“…The incidence of nausea and vomiting with morphine, buprenorphine and tramadol (Ultram ® , Johnson & Johnson, PA, USA) is often reported to be high because up to 50% of children may develop emesis [61][62][63][64]. Nausea and vomiting may occur significantly less often with fentanyl and sufentanil (Sufenta ® , Wyeth-Ayerst Laboratories, PA, USA) [38,47,[65][66][67].…”