Continuamos, contanto que o doador de sangue se hidrate.

Continuamos is the 1st person plural form of continuar in the present indicative: we continue.

Depending on context, Portuguese present tense can sometimes sound like English we continue, we are continuing, or even we’ll continue in a practical sense. But grammatically, it is the present indicative form.

The comma separates the main clause from the conditional clause:

• Continuamos = main idea
• contanto que o doador de sangue se hidrate = condition

So the structure is basically:

• We continue, provided that ...

In Portuguese, it is very common to use a comma before a clause introduced by contanto que.

Contanto que means provided that, as long as, or on condition that.

It introduces a condition that must be met for the main action to happen.

Examples:

• Vou, contanto que você vá também. = I’ll go, provided that you go too.
• Podemos começar, contanto que todos cheguem a tempo. = We can start, as long as everyone arrives on time.

Because contanto que normally requires the subjunctive.

The subjunctive is used here because the hydration of the blood donor is a condition, not a stated fact.

So:

• se hidrate = present subjunctive
• not se hidrata = present indicative

This is very common in Portuguese after expressions like:

• contanto que
• desde que
• a menos que
• para que

The infinitive is hidratar = to hydrate.

Hidrate is the 3rd person singular present subjunctive form.

Conjugation in the present subjunctive:

• eu hidrate
• você/ele/ela hidrate
• nós hidratemos
• vocês/eles/elas hidratem

Since the subject is o doador de sangue (singular), hidrate is the correct form.

Here, se hidratar means to hydrate oneself or simply to stay hydrated.

So se is a reflexive pronoun. It shows that the subject is receiving the action in a reflexive sense:

• o doador de sangue se hidrate = the blood donor hydrates himself/herself

In natural English, we usually would not say hydrate himself/herself every time; we would more naturally say stays hydrated or hydrates properly. But in Portuguese, the reflexive form is very normal.

Literally, it means the donor of blood, but the natural English equivalent is the blood donor.

Breakdown:

• o = the
• doador = donor
• de sangue = of blood

So Portuguese often uses a noun + de + noun structure where English prefers a compound noun:

• doador de sangue = blood donor
• banco de sangue = blood bank

Portuguese uses definite articles more often than English does.

So o doador de sangue can mean:

• the blood donor
• sometimes even a blood donor, depending on context, though literally it is the

In many cases, Portuguese sounds more natural with the article, even where English might leave it out.

Historically, yes, but for a learner it is best to treat contanto que as a fixed expression meaning provided that.

In modern usage, you usually do not analyze contanto separately in everyday speech. Learn the whole chunk:

• contanto que = provided that / as long as

That will help you use it naturally.

Yes. Continuaremos means we will continue, and that version may sound more explicitly future-oriented.

Compare:

• Continuamos... = we continue / we are continuing
• Continuaremos... = we will continue

Both can work, depending on the context and the intended meaning.

Yes. A few common alternatives are:

• Continuamos, desde que o doador de sangue se hidrate.
• Continuamos, desde que ele se hidrate.
• Podemos continuar, contanto que o doador de sangue se hidrate.

These all keep the idea of continuing only if the donor stays hydrated.
The exact choice depends on tone and context, but contanto que is perfectly correct and natural.