***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Because no completely effective antiemetic exists for the prevention of postoperative nausea and vomiting ( PONV ) , we hypothesize that a multimodal approach to management of PONV may reduce both vomiting and the need for rescue antiemetics in high-risk patients . After IRB approval , women undergoing outpatient laparoscopy were r and omized to one of three groups . Group I ( n = 60 ) was managed by using a predefined multimodal clinical care algorithm .  Patients undergoing the same surgical procedure who received a st and ard balanced outpatient anesthetic with ondansetron 4 mg ( Group II , n = 42 ) or placebo ( Group III , n = 37 ) prophylaxis were chosen to establish baseline incidence of nausea and vomiting . None of the Group I patients vomited before discharge , compared with 7 % in Group II ( P = 0.07 ) and 22 % in Group III ( P = 0.0003 ) . However , one patient ( 2 % ) in Group I required treatment for symptoms in the postanesthesia care unit , compared with 24 % in Group II ( P < 0.0001 ) and 41 % in Group III ( P < 0.0001 ) . Time to discharge-ready was significantly shorter in Group I ( 128 , 118–139 min ; mean , 95 % confidence interval ) versus Group II ( 162 , 145–181 min;P = 0.0015 ) and Group III ( 192 , 166–222 min;P = 0.0001 ) . Patient satisfaction with control of PONV was not different between Group I and Group II . Return to normal daily activity and overall satisfaction were not different among groups . Multimodal management result ed in a 98 % complete response rate and a 0 % incidence of vomiting before discharge ; however , this improvement did not result in an increased level of patient satisfaction when compared with routine monotherapy prophylaxis . We conclude that both multimodal management and routine monotherapy antiemetic prophylaxis result ed in an increased level of patient satisfaction than symptomatic treatment in this high-risk population . Implication s Use of a multimodal clinical care algorithm eliminates predischarge vomiting and improves satisfaction in patients undergoing outpatient laparoscopy Preoperative anxiety has been suggested as a predictor of  postoperative nausea and vomiting ( PONV ) , but supporting data are lacking . We quantified the added predictive value of preoperative anxiety to established predictors of PONV in 1389 surgical in patients undergoing various procedures , by using multivariate logistic regression analysis . Investigated predictors were a history of PONV or motion sickness , smoking , sex , age , ethnicity , body mass index , ASA physical status , surgery type , duration of anesthesia , anesthetic technique , and postoperative opioid analgesia .  Anxiety was measured by the Spielberger State-Trait Anxiety Inventory and the Amsterdam Preoperative Anxiety and Information Scale .  The outcome was the occurrence of PONV in the first 24 h after surgery . The area under the receiver operating characteristic curve of a multivariate ( logistic regression ) model including sex , age , smoking , history of PONV or motion sickness , surgery type , and anesthetic technique was 0.72 ( 95 % confidence interval , 0.70–0.74 ) . There was a weak but significant association of anxiety with PONV , but the addition of anxiety to the model did not further increase the area under the receiver operating characteristic curve . Therefore , routine preoperative measurement of anxiety does not seem warranted , provided that the other predictors are already considered Background It is commonly stated that risk factors for postoperative nausea are the same as for vomiting . The authors design ed a prospect i ve study to identify and differentiate the risk factors for postoperative nausea and vomiting in various surgical population s in a clinical audit setting . Methods The study included 671 consecutive surgical in patients , aged 15 yr or more , undergoing various procedures . The study focused on postoperative  nausea visual analog scale scores every 4 h and vomiting episodes within 72 h. Both vomiting and retching were considered as emetic events . Patient- , anesthesia- , and surgery-related variables that were considered to have a possible effect on the proportion of patients experiencing postoperative nausea and /or vomiting were examined . The bivariate Dale model for binary correlated outcomes was used to identify selectively the potential risk factors of postoperative nausea and vomiting . Results Among the 671 patients in the study , 126 ( 19 % ) reported one or more episodes of nausea , and 66 patients ( 10 % ) suffered one or more emetic episodes during the studied period . There was a highly significant association between the two outcomes . Some risk factors were predictive of both nausea and vomiting ( female gender , nonsmoking status , and general anesthesia ) . History of