Previous history of nausea and vomiting induced by prior chemotherapy still not included as predictive factor of postoperative nausea and vomiting, although has been demonstrated that has influence in postoperative outcome.

The project aims to evaluate the efficacy of a simplified algorithm in prevention postoperative nausea and vomiting , with pacients with previous history of nausea and vomiting induced by prior chemotherapy, submitted to medium or large surgery.

Quasi-experimental study, with evaluation after the application of a specific postoperative nausea and vomiting prevention algorithm for cancer patients.

The study will be carried out in 2 phases:

Phase 1: Team training. In this phase, a protocol was established for PONV prophylaxis, using two questions:

1. Patient undergoing chemotherapy before surgery;
2. Patient presented chemotherapy induced nausea and vomiting (CINV).

If the answer is yes to both questions, the anesthetist administers 3 antiemetics (4mg dexametasone, 4mg ondansetron and 0,625mg droperidol). If the answer is no to one of the questions, the anesthetist administers 2 antiemetics (4mg dexametasone and 4mg ondansetron); In this phase, educational measures will be implemented by team meetings and individual approach of all anesthesiologists at ICESP to present the study project and the algorithm. A summary of the the study will be sent daily through the social network Whats App®.

The number of patients was calculated taking into account adherence to the new prophylaxis protocol for post-operative nausea and vomiting. If we consider an alpha error of 5% and test power of 80%, to have a NVPO reduction of 41% (current overall incidence) to 25% (incidence after protocol adherence) in high-risk patients, we need to study 270 patients (135 each group adherence and non-adherence to the protocol).

Phase 2: Post-training assessment. In the second phase of the study, after the end of the dissemination of the protocol among doctors, the patients will be evaluated on the first postoperative day. The following variables were analyzed: sex, race, age, body mass index, general state of American Society of Anesthesiologist, Apfel scale, type of surgery and anesthesia, use and type of opioids, history of chemotherapy induced nausea and vomiting, type of antiemetics used in the operating room and in the first postoperative day, duration of anesthesia and surgery and nausea and vomiting in 6 and 24 hours after surgery.

Inclusion Criteria:

• All patients who underwent medium to large surgery

Exclusion Criteria:

• Patients who are unable to communicate (orotracheal intubation after the surgery, confusion or agitation) or understand the Portuguese language;
• Insulin dependent patients
• Patients who underwent emergency surgery and neurosurgery
• Pacients who had an increased QT interval on the electrocardiogram
• History of allergy to dexametasone, ondansetron or droperidol
• Refusal to participate

The patient didn't know if he received the third anti emetic