Stavros G. Memtsoudis

Perioperative Comparative Effectiveness of Anesthetic Technique in Orthopedic Patients

Background:The impact of anesthetic technique on perioperative outcomes remains controversial. We studied a large national sample of primary joint arthroplasty recipients and hypothesized that neuraxial anesthesia favorably influences perioperative outcomes. Methods:Data from approximately 400 hospitals between 2006 and 2010 were accessed. Patients who underwent primary hip or knee arthroplasty were identified and subgrouped by anesthesia technique: general, neuraxial, and combined neuraxial–general. Demographics, postoperative complications, 30-day mortality, length of stay, and patient cost were analyzed and compared. Multivariable analyses were conducted to identify the independent impact of choice of anesthetic on outcomes. Results:Of 528,495 entries of patients undergoing primary hip or knee arthroplasty, information on anesthesia type was available for 382,236 (71.4%) records. Eleven percent were performed under neuraxial, 14.2% under combined neuraxial–general, and 74.8% under general anesthesia. Average age and comorbidity burden differed modestly between groups. When neuraxial anesthesia was used, 30-day mortality was significantly lower (0.10, 0.10, and 0.18%; P < 0.001), as was the incidence of prolonged (>75th percentile) length of stay, increased cost, and in-hospital complications. In the multivariable regression, neuraxial anesthesia was associated with the most favorable complication risk profile. Thirty-day mortality remained significantly higher in the general compared with the neuraxial or neuraxial–general group for total knee arthroplasty (adjusted odds ratio [OR] of 1.83, 95% CI 1.08–3.1, P = 0.02; OR of 1.70, 95% CI 1.06–2.74, P = 0.02, respectively). Conclusions:The utilization of neuraxial versus general anesthesia for primary joint arthroplasty is associated with superior perioperative outcomes. More research is needed to study potential mechanisms for these findings.

Perioperative pulmonary outcomes in patients with sleep apnea after noncardiac surgery.

BACKGROUND:Although patients with sleep apnea (SA) are considered to be at increased risk for postoperative complications, evidence supporting increased risk of perioperative pulmonary morbidity is limited. The objective of this study, therefore, was to analyze perioperative demographics and pulmonary outcomes of patients with SA after orthopedic and general surgical procedures using a population-based sample. We hypothesized that SA is an independent risk factor for perioperative pulmonary complications, thus providing a basis for an increase in the utilization of resources, including intensive monitoring and development of strategies to prevent and treat these events. METHODS:National Inpatient Sample data for each year between 1998 and 2007 were accessed. Orthopedic and general surgical procedures were included and discharges with a diagnosis code for SA were identified. Patients with the diagnosis of SA were matched to those without the disease based on demographic variables using the propensity scoring method. Aspiration pneumonia, adult respiratory distress syndrome (ARDS), pulmonary embolism (PE), and the need for intubation and mechanical ventilation were the primary outcomes. Odds ratio (OR) and absolute risk reduction along with 95% confidence interval were reported. RESULTS:We identified 2,610,441 entries for orthopedic and 3,441,262 for general surgical procedures performed between 1998 and 2007. Of those, 2.52% and 1.40%, respectively, carried a diagnosis of SA. Patients with SA developed pulmonary complications more frequently than their matched controls after both orthopedic and general surgical procedures, respectively (i.e., aspiration pneumonia: 1.18% vs 0.84% and 2.79% vs 2.05%; ARDS: 1.06% vs 0.45% and 3.79% vs 2.44%; intubation/mechanical ventilation: 3.99% vs 0.79% and 10.8% vs 5.94%, all P values <0.0001). Comparatively, PE was more frequent in SA patients after orthopedic procedures (0.51% vs 0.42%, P = 0.0038) but not after general surgical procedures (0.45% vs 0.49%, P = 0.22). SA was associated with a significantly higher adjusted OR of developing pulmonary complications after both orthopedic and general surgical procedures, respectively, with the exception of PE (OR for aspiration pneumonia: 1.41 [1.35, 1.47] and 1.37 [1.33, 1.41]; for ARDS: 2.39 [2.28, 2.51] and 1.58 [1.54, 1.62]; for PE: OR 1.22 [1.15, 1.29] and 0.90 [0.84, 0.97]; for intubation/mechanical ventilation: 5.20 [5.05, 5.37] and 1.95 [1.91, 1.98]). CONCLUSION:SA is an independent risk factor for perioperative pulmonary complications. Our results may be used for hypothesis generation for clinical studies targeted to improve perioperative outcomes in this patient population.

