在急救情况下，及时报警或拨打救援电话是至关重要的。以下是一些用英语表达求救的例子：

1. Call 911/Nine-one-one. （拨打911电话）

2. Call for an ambulance. （打电话叫救护车）

3. Can someone call for help？ （能有人帮忙叫救护车吗？）

4. Please call the police/ambulance. （请报警/叫救护车）

此外，以下是一些涉及急救措施的常用英语对话：

紧急情况：

John: Excuse me, is there a problem？

Bob: Yes, I need help! My wife has fallen down the stairs and she can’t move.

John: OK, stay calm. I’m going to call an ambulance, but in the meantime, tell me where you are and I’ll come over to help.

Bob: We’re at home. The address is 123 Maple Street.

John: Got it. Is your wife conscious？

Bob: Yes, she’s awake but she’s in a lot of pain.

John: Try to keep her calm and comfortable. Don’t move her unless it’s absolutely necessary. The ambulance should arrive soon.

心脏骤停：

Mary: Help! My husband has collapsed and he’s not breathing!

Tom: OK, we need to start CPR right away. Do you know how to do it？

Mary: No, I don’t. Please help me!

Tom: First, we need to make sure the airway is clear.

这些句子和对话涵盖了在紧急情况下可能需要的基本急救措施和沟通内容。希望这些信息对你有所帮助。