診察をご希望ですか?（Shin-satsu wo go-kibou desuka?）

You can safely say “医者をご希望ですか（isha wo go-kibou desuka? =Do you need a doctor?）” even.

While the term “medical attention” literally implies “治療 (chiryou)” or ”診療（shinryou）” rather than “診察（＝medical examination）,” the above translation sounds natural in the given situation, for it’s up to a doctor, not the guest, to decide whether he/she needs 治療 or 診療.

There are few ways to say this.
I assume you write it on something to draw your Japanese guests' attention that you are ready to handle certain situation that calls for medical attention, since no one speaks the language.
Then on writing it should be brief and precise, yet conveys the fact that you have a contact to medical facility (or in-house doctor?).

As you see this answer does not have a question mark at the end, so it is not addressed in ? form. What it says is, literally:
"If your physical condition is demanding (i.e. due to fatigue or other illness or injured), please don't hesitate to let us know."

If you prefer question format, then:
お医者さまに見ていただきますか？(Would you like to see a doctor?)
Although this is kind an abrupt as a sign in writing.
I recommend the titled expression.

Good luck!

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Note added at 8 hrs 20 mins (2005-02-20 15:46:03 GMT)
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The character garbled.
I don¥'t think I can solve this through this mode.
So this is an alternate yet same message ........

体調の悪い方は遠慮なくお知らせください。

iryou saabisu wo gokibou desuka?
(Rather polite way of addressing to your costomers by the phrase "Do you need a medical service?")

I suppose it should depend on how far the term "meical attention" could include as its serｖice to the guests to decide right ways of translating the phrase. Probably that ranges from a simple medical advice or care such as bandage or a couple of meicines to some possible more serious cases in need of consultation to a doctor. For that reason, I try replacing "medical attention" with "medical service" to connote it with a broader range of medical assistances. In consideration to how and where you would use the phrase, I would assume you may address to your guests to make an inquiry about their need for a medical service in general, if it is, I mean, of course. For that, I guess we would need your advice.

Just an attempt. Hope helps you in some way.

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Note added at 19 hrs 54 mins (2005-02-21 03:20:47 GMT)
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meical → medical
meicines → medicines

Not a direct translation, but, in the given situation above, I would say, 病院に行かれますか。／お医者さんに診てもらいますか。
Just a thought.