Associations of dexamethasone's effect on morphine consumption after total knee arthroplasty-Subgroup analyses.

The DEXamethasone twice for pain treatment after Total Knee Arthroplasty (DEX-2-TKA) trial showed that adding one and two doses of 24 mg intravenous dexamethasone to paracetamol, ibuprofen and local infiltration analgesia, reduced morphine consumption (primary outcome) within 48 h after TKA. We aimed to explore the differences in the effect of dexamethasone on morphine consumption in different subgroups. Quantile regression adjusted for site was used to test for significant interaction between the predefined dichotomised subgroups and treatment group. The subgroups were defined based on baseline data: sex (male/female), age (≤65 years/>65 years), American Society of Anaesthesiologists (ASA)-score (ASA I + II/III), visual analogue score of preoperative pain at rest (≤30 mm/>30 mm), pain during mobilisation (≤30 mm/>30 mm), type of anaesthesia (spinal anaesthesia/general anaesthesia and spinal converted to general anaesthesia), and prior daily use of analgesics (either paracetamol and/or NSAID/neither). These analyses were supplemented with post hoc multivariate linear regression analyses. Test of interaction comparing sex in the pairwise comparison between DX2 (dexamethasone [24 mg] + dexamethasone [24 mg]) versus placebo (p = .02), showed a larger effect of dexamethasone on morphine consumption in male patients compared to females. Test of interaction comparing age in the pairwise comparison between DX1 (dexamethasone [24 mg] + placebo) versus placebo (p = .04), showed a larger effect of dexamethasone on morphine consumption in younger patients (≤65 years) compared to older. All remaining subgroup analyses showed no evidence of a difference. The supplemental multivariate analyses did not support any significant interaction for sex (p = .256) or age (p = .730) but supported a significant interaction with the type of anaesthesia (p < .001). Our results from the quantile regression analyses indicate that the male sex and younger age (≤65 years) may be associated with a larger analgesic effect of dexamethasone than the effects in other types of patients. However, this is not supported by post-hoc multivariate linear regression analyses. The two types of analyses both supported a possible interaction with the type of anaesthesia.

Pain treatment after total hip arthroplasty: Detailed statistical analysis plan for the RECIPE randomised clinical trial.

BACKGROUND: The RECIPE trial systematically investigates the effects of different combinations of paracetamol, ibuprofen and dexamethasone for pain treatment after total hip arthroplasty. To preserve transparency, minimise risk of bias and to prevent data-driven analysis, we present this detailed statistical analysis plan. METHODS: The RECIPE trial is a randomised, blinded, parallel four-group multicenter clinical trial for patients undergoing planned primary total hip arthroplasty. Interventions are initiated preoperatively and continued for 24 h postoperatively. Primary outcome is total opioid consumption 0-24 h after end of surgery. Primary analysis will be performed in the modified intention to treat population of all patients undergoing total hip arthroplasty, and all analyses will be stratified for site. We will perform pairwise comparisons between each of the four groups. The primary outcome will be analysed using the van Elteren test and we will present Hodges-Lehmann median differences and confidence intervals. Binary outcomes will be analysed using logistic regression. To preserve a family-wise error rate of <0.05, we will use a Bonferroni-adjusted alfa of 0.05/6 = 0.0083 for all six pairwise comparisons between groups when analysing the primary outcome. We will systematically assess the underlying statistical assumptions for each analysis. Data will be analysed by two blinded independent statisticians, and we will write abstracts covering all possible combinations of conclusions, before breaking the blind. DISCUSSION: The RECIPE trial will provide important information on benefit and harm of combinations of the most frequently used non-opioid analgesics for pain after primary hip arthroplasty.

Effect of Dexamethasone on Myocardial Injury After Total Knee Arthroplasty: A Substudy of the Randomized Clinical DEX-2-TKA Trial.

