Local and Intra-articular Administration of Nonsteroidal Anti-inflammatory Drugs for Pain Management in Orthopedic Surgery.

BACKGROUND: Although growing evidence demonstrates the benefits of locally administered nonsteroidal anti-inflammatory drugs (NSAIDs) for postoperative pain management, there is ongoing debate regarding NSAID use in orthopedic surgery. AREAS OF UNCERTAINTY: Current data largely support a local site of NSAID action and suggest that effective pain control can be achieved with delivery of NSAIDs intra-articularly (IA) and/or locally at the site of injury, where they can block peripheral production of inflammatory mediators and may desensitize nociceptors. Improvements in postoperative pain control with locally administered NSAIDs have been widely reported in the total joint arthroplasty literature and may offer benefits in patient's undergoing arthroscopic procedures and those with osteoarthritis as well. The purpose of this review is to examine the available evidence in the literature regarding the efficacy and safety profile of the use of local and IA NSAIDs in orthopedic surgery. DATA SOURCES: Narrative literature review using keywords, expert opinion, either during or from live conference. THERAPEUTIC ADVANCES: Local and IA administration of NSAIDs for pain management in orthopedic surgery. CONCLUSION: There is convincing evidence that NSAIDs administered locally in and around the joint reduce postoperative pain scores and opioid consumption in patients undergoing total joint arthroplasty, yet further research is required regarding the risks of potential chondrotoxicity and the inhibition of bone and soft-tissue healing with locally administered NSAIDs.

Perioperative bleeding and non-steroidal anti-inflammatory drugs: An evidence-based literature review, and current clinical appraisal.

Patient satisfaction measures and the opioid epidemic have highlighted the need for effective perioperative pain management. Multimodal analgesia, including non-steroidal anti-inflammatory drugs (NSAIDs), have been shown to maximize pain relief and reduce opioid consumption, but are also associated with potential perioperative bleeding risks.A multidisciplinary panel conducted a clinical appraisal of bleeding risks associated with perioperative NSAID use. The appraisal consisted of review and assessment of the current published evidence related to the statement "In procedures with high bleeding risk, NSAIDs should always be avoided perioperatively." We report the presented literature and proceedings of the subsequent panel discussion and national pilot survey results. The authors' assessment of the statement based on current evidence was compared to the attempted national survey data, which revealed a wide range of opinions reflecting the ongoing debate around this issue in a small number of respondents.The appraisal concluded that caution is warranted with respect to perioperative use of NSAIDs. However, summarily excluding NSAIDs from perioperative use based on potential bleeding risks would be imprudent. It is recommended that NSAID use be guided by known patient- and procedure-specific factors to minimize bleeding risks while providing effective pain relief.

Fourth Consensus Guidelines for the Management of Postoperative Nausea and Vomiting.

This consensus statement presents a comprehensive and evidence-based set of guidelines for the care of postoperative nausea and vomiting (PONV) in both adult and pediatric populations. The guidelines are established by an international panel of experts under the auspices of the American Society of Enhanced Recovery and Society for Ambulatory Anesthesia based on a comprehensive search and review of literature up to September 2019. The guidelines provide recommendation on identifying high-risk patients, managing baseline PONV risks, choices for prophylaxis, and rescue treatment of PONV as well as recommendations for the institutional implementation of a PONV protocol. In addition, the current guidelines focus on the evidence for newer drugs (eg, second-generation 5-hydroxytryptamine 3 [5-HT3] receptor antagonists, neurokinin 1 (NK1) receptor antagonists, and dopamine antagonists), discussion regarding the use of general multimodal PONV prophylaxis, and PONV management as part of enhanced recovery pathways. This set of guidelines have been endorsed by 23 professional societies and organizations from different disciplines (Appendix 1).Guidelines currently available include the 3 iterations of the consensus guideline we previously published, which was last updated 6 years ago; a guideline published by American Society of Health System Pharmacists in 1999; a brief discussion on PONV management as part of a comprehensive postoperative care guidelines; focused guidelines published by the Society of Obstetricians and Gynecologists of Canada, the Association of Paediatric Anaesthetists of Great Britain & Ireland and the Association of Perianesthesia Nursing; and several guidelines published in other languages.The current guideline was developed to provide perioperative practitioners with a comprehensive and up-to-date, evidence-based guidance on the risk stratification, prevention, and treatment of PONV in both adults and children. The guideline also provides guidance on the management of PONV within enhanced recovery pathways.The previous consensus guideline was published 6 years ago with a literature search updated to October 2011. Several guidelines, which have been published since, are either limited to a specific populations or do not address all aspects of PONV management. The current guideline was developed based on a systematic review of the literature published up through September 2019. This includes recent studies of newer pharmacological agents such as the second-generation 5-hydroxytryptamine 3 (5-HT3) receptor antagonists, a dopamine antagonist, neurokinin 1 (NK1) receptor antagonists as well as several novel combination therapies. In addition, it also contains an evidence-based discussion on the management of PONV in enhanced recovery pathways. We have also discussed the implementation of a general multimodal PONV prophylaxis in all at-risk surgical patients based on the consensus of the expert panel.