migraine and type of surgery were mainly responsible for nausea but not for vomiting . The predictive effect of risk factors was controlled for postoperative pain and analgesic drugs . Conclusion This study shows that differences exist in risk factors of postoperative nausea and vomiting . These could be explained by differences in the physiopathology of the two symptoms Risk scores to predict the occurrence of postoperative vomiting ( PV ) or nausea and vomiting that were developed for adult patients do not fit for children , because several risk factors are difficult to assess or are usually not applicable in pediatric patients ( e.g. , smoking status ) . Thus , in the present study , we sought to develop and to vali date a simple score to predict PV in children ( POVOC-score ) . Development and validation of the new score was based on data from 4 independent institutions of 1257 children ( aged 0–14 yr ) undergoing various types of surgery under general anesthesia without antiemetic prophylaxis .  Preoperatively , several potential risk factors were recorded . Postoperatively , the occurrence of PV was observed for up to 24 h. The data set was r and omly split into an evaluation set ( n = 657 ) that was analyzed using a forward logistic regression technique and a validation set ( n = 600 ) that was used to confirm the accuracy of prediction by means of the area under a receiver operating characteristic curve . Four independent risk factors for PV were identified in the final analysis : duration of surgery ≥30 min , age ≥3 yr , strabismus surgery , and a positive history of PV in the children or PV/postoperative nausea and vomiting in relatives ( mother , father , or siblings ) . The incidence of PV was 9 % , 10 % , 30 % , 55 % , and 70 % for 0 , 1 , 2 , 3 , and 4 risk factors observed . Using these incidences as cut-off values in the validation data set , the area under the receiver operating characteristic curve was 0.72 ( 95 % confidence interval : 0.68–0.77 ) . Our data suggest that PV can be predicted with an acceptable accuracy using a four-item simplified risk score In this prospect i ve , r and omized , double-blind study , we compared the efficacy and safety of ondansetron and metoclopramide in the treatment of  postoperative nausea and vomiting ( PONV ) . One hundred seventyfive patients with PONV during recovery from anesthesia for gynecological laparoscopy were treated intravenously with either ondansetron 4 mg ( 58 patients ) , metoclopramide 10 mg ( 57 patients ) , or placebo ( 60 patients ) . Early antiemetic efficacy ( abolition of vomiting within 10 min and of nausea within 30 min from the administration of the study drugs with no further vomiting or nausea episodes during the first hour ) was obtained in 54 of 58 patients ( 93.1 % ) in the ondansetron group , in 38 of 57 patients ( 66.7 % ) in the metoclopramide group , and in 21 of 60 patients ( 35 % ) in the placebo group ( P < 0.001 ) . This difference was still significant when controlling for age , body weight , history of motion sickness , previous PONV episodes , duration of anesthesia , and intraoperative fentanyl consumption using a logistic model . Early antiemetic efficacy was inversely related to the amount of fentanyl administered during anesthesia , regardless of treatment . According to the Kaplan-Meier method , the probability of remaining PONV-free for 48 h after a successful treatment was 0.59 ( 95 % confidence interval 0.45 - 0.71 ) in the ondansetron group , 0.45 ( 0.29 - 0.60 ) in the metoclopramide group , and 0.33 ( 0.15 - 0.53 ) in the placebo group ( P = 0.003 ) . In conclusion , ondansetron 4 mg is more effective than metoclopramide 10 mg and placebo in the treatment of established PONV . ( Anesth Analg 1997;85:395 - 9 Supplemental oxygen maintained during and for 2 h after colon resection halves the incidence of nausea and vomiting . Whether supplemental oxygen restricted to the intraoperative period is sufficient remains unknown . Similarly , the relative efficacy of supplemental oxygen and ondansetron is unknown . We tested the hypothesis that intraoperative supplemental oxygen reduces the incidence of postoperative nausea and vomiting .  