BACKGROUND: Myocardial injury after noncardiac surgery (MINS) carries a high postoperative mortality. In this preplanned, subgroup analysis of the randomized DEX-2-TKA Trial, we investigated the effect of dexamethasone versus placebo on the concentration of cardiac troponin I and T (TnI and TnT) on the first postoperative morning after total knee arthroplasty. In addition, frequency of MINS, myocardial infarction, and major adverse cardiovascular events where evaluated. METHODS: We included 290 patients who received either 24 mg of dexamethasone intravenously (given perioperatively) or placebo. Blood samples were analyzed as either TnI or T depending on trial site. RESULTS: A total of 236 samples were eligible for analysis of TnI and 38 samples for TnT on the first postoperative morning. The median (IQR) TnI concentration was 4.6 ng/L (0-7.2 ng/L) in the dexamethasone group and 4.5ng/l (0-7.0 ng/L) in the placebo group (P = .96) on the first postoperative morning. The median TnT was 9 ng/L (6-11 ng/L) in the dexamethasone group and 8 ng/L (5-10 ng/L) in the placebo group (P = .68). The frequencies of MINS, myocardial infarction, and major adverse cardiovascular events were similar in the compared groups, but these analyses were underpowered. CONCLUSION: We found no effect of dexamethasone on postoperative concentration of troponin I or T on the first postoperative morning after total knee arthroplasty.

Systemic glucocorticoids as an adjunct to treatment of postoperative pain after total hip and knee arthroplasty: A systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: Postoperative analgesic effects of systemic glucocorticoids given as an adjunct to treatment are largely undetermined in alloplastic procedures. OBJECTIVES: To investigate the beneficial and harmful effects of peri-operative systemic glucocorticoid treatment for pain after total hip arthroplasty (THA) or total knee arthroplasty (TKA). DESIGN: A systematic review of randomised clinical trials (RCTs) with meta-analyses, trial sequential analyses and GRADE. Primary outcome was 24 h intravenous (i.v.) morphine (or equivalent) consumption with a predefined minimal important difference (MID) of 5 mg. Secondary outcomes included pain at rest and during mobilisation (MID, VAS 10 mm), adverse and serious adverse events (SAEs). DATA SOURCES: We searched EMBASE, Cochrane CENTRAL, PubMed and Google Scholar up to October 2021. ELIGIBILITY CRITERIA: RCTs investigating peri-operative systemic glucocorticoid versus placebo or no intervention, for analgesic pain management of patients at least 18 years undergoing planned THA or TKA, irrespective of publication date and language. RESULTS: We included 32 RCTs with 3521 patients. Nine trials were at a low risk of bias. Meta-analyses showed evidence of a reduction in 24 h cumulative morphine consumption with glucocorticoids by 5.0 mg (95% CI 2.2 to 7.7; P  = 0.0004). Pain at rest was reduced at 6 h by 7.8 mm (95% CI 5.5 to 10.2; P  < 0.00001), and at 24 h by 6.3 mm (95% CI 3.8 to 8.8; P  < 0.00001). Pain during mobilisation was reduced at 6 h by 9.8 mm (95% CI 6.9 to 12.8; P  < 0.00001), and at 24 h by 9.0 mm (95% CI 5.5 to 12.4, P  < 0.00001). Incidence of adverse events was generally lower in the glucocorticoid treatment group. SAEs were rarely reported. The GRADE rated quality of evidence was low to very low. CONCLUSION: Peri-operative systemic glucocorticoid treatment reduced postoperative morphine consumption to an individually relevant level following hip and knee arthroplasty. Pain levels were reduced but were below the predefined MID. The quality of evidence was generally low. REGISTRATION: PROSPERO ID: CRD42019135034.

Fatal outcome and intensive care unit admission after total hip and knee arthroplasty: An analytic of preoperative frailty and comorbidities.

BACKGROUND: With increasing demand for total hip arthroplasty (THA) and total knee arthroplasty (TKA), a higher percentage of patients are identified with comorbidities that might increase the risk of complications. We aimed to elucidate the preoperative characteristics of patients with a fatal outcome or admission to the Intensive Care Unit (ICU) within 90 days after THA or TKA. We arbitrarily hypothesized that more than 50% of those patients would be frail. METHODS: This is a register based, explorative study including patients undergoing elective, unilateral, primary THA or TKA in the Capital Region of Denmark from 2010 to 2017, and who subsequently died or were admitted to the ICU within 90 days. The modified Frailty Index (mFI) was calculated from the medical records, and a score of ≥0.36 defined frailty. RESULTS: A total of 33,758 patients underwent THA or TKA, and 284 patients (0.8%) died or were admitted to the ICU within 90 days. Fifty-seven patients (20%) were frail (95% CI 16.2-25.7%). The most common comorbidities were hypertension (63%) and pulmonary diseases (32%), and 56% used walking aids. Two or more comorbidities were present in 65% of patients, and 14% had no comorbidities at all. CONCLUSION: Only 20% of patients with a fatal outcome or ICU admission after elective THA or TKA could be categorized as frail based on the mFI. Further studies with a prospective design are needed to clarify the mFI as a risk stratification tool in elderly multimorbid patients undergoing elective arthroplasty surgery.