Current Perspective on the Use of Opioids in Perioperative Medicine: An Evidence-Based Literature Review, National Survey of 70,000 Physicians, and Multidisciplinary Clinical Appraisal.

Objective: Opioids represent an important analgesic option for physicians managing acute pain in surgical patients. Opioid management is not without its drawbacks, however, and current trends suggest that opioids might be overused in the United States. An expert panel was convened to conduct a clinical appraisal regarding the use of opioids in the perioperative setting. Methods: The clinical appraisal consisted of the review, presentation, and assessment of current published evidence as it relates to the statement "Opioids are not overused in the United States, even though opioid adjunct therapy achieves greater pain control with less risk." The authors' evaluation of this statement was also compared with the results of a national survey of surgeons and anesthesiologists in the United States. Results: We report the presented literature and proceedings of the panel discussion. The national survey revealed a wide range of opinions regarding opioid overuse in the United States. Current published evidence provides support for the efficacy of opioid therapy in surgical patients; however, it is not sufficient to conclude unequivocally that opioids are-or are not-overused in the management of acute surgical pain in the United States. Conclusions: Opioids remain a key component of multimodal perioperative analgesia, and strategic opioid use based on clinical considerations and patient-specific needs represents an opportunity to support improved postoperative outcomes and satisfaction. Future studies should focus on identifying optimal procedure-specific and patient-centered approaches to multimodal perioperative analgesia.

Nausea and Vomiting following Balanced Xenon Anesthesia Compared to Sevoflurane: A Post-Hoc Explorative Analysis of a Randomized Controlled Trial.

OBJECTIVE: Like other inhalational anesthetics xenon seems to be associated with post-operative nausea and vomiting (PONV). We assessed nausea incidence following balanced xenon anesthesia compared to sevoflurane, and dexamethasone for its prophylaxis in a randomized controlled trial with post-hoc explorative analysis. METHODS: 220 subjects with elevated PONV risk (Apfel score ≥2) undergoing elective abdominal surgery were randomized to receive xenon or sevoflurane anesthesia and dexamethasone or placebo after written informed consent. 93 subjects in the xenon group and 94 subjects in the sevoflurane group completed the trial. General anesthesia was maintained with 60% xenon or 2.0% sevoflurane. Dexamethasone 4mg or placebo was administered in the first hour. Subjects were analyzed for nausea and vomiting in predefined intervals during a 24h post-anesthesia follow-up. RESULTS: Logistic regression, controlled for dexamethasone and anesthesia/dexamethasone interaction, showed a significant risk to develop nausea following xenon anesthesia (OR 2.30, 95% CI 1.02-5.19, p = 0.044). Early-onset nausea incidence was 46% after xenon and 35% after sevoflurane anesthesia (p = 0.138). After xenon, nausea occurred significantly earlier (p = 0.014), was more frequent and rated worse in the beginning. Dexamethasone did not markedly reduce nausea occurrence in both groups. Late-onset nausea showed no considerable difference between the groups. CONCLUSION: In our study setting, xenon anesthesia was associated with an elevated risk to develop nausea in sensitive subjects. Dexamethasone 4mg was not effective preventing nausea in our study. Group size or dosage might have been too small, and change of statistical analysis parameters in the post-hoc evaluation might have further contributed to a limitation of our results. Further trials will be needed to address prophylaxis of xenon-induced nausea. TRIAL REGISTRATION: EU Clinical Trials EudraCT-2008-004132-20 ClinicalTrials.gov NCT00793663.

