conditionally create a new column in data frame in R (equivalent of if then statement in SAS)

I've a dataframe where I want to add a new column(newcol) based on the conditionally applying on the others columns(parameter,value). The code has to be written in a way that "if value is not missing then if parameter= "SYSBP" and value >140 and if parameter= "DIABP" and value <80 then newcol="Y". There is no value for else condition, it has to remain blank.

A glimpse of dataset

PATIENT parameter value
001     SYSBP     190
001     DIABP     78
001     SYSBP     180
001     DIABP     72
002     SYSBP     NA
002     DIABP     NA
002     SYSBP     180
002     DIABP     72

As a SAS programmer, I'm looking for an equivalent to if then statement and I found ifelse() to be the closest one in R, if someone knows a better match for the if then match, then kindly help me know.