Clinical considerations for reposition of a dislocated hip: A qualitative study.

BACKGROUND: A well-known complication of having hip alloplasty surgery is dislocation of the prothesis. This affects 2%-4% of the patients, and 75% of the dislocations occur within the first year after surgery. The aim of our study was to gain knowledge about the clinical considerations underlying the choice of anaesthesia for, and treatment of, patients with dislocated hips by specialists in anaesthesiology and orthopaedic surgery. METHODS: We used semi-structured group interviews of specialists in anaesthesiology and orthopaedic surgery. An interview guide was developed and pilot tested before the group interviews. In total, 25 specialists participated, recruited from two university hospitals in Denmark. Data saturation was reached after seven group interviews. Inductive content analysis was used in the data analysis. RESULTS: We identified four overall themes, describing essential considerations made by the specialists: "Adhering to the principle of minimal intervention", "Ensuring patient safety through optimal working conditions", "Organisational considerations" and "Pain induced gastric retention". CONCLUSION: Our study illustrates different clinical considerations made by specialists in anaesthesiology and orthopaedic surgery in relation to the treatment of patients with dislocated hips. Our results hope to promote mutual understanding in joint clinical decision-making in relation to patients with dislocated hips as well as to inspire less-experienced anaesthesiologists and orthopaedic surgeons. Additionally, our results suggest a set of "rules of thumb" for how jointly to decide on the repositioning site of the patient during the procedure.

Introducing the "hip call" to facilitate early surgical treatment of hip fractures: A feasibility study.

INTRODUCTION: Surgical treatment of hip fractures within 24-48 hours decreases morbidity and mortality, but goals for early surgery have not been widely achieved so far. The primary aim of this study was to investigate the feasibility of implementation of a hip call, and the secondary aim was to investigate the effect of the hip call on time for pre-operative preparation and surgery compared to a historical control cohort. MATERIALS AND METHODS: From March 4, 2019 until June 30, 2019, admission of patients at Copenhagen University Hospital, Bispebjerg, Denmark, with a suspected hip fracture triggered an acute hip call. Key personnel are summoned to secure rapid pre-operative preparation and surgery. The implementation was defined feasible, if ≥ 75% of the patients were ready for surgery within 4 hours and had surgery initiated within 24 hours of hospital arrival. The historical control cohort was patients with hip fractures in the same period in 2018. RESULTS: A total of 128 patients were included in 2019, and 99 in 2018. After implementation of hip call, 83% of patients were ready for surgery within 4 hours. After vs before hip call, 88% vs 51% were operated within 24 hours and 96% vs 79% within 36 hours. Time from admission to surgery (hh:mm) was reduced by mean 10:33 (CI 07:46-13:20), P < .001. CONCLUSION: The implementation of a hip call was feasible with 83% of patients being ready for surgery within 4 hours, and 88% being operated within 24 hours. Future large-scale studies should clarify potential benefits on clinical outcome.

DEX-2-TKA - DEXamethasone twice for pain treatment after Total Knee Arthroplasty: Detailed statistical analysis plan for a randomized, blinded, three-group multicentre clinical trial.

BACKGROUND: Optimization of post-operative pain treatment is of upmost importance. Multimodal analgesia is the main post-operative pain treatment principle, but the evidence on optimal analgesic combinations is unclear. With the "DEXamethasone twice for pain treatment after TKA" trial, we aim to investigate the role of one or two doses of glucocorticoid for post-operative pain treatment after total knee arthroplasty. To ensure transparency and minimization of bias, we present this article with a detailed statistical analysis plan, to be published before the last participant is enrolled. METHODS: "DEXamethasone twice for pain treatment after TKA" (DEX-2-TKA) is a randomized, blinded, three-group multicentre clinical trial. Participants will be randomized to one of three intervention groups: single dose of iv dexamethasone 24 mg, two consecutive doses of iv dexamethasone 24 mg or matching iv placebo. All three intervention groups will receive paracetamol, NSAID (ibuprofen) and local infiltration analgesia. Participants, treatment providers, outcome assessors, data managers, statisticians and conclusion drawers will be blinded to the allocated intervention. The primary outcome is total opioid consumption (iv morphine milligram equivalents) 0-48 hours post-operatively. Secondary outcomes are (1) visual analogue scale pain levels: (a) during active 45 degrees flexion of the knee at 24 and 48 hours post-operatively, (b) at rest at 24 and 48 hours post-operatively, and (c) during 0-24 hours (highest score) and 24-48 hours post-operatively (highest score); and (2) the proportion of participants with one or more adverse events within 48 hours post-operatively. DISCUSSION: The DEX-2-TKA trial will provide high quality data regarding benefits and harms of adding one or two high-doses of dexamethasone to a multimodal analgesic regimen. TRIAL REGISTRATION: EudraCT: 2018-001099-39 (08/06-18); ClinicalTrials.gov: NCT03506789 (24/04-2019).