Propofol Breath Monitoring as a Potential Tool to Improve the Prediction of Intraoperative Plasma Concentrations.

INTRODUCTION: Monitoring of drug concentrations in breathing gas is routinely being used to individualize drug dosing for the inhalation anesthetics. For intravenous anesthetics however, no decisive evidence in favor of breath concentration monitoring has been presented up until now. At the same time, questions remain with respect to the performance of currently used plasma pharmacokinetic models implemented in target-controlled infusion systems. In this study, we investigate whether breath monitoring of propofol could improve the predictive performance of currently applied, target-controlled infusion models. METHODS: Based on data from a healthy volunteer study, we developed an addition to the current state-of-the-art pharmacokinetic model for propofol, to accommodate breath concentration measurements. The potential of using this pharmacokinetic (PK) model in a Bayesian forecasting setting was studied using a simulation study. Finally, by introducing bispectral index monitor (BIS) measurements and the accompanying BIS models into our PK model, we investigated the relationship between BIS and predicted breath concentrations. RESULTS AND DISCUSSION: We show that the current state-of-the-art pharmacokinetic model is easily extended to reliably describe propofol kinetics in exhaled breath. Furthermore, we show that the predictive performance of the a priori model is improved by Bayesian adaptation based on the measured breath concentrations, thereby allowing further treatment individualization and a more stringent control on the targeted plasma concentrations during general anesthesia. Finally, we demonstrated concordance between currently advocated BIS models, relying on predicted effect-site concentrations, and our new approach in which BIS measurements are derived from predicted breath concentrations.

The Relationship of Pain and Nausea in Postoperative Patients for 1 Week After Ambulatory Surgery.

OBJECTIVES: The purpose of this study was to determine if pain level was associated with demographic or surgery-specific characteristics among patients recovering from ambulatory surgery; and to assess the relationship between pain level and nausea over the 7-day postoperative period, controlling for demographic and surgery-related covariates. MATERIALS AND METHODS: This longitudinal study assessed the pain and nausea of 248 eligible patients during the day of surgery (DOS) and the 7 days following ambulatory surgery. Postoperative data were assessed using standardized questions about severity of pain and nausea symptoms. Participants who had a cumulative pain score of ≥24 over the 8-day period were categorized as having high pain. Repeated-measures analysis of variance was used to assess differences in nausea by pain group over time, controlling for demographic, surgical variables, and antiemetic and analgesic use. RESULTS: There were significant differences between 2 pain groups in age, surgical procedure, cumulative morphine equivalent dose, and use of antiemetics postdischarge. The longitudinal analysis demonstrated that patients in the high-pain group reported a greater degree of nausea on DOS and on each of the first 5 days postsurgery, controlling for differences in age, sex, education, use of antiemetics presurgery and postsurgery, use of acetaminophen postsurgery, daily morphine equivalent dose, and surgical procedure. DISCUSSION: Younger patients and those receiving orthopedic procedures may be at greatest risk for postoperative pain. Patients with high pain reported a significantly greater degree of nausea on DOS through the first 5 days postdischarge. As the majority of surgeries are now conducted in the ambulatory setting, it is imperative that we determine pain management regimens and patient education practices that will allow for a more comfortable recovery for our patients.

Patient satisfaction with intravenous acetaminophen: a pooled analysis of five randomized, placebo-controlled studies in the acute postoperative setting.

