You have arrived on the scene of a paramedic who was shot as she approached a residence on a call. The scene has since been secured. Your patient is a 38-year-old woman with one gunshot wound to the left side of the chest at the fifth intercostal space in the midaxillary line. She is pale, cool, and awake but agitated. She is diaphoretic and complaining of pain in her left side and difficulty

breathing. The patient's EMT partner has applied oxygen by nonrebreathing mask and placed an occlusive dressing over the entry wound before your arrival. As you continue your assessment, the patient's level of consciousness decreases. She responds to verbal stimuli. Her airway is clear, her respiratory rate is 38 per minute and shallow, her neck veins are flat, and her breath sounds are absent on the left side. The patient lacks a radial pulse, and the abdomen is non-guarded and non-tender. Which of the following should you do first?

A) Start a large-bore IV of isotonic crystalloid solution.
B) Do a rapid trauma assessment.
C) Assist ventilations with a bag-valve-mask device.
D) Do an immediate needle chest decompression.

C