If you do a Google Images search for "consent for anesthesia form", you'll see that receiving all the information on the procedure forms part of the text that the patient signs. No need to include it in the title of the form. If the context was different then you might translate it, but not here.

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Note added at 57 mins (2021-02-19 11:38:59 GMT)
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You're welcome! Google Images is a great resource for situations such as these.

I am assuming you mean not "Dichiarazione di avvenuta informazione AND consenso all'anestesia" but "Dichiarazione di avvenuta informazione E consenso all'anestesia", so that "Dichiarazione di" applies not just to "avvenuta informazione" but also to "consenso".

With regard to "avvenuta", here "informazione" does not mean "information" (i.e., "facts"; in Italian this is always conveyed using the plural, "informazionI") but instead "the act of informing" (l'informare), so "avvenuta informazione" means "having been informed" (literally, "the informing having been carried out").

Therefore "avvenuta informazione E consenso" could be translated as "notification and consent", "Dichiarazione di avvenuta informazione e consenso" could be translated as "Notification and consent form", and "Dichiarazione di avvenuta informazione e consenso all'anestesia" could be translated as "Anesthesia notification and consent form".

But if it is not necessary that the informing and the consenting be separated in the translation, then it would be best to use Phil's suggestion, "informed consent", writing something along the lines of "Informed Consent Form for Anesthesia" or "Declaration of Informed Consent Regarding Anesthesia".

Hello this is what I would do.. based on my experience and the link below. I hope this helps. Naomi H.