Bottom line:  There are a number of experimental studies, mostly about use of aromatherapy to relieve pain.  Results from 2 RCTs indicate that aromatherapy is associated with improvement in postoperative pain and nausea.  However, other studies provide conflicting data.

Here are references from a PubMed search of the question concepts:
postoperative patients
aromatherapy
yoga
postoperative complications, postoperative pain

(postoperative care OR postoperative complications OR postoperative pain) AND (aromatherapy OR yoga) Limit: English

Here are references to the randomized trials on aromatherapy