Postoperative nausea and vomiting (PONV) remains a common adverse event after surgery and
anaesthesia causing much dissatisfaction among patients. PONV incidence is reported at
30% in all surgical patients and up to 80% in high-risk patients. Idiopathic scoliosis is
a common form of structural spinal deformities with a Cobb angle of >/ 10 degrees. It
affects young females in the early pubertal stage more than young men by 1% and 4%.
Posterior spinal fusion (PSF) surgery is commonly performed in patients with severe
scoliosis. It is a long complex surgery inflicting extensive surgical field requiring
opioids as the mainstay of analgesia during the perioperative period. These targeted
population are particularly adolescent female requiring intraoperative and postoperative
opioids who are at high risk of developing PONV.
Dexamethasone and anti-serotonergic drugs like granisetron are commonly used antiemetics
due to their efficacy and safety profiles. Dexamethasone is particularly favoured for its
long duration of action and pain-reducing effects.
Palonosetron, a second-generation anti-serotonergic drug, has a unique pharmacokinetic
profile with a prolonged duration of action. It may be more beneficial for patients on
prolonged opioid-based analgesic regimens. However, its higher cost and inconsistent
study findings limit its widespread use, especially in scoliosis patients undergoing
spinal fusion surgery.
Total intravenous anaesthesia (TIVA) is recommended for high-risk PONV patients, as it
reduces the emetogenic effect of volatile anaesthetics. Propofol, used in TIVA, is itself
an effective antiemetic. TIVA with propofol has been shown to be as effective as giving a
single antiemetic and can further reduce the risk of PONV when combined with other
prophylactic antiemetics.
The standard practice for managing PONV involves the administration of two antiemetics
and considering TIVA for high-risk patients. This study aims to compare the effectiveness
of palonosetron and ondansetron when administered alongside dexamethasone in scoliosis
patients undergoing spinal fusion under TIVA. The study will also evaluate the number of
rescue antiemetics needed, assess adverse effects, and measure patient satisfaction.
The study will be randomized and double-blinded, to be conducted in University Malaya
Medical Centre (UMMC). The sample size is calculated to be 92 participants, after taking
into account a 20% dropout rate. Adult and adolescent idiopathic scoliosis patients
undergoing PSF surgery will be eligible for the study. Written informed consent will be
obtained from participants or their guardians, and assent will be obtained from
adolescent participants. Patients will be randomized to receive either palonosetron or
ondansetron along with dexamethasone.
The study will follow standard anaesthetic techniques, including TIVA with remifentanil
and propofol. Intravenous injections of the study drugs or placebo will be given during
surgery, and dexamethasone will be administered as a baseline antiemetic. Morphine will
be administered before the end of surgery for pain management.