Comparison of Granisetron Versus Midazolam and Thier Combination for Prophylaxis of Postoperative Nausea and Vomiting in Laparoscopic Surgery in Children

Postoperative nausea and vomiting (PONV) is one of the most common complications of general anesthesia in pediatrics. Pediatric rates of nausea and vomiting are approximately double those of adult patients.

The physiology of PONV is complex and not perfectly understood. According to our current model, the brain structures involved in the pathophysiology of vomiting are distributed throughout the medulla oblongata of the brainstem, not centralized in an anatomically defined 'vomiting centre. Such structures include the chemoreceptor trigger zone (CRTZ), located at the caudal end of the fourth ventricle in the area postrema, and the nucleus tractus solitarius (NTS), located in the area postrema and lower pons. The CRTZ receives input from vagal afferents in the gastrointestinal tract, and it can also detect emetogenic toxins, metabolites, and drugs circulating in the blood and cerebrospinal fluid due to its lack of the bloodbrain barrier. Multiple neurotransmitter pathways are implicated in the physiology of nausea and vomiting. Enterochromaffin cells in the gastrointestinal tract release serotonin, and the vagus nerve communicates with the CRTZ via 5-HT3 receptors. The CRTZ communicates with the NTS primarily via dopamine-2 (D2) receptors.

PONV may increase hospital expenditure by prolongation of hospital stay, and management of vomiting related complications such as dehydration, electrolyte disturbances, and pulmonary aspiration. Pediatric laparoscopic surgery is commonly associated with higher incidence of PONV. Mixtures of different classes of antiemetics have been used successfully to decrease the incidence of PONV but there was no agreement on the optimal combination. Granisetron a newer 5-HT3 antagonist has stronger receptor binding and has been found to be more potent and longer acting as antiemetic for preventing postoperative nausea and vomiting following laparoscopic surgery. Midazolam is commonly used as a premedication to relief anxiety. Midazolam given intravenously before the end of surgery was effective in decreasing the incidence of PONV. sub-hypnotic dose of midazolam was suggested that have a role in the management of PONV.