A client arrives at the emergency department reporting sever…

A client arrives at the emergency department reporting severe epigastric pain and dizziness. The client has a history of a diagnosed gastric ulcer and states, “I feel very weak and nauseated.” The nurse notes that the client appears pale and diaphoretic. The client reports passing black, tarry stools earlier in the day and begins vomiting material that looks like coffee grounds. Vital signs are as follows:BP: 86/54 mmHgHR: 122 beats/minRR: 24 breaths/minSpO₂: 95% on room air The client becomes increasingly lightheaded when sitting up. Which action should the nurse take first?