Why would you place a OGT and give zofran in the middle of a surgery?

Assuming that the patient hadn't eaten anything 8-12 hours prior to surgery, its easier to place the OGT when the patient is intubated and sedated.

I'm just a regular RN, but I know that at least one of our anesthesiologists routinely gives Zofran. '

Don't know about the OGT during OR, but I will say that anybody we intubate in critical care gets an NGT or OGT to ILWS. We start feeds the next day if they aren't getting extubated.

Pretty much any abdominal case gets an OGT to decompress the stomach during surgery (less chance it will get in the way during surgery that way). Also, patients with GERD, Diabetes, trauma, hx of PONV or any of several other things that could put them at increased risk for aspiration we will often place an OGT for surgery.
Zofran takes about 30min to have a peak effect and lasts up to 12hrs. Some providers give it for every case, and some anesthesia providers only give when it is indicated. When is the best time to give Zofran is debatable.