barrier.
Diseases that affect the perfusion (e.g., pulmonary embolism) or ventilation (e.g., foreign body aspiration) can cause a V/Q mismatch. The Euler-Liljestrand mechanism regulates the perfusion of nonventilated alveoli: if a lung section is perfused but not ventilated, there will be a drop in the oxygen concentration in the blood, resulting in hypoxic vasoconstriction. The ventilation-perfusion ratio is higher in the apex of the lung than at its base.
Perfusion of the pulmonary capillaries is closely regulated to match ventilation in order to maximize gas exchange. The physiologic dead space is the volume of inspired air that does not participate in gas exchange. Ventilation is the movement of air through the respiratory tract into (inspiration) and out of (expiration) the respiratory zone ( lungs). Neonatal cardiopulmonary resuscitation newborn resuscitation noninvasive respiratory support term newborn.The main function of the respiratory system is gas exchange (O 2 and CO 2). Our study indicates that face mask CPAP leads to an increase in dead space and a decrease in ventilation efficiency under certain circumstances. Oxygen concentration rise time in the face mask CPAP model was significantly longer at various continuous flow rates and points of the inner space of the face mask compared with that of the modified face mask CPAP model. The volume of inner space of the face mask was 38.3 ml. To evaluate the ventilation in the inner space of each model, we measured the oxygen concentration rise time, that is, the time needed for the oxygen concentration of each model to reach 35% after the oxygen concentration of the continuous flow was raised from 21% to 40%. We passed a continuous flow of 21% oxygen through each model and we controlled the inner pressure to 5 cmH 2 O by adjusting the flow-relief valve. We devised a face mask CPAP model, in which the outlet of the mask was covered with plastic and three modified face mask CPAP models, in which holes were drilled near to the cushion of the covered face mask to alter the air exit. We estimated the volume of the inner space of the mask. We evaluated the effect of face mask CPAP on system dead space. Continuous positive airway pressure (CPAP) by face mask is commonly performed in newborn resuscitation.
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