У міру того як лікар змінює дозу, артеріальний тиск пацієнта змінюється.

It is a set expression meaning as, in proportion as, or to the extent that.

So the sentence describes two changes happening in relation to each other:

• У міру того як лікар змінює дозу... = As the doctor changes the dose...
• ...артеріальний тиск пацієнта змінюється. = ...the patient’s blood pressure changes.

This expression is a bit more formal and precise than simply using коли (when).

Because this expression uses the noun міра in a fixed case form:

• dictionary form: міра = measure
• in the phrase у міру: міру is accusative singular

So у міру того як is an idiomatic construction. You should learn it as a whole phrase rather than trying to translate each word literally every time.

This is a very important difference.

• змінює = changes something
• змінюється = changes, is changing, undergoes change

So:

• лікар змінює дозу = the doctor changes the dose
  • the verb is transitive: it takes an object
• артеріальний тиск пацієнта змінюється = the patient’s blood pressure changes
  • the verb is intransitive/reflexive with -ся

In other words:

• the doctor changes something else → дозу
• the blood pressure itself changes → змінюється

The ending -ся often makes a verb reflexive or gives it an intransitive meaning.

Here it does not mean that the blood pressure is literally changing itself in a conscious sense. Instead, it means undergoes change or simply changes.

Compare:

• лікар змінює дозу = the doctor changes the dose
• доза змінюється = the dose changes
• тиск змінюється = the pressure changes

So -ся is helping turn змінювати into the version meaning to change / to vary without a direct object.

Because дозу is the direct object of змінює.

• dictionary form: доза
• accusative singular: дозу

Since лікар змінює means the doctor changes, we need to show what the doctor changes. That thing is the direct object, so доза becomes дозу.

Пацієнта is in the genitive singular because it shows possession or relationship:

• артеріальний тиск = blood pressure
• пацієнта = of the patient

So the whole phrase means:

• артеріальний тиск пацієнта = the patient’s blood pressure

This is a very common Ukrainian pattern:

• книга студента = the student’s book
• кабінет лікаря = the doctor’s office
• артеріальний тиск пацієнта = the patient’s blood pressure

Because the sentence expresses a general relationship or regular process, not just one single event happening right now.

In Ukrainian, the present tense is often used for:

• general truths
• scientific or medical statements
• repeated or typical processes

So this sentence means something like:

• Whenever / as the doctor changes the dose, the patient’s blood pressure changes accordingly.

It sounds natural in Ukrainian for this kind of statement.

Because the sentence focuses on an ongoing process or gradual relationship, not on a single completed result.

• змінювати / змінюватися = imperfective
• змінити / змінитися = perfective

Here, imperfective is the right choice because the idea is:

• the doctor is adjusting the dose
• the blood pressure changes as that happens

This is not about one completed change, but about the process of changing.

Because the first part is a subordinate clause introduced by У міру того як.

Structure:

• У міру того як лікар змінює дозу,
• артеріальний тиск пацієнта змінюється.

In English, we also usually put a comma after an introductory subordinate clause:

• As the doctor changes the dose, the patient’s blood pressure changes.

So the comma works very similarly here.

Yes. Ukrainian word order is flexible, although some orders sound more neutral than others.

The given sentence is neutral and clear:

• У міру того як лікар змінює дозу, артеріальний тиск пацієнта змінюється.

You could also reverse the main and subordinate clauses:

• Артеріальний тиск пацієнта змінюється у міру того, як лікар змінює дозу.

That is also natural.

What usually matters most is:

• the case endings
• the overall clause structure
• the intended emphasis

You may hear по мірі того як, but standard Ukrainian strongly prefers у міру того як.

So for careful, correct Ukrainian, use:

• у міру того як

This is the version you should learn and produce.

Not exactly. Коли usually just means when, while у міру того як emphasizes a gradual proportional relationship.

Compare:

• Коли лікар змінює дозу, артеріальний тиск пацієнта змінюється.
  • When the doctor changes the dose, the patient’s blood pressure changes.
• У міру того як лікар змінює дозу, артеріальний тиск пацієнта змінюється.
  • As / in proportion as the doctor changes the dose, the patient’s blood pressure changes.

The second version better expresses step-by-step correspondence between the two changes.

Grammatically, лікар is a masculine noun.

So in this sentence:

• лікар is masculine in form
• змінює agrees with a third-person singular subject, so the present tense does not show gender

Important point: in the present tense, the verb form змінює does not tell you whether the doctor is male or female. Only the noun form лікар is masculine grammatically.

In real usage, лікар can refer to a doctor regardless of sex, depending on context, although feminine alternatives may also be used in modern Ukrainian in some situations.