Patients ( n = 240 ) undergoing gynecological laparoscopy were given a st and ardized isoflurane anesthetic . After induction , they were r and omly assigned to the following three groups : routine oxygen administration with 30 % oxygen , balance nitrogen ( 30 % Oxygen group ) , supplemental oxygen administration with 80 % oxygen , balance nitrogen ( 80 % Oxygen group ) , and Ondansetron 8 mg ( immediately after induction ) , combined with 30 % oxygen , balance nitrogen ( Ondansetron group ) . The overall incidence of nausea and /or vomiting during the initial 24 postoperative h was 44 % in the patients assigned to 30 % oxygen and 30 % in the Ondansetron group , but only 22 % in those given 80 % oxygen . The incidence was thus halved by supplemental oxygen and was significantly less than with 30 % oxygen . There were , however , no significant differences between the 30 % oxygen and ondansetron groups , or between the ondansetron and 80 % oxygen groups . We conclude that supplemental oxygen effectively prevents postoperative nausea and vomiting after gynecological laparoscopic surgery ; furthermore , ondansetron is no more effective than supplemental oxygen . IMPLICATION S Supplemental oxygen reduces the risk of postoperative nausea and vomiting ( PONV ) as well or better than 8 mg of ondansetron . Because oxygen is inexpensive and essentially risk-free , supplemental oxygen is a preferable method of reducing PONV BACKGROUND Untreated , one third of patients who undergo surgery will have postoperative nausea and vomiting . Although many trials have been conducted , the relative benefits of prophylactic antiemetic interventions given alone or in combination remain unknown . METHODS We enrolled 5199 patients at high risk for postoperative nausea and vomiting in a r and omized , controlled trial of factorial design that was powered to evaluate interactions among as many as three antiemetic interventions . Of these patients , 4123 were r and omly assigned to 1 of 64 possible combinations of six prophylactic interventions : 4 mg of ondansetron or no ondansetron ; 4 mg of dexamethasone or no dexamethasone ; 1.25 mg of droperidol or no droperidol ; propofol or a volatile anesthetic ; nitrogen or nitrous oxide ; and remifentanil or fentanyl . The remaining patients were r and omly assigned with respect to the first four interventions . The primary outcome was nausea and vomiting within 24 hours after surgery , which was evaluated blindly . RESULTS Ondansetron , dexamethasone , and droperidol each reduced the risk of postoperative nausea and vomiting by about 26 percent . Propofol reduced the risk by 19 percent , and nitrogen by 12 percent ; the risk reduction with both of these agents ( i.e. , total intravenous anesthesia ) was thus similar to that observed with each of the antiemetics . All the interventions acted independently of one another and independently of the patients ' baseline risk . Consequently , the relative risks associated with the combined interventions could be estimated by multiplying the relative risks associated with each intervention . Absolute risk reduction , though , was a critical function of patients ' baseline risk . CONCLUSIONS Because antiemetic interventions are similarly effective and act independently , the safest or least expensive should be used first . Prophylaxis is rarely warranted in low-risk patients , moderate-risk patients may benefit from a single intervention , and multiple interventions should be reserved for high-risk patients Background Intraoperative hypovolemia is common and is a potential cause of organ dysfunction , increased postoperative morbidity , length of hospital stay , and death . The objective of this prospect i ve , r and omized study was to assess the effect of goal -directed intraoperative fluid administration on length of postoperative hospital stay . Methods One hundred patients who were to undergo major elective surgery with an anticipated blood loss greater than 500 ml were r and omly assigned to a control group ( n = 50 ) that received st and ard intraoperative care or to a protocol group ( n = 50 ) that , in addition , received intraoperative plasma volume expansion guided by the esophageal Doppler 
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Modern PONV risk research began in the 1990s with publication of studies using logistic regression analysis to simultaneously identify multiple independent PONV predictors and publication of meta-analyses and systematic review s. This literature shows that female gender post-puberty , nonsmoking status , history of PONV or motion sickness , childhood after infancy and younger adulthood , increasing duration of surgery , and use of volatile anesthetics , nitrous oxide , large-dose neostigmine , or intraoperative or postoperative opioids are well established PONV risk factors .
Possible risk factors include history of migraine , history of PONV or motion sickness in a child 's parent or sibling , better ASA physical status , intense preoperative anxiety , certain ethnicities or surgery types , decreased perioperative fluids , crystalloid versus colloid administration , increasing duration of anesthesia , general versus regional anesthesia or sedation , balanced versus total IV anesthesia , and use of longer-acting versus shorter-acting opioids .
Early-phase menstruation , obesity and lack of supplemental oxygen are disproved risk factors .
Current risk scoring systems have approximately 55%-80 % accuracy in predicting which patient groups will suffer PONV .