下列哪项是区分急性呼吸衰竭和慢性呼吸衰竭的依据（） ["有无发绀","有无CO2潴留","动脉血氧分压下降的程度","呼吸困难程度","起病缓急"]
慢性呼吸衰竭的最常见病因是（） ["COPD","严重肺结核","SAS","支气管哮喘","肺血管病变"]
关于急性型特发性血小板减少性紫癜，正确的是（） ["青年女性常见","病前1～3周常有服药史","出血往往较轻","病程有自限性","常见脑出血死亡"]
特发性血小板减少性紫癜的首选治疗是（） ["输新鲜血液","糖皮质激素","雄激素","免疫抑制剂","脾切除术"]
慢性肺源性心脏病急性加重期患者应慎用（） ["镇静药","祛痰药","解痉平喘药","呼吸兴奋药","抗感染药物"]
简述骨髓穿刺术