DEX-2-TKA-DEXamethasone twice for pain treatment after Total Knee Arthroplasty: A protocol for a randomized, blinded, three-group multicentre clinical trial.

BACKGROUND: Multimodal analgesia is considered the leading principle for post-operative pain treatment, but no gold standard after total knee arthroplasty (TKA) exists. AIM: To investigate the beneficial and harmful effects of one or two doses of 24 mg intravenous dexamethasone (DXM) as part of a multimodal analgesic regimen (paracetamol, NSAID and perioperative local infiltration analgesia) after TKA. We hypothesize that addition of DXM will reduce post-operative opioid consumption. METHODS: DEXamethasone twice for pain treatment after TKA is a randomized, blinded, three-group multicentre clinical trial. Participants will be randomized to one of three groups: placebo, single dose of DXM or two consecutive doses of DXM. Participants, treatment providers and investigators will be blinded to the allocated intervention. The primary outcome is total opioid consumption (units of morphine equivalents) 0-48 hours post-operatively. INCLUSION CRITERIA: unilateral, primary TKA; age ≥18 years; American Society of Anesthesiologists-Score 1-3; Body Mass Index ≥18 and ≤40; for women-not pregnant; and written informed consent. EXCLUSION CRITERIA: allergy or contraindications against trial medication; daily use of high dose opioid and/or use of methadone/transdermal opioids; daily use of systemic glucocorticoids; dysregulated diabetes; and patients suffering from alcohol and/or drug abuse. Four-hundred-and-eighty-six eligible participants are needed to detect or discard a difference of 10 mg morphine equivalents 0-48 hours post-operatively maintaining a familywise error rate of 0.05 and a power of 90% for the three possible pairwise comparisons. DISCUSSION: Recruiting is planned to commence September 2018 and expected to finish March 2020. TRIAL REGISTRATION: EudraCT: 2018-001099-39 (08/06-18); ClinicalTrials.gov: NCT03506789 (24/04-2019). Editorial Comment This is the protocol for the largest randomized clinical trial investigating the effect of one or two doses of dexamethasones on pain treatment after total knee arthroplasty. Due to the pragmatic and rigerous design this study will deliver results of high quality and external validity.

Analgesic effect of perioperative escitalopram in high pain catastrophizing patients after total knee arthroplasty: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Sufficient pain treatment remains a challenge after total knee arthroplasty (TKA), especially in high pain catastrophizing patients. Serotonergic signaling may be involved in pain processing, but the effect of selective serotonin reuptake inhibitors on well-defined postoperative pain has not previously been investigated. The authors hypothesized that perioperative escitalopram would reduce pain after TKA in high pain catastrophizing patients. METHODS: A total of 120 pain catastrophizing patients (selected using the pain catastrophizing scale as preoperative screening tool) scheduled for TKA were randomized in a double-blind manner to either 10 mg escitalopram or placebo daily from preanesthesia to postoperative day 6 in addition to a standardized analgesic regime. The primary outcome was pain upon ambulation 24 h after surgery. Secondary outcomes were overall pain during well-defined mobilizations and at rest from 2 to 48 h and from days 2 to 6, morphine equivalents, anxiety, depression, and side effects. RESULTS: Pain upon ambulation (mean [95% CI]) 24 h after surgery in the escitalopram versus placebo group was 58 (53 to 64) versus 64 (58 to 69), the mean difference being -5 (-13 to 3), P = 0.20. Overall pain upon ambulation and at rest from days 2 to 6 was lower in the escitalopram versus placebo group, as was depression score at day 6 (all P ≤ 0.01 in analyses uncorrected for multiple tests). Side effects were nonsignificant except for reduced tendency to sweat and prolonged sleep in the escitalopram group. No other between-group differences were observed. CONCLUSIONS: Escitalopram did not reduce pain upon ambulation 24 h after TKA in high pain catastrophizing patients. Future studies on optimal timing, dose, and duration of selective serotonin reuptake inhibitor treatment might be warranted.