Intravenous (IV) acetaminophen has been shown to reduce postoperative pain and opioid consumption, which may lead to increased patient satisfaction. To determine the effect IV acetaminophen has on patient satisfaction, a pooled analysis from methodologically homogenous studies was conducted. We obtained patient-level data from five randomized, placebo-controlled studies in adults undergoing elective surgery in which patient satisfaction was measured using a 4-point categorical rating scale. The primary endpoint was "excellent" satisfaction and the secondary endpoint was "good" or "excellent" satisfaction at 24 hr after first study drug administration. Bivariate analyses were conducted using the chi-square test and Student's t-test and multivariable analyses were conducted using logistic regression analysis. Patients receiving IV acetaminophen were more than twice as likely as those who received placebo to report "excellent" patient satisfaction ratings (32.3% vs. 15.9%, respectively). Of all variables that remained statistically significant in the multivariable analysis (i.e., type of surgery, duration of anesthesia, last pain rating, and opioid consumption), IV acetaminophen had the strongest positive effect on "excellent" patient satisfaction with an odds ratio of 2.76 (95% CI 1.81-4.23). Results for "excellent" or "good" satisfaction were similar. When given as part of a perioperative analgesic regimen, IV acetaminophen was associated with significantly improved patient satisfaction.

Anaesthetic techniques for risk of malignant tumour recurrence.

BACKGROUND: Surgery remains a mainstay of treatment for malignant tumours; however, surgical manipulation leads to a significant systemic release of tumour cells. Whether these cells lead to metastases is largely dependent on the balance between aggressiveness of the tumour cells and resilience of the body. Surgical stress per se, anaesthetic agents and administration of opioid analgesics perioperatively can compromise immune function and might shift the balance towards progression of minimal residual disease. Regional anaesthesia techniques provide perioperative pain relief; they therefore reduce the quantity of systemic opioids and of anaesthetic agents used. Additionally, regional anaesthesia techniques are known to prevent or attenuate the surgical stress response. In recent years, the potential benefit of regional anaesthesia techniques for tumour recurrence has received major attention and has been discussed many times in the literature. In preparing this review, we aimed to summarize the current evidence systematically and comprehensively. OBJECTIVES: To establish whether anaesthetic technique (general anaesthesia versus regional anaesthesia or a combination of the two techniques) influences the long-term prognosis for individuals with malignant tumours. SEARCH METHODS: We searched The Cochrane Library (2013, Issue 12), PubMed (1950 to 15 December 2013), EMBASE (1974 to 15 December 2013), BIOSIS (1926 to 15 December 2013) and Web of Science (1965 to 15 December 2013). We handsearched relevant websites and conference proceedings and reference lists of cited articles. We applied no language restrictions. SELECTION CRITERIA: We included all randomized controlled trials or controlled clinical trials that investigated the effects of general versus regional anaesthesia on the risk of malignant tumour recurrence in patients undergoing resection of primary malignant tumours. Comparisons of interventions consisted of (1) general anaesthesia alone versus general anaesthesia combined with one or more regional anaesthetic techniques; (2) general anaesthesia combined with one or more regional anaesthetic techniques versus one or more regional anaesthetic techniques; and (3) general anaesthesia alone versus one or more regional anaesthetic techniques. Primary outcomes included (1) overall survival, (2) progression-free survival and (3) time to tumour progression. DATA COLLECTION AND ANALYSIS: Two review authors independently scanned the titles and abstracts of identified reports and extracted study data.All primary outcome variables are time-to-event data. If the individual trial report provided summary statistics with odds ratios, relative risks or Kaplan-Meier curves, extracted data enabled us to calculate the hazard ratio using the hazard ratio calculating spreadsheet. To assess risk of bias, we used the standard methodological procedures expected by The Cochrane Collaboration. MAIN RESULTS: We included four studies with a total of 746 participants. All studies included adult patients undergoing surgery for primary tumour resection. Two studies enrolled male and female participants undergoing major abdominal surgery for cancer. One study enrolled male participants undergoing surgery for prostate cancer, and one study male participants undergoing surgery for colon cancer. Follow-up time ranged from nine to 17 years. All four studies compared general anaesthesia alone versus general anaesthesia combined with epidural anaesthesia and analgesia. All four studies are secondary data analyses of previously conducted prospective randomized controlled trials.Of the four included studies, only three contributed to the outcome of overall survival, and two each to the outcomes of progression-free survival and time to tumour progression. In our meta-analysis, we could not find an advantage for either study group for the outcomes of overall survival (hazard ratio (HR) 1.03, 95% confidence interval (CI) 0.86 to 1.24) and progression-free survival (HR 0.88, 95% CI 0.56 to 1.38). For progression-free survival, the level of inconsistency was high. Pooled data for time to tumour progression showed a slightly favourable outcome for the control group (general anaesthesia alone) compared with the intervention group (epidural and general anaesthesia) (HR 1.50, 95% CI 1.00 to 2.25).Quality of evidence was graded low for overall survival and very low for progression-free survival and time to tumour progression. The outcome of overall survival was downgraded for serious imprecision and serious indirectness. The outcomes of progression-free survival and time to tumour progression were also downgraded for serious inconsistency and serious risk of bias, respectively.Reporting of adverse events was sparse, and data could not be analysed. AUTHORS' CONCLUSIONS: Currently, evidence for the benefit of regional anaesthesia techniques on tumour recurrence is inadequate. An encouraging number of prospective randomized controlled trials are ongoing, and it is hoped that their results, when reported, will add evidence for this topic in the near future.