Tranexamic acid use and postoperative outcomes in patients undergoing total hip or knee arthroplasty in the United States: retrospective analysis of effectiveness and safety

Objective To determine the effectiveness and safety of perioperative tranexamic acid use in patients undergoing total hip or knee arthroplasty in the United States. Design Retrospective cohort study; multilevel multivariable logistic regression models measured the association between tranexamic acid use in the perioperative period and outcomes. Setting 510 US hospitals from the claims based Premier Perspective database for 2006-12. Participants 872 416 patients who had total hip or knee arthroplasty. Intervention Perioperative intravenous tranexamic acid use by dose categories (none, ≤1000 mg, 2000 mg, and ≥3000 mg). Main outcome measures Allogeneic or autologous transfusion, thromboembolic complications (pulmonary embolism, deep venous thrombosis), acute renal failure, and combined complications (thromboembolic complications, acute renal failure, cerebrovascular events, myocardial infarction, in-hospital mortality). Results While comparable regarding average age and comorbidity index, patients receiving tranexamic acid (versus those who did not) showed lower rates of allogeneic or autologous transfusion (7.7% v 20.1%), thromboembolic complications (0.6% v 0.8%), acute renal failure (1.2% v 1.6%), and combined complications (1.9% v 2.6%); all P<0.01. In the multilevel models, tranexamic acid dose categories (versus no tranexamic acid use) were associated with significantly (P<0.001) decreased odds for allogeneic or autologous blood transfusions (odds ratio 0.31 to 0.38 by dose category) and no significantly increased risk for complications: thromboembolic complications (odds ratio 0.85 to 1.02), acute renal failure (0.70 to 1.11), and combined complications (0.75 to 0.98). Conclusions Tranexamic acid was effective in reducing the need for blood transfusions while not increasing the risk of complications, including thromboembolic events and renal failure. Thus our data provide incremental evidence of the potential effectiveness and safety of tranexamic acid in patients requiring orthopedic surgery.

The Usefulness of Transesophageal Echocardiography During Intraoperative Cardiac Arrest in Noncardiac Surgery

According to guidelines established by the American Society of Anesthesiologists and the Society of Cardiovascular Anesthesiologists, life-threatening hemodynamic disturbances are classified as a category I indication for the intraoperative use of transesophageal echocardiography (TEE). However, the usefulness of TEE during intraoperative cardiac arrest and its impact on patient management have not been rigorously investigated. Using our departmental TEE database, we identified a population of 22 patients who underwent noncardiac surgical procedures and experienced unexpected intraoperative hemodynamic collapse requiring the initiation of Advanced Cardiac Life Support procedures between the time of induction of general anesthesia and the termination of the surgical procedure. Results of TEE examinations, patient records, detailed operative records, and outcome of patients were reviewed for the utility of TEE to diagnose the etiology of the hemodynamic collapse. Furthermore, the impact on subsequent patient management was evaluated. A primary suspected diagnosis of the underlying pathological process was established in 19 of 22 patients with TEE, including 9 with thromboembolic events, 6 with acute myocardial ischemia, 2 with hypovolemia, and 2 patients with pericardial tamponade. A definitive diagnosis could not be made in 3 patients with TEE. In 18 patients, TEE guided specific management beyond implementation of Advanced Cardiac Life Support protocols, including the addition of surgical procedures in 12 patients. Fourteen patients survived to leave the operating room, and 7 of these patients were eventually discharged from the hospital. Thus, TEE may provide additional diagnostic information in patients with intraoperative cardiac arrest and may directly guide specific, potentially life-saving therapy.

