Endotracheal Measurement of Thyroarytenoid Activity in Newborn Lambs

Abstract

Laryngeal control of expiratory airflow is a principal means by which the newborn establishes and maintains absolute lung volume. Specifically, retardation of expiratory airflow is effected by the major adductors of the larynx, the thyroarytenoid (TA) muscles. The long-term aim of this research is to determine if monitoring TA activity can be used to optimize absolute lung volume during artificial ventilation of the human baby. This initial study, performed in unanesthetized chronically instrumented newborn lambs, tests the hypothesis that the timings of the onsets, peaks and durations of TA activity recorded by the endotracheal electrode are equivalent to those measured by a surgically placed intramuscular electrode. Endotracheal measurement of TA activity is accurate and specific and can monitor changes in airway pressure and lung volume.

Non-invasive neurally adjusted ventilatory assist in rabbits with acute lung injury

“…Intubation bypasses the glottis and therefore interferes with the maintenance of end-expiratory lung volume (EELV). With an endotracheal tube in place, the glottal constrictor muscles may be electrically activated in an attempt to maintain EELV [28], but their contraction around the endotracheal tube cannot increase end-expiratory resistance. When no PEEP is applied, one compensating mechanism for the loss of laryngeal braking is that the diaphragm "takes over" the role of maintaining EELV during intubation, as is evidenced by the instantaneous increase in tonic activity of the diaphragm when the PEEP was removed in the present study (Fig.…”

Non-invasive positive pressure ventilation in the preterm neonate: reducing endotrauma and the incidence of bronchopulmonary dysplasia

“…During normal spontaneous tidal breathing, the dynamic chest wall and lung volume–pressure (V–P) curves show that minimal pressure is applied to the epithelium and capillaries 25. When the upper airway is bypassed by an endotracheal tube (ETT), the coordinated laryngeal and diaphragmatic control of respiratory pattern and EEV is disrupted 30. Invasive artificial ventilation from a low EEV and with large tidal volumes leads to surfactant damage, decreased compliance and trauma 14 28…”

“…The asphyxiated neonate with a low EEV at birth may breathe out against a closed glottis, promoting recruitment 38 39. After endotracheal intubation this manoeuvre is ineffective,30 producing a rejection reflex 38…”

Very Preterm Infants Failing CPAP Show Signs of Fatigue Immediately after Birth

“…[ 8 – 13 ] To date, the respiratory pattern and effort at birth have not been investigated although they are a major determinant of lung gas volumes [ 14 ] and may correlate with respiratory distress severity and predict CPAP failure. [ 15 ] As the preterm infant’s chest wall is highly compliant and transiently expands immediately after birth [ 16 ], it has limited capacity to oppose lung recoil. [ 17 ] As such, these infants must utilise their breathing pattern to develop and maintain functional residual capacity (FRC) immediately after birth.…”