Postdischarge nausea and vomiting: management strategies and outcomes over 7 days.

PURPOSE: The purpose of this study is to determine patient management strategies and outcomes for self-care of postdischarge nausea and vomiting (PDNV). DESIGN: Prospective, comparative, descriptive, and longitudinal study. METHODS: The sample consisted of 248 patients aged 18 years or older undergoing a procedure requiring general anesthesia. Patients recorded incidence and severity of nausea and vomiting, the impact of symptoms, and actions taken to alleviate symptoms for 7 days postdischarge. FINDINGS: The prevalence of PDNV was 56.9%. The methods used to relieve symptoms included antiemetic use by a minority and nonpharmacologic techniques of self-management by some. The effect of nausea on QOL, patient functioning, and patient satisfaction was significantly worse for those who experienced postdischarge nausea on all days. CONCLUSION: Patients with PDNV use minor self-care strategies to manage symptoms. The presence of PDNV affects overall quality of life, patient functioning, and patient satisfaction.

Consensus guidelines for the management of postoperative nausea and vomiting.

The present guidelines are the most recent data on postoperative nausea and vomiting (PONV) and an update on the 2 previous sets of guidelines published in 2003 and 2007. These guidelines were compiled by a multidisciplinary international panel of individuals with interest and expertise in PONV under the auspices of the Society for Ambulatory Anesthesia. The panel members critically and systematically evaluated the current medical literature on PONV to provide an evidence-based reference tool for the management of adults and children who are undergoing surgery and are at increased risk for PONV. These guidelines identify patients at risk for PONV in adults and children; recommend approaches for reducing baseline risks for PONV; identify the most effective antiemetic single therapy and combination therapy regimens for PONV prophylaxis, including nonpharmacologic approaches; recommend strategies for treatment of PONV when it occurs; provide an algorithm for the management of individuals at increased risk for PONV as well as steps to ensure PONV prevention and treatment are implemented in the clinical setting.

Incidence and predictors of postdischarge nausea and vomiting in a 7-day population.

STUDY OBJECTIVE: 1) To quantify the incidence and severity of postdischarge nausea and vomiting (PDNV) for 7 days in adults undergoing outpatient surgeries with general anesthesia; 2) to evaluate whether a risk model previously developed for the first two postoperative days may be used to predict the patient's risk of PDNV for 7 days; and 3) to verify whether the same risk factors are applicable in the 3 to 7 day period. DESIGN: Prospective study. SETTING: Two university-affiliated centers. PATIENTS: 248 adult (>18 years) surgical outpatients undergoing ambulatory surgical procedures with general anesthesia between 2007 and 2008. MEASUREMENTS: The incidence and severity of PDNV and a simplified risk score for PDNV was assessed prospectively from discharge up to 7 postoperative days. MAIN RESULTS: The overall incidence of nausea was 56.9% and of emesis was 19.4%. The incidence of PDNV was highest on the day of surgery (DOS), with PDNV of 44.8% and decreasing over time to 6.0% on day 7. Using the simplified risk score for PDNV the area under the receiver operating characteristic (ROC) curve was 0.766 (0.707, 0.825). A previous history of postoperative nausea and vomiting (PONV; OR 3.51, CI 1.70 - 7.27), operating room time (odds ratio [OR] 2.19, 95% CI 1.34 - 3.60), use of ondansetron in the Postanesthesia Care Unit (PACU; OR 6.39, CI 1.65-24.79), and pain during days 3-7 (OR 1.67, CI 1.30 - 2.14) were the strongest predictors of PDNV on days 3-7. CONCLUSIONS: PDNV affects a significant number of patients after ambulatory surgery, and our simplified PDNV score may be applied to a 7-day population. Pain appears to be a factor in late PDNV. It is possible that the presence of PDNV during days 3-7 has different origins from the PDNV that resolved over the first 48 hours.