Perioperative outcomes after unilateral and bilateral total knee arthroplasty

Background:The safety of bilateral total knee arthroplasties (BTKAs) during the same hospitalization remains controversial. The authors sought to study differences in perioperative outcomes between unilateral and BTKA and to further compare BTKAs performed during the same versus different operations during the same hospitalization. Methods:Nationwide Inpatient Sample data from 1998 to 2006 were analyzed. Entries for unilateral and BTKA procedures performed on the same day (simultaneous) and separate days (staged) during the same hospitalization were identified. Patient and healthcare system–related demographics were determined. The incidences of in-hospital mortality and procedure-related complications were estimated and compared between groups. Multivariate regression was used to identify independent risk factors for morbidity and mortality. Results:Despite younger average age and lower comorbidity burden, procedure-related complications and in-hospital mortality were more frequent after BTKA than after unilateral procedures (9.45% vs. 7.07% and 0.30% vs. 0.14%; P < 0.0001 each). An increased rate of complications was associated with a staged versus simultaneous approach with no difference in mortality (10.30% vs. 9.15%; P < 0.0001 and 0.29% vs. 0.26%; P = 0.2875). Independent predictors for in-hospital mortality included BTKA (simultaneous: odds ratio, 2.23 [95% confidence interval, 1.69–2.95]; P < 0.0001; staged: odds ratio, 2.01 [confidence interval, 1.28–3.41]; P = 0.0031), male sex (odds ratio, 2.02 [confidence interval, 1.75–2.34]; P < 0.0001), age older than 75 yr (odds ratio, 3.96 [confidence interval, 2.77–5.66]; P < 0.0001), and the presence of a number of comorbidities and complications. Conclusion:BTKAs carry increased risk of perioperative morbidity and mortality compared with unilateral procedures. Staging BTKA procedures during the same hospitalization offers no mortality benefit and may even expose patients to increased morbidity.

Beyond repeated-measures analysis of variance: advanced statistical methods for the analysis of longitudinal data in anesthesia research.

Background and Objectives Research in the field of anesthesiology relies heavily on longitudinal designs for answering questions about long-term efficacy and safety of various anesthetic and pain regimens. Yet, anesthesiology research is lagging in the use of advanced statistical methods for analyzing longitudinal data. The goal of this article was to increase awareness of the advantages of modern statistical methods and promote their use in anesthesia research. Methods Here we introduce 2 modern and advanced statistical methods for analyzing longitudinal data: the generalized estimating equations (GEE) and mixed-effects models (MEM). These methods were compared with the conventional repeated-measures analysis of variance (RM-ANOVA) through a clinical example with 2 types of end points (continuous and binary). In addition, we compared GEE and MEM to RM-ANOVA through a simulation study with varying sample sizes, varying number of repeated measures, and scenarios with and without missing data. Results In the clinical study, the 3 methods are found to be similar in terms of statistical estimation, whereas the parameter interpretations are somewhat different. The simulation study shows that the methods of GEE and MEM are more efficient in that they are able to achieve higher power with smaller sample size or lower number of repeated measurements in both complete and missing data scenarios. Conclusions Based on their advantages over RM-ANOVA, GEE and MEM should be strongly considered for the analysis of longitudinal data. In particular, GEE should be used to explore overall average effects, and MEM should be used when subject-specific effects (in addition to overall average effects) are of primary interest.

Inpatient falls after total knee arthroplasty: the role of anesthesia type and peripheral nerve blocks.

