careful, close, systematic
frequent, periodic, regular
long-term, ongoing
constant, continuous
routine
The problem was discovered during routine monitoring.

independent
environmental
cardiac, foetal/fetal
electronic
Many employers are resorting to electronic monitoring of their workforce.

remote

need, require
It is a problem that requires constant monitoring.

agency, body, committee, group, network, organization, team, unit
a UN monitoring team

device, equipment
procedure, process, system
programme/program
visit

Monitoring is used with these nouns:
device, system