Determination of breath isoprene allows the identification of the expiratory fraction of the propofol breath signal during real-time propofol breath monitoring.

Real-time measurement of propofol in the breath may be used for routine clinical monitoring. However, this requires unequivocal identification of the expiratory phase of the respiratory propofol signal as only expiratory propofol reflects propofol blood concentrations. Determination of CO2 breath concentrations is the current gold standard for the identification of expiratory gas but usually requires additional equipment. Human breath also contains isoprene, a volatile organic compound with low inspiratory breath concentration and an expiratory concentration plateau. We investigated whether breath isoprene could be used similarly to CO2 to identify the expiratory fraction of the propofol breath signal. We investigated real-time breath data obtained from 40 study subjects during routine anesthesia. Propofol, isoprene, and CO2 breath concentrations were determined by a combined ion molecule reaction/electron impact mass spectrometry system. The expiratory propofol signal was identified according to breath CO2 and isoprene concentrations and presented as median of intervals of 30 s duration. Bland-Altman analysis was applied to detect differences (bias) in the expiratory propofol signal extracted by the two identification methods. We investigated propofol signals in a total of 3,590 observation intervals of 30 s duration in the 40 study subjects. In 51.4 % of the intervals (1,844/3,590) both methods extracted the same results for expiratory propofol signal. Overall bias between the two data extraction methods was -0.12 ppb. The lower and the upper limits of the 95 % CI were -0.69 and 0.45 ppb. Determination of isoprene breath concentrations allows the identification of the expiratory propofol signal during real-time breath monitoring.

Intravenous acetaminophen reduces postoperative nausea and vomiting: a systematic review and meta-analysis.

Opioids are a key risk factor for postoperative nausea and vomiting (PONV). As intravenous (i.v.) acetaminophen reduces postoperative pain and opioid requirements, one would expect i.v. acetaminophen to be associated with a lower incidence of opioid-induced side effects, including PONV. We conducted a systematic search using Medline and Cochrane databases supplemented with hand search of abstract proceedings to identify randomized-controlled trials of i.v. acetaminophen. Inclusion criteria were (a) randomized for i.v. acetaminophen vs a placebo control, (b) general anesthesia, and (c) reported or obtainable PONV outcomes. Primary outcome was postoperative nausea and secondary outcome was postoperative vomiting. We included 30 studies with 2364 patients (1223 in the acetaminophen group, 1141 in the placebo group). The relative risk (95% confidence interval) was 0.73 (0.60-0.88) for nausea and 0.63 (0.45-0.88) for vomiting. Data showed significant heterogeneity for both nausea (P=0.02, I(2)=38%) and vomiting (P=0.006, I(2)=47%), but were homogeneous when studies were grouped according to timing of first administration: i.v. acetaminophen reduced nausea when given prophylactically either before surgery, 0.54 (0.40-0.74), or before arrival in the postanesthesia care unit, 0.67 (0.55-0.83); but not when given after the onset of pain, 1.12 (0.85-1.48). When i.v. acetaminophen was given prophylactically, the reduction of nausea correlated with the reduction of pain (odds ratio 0.66, 0.47-0.93), but not with reduction in postoperative opioids (odds ratio 0.89, 0.64-1.22). Prophylactically administered i.v. acetaminophen reduced PONV, mainly mediated through superior pain control.

Transversus abdominis block: clinical uses, side effects, and future perspectives.

