| BackgroundGastroscopy is the most common and reliable examination method for upper gastrointestinal disease. But most of the patients will feel anxious and nervous before this examination. Moreover, during the procedure, the invasive stimulation easily induces the following complications, such as nausea and vomiting, cough, elevation of blood pressure, tachycardia, etc. Sometimes, the more serious complications will be seen in a few patients, such as angina, myocardial infarction, sudden cardiac arrest, stroke, etc. However, with the development of economy and the improvement of people’s living standard, the patients’ the requirement for the medical quality and the demand for comfortable digestive endoscopy are increasing. Therefore, the sedation and anesthesia of digestive endoscopy become more and more important.The local anesthetic of throat was often used for conventional gastroscopy, such as using lidocaine, tetracaine, benzocaine, etc. Although to a certain extent, the local anesthetic could relieve the discomfort of patients during gastroscopy, some minor complications also would arise, such as nausea and vomiting, cough, sore throat, pharyngeal bleeding, etc. In order to reduce the patient’s anxiety and fear, improve patient’s satisfactory rate, and reduce the injury of inspection during the process, pain-free digestive endoscopic technology arises. In order to regulate its indications, contraindications, preoperative preparation, operation process and postoperative recovery, prevention and cure of complications, the pain-free digestive endoscopy application guide was written by the Chinese Medical Association(CMA) to promote and popularize this technique. The depth of sedation and anesthesia in the implementation of digestive endoscopy is affected by many factors, including the health status of patients, age, education degree, state of anxiety, pain tolerance, drugs, category of endoscopy and proficiency of endoscopic physicians, etc. Therefore, the depth of sedation and anesthesia is different to each individual. According to inhibition degree of consciousness level, the depth of sedation and anesthesia is divided into four levels:mild sedation, moderate sedation, deep calm, general anesthesia. The ideal depth of sedation and anesthesia for endoscopy would be acceptable to patients and enable their cooperation, make both patients and endoscopists satisfied, and not reduce the quality of the examination.Currently, intravenous sedation with propofol is often used to implement simple gastroscopy and biopsy and treatment for its advantages:fast onset, satisfactory controllability, and rapid recovery. Propofol’s sedation and hypnotic effect is closely related to the potentiation of GABA, through a reduction in the rate of GABA-receptor dissociation. It can effectively restrain the throat reflection, which is advantageous for the inspection and avoid the emergence of laryngospasm. Several factors can significantly affect its pharmacokinetic characteristics and clinical sedation anesthesia effect, including the age, weight, gender, dose, infusion speed, accompanied diseases, etc. However, it has obvious inhibitory effects in the cardio-pulmonary function, such as hypoxemia, hypotension, bradycardia and respiratory depression, which are closely related to its dose and injection rate. Cohen et al reported that the combination of propofol with an opioid agonist and benzodiazepine leaded to a reduction in blood pressure of more than 20 mmHg. Ryu JH et al reported that respiratory depression, which was defined as the oxygen saturation (SpO2) of 90% or lower, developed in 30% of patients who accepted propofol sedation combined with remifentanil or fentanyl. Furthermore, up to more than 50% of the patients during intravenous sedation with propofol have local pain at the injection site. In addition, it needs special anesthesiologists to operate and supervise, which restricts its the further promotion in the primary hospital to a certain extent. According to a recent investigation about domestic painless endoscopy, the number of primary hospitals which can carry out painless endoscopy is still low. The lack of anesthesiologists or anesthesia nurses is the main problem at present.When faced with the status quo:an increasing demand of painless digestive endoscopy, the bigger and bigger amount of digestive endoscopy in the outpatient, obvious inhibitory effects of propofol in the cardio-pulmonary function, the lack of anesthesiologists or anesthesia nurses, etc, it is particularly important to look for a kind of appropriate anesthesia method to carry out painless endoscopy, especially in the primary hospital. Conscious sedation by nitrous oxide inhalation is applied to painless digestive endoscopy in recent years, because of its advantages:simple operation, less adverse reaction, no need professional anesthesiologists to operate and supervise, satisfactory sedation effect, relatively cheap price, etc.Nitrous oxide(N2O) is colourless, odorless to sweet smelling, and