IELTS for a caregiver? If you are applying under the skilled worker program, that is the topic you have posted under, then IELTS is necessary. Applications without one are seen as incomplete and returned to you. As a registered nurse, you are in one of the 29 most wanted occupations although your CAP is filled. If you have work experience that matches practical nurse, you can apply under there.
For a caregiver, IELTS is not mandatory. If you look at the local instructions for caregiver, Philippines at http://www.canadainternational.gc.ca/philippines/visas/working-travailler.aspx?lang=eng#n5 you will see that IELTS is recommended but not mandatory.