Overexpression of ACE2 prevents hypoxia-induced pulmonary hypertension in rats by inhibiting proliferation and immigration of PASMCs.

OBJECTIVE: Imbalance of the ratio of angiotensin converting enzyme (ACE) and ACE2 may lead to pathological conditions in lung. However, its effect on hypoxia-induced pulmonary hypertension (HPH) remains unclear. Therefore, the aim of this study was to investigate the effects of ACE2 overexpression on rat primary pulmonary arterial smooth muscle cells (PASMCs) and HPH rat model. MATERIALS AND METHODS: ACE and ACE2 expression in rat PASMCs under hypoxia condition, as well as in HPH rat model, was detected. The overexpressed ACE2 gene was transfected into PASMCs by Lentiviral. Later, the proliferation and migration of PASMCs were evaluated. Meanwhile, the overexpressed ACE2 gene was transfected into rats and exposed to hypoxia for four weeks. Finally, the right ventricular systolic pressure, the right ventricular hypertrophy, and the percentage of the medial wall thickness were measured to evaluate the development of HPH. RESULTS: Imbalance of the expression of ACE/ACE2 was indicated in rat PASMCs under hypoxia condition and in the HPH rat model, respectively. The overexpression of ACE2 significantly inhibited PASMCs proliferation and migration. Moreover, the overexpressed ACE2 could significantly attenuate pulmonary hypertension, pulmonary vascular remodeling, and right ventricular hypertrophy in HPH rat model. CONCLUSIONS: ACE2 is related to the formation of pulmonary vascular remodeling and pulmonary hypertension. Furthermore, it may prevent hypoxia-induced pulmonary hypertension by inhibiting the proliferation of PASMCs.

Ventilation strategy and anesthesia management in patients with severe tracheal stenosis undergoing urgent tracheal stenting.

BACKGROUND: Stenting of airway stenosis is a common procedure in specialized centers. The aim of this study was to summarize our clinical experience in ventilation strategy and anesthesia management of patients undergoing urgent tracheal stenting. METHODS: Clinical data of 22 patients with severe tracheal stenosis who underwent urgent endoscopic placement of a tracheal stent during a 2-year period were retrospectively reviewed. The efficacy and safety of different ventilation strategies and veno-arterial extracorporeal membrane oxygenation (ECMO), individualized based on the cause and location of tracheal narrowing, were evaluated. RESULTS: Sufficient ventilation was successfully established in all patients; ECMO was used in five patients with stenosis in the mid-trachea who were unable to tolerate conventional intubation; a laryngeal mask airway (LMA) was used in five patients with post-intubation tracheal stenosis; a cuffed tracheal tube was used in eight patients with lower tracheal stenosis; and low-frequency jet ventilation in rigid bronchoscopy was used in four patients with mid- or lower tracheal stenosis. Tracheal stents were successfully placed and there were significant improvements in dyspnea. There were significant increases in the partial pressure of carbon dioxide in patients ventilated with the LMA and cuffed tracheal tube. There was no hypoxia during the operative period. CONCLUSION: Establishment of effective airway ventilation in patients with severe tracheal stenosis should be based on the cause, location, and severity of tracheal narrowing. Veno- arterial ECMO may be considered in patients with severe stenosis, if they are judged unable to tolerate conventional ventilation or jet ventilation.

An evaluation of the laryngeal mask airway supreme' in 100 patients.

The Laryngeal Mask Airway (LMA) Supreme is a new supraglottic airway incorporating features of the LMA Proseal, LMA Fastrach and LMA Unique. We evaluated the LMA Supreme in 100 patients with normal airways having elective surgery. Our success rates of insertion and ventilation were 96% at the first attempt and 100% after two attempts. The median time to successful placement was 15 seconds (interquartile range 12 to 18 seconds). Forty-five patients breathed spontaneously and 55 patients had controlled ventilation. The incidence of blood staining on removal was 7% and 7% of patients had mild sore throat one hour postoperatively. One patient who had been placed in the left lateral position during surgery had left lingual nerve palsy postoperatively, which recovered completely after one month. Our findings suggest that in patients with normal airways, the LMA Supreme is easy to insert and provides a satisfactory airway with adequate seal pressures for ventilation.