nonirritating to the tissues. It was discovered in 1793 by the English scientist Joseph Priestley. Sir Humphrey Davy gave it the term "laughing gas" for the first time in 1799. The American dentist Horace Wells first used laughing gas for clinical treatment about tooth in 1844. Nitrous oxide has always been the most widely used inhaled general anesthesia drugs up to now. It is the least potent among the inhalants, with a minimum alveolar concentration (MAC) of 104, which has analgesic, anxiolytic and amnestic properties. This agent is insoluble, effectively transferred into blood, through alveoli in a free gas state, which lead to a rapid onset of effect and fast recovery. Moreover, Nitrous oxide has a high safety rating, having minimal influence on vital functions. Through letting patients inhaling gas mixture with nitrous oxide and oxygen gas, conscious sedation by nitrous oxide inhalation is a safe and effective sedation method to achieve its analgesic, anxiolytic and amnestic effect, which has been applied to painless digestive endoscopy in recent years, such as gastroscopy, colonoscopy, upper gastrointestinal endoscopic ultrasonography, transnasal gastroscopy, etc. Its clinical effect is satisfactory.But at present, there is no unified operation specification of nitrous oxide inhalation in digestive endoscopic applications in China. Furthermore, how to identify its ideal anesthesia effect? What are the important factors to influence its safety and effectiveness? Above problems are worth further discussion. ObjectThis study was conducted to research the induction process of nitrous oxide (N2O) and its characteristics, and compare the safety and effectiveness of conscious sedation by nitrous oxide inhalation to intravenous sedation with propofol for diagnostic upper gastrointestinal(UGI) endoscopy. Meanwhile, this study also explores the factors effecting the efficacy and safety during conscious sedation by nitrous oxide inhalation.Methods400 patients undergoing UGI endoscopy in our hospital from April 2013 to October 2013 were randomly assigned to two groups, to receive N2O inhalation (n=200) or intravenous sedation with propofol (n=200). All these patients including 196 male and 204 female were between 18 and 82 years of age, who met the ASA classification level I or II grade. There were no obvious differences between the two groups, such as the gender, age, body mass index, ASA grade, history of gastroscopy. Seven patients in total from either the N2O group or the propofol group were retracted from the study immediately before or early during the endoscopic procedure because of abrupt high blood pressure (216/99mmHg、192/94mmHg; n=2), food retention in the stomach(n=2), intolerance to introduction of the endoscope (n=1), the failure of the introduction because of the esophageal stricture(n=1), a feeling of excessive tension and fear (n=1).This left 197 subjects in the N2O group and 196 subjects in the propofol group respectively. Written consent was obtained from each patient. The cardiorespiratory functions, onset time, procedure duration, degree of sedation, recovery time, length of hospital stay, complications, satisfaction ratings of doctors or patients, and the number of patients willing to accept the examination again were recorded.ResultsThe average time of ideal sedation for N2O was 3.16±0.65min,and there was no difference between the male and female.(3.16±0.7 min vs 3.16±0.58 min, t=0.006, P>0.05) The average concentration was (43.68±5.05)%,which was higher in male than in female(45.3±4.99)%vs(41.46±4.30)%, t=3.042, P<0.05.Compared to before the endoscopy, the systolic pressures, diastolic pressures, heart rates and oxygen saturation of patients in the propofol group significantly reduced during the procedure (P<0.05),while the same measurements excluding oxygen saturation for those in the N2O group significantly increased (P<0.05). Compared to the propofol group, patients inhaling N2O had significantly shorter recovery and hospital stay time, but a longer onset time and procedure duration(P<0.05). Three complications occurred in some patients of propofol group:hyoxemia, hypotension, bradycardia, while the major complication in the N2O group was nausea. The satisfaction ratings of doctors or patients and the number of patients willing to accept the examination again in N2O group were smaller than those in propofol group (86±3.7 vs 96±2.6,87±2.8 vs 98±1.2, 87%vs99%, P<0.05).ConclusionsBoth conscious sedation by N2O inhalation and intravenous sedation with propofol were effective for diagnostic UGI endoscopy. The safety of the former were superior to the latter, while the satisfaction ratings of doctors or patients in the propofol group were higher. The key to complete the conscious sedation by nitrous oxide inhalation was to accurately identify the ideal sedation of N2O and master the dose titration technique. Paying attention to the night factors had certain guiding significance during operation. |
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