Prediction of postoperative pain by preoperative pain response to heat stimulation in total knee arthroplasty.

It has been estimated that up to 54% of the variance in postoperative pain experience may be predicted with preoperative pain responses to experimental stimuli, with suprathreshold heat pain as the most consistent test modality. This study aimed to explore whether 2 heat test paradigms could predict postoperative pain after total knee arthroplasty (TKA). Patients scheduled for elective, unilateral, primary TKA under spinal anesthesia were consecutively included in this prospective, observational study. Perioperative analgesia was standardized for all patients. Outcomes were postoperative pain during walk: from 6 to 24 hours (primary), from postoperative day (POD) 1 to 7 (secondary), and from POD 14 to 30 (tertiary). Two preoperative tonic heat stimuli with 47°C were used; short (5 seconds) and long (7 minutes) stimulation upon which patients rated their pain response on an electronic visual analog scale. Multivariate stepwise linear and logistic regressions analyses were carried out, including 8 potential preoperative explanatory variables (among these anxiety, depression, preoperative pain, and pain catastrophizing) to assess pain response to preoperative heat pain stimulation as an independent predictor for postoperative pain. A total of 100 patients were included, and 3 were later excluded. A weak correlation [rho (95% confidence interval); P value] was observed between pain from POD 1 to 7 and pain response to short [rho=0.25(0.04 to 0.44); P=.02] and to long [rho=0.27 (0.07 to 0.46); P=.01] heat pain stimulation. However, these positive correlations were not supported by the linear and logistic regression analyses, in which only anxiety, preoperative pain, and pain catastrophizing were significant explanatory variables (but with low R-squares; 0.05 to 0.08). Pain responses to 2 types of preoperative heat stimuli were not independent clinically relevant predictors for postoperative pain after TKA.

No effect of fibrin sealant on drain output or functional recovery following simultaneous bilateral total knee arthroplasty: a randomized, double-blind, placebo-controlled study.

BACKGROUND AND PURPOSE: Blood loss after total knee arthroplasty (TKA) may lead to anemia, blood transfusions, and increased total costs. Also, bleeding into the periarticular tissue may cause swelling and a reduction in quadriceps strength, thus impairing early functional recovery. In this randomized, double-blind, placebo-controlled study, we analyzed the possible effect of fibrin sealant on blood loss and early functional recovery in a fast-track setting. METHODS: 24 consecutive patients undergoing bilateral simultaneous TKA were included. 10 mL of fibrin sealant (Evicel) was sprayed onto one knee whereas the contralateral knee had saline. Drain output, the primary outcome, was measured from knee drains removed exactly 24 h after surgery. Secondary outcomes (knee swelling, pain, strength of knee extension, and range of movement (ROM)) were evaluated up to 21 days after surgery. RESULTS: The drain output in knees treated with fibrin sealant and placebo was similar (582 mL and 576 mL, respectively). Likewise, no statistically significant differences were found between groups regarding swelling, pain, strength of knee extension, and ROM. INTERPRETATION: Fibrin sealant as a local hemostatic in TKA showed no benefit in reducing drain output or in facilitating early functional recovery when used with a tourniquet, tranexamic acid, and a femoral bone plug.

Why still in hospital after fast-track hip and knee arthroplasty?

BACKGROUND AND PURPOSE: Length of stay (LOS) following total hip and knee arthroplasty (THA and TKA) has been reduced to about 3 days in fast-track setups with functional discharge criteria. Earlier studies have identified patient characteristics predicting LOS, but little is known about specific reasons for being hospitalized following fast-track THA and TKA. PATIENTS AND METHODS: To determine clinical and logistical factors that keep patients in hospital for the first postoperative 24-72 hours, we performed a cohort study of consecutive, unselected patients undergoing unilateral primary THA (n = 98) or TKA (n = 109). Median length of stay was 2 days. Patients were operated with spinal anesthesia and received multimodal analgesia with paracetamol, a COX-2 inhibitor, and gabapentin-with opioid only on request. Fulfillment of functional discharge criteria was assessed twice daily and specified reasons for not allowing discharge were registered. RESULTS: Pain, dizziness, and general weakness were the main clinical reasons for being hospitalized at 24 and 48 hours postoperatively while nausea, vomiting, confusion, and sedation delayed discharge to a minimal extent. Waiting for blood transfusion (when needed), for start of physiotherapy, and for postoperative radiographic examination delayed discharge in one fifth of the patients. INTERPRETATION: Future efforts to enhance recovery and reduce length of stay after THA and TKA should focus on analgesia, prevention of orthostatism, and rapid recovery of muscle function.

