If someone is having breathing difficulty, call 911 or your local emergency number right away, then:

• Check the person's airway, breathing, and pulse. If necessary, begin CPR
• Loosen any tight clothing
• Help the person use any prescribed medicine (an asthma inhaler or home oxygen)
• Continue to monitor the person's breathing and pulse until medical help arrives. DO NOT assume that the person's condition is improving if you can no longer hear abnormal breath sounds, such as wheezing
• If there are open wounds in the neck or chest, they must be closed immediately, especially if air bubbles appear in the wound. Bandage such wounds at once
• A "sucking" chest wound allows air to enter the person's chest cavity with each breath. This can cause a collapsed lung. Bandage the wound with plastic wrap, a plastic bag, or gauze pads covered with petroleum jelly, sealing it except for one corner. This allows trapped air to escape from the chest, but it prevents air from entering the chest through the wound

DO NOT:

• Give the person food or drink
• Move the person if there has been a head, neck, chest or airway injury, unless it is absolutely necessary. Protect the neck if the person must be moved
• Place a pillow under the person's head. This can close the airway
• Wait to see if the person's condition improves before getting medical help. Get help immediately

Source: https://medlineplus.gov/ency/article/000007.html