【正文】 event hypercapnia. When do you select mechanical ventilation? This is a question we always meet in our clinical work. elevation in PaCO27080mmHg hypoxemia, after oxygen therapy, PaO240mmHg rates35 per minute or severe breathlessness metabolic acidosis or pulmonary encephalopathy 第二十四頁，共四十九頁。 Clinical manifestations ? Clinical signs include not only symptoms associated with primary diseases but also those caused by hypoxic and hypercapnichypoxic respiratory failure. ? Hypoxemia and hypercapnia mainly influence the function of important ans, including respiratory system, central nervous system, cardiovascular system, digestive system, renal functions. 第十六頁，共四十九頁。 Pathogenesis ? Respiratory failure is mainly associated with pulmonary gas exchange and pulmonary ventilation. 第八頁，共四十九頁。Respiratory Failure 第一頁，共四十九頁。 1. pulmonary gas exchange is mainly determined by ventilationperfusion(V/Q) ratios and diffuse ability ? V/Q mismatch: An effective lung gas exchange needs not only sufficient lung ventilation and lung blood volumes but also an adequate V/Q ratios. Usually, the volume of ventilation is 4 liters/min. The volume of lung blood is 5 liters/min. So the ratios is 第九頁，共四十九頁。 ? The unbalance of acidalkalose metabolic and dielectric abnormality are usually exist in the course of respiratory failure. ? Table 1. Clinical manifestations of hypoxia and hypercapnia. 第十七頁，共四十九頁。 (2)Antiinfectious therapy ? Repeated bronchial and pulmonary infection is a major cause of chronic respiratory failure. About 90% of COPD patients with respiratory failure is caused by acute bronchial or pulmonary infection. Infection may also increase bronchial secretion and CO2 production. So antiinfectious therapy is an important method to treat respiratory failure. 第二十五頁，共四十九頁。 (8)Nutritional support therapy 第三十三頁，共四十九頁。 The main diagnosis standard includes: ? A factor which may leads to ARDS ? The onset is acute. Tachypnea is exist. ? Hypoxia ? Chest Xray shows pulmonary infiltrate involved two lungs. ? PCWP=18mmHg or except cardiogenic pulmonary edema. 第四十一頁，共四十九頁。 (2)The mon modes of mechanical ventilatory ? Assisted ventilation, AV ? Controlled ventilation, CV ? Assistcontrol ventilation, ACV ? Intermittent mandatory ventilation, IMV ? Synchronized intermittent mandatory ventilation, SIMV ? Pressure support ventilation, PSV or Inspiratory pressure support, IPS ? Mandatory minute ventilation, MMV Continuous positive airway pressure, CPAP/positive endexpiratory pressure, PEEP ? Biphasic positive airway pressure, BiPAP 第四十八頁，共四十九頁。 (1)Artifical airways。 ? Use of PEEP PEEP means positive end expiratory pressure. 第四十三頁，共四十九頁。 ARDS, which is a from of acute lung injury often seen in previously healthy