Poorly controlled acute pain during the postoperative setting after abdominal surgery can be detrimental to the patient. Current pain management practices for the postoperative abdominal surgery patient rely heavily on opioids, which are associated with many unwanted side effects. Recently, interest surrounding regional anesthesia has been growing owing to its demonstrated efficacy and safety outcomes. More specifically, the transversus abdominis plane (TAP) block procedure has attracted attention owing to its ability to successfully block peripheral pain signaling in the abdomen, its ease of use, few complications, and its greater acceptability. A majority of the studies published has demonstrated the successful reduction in pain in many abdominal surgical procedures using local anesthetics during the TAP block. However, the short duration of the pain block causes the patient to still rely on other analgesics throughout the additional postoperative days. Preliminary studies using continuous infusion catheters placed in the TAP has been one of the ways to prolong the nerve block in the abdomen; however, technical and operational issues currently limit the widespread adoption of this method. In this review, current studies will be presented and summarized to update the field on the potential benefits of the TAP block procedure, in addition to providing insight into the future direction of the drugs that could be used for TAP block.

Breath isoprene concentrations in persons undergoing general anesthesia and in healthy volunteers.

Human breath contains an abundance of volatile organic compounds (VOCs). Analysis of breath VOC may be used for diagnosis of various diseases or for on-line monitoring in anesthesia and intensive care. However, VOC concentrations largely depend on the breath sampling method and have a large inter-individual variability. For the development of breath tests, the influence of breath sampling methods and study subject characteristics on VOC concentrations has to be known. Therefore, we investigated the VOC isoprene in 62 study subjects during anesthesia and 16 spontaneously breathing healthy volunteers to determine (a) the influence of artificial and spontaneous ventilation and (b) the influence of study subject characteristics on breath isoprene concentrations. We used ion molecule reaction mass spectrometry for high-resolution breath-by-breath analysis of isoprene. We found that persons during anesthesia had significantly increased inspiratory and end-expiratory isoprene breath concentrations. Measured isoprene concentrations (median [first quartile-third quartile]) were in the anesthesia group: 54 [40-79] ppb (inspiratory) and 224 [171-309] ppb (end-expiratory), volunteer group: 14 [11-17] ppb (inspiratory) and 174 [124-202] ppb (end-expiratory). Higher end-tidal CO(2) concentrations in ventilated subjects were associated with higher expiratory isoprene levels. Furthermore, inspiratory and end-expiratory isoprene concentrations were correlated during anesthesia (r = 0.603, p < 0.001). Multivariate analysis showed that men had significantly higher end-expiratory isoprene concentrations than women. Rebreathing of isoprene from the anesthesia machine possibly accounts for the observed increase in isoprene in the anesthesia group.

Who is at risk for postdischarge nausea and vomiting after ambulatory surgery?

BACKGROUND: About one in four patients suffers from postoperative nausea and vomiting. Fortunately, risk scores have been developed to better manage this outcome in hospitalized patients, but there is currently no risk score for postdischarge nausea and vomiting (PDNV) in ambulatory surgical patients. METHODS: We conducted a prospective multicenter study of 2,170 adults undergoing general anesthesia at ambulatory surgery centers in the United States from 2007 to 2008. PDNV was assessed from discharge until the end of the second postoperative day. Logistic regression analysis was applied to a development dataset and the area under the receiver operating characteristic curve was calculated in a validation dataset. RESULTS: The overall incidence of PDNV was 37%. Logistic regression analysis of the development dataset (n=1,913) identified five independent predictors (odds ratio; 95% CI): female gender (1.54; 1.22 to 1.94), age less than 50 yr (2.17; 1.75 to 2.69), history of nausea and/or vomiting after previous anesthesia (1.50; 1.19 to 1.88), opioid administration in the postanesthesia care unit (1.93; 1.53 to 2.43), and nausea in the postanesthesia care unit (3.14; 2.44-4.04). In the validation dataset (n=257), zero, one, two, three, four, and five of these factors were associated with a PDNV incidence of 7%, 20%, 28%, 53%, 60%, and 89%, respectively, and an area under the receiver operating characteristic curve of 0.72 (0.69 to 0.73). CONCLUSIONS: PDNV affects a substantial number of patients after ambulatory surgery. We developed and validated a simplified risk score to identify patients who would benefit from long-acting prophylactic antiemetics at discharge from the ambulatory care center.