Kad teško dišem, koristim inhalator i odmah sjednem kraj prozora.

Here kad means when.

In this sentence, Kad teško dišem... means When I breathe with difficulty... or When I have trouble breathing...

Croatian kad is very common and can introduce:

• a specific time: Kad dolaziš? = When are you coming?
• a repeated situation: Kad sam umoran, rano spavam. = When I’m tired, I sleep early.

In some contexts, kad can sound a bit like if, especially in everyday speech, but here the meaning is clearly when/whenever.

Teško is an adverb here, and it means with difficulty, hard, or heavily, depending on context.

So:

• dišem = I breathe
• teško dišem = I breathe with difficulty / I’m breathing heavily

It does not mean that breathing itself is emotionally difficult; it refers to the physical act of breathing being difficult.

Compare:

• teško radim = I work hard
• teško hodam = I walk with difficulty
• teško dišem = I breathe with difficulty

Because Croatian usually drops subject pronouns when they are not needed.

The verb endings already show who the subject is:

• dišem = I breathe
• koristim = I use
• sjednem = I sit down

So ja is unnecessary here.

You could say Kad ja teško dišem..., but that would add emphasis, something like:

• When I have trouble breathing...

Normally, Croatian prefers to leave ja out.

Dišem is the 1st person singular present tense of disati = to breathe.

So:

• ja dišem = I breathe / I am breathing

Croatian present tense can translate into English in different ways depending on context:

• I breathe
• I am breathing
• I do breathe

In this sentence, it expresses a repeated or typical situation:

• When I have trouble breathing...

Inhalator is the direct object of koristim (I use), so it is in the accusative case.

However, inhalator is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular looks the same as the nominative singular.

So:

• nominative: inhalator
• accusative: inhalator

That is why you do not see a change.

Examples:

• Imam stol. = I have a table.
• Koristim inhalator. = I use an inhaler.

Both stol and inhalator stay the same in the accusative because they are masculine inanimate nouns.

Because koristiti is a very natural verb for using a device or tool.

• koristim inhalator = I use an inhaler

If you said uzimam inhalator, that would mean more literally:

• I take the inhaler

That focuses more on physically taking it in your hand or taking medicine, not necessarily on using it as intended.

So in this sentence:

• koristim inhalator is the best choice if the idea is I use my inhaler

Odmah means immediately or right away.

So:

• i odmah sjednem = and I immediately sit down

Its position before the verb gives a very natural emphasis to the immediacy of the action.

You could also hear:

• i sjednem odmah

That is also possible, but odmah sjednem sounds very smooth and common here.

This is an important difference.

• sjesti / sjednem = to sit down
  → focuses on the action of moving into a sitting position
• sjediti / sjedim = to be sitting
  → focuses on the state of already sitting

So:

• odmah sjednem kraj prozora = I immediately sit down by the window
• odmah sjedim kraj prozora would mean I am immediately sitting by the window, which sounds unnatural here

The sentence describes an action taken in response to breathing difficulty, so sjednem is the right choice.

Croatian aspect and tense do not always match English exactly.

Sjesti is a perfective verb, and sjednem is its present-tense form. Perfective present usually does not describe an ongoing action like English present continuous. Instead, it often refers to:

• a completed action in the future, or
• a repeated action in a typical sequence

Here the sentence describes a habitual reaction:

• When I have trouble breathing, I use an inhaler and immediately sit down by the window.

So sjednem works well because it means the action is completed each time:
I sit down rather than I am sitting.

This is very natural in Croatian.

Kraj prozora means by the window, next to the window, or near the window.

• kraj = beside / near / by
• prozora = of the window / genitive form of prozor

So literally, kraj prozora is something like:

• at the side of the window

In natural English, though, you would simply say:

• by the window
• next to the window

Because the preposition kraj requires the genitive case.

The base noun is:

• prozor = window

But after kraj, it changes to genitive singular:

• kraj prozora = by the window

This is something you simply have to learn with the preposition:

• kraj kuće = by the house
• kraj vrata = by the door
• kraj prozora = by the window

So the important point is:

• kraj + genitive

Yes, but the nuance is a little different.

• kraj prozora = by/next to the window
• pokraj prozora = also beside/next to the window, very similar
• uz prozor = up against / right by the window

In many everyday situations, kraj prozora and pokraj prozora are very close in meaning.

Uz prozor can sound a bit more physically adjacent, as if right next to it.

So in this sentence, kraj prozora is a very natural choice.

It most naturally describes a habitual or typical action.

• Kad teško dišem, koristim inhalator i odmah sjednem kraj prozora.

This means something like:

• When I have trouble breathing, I use an inhaler and immediately sit down by the window.

So it is not mainly about one single event happening at this moment. It describes what the speaker عادة/typically does in that situation.

Croatian present tense is often used for habits and general routines, just like English present simple.

Yes, Croatian word order is fairly flexible, although some versions sound more natural than others.

The original:

• Kad teško dišem, koristim inhalator i odmah sjednem kraj prozora.

Possible variations:

• Kad teško dišem, odmah koristim inhalator i sjednem kraj prozora.
• Kad teško dišem, koristim inhalator i sjednem odmah kraj prozora.
• Kada teško dišem, koristim inhalator i odmah sjednem kraj prozora.

The original version sounds natural and balanced.
Placing odmah before sjednem emphasizes that sitting down happens right away.

They mean the same thing here: when.

• kad = shorter, very common in everyday speech
• kada = slightly fuller form, sometimes a bit more formal or careful

So both are correct:

• Kad teško dišem...
• Kada teško dišem...

In normal conversation, kad is extremely common.

They would understand it as a natural sequence of actions:

1. Kad teško dišem = When I have trouble breathing
2. koristim inhalator = I use an inhaler
3. i odmah sjednem kraj prozora = and immediately sit down by the window

So the sentence presents a routine response to breathing difficulty:

• first the condition,
• then the reaction,
• then the immediate follow-up action.

That structure is very common and natural in Croatian.