What point(s) on the capnographic waveform represents) a mixture of alveolar gas and dead space gas1/19/2024 ![]() ![]() 1 The latter enables breath by breath analysis of carbon dioxide elimination in relation to tidal volume and by construction of a capnogram waveform can allow calculation of the end-tidal CO 2 and physiological dead space. ![]() The best determinant of alveolar plateau presence in preterm infants was the expired tidal volume.Ĭapnography allows for continuous measurement of carbon dioxide (CO 2) expired from the large conducting and smaller gas exchanging airways during ventilation and can be represented relative to time or volume. Ventilation inhomogeneity increased immediately post-surfactant administration during the resuscitation of preterm infants, producing a characteristic up-slanting appearance to the alveolar plateau. Volumetric capnography can be used to assess homogeneity of ventilation by S III analysis. Ventilation inhomogeneity increased post-surfactant likely due to airway obstruction caused by liquid surfactant present in the airways. It was feasible to evaluate the alveolar plateau pre-surfactant in preterm infants. An increase in S III produced an up-slanting appearance to the plateau indicating regional obstruction. ![]() Normalised for tidal volume S III pre-surfactant was 18.89 mmHg and post-surfactant was 24.86 mmHg ( p = 0.006). ![]() There was adequate slope in 134 (74.4%) capnograms pre and in 100 (55.6%) capnograms post-surfactant ( p = 0.004). Three hundred and sixty capnograms (180 pre and post) were evaluated. Average time between pre- and post-surfactant was 3.2 min. Thirty-six infants were included, median gestational age of 28.7 weeks and birth weight of 1055 g. If a plateau was present S III was calculated by regression analysis. Ten capnograms were constructed for each infant: five pre- and post-surfactant. Respiratory function traces of preterm infants resuscitated at birth were analysed. We aimed to assess the feasibility of measuring S III during newborn resuscitation and determine if S III decreased after surfactant indicating ventilation inhomogeneity improvement. The slope of the alveolar plateau of the capnogram (S III) could provide information regarding ventilation homogeneity. Volumetric capnography allows for continuous monitoring of expired tidal volume and carbon dioxide. ![]()
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