Background:Much controversy remains on the role of anesthesia technique and peripheral nerve blocks (PNBs) in inpatient falls (IFs) after orthopedic procedures. The aim of the study is to characterize cases of IFs, identify risk factors, and study the role of PNB and anesthesia technique in IF risk in total knee arthroplasty patients. Methods:The authors selected total knee arthroplasty patients from the national Premier Perspective database (Premier Inc., Charlotte, NC; 2006–2010; n = 191,570, >400 acute care hospitals). The primary outcome was IF. Patient- and healthcare system–related characteristics, anesthesia technique, and presence of PNB were determined for IF and non-IF patients. Independent risk factors for IFs were determined by using conventional and multilevel logistic regression. Results:Overall, IF incidence was 1.6% (n = 3,042). Distribution of anesthesia technique was 10.9% neuraxial, 12.9% combined neuraxial/general, and 76.2% general anesthesia. PNB was used in 12.1%. Patients suffering IFs were older (average age, 68.9 vs. 66.3 yr), had higher comorbidity burden (average Deyo index, 0.77 vs. 0.66), and had more major complications, including 30-day mortality (0.8 vs. 0.1%; all P < 0.001). Use of neuraxial anesthesia (IF incidence, 1.3%; n = 280) had lower adjusted odds of IF compared with adjusted odds of IF with the use of general anesthesia alone (IF incidence, 1.6%; n = 2,393): odds ratio, 0.70 (95% CI, 0.56–0.87). PNB was not significantly associated with IF (odds ratio, 0.85 [CI, 0.71–1.03]). Conclusions:This study identifies several risk factors for IF in total knee arthroplasty patients. Contrary to common concerns, no association was found between PNB and IF. Further studies should determine the role of anesthesia practices in the context of fall-prevention programs.

Protective versus Conventional Ventilation for Surgery: A Systematic Review and Individual Patient Data Meta-analysis.

Background:Recent studies show that intraoperative mechanical ventilation using low tidal volumes (VT) can prevent postoperative pulmonary complications (PPCs). The aim of this individual patient data meta-analysis is to evaluate the individual associations between VT size and positive end–expiratory pressure (PEEP) level and occurrence of PPC. Methods:Randomized controlled trials comparing protective ventilation (low VT with or without high levels of PEEP) and conventional ventilation (high VT with low PEEP) in patients undergoing general surgery. The primary outcome was development of PPC. Predefined prognostic factors were tested using multivariate logistic regression. Results:Fifteen randomized controlled trials were included (2,127 patients). There were 97 cases of PPC in 1,118 patients (8.7%) assigned to protective ventilation and 148 cases in 1,009 patients (14.7%) assigned to conventional ventilation (adjusted relative risk, 0.64; 95% CI, 0.46 to 0.88; P < 0.01). There were 85 cases of PPC in 957 patients (8.9%) assigned to ventilation with low VT and high PEEP levels and 63 cases in 525 patients (12%) assigned to ventilation with low VT and low PEEP levels (adjusted relative risk, 0.93; 95% CI, 0.64 to 1.37; P = 0.72). A dose–response relationship was found between the appearance of PPC and VT size (R2 = 0.39) but not between the appearance of PPC and PEEP level (R2 = 0.08). Conclusions:These data support the beneficial effects of ventilation with use of low VT in patients undergoing surgery. Further trials are necessary to define the role of intraoperative higher PEEP to prevent PPC during nonopen abdominal surgery.

Trends in in-hospital major morbidity and mortality after total joint arthroplasty: United States 1998-2008.

