【正文】 ? progressive patient fatigue despite appropriate treatment. ? Adjust modes and settings for mechanical ventilation according to blood gas analysis and clinical judgment 66 Treatment Management of electrolyte and acidbase disturbance ? Respiratory acidosis ? improve alveolar ventilation ? Respiratory acidosis + metabolic acidosis ? Etiology management of acidosis ? improve alveolar ventilation ? appropriate alkali supplement ? Respiratory acidosis + metabolic alkalosis ? Avoid Iatrogenic factors 67 。 ? acute hypercapnia that is not quickly reversed by appropriate specific therapy。 impaired airway protection。 ? Decrease work of breathing, reverse respiratory muscle fatigue. ? Indications for mechanical ventilation : ? apnea。 60 Venturi mask Venturi面罩 ? Venturi面罩可較精確地調(diào)整 FiO2，但面罩必須佩戴正確才能使預(yù)期的氧量得到輸送 61 Treatment Oxygen therapy Side effects ? Inhibition of respiratory center in patients with type Ⅱ respiratory failure, who are dependent on hypoxic drive for ventilation ? CO2 retention ↑ ? Absorption atelectasis/denitrogenisation 吸收性肺不張 ): nitrogen is replaced by more absorptive oxygen ? Oxygen poisoning : High concentrations of inspired oxygen ?injury of pulmonary capillary epithelium 62 Treatment Ensure adequate ventilation, correct CO2 retention Respiratory stimulant: mainly used in CNS depression ? Principles for respiratory stimulant (呼吸興奮劑 ) : ? Maintain potency of airway to avoid respiratory muscles fatigue and deteriorate CO2 retention ? Be cautious when used in patients with frequent convulsion caused by cerebral anoxia, cerebral edema ? Suitable for patients with normal respiratory muscle strength ? Not suitable for patients only with oxygenation failure ? Avoid sudden withdrawal ? Drug: coramine, lobeline, doxapram 63 Treatment Noninvasive positive pressure ventilation, NIPPV ? Indications ? Conscious and cooperative ? Stable circulation ? Be able to protect airway ? No facial trauma, injury and deformity ? Be endurable to mask 64 Different kind of masks 各款口鼻面罩 65 Treatment Mechanical ventilation ? Goals of Mechanical Ventilation: ? improve alveolar ventilation, decrease PaCO2。因?yàn)殡S呼吸頻率、每分鐘通氣量、室內(nèi)空氣的流動、輸氧裝置的放置等因素的不同而改變。 less irritative to nasopharyngeal mucosa ? Disadvantage: inconvenient for patients to expectorate, eat and drink Treatment Oxygen therapy 58 Nasal cannula/prongs 鼻導(dǎo)管吸氧 ? 鼻導(dǎo)管給氧的上限量為 6L/min，大于這一流量時，由于管道和鼻咽內(nèi)產(chǎn)生渦流，吸氧濃度不再增加。 high flow rates irritate nasopharyngeal mucosa ? Guide: Delivers 4% Oxygen per liter flow。 laboratory Diagnosis 37 Diagnostic criteria The acute respiratory distress syndrome (ARDS) ARDS is a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies: ? Progressive dyspnea and hypoxia which can not be relieved by oxygen therapy ? Bilateral infiltrates on chest radiograph ? PaO2/FiO2 200 ? Excluding patients with signs of heart failure or a pulmonary capillary wedge pressure (PCWP) 18 mmHg 38 Treatment (outline of principle) ? Etiology Management ? Keep airway open ? Oxygen therapy ? Ensure adequate alveolar ventilation, correct CO2 retention ? Respiratory stimulant ? Mechanical Ventilation ? General supportive care ? Transfer to ICU for critical care and treatment ? Infection control ? Management of electrolyte and acidbase disturbance ? Management of cor pulmonale, pulmonary encephalopathy, multian dysfunction syndrome(MODS). ? Nutrition support 39 Treatment Etiology Management ? Management of any underlying diseases : upper airway obstruction, severe pneumothorax, massive pleural effusions ? Eliminate any factors that cause respiratory failure secondary to infection or shock ? Any inducement leading to acute deterioration of chronic respiratory failure： infection, malnutrition, inappropriate medication usage 40 Causes of Upper Airway Obstruction ? CNS depressionanesthesia, drug overdose ? Cardiac arrest ? Loss of consciousness ? Foreign body or tumor 41 Treatment Keep airway open 保持氣道通暢 Importance of airway open : ? Airway obstruction: resistance ↑ → WOB↑