Learn Farsi: طی بحران، دکترها بیماران را نیز معاینه کردند. - During the crisis, the doctors also examined the patients.

The adverb نیز (also / as well) usually comes immediately after the word or phrase it modifies. By placing it after بیماران را (the patients), it emphasizes that the patients were also examined (perhaps in addition to doing other tasks or seeing other groups). If it were placed after دکترها, it would mean the doctors also did it (along with the nurses, for example).

Could I just use هم instead of نیز here?

Grammatically yes, but نیز is the formal, written equivalent of هم. Because this sentence uses formal vocabulary like طی (during) and the formal plural بیماران (patients), نیز fits the official register perfectly. You will see نیز constantly in news, literature, and formal reports.

Is طی used the same way as در طول for saying "during"?

Yes, طی (tey) and در طول (dar toul-e) both mean "during" or "throughout." However, طی is slightly more formal and is heavily used in journalism or official contexts. Just like other prepositions of time, it requires an ezafe to connect to the noun: طیِ بحران (tey-e bohran).

Why does the word for patients use the ان plural suffix instead of ها?