BACKGROUND:The use of total joint arthroplasties is increasing worldwide. In this work we aim to elucidate recent trends in demographics and perioperative outcomes of patients undergoing total hip (THA) or total knee arthroplasty (TKA). METHODS:Data from the US Nationwide Impatient Sample between 1998 and 2008 were gathered for primary THAs and TKAs. Trends in patient age, comorbidity burden, length of hospitalization, frequency of major perioperative complications, and in-hospital mortality were analyzed. In-hospital outcomes were reported as events per 1000 inpatient days to account for changes in length of hospitalization over time. Deyo index, discharge status, and the interaction effect of time and discharge status were included in the adjusted trend analysis for morbidity. RESULTS:Between 1998 and 2008, the average age of patients undergoing TKA and THA decreased by 2 to 3 years (P < 0.001). The average length of stay decreased by approximately 1 day over the time interval studied (P < 0.001). The percentage of patients being discharged home declined from 29.7% to 25.4% after TKA and from 29.3% to 24.2% after THA, in favor of dispositions to long- and short-term care facilities (P < 0.0001). Comorbidity burden as measured by the Deyo comorbidity index increased by 35% and 30% for TKA and THA patients, respectively (P < 0.0001). After TKA, there was an increase in the incidence of the following major complications: pulmonary embolism (coefficient estimate [CE] 0.069; 95% confidence interval [CI], 0.059–0.079; P < 0.0001), sepsis (CE 0.034; 95% CI, 0.014–0.054; P = 0.001), nonmyocardial infarction cardiac complications (CE 0.038; 95% CI, 0.035–0.041; P < 0.0001), and pneumonia (CE 0.039; 95% CI, 0.031–0.047; P < 0.0001). After THA, there was an increase in the incidence of the following major complications: pulmonary embolism (CE 0.031; 95% CI, 0.012–0.049; P = 0.001), sepsis (CE 0.060; 95% CI, 0.039–0.081; P < 0.0001), nonmyocardial infarction cardiac complications (CE 0.040; 95% CI, 0.036–0.043; P < 0.0001), and pneumonia (CE 0.039; 95% CI, 0.029–0.048). In-hospital mortality declined after both TKA (CE −0.059; 95% CI, −0.077 to −0.040; P < 0.0001) and THA (CE −0.068; 95% CI, −0.086 to −0.051; P < 0.0001). CONCLUSION:Between 1998 and 2008, trends show increases in several major in-hospital complications after THA and TKA, including pulmonary embolism, sepsis, nonmyocardial infarction cardiac complications, and pneumonia. Despite the increase in complications, declining in-hospital mortality was noted over this period.

Validation of the STOP-Bang Questionnaire as a Screening Tool for Obstructive Sleep Apnea among Different Populations: A Systematic Review and Meta-Analysis

Background Diagnosing obstructive sleep apnea (OSA) is clinically relevant because untreated OSA has been associated with increased morbidity and mortality. The STOP-Bang questionnaire is a validated screening tool for OSA. We conducted a systematic review and meta-analysis to determine the effectiveness of STOP-Bang for screening patients suspected of having OSA and to predict its accuracy in determining the severity of OSA in the different populations. Methods A search of the literature databases was performed. Inclusion criteria were: 1) Studies that used STOP-Bang questionnaire as a screening tool for OSA in adult subjects (>18 years); 2) The accuracy of the STOP-Bang questionnaire was validated by polysomnography—the gold standard for diagnosing OSA; 3) OSA was clearly defined as apnea/hypopnea index (AHI) or respiratory disturbance index (RDI) ≥ 5; 4) Publications in the English language. The quality of the studies were explicitly described and coded according to the Cochrane Methods group on the screening and diagnostic tests. Results Seventeen studies including 9,206 patients met criteria for the systematic review. In the sleep clinic population, the sensitivity was 90%, 94% and 96% to detect any OSA (AHI ≥ 5), moderate-to-severe OSA (AHI ≥15), and severe OSA (AHI ≥30) respectively. The corresponding NPV was 46%, 75% and 90%. A similar trend was found in the surgical population. In the sleep clinic population, the probability of severe OSA with a STOP-Bang score of 3 was 25%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability rose proportionally to 35%, 45%, 55% and 75%, respectively. In the surgical population, the probability of severe OSA with a STOP-Bang score of 3 was 15%. With a stepwise increase of the STOP-Bang score to 4, 5, 6 and 7/8, the probability increased to 25%, 35%, 45% and 65%, respectively. Conclusion This meta-analysis confirms the high performance of the STOP-Bang questionnaire in the sleep clinic and surgical population for screening of OSA. The higher the STOP-Bang score, the greater is the probability of moderate-to-severe OSA.