Background Sedative-hypnotics are a group of drugs that cause CNS depression. Benzodiazepines (BZD) barbiturates nonbarbiturate nonbenzodiazepine sedativehypnotics (NBNB) the most commonly used agents
1.Definition It is directly caused by chronic alterations in pulmonary circulation or chronic chest diseases that lead to pulmonary arterial hypertension, right ventricular enlargement, even right heart failure