The benefits of comfort and painlessness of painless digestive endoscopy is favored by more and more patients. Compared with general anesthesia with tracheal intubation, the anesthesia for painless gastrointestinal endoscopy is relatively simpler, easier to operate, but the quality of anesthesia recovery for painless gastroscopy is not always ideal because of the fast pace, the huge rising numbers and the relative shortage of anesthesiologists in China. Patients may experience nausea and vomiting and other complications after the examination which decreases patients’ satisfaction. So, how to improve this condition is our study’s aim.
In this study, we found that the incidence of nausea or vomiting after the painless digestive endoscopy is 4.3%. Among them,4.2% patients had nausea with or without vomiting and 2.9% patients had vomiting with or without nausea. The incidence of nausea or vomiting in our study is relatively lower than other similarly endoscopic studies [4, 5]. It is obviously that the incidence of nausea is higher than the incidence of vomiting after this painless inspection. The difference incidence may be caused by different mechanisms of nausea and vomiting and vomiting often causing more harm to patients than nausea.
We also found nausea and vomiting after painless digestive endoscopy mostly occurred early after the examination within 4~6h, and rarely more than 12h after the examination. The incidence of nausea and vomiting is highest within 2 hours after the examination (42.1%).
There are many influencing factors, such as patient factors (age, gender, history of motion sickness, smoking history, and individual differences), anesthetic factors (anesthetic modality and drugs), and surgical factors (surgical site, modality, and time) [6]. For general anesthesia with tracheal intubation, women, history of previous chemotherapy, and higher education are important risk factors for postoperative nausea and vomiting [7]. Similarly, this study found that female is one of the independent risk factors of nausea and vomiting after painless digestive endoscopy, with the risk of nausea and vomiting approaching 3 times than that of male. The mechanisms may be related to hormones and emotions [8]. Another study also show that women are more prone to nausea and vomiting after laparoscopic cholecystectomy under general anesthesia relative to men, and the risk of nausea and vomiting is approximately 2~3 times higher in women than in men [9]. Other risk factors such as history of motion sickness and history of smoking which may be correlated with nausea and vomiting did not play a significant role in our study.
In the present study, remarkably, there was a strong association of diazoxide dose over 2.5mg with painless gastroenteroscopic nausea and vomiting (OR=2.074). Even though diazoxide with propofol is safe and effective for painless colonoscopy with low respiratory depression and better analgesic effect [10], diazoxide has some side effect. One of the common side effects is nausea and vomiting. Opioids cause the occurrence of nausea and vomiting through multiple pathways including central and peripheral effects [11]. Increasing the dose of opioids leads to an increased risk of postoperative nausea and dizziness. But it's not as if the lower the dose of diazoxide, the better. It was showed that there was no statistical difference in the incidence of nausea and vomiting after the examination between small doses of diazoxide (20ug/kg) combined with propofol for painless gastroscopy compared with propofol alone [12]. In future studies, the effects of propofol compounded with different doses of diazoxide or opioid-sparing analgesics on the incidence of nausea and vomiting after the painless digestive endoscopy worth to be investigated.
In this study, weight <60 kg was found to be one of the independent risk factors for nausea and vomiting in painless gastroenterology. Due to the mean weight of all patients in this study was 63.05±11.29 years, we take 60 kg as the basis for classification in this study, which showed that the risk of nausea and vomiting was 0.381 times higher in patients weight <60kg than in those weight ≥60 kg. The reason for this is presumed to be the fact that low body weight may increase the difficulty of colonoscopy and the lighter weight is generally associated with female patients who are prone to have nausea vomiting. This was in accordance with the results of Poon’s study [13] which showed body weight (OR 0.98) was one of the independent predictors for postoperative vomiting under trauma surgery and the risk of postoperative vomiting decreases when body weight increases.
In conclusion, female, weight less than 60kg, diazoxide dose exceeding 2.5 mg are the main risk factors of painless digestive endoscopy. To reduce the incidence of nausea and vomiting after painless digestive endoscopy, this study suggests using no more than 2.5 mg of diazoxide when performing painless gastrointestinal endoscopy especially for female patients weighing less than 60kg.