Intraoperative local infiltration analgesia for early analgesia after total hip arthroplasty: a randomized, double-blind, placebo-controlled trial.

BACKGROUND AND OBJECTIVES: High-volume local infiltration analgesia (LIA) is widely applied as part of a multimodal pain management strategy in total hip arthroplasty (THA). However, methodological problems hinder the exact interpretation of previous trials, and the evidence for LIA in THA remains to be clarified. Therefore, we evaluated whether intraoperative high-volume LIA, in addition to a multimodal oral analgesic regimen, would further reduce acute postoperative pain after THA. METHODS: Patients scheduled for unilateral, primary THA under spinal anesthesia were included in this randomized, double-blind, placebo-controlled trial receiving high-volume (150 mL) wound infiltration with ropivacaine 0.2% with epinephrine (10 µg/mL) or saline 0.9%. A multimodal oral analgesic regimen consisting of slow-release acetaminophen 2 g, celecoxib 400 mg, and gabapentin 600 mg was instituted preoperatively. Rescue analgesic consisted of oral oxycodone. Pain was assessed repeatedly the first 8 hrs after surgery using the 100-mm visual analog scale. The primary end point was pain during walking (5 m) 8 hrs after surgery. Secondary end points were pain at rest, pain on 45 degrees of passive flexion of the hip with the leg straight, and cumulative consumption of oxycodone. RESULTS: A total of 120 patients were included. Pain during walking (median [interquartile range] [95% confidence interval]) was low in the ropivacaine versus the placebo group (20 [14-38] [0-93] vs 22 [10-40] [0-83]) and did not differ significantly (P = 0.71). Consumption of rescue oxycodone (5 mg [0-10 mg] [0-24 mg] vs 10 mg [0-15 mg] [0-29 mg]) did not differ (P = 0.45). CONCLUSIONS: Intraoperative high-volume LIA with ropivacaine 0.2% provided no additional reduction in acute pain after THA when combined with a multimodal oral analgesic regimen consisting of acetaminophen, celecoxib, and gabapentin and is therefore not recommended.

Effect of high perioperative oxygen fraction on surgical site infection and pulmonary complications after abdominal surgery: the PROXI randomized clinical trial.

CONTEXT: Use of 80% oxygen during surgery has been suggested to reduce the risk of surgical wound infections, but this effect has not been consistently identified. The effect of 80% oxygen on pulmonary complications has not been well defined. OBJECTIVE: To assess whether use of 80% oxygen reduces the frequency of surgical site infection without increasing the frequency of pulmonary complications in patients undergoing abdominal surgery. DESIGN, SETTING, AND PATIENTS: The PROXI trial, a patient- and observer-blinded randomized clinical trial conducted in 14 Danish hospitals between October 2006 and October 2008 among 1400 patients undergoing acute or elective laparotomy. INTERVENTIONS: Patients were randomly assigned to receive either 80% or 30% oxygen during and for 2 hours after surgery. MAIN OUTCOME MEASURES: Surgical site infection within 14 days, defined according to the Centers for Disease Control and Prevention. Secondary outcomes included atelectasis, pneumonia, respiratory failure, and mortality. RESULTS: Surgical site infection occurred in 131 of 685 patients (19.1%) assigned to receive 80% oxygen vs 141 of 701 (20.1%) assigned to receive 30% oxygen (odds ratio [OR], 0.94; 95% confidence interval [CI], 0.72-1.22; P = .64). Atelectasis occurred in 54 of 685 patients (7.9%) assigned to receive 80% oxygen vs 50 of 701 (7.1%) assigned to receive 30% oxygen (OR, 1.11; 95% CI, 0.75-1.66; P = .60), pneumonia in 41 (6.0%) vs 44 (6.3%) (OR, 0.95; 95% CI, 0.61-1.48; P = .82), respiratory failure in 38 (5.5%) vs 31 (4.4%) (OR, 1.27; 95% CI, 0.78-2.07; P = .34), and mortality within 30 days in 30 (4.4%) vs 20 (2.9%) (OR, 1.56; 95% CI, 0.88-2.77; P = .13). CONCLUSION: Administration of 80% oxygen compared with 30% oxygen did not result in a difference in risk of surgical site infection after abdominal surgery. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00364741.