Easily email or text everyone in a practitioner's diary on a particular day

Can you add a filter in connect that would allow us to text or email all the patients in a particular practitioner's diary and on a specific date? This is mainly needed when the practitioner can't get to clinic at short notice through illness etc. Currently we have to send a manual SMS one by one to each patient, which on a busy day can take a long time and could be easily automated :)