No description available.

In surgery for airway obstruction, the anesthetist and the ear-nose-throat surgeon share the approach to the airway and jet ventilation (JV) is a mutually convenient ventilation technique for both parties. As a consequence of the open system jet ventilation is applied in, bedside measurements of lung volumes are cumbersome to perform and thus, there is a lack of studies comparing different modes of JV or investigating the influence of ventilator settings on lung volumes and gas exchange. In this thesis, single frequency jet ventilation and superimposed high frequency jet ventilation (SHFJV) at different frequencies are systematically compared with respect to lung volume changes, underlying airway pressure variations and the resulting gas exchange. We compared three single-frequency JV modalities with SHFJV in patients. Moreover, we performed a systematic investigation of single frequency JV and SHFJV in a porcine model. Single frequency JV and SHFJV were compared frequency-wise in intact airways and in a newly developed model of tracheal obstruction. This model was also used to assess the influence of variable airway diameter on ventilation effectiveness during SHFJV. We measured chest wall volume variations with opto-electronic plethysmography and obtained airway pressures as well as gas exchange parameters. In unobstructed airways, both single-frequency JV and SHFJV provided adequate oxygenation, despite differences in lung volumes. Carbon dioxide removal was most effective using single frequency JV at a frequency of 150 min-1. During SHFJV, for both intact and obstructed airways, the choice of frequency for the high frequency component had little influence on lung volumes, airway pressures and gas exchange. With decreasing airway diameter and SHFJV, we observed air trapping and lower tidal volumes and acceptable oxygenation. Carbon dioxide removal, however, was insufficient at the narrowest airway diameter. In single frequency JV, very high frequencies resulted in negligible tidal volume and inacceptable gas exchange. Airway obstruction potentiated this frequency dependence. In conclusion, in intact airways, single frequency JV at sufficiently low frequencies provided adequate oxygenation and better CO2 removal than SHFJV. With decreasing airway diameter, SHFJV provided better oxygenation and CO2 removal and may therefore be the mode of choice in more complicated cases.

Idiopathic tracheal stenosis (ITS) is a rare condition, and diagnosis of exclusion should be suspected in patients with exercise intolerance, wheezing, and dyspnea on exertion with a flow-volume loop suggestive of fixed airway obstruction. We report a case of a 32-year-old asthmatic woman with an existing diagnosis of vocal cord dysfunction and previous normal CT scan of the neck. She continued to have fixed upper airway obstruction on repeated flow-volume loops with persistent wheezing and cough along with occasional stridor and hoarseness of voice despite appropriate management of her asthma. She was finally diagnosed with ITS on a repeat CT scan of the neck for which she underwent laser surgery, steroid injection, and controlled radial expansion balloon dilation with a successful reduction of stenosis. This case illustrates the importance of clinical suspicion for early diagnosis of ITS in poorly controlled asthmatic patients and the relevance of non-surgical management of this condition.

No description available.

Long segment tracheal obstruction is a potentially fatal condition arising from primary malignancy, congenital tracheal stenosis, or benign strictures. Shorter lesions are amenable to primary surgical repair, but anastomotic tension remains a limiting factor. Attention has therefore turned towards tissue engineered interposition grafts, consisting of cartilage, vascular, and airway epithelial cell layers. For clinical applications, it is essential to develop tools for noninvasive monitoring of in vivo graft development. This investigation therefore sough to optimize a tracheal patch and tube model suitable for SCID mouse implantation, and to demonstrate simultaneous tracking of human chondrocytes and epithelial cells labeled with contrasting intracellular magnetic resonance labels. Cartilage labeled with iron oxide nanoparticles was successfully distinguished from unlabeled control tissue both in vitro and in vivo. Gadolinium dendrimer labeling of adjacent airway epithelial cells, however, did not initially permit enhanced visualization. Further model optimization is required for simultaneous cell tracking.