A Lower Tidal Volume Regimen during One-lung Ventilation for Lung Resection Surgery Is Not Associated with Reduced Postoperative Pulmonary Complications.

BACKGROUND: Protective ventilation may improve outcomes after major surgery. However, in the context of one-lung ventilation, such a strategy is incompletely defined. The authors hypothesized that a putative one-lung protective ventilation regimen would be independently associated with decreased odds of pulmonary complications after thoracic surgery. METHODS: The authors merged Society of Thoracic Surgeons Database and Multicenter Perioperative Outcomes Group intraoperative data for lung resection procedures using one-lung ventilation across five institutions from 2012 to 2016. They defined one-lung protective ventilation as the combination of both median tidal volume 5 ml/kg or lower predicted body weight and positive end-expiratory pressure 5 cm H2O or greater. The primary outcome was a composite of 30-day major postoperative pulmonary complications. RESULTS: A total of 3,232 cases were available for analysis. Tidal volumes decreased modestly during the study period (6.7 to 6.0 ml/kg; P < 0.001), and positive end-expiratory pressure increased from 4 to 5 cm H2O (P < 0.001). Despite increasing adoption of a "protective ventilation" strategy (5.7% in 2012 vs. 17.9% in 2016), the prevalence of pulmonary complications did not change significantly (11.4 to 15.7%; P = 0.147). In a propensity score matched cohort (381 matched pairs), protective ventilation (mean tidal volume 6.4 vs. 4.4 ml/kg) was not associated with a reduction in pulmonary complications (adjusted odds ratio, 0.86; 95% CI, 0.56 to 1.32). In an unmatched cohort, the authors were unable to define a specific alternative combination of positive end-expiratory pressure and tidal volume that was associated with decreased risk of pulmonary complications. CONCLUSIONS: In this multicenter retrospective observational analysis of patients undergoing one-lung ventilation during thoracic surgery, the authors did not detect an independent association between a low tidal volume lung-protective ventilation regimen and a composite of postoperative pulmonary complications.

Sugammadex versus Neostigmine for Reversal of Neuromuscular Blockade and Postoperative Pulmonary Complications (STRONGER): A Multicenter Matched Cohort Analysis.

BACKGROUND: Five percent of adult patients undergoing noncardiac inpatient surgery experience a major pulmonary complication. The authors hypothesized that the choice of neuromuscular blockade reversal (neostigmine vs. sugammadex) may be associated with a lower incidence of major pulmonary complications. METHODS: Twelve U.S. Multicenter Perioperative Outcomes Group hospitals were included in a multicenter observational matched-cohort study of surgical cases between January 2014 and August 2018. Adult patients undergoing elective inpatient noncardiac surgical procedures with general anesthesia and endotracheal intubation receiving a nondepolarizing neuromuscular blockade agent and reversal were included. Exact matching criteria included institution, sex, age, comorbidities, obesity, surgical procedure type, and neuromuscular blockade agent (rocuronium vs. vecuronium). Other preoperative and intraoperative factors were compared and adjusted in the case of residual imbalance. The composite primary outcome was major postoperative pulmonary complications, defined as pneumonia, respiratory failure, or other pulmonary complications (including pneumonitis; pulmonary congestion; iatrogenic pulmonary embolism, infarction, or pneumothorax). Secondary outcomes focused on the components of pneumonia and respiratory failure. RESULTS: Of 30,026 patients receiving sugammadex, 22,856 were matched to 22,856 patients receiving neostigmine. Out of 45,712 patients studied, 1,892 (4.1%) were diagnosed with the composite primary outcome (3.5% sugammadex vs. 4.8% neostigmine). A total of 796 (1.7%) patients had pneumonia (1.3% vs. 2.2%), and 582 (1.3%) respiratory failure (0.8% vs. 1.7%). In multivariable analysis, sugammadex administration was associated with a 30% reduced risk of pulmonary complications (adjusted odds ratio, 0.70; 95% CI, 0.63 to 0.77), 47% reduced risk of pneumonia (adjusted odds ratio, 0.53; 95% CI, 0.44 to 0.62), and 55% reduced risk of respiratory failure (adjusted odds ratio, 0.45; 95% CI, 0.37 to 0.56), compared to neostigmine. CONCLUSIONS: Among a generalizable cohort of adult patients undergoing inpatient surgery at U.S. hospitals, the use of sugammadex was associated with a clinically and statistically significant lower incidence of major pulmonary complications.

Preoperative Risk and the Association between Hypotension and Postoperative Acute Kidney Injury.

BACKGROUND: Despite the significant healthcare impact of acute kidney injury, little is known regarding prevention. Single-center data have implicated hypotension in developing postoperative acute kidney injury. The generalizability of this finding and the interaction between hypotension and baseline patient disease burden remain unknown. The authors sought to determine whether the association between intraoperative hypotension and acute kidney injury varies by preoperative risk. METHODS: Major noncardiac surgical procedures performed on adult patients across eight hospitals between 2008 and 2015 were reviewed. Derivation and validation cohorts were used, and cases were stratified into preoperative risk quartiles based upon comorbidities and surgical procedure. After preoperative risk stratification, associations between intraoperative hypotension and acute kidney injury were analyzed. Hypotension was defined as the lowest mean arterial pressure range achieved for more than 10 min; ranges were defined as absolute (mmHg) or relative (percentage of decrease from baseline). RESULTS: Among 138,021 cases reviewed, 12,431 (9.0%) developed postoperative acute kidney injury. Major risk factors included anemia, estimated glomerular filtration rate, surgery type, American Society of Anesthesiologists Physical Status, and expected anesthesia duration. Using such factors and others for risk stratification, patients with low baseline risk demonstrated no associations between intraoperative hypotension and acute kidney injury. Patients with medium risk demonstrated associations between severe-range intraoperative hypotension (mean arterial pressure less than 50 mmHg) and acute kidney injury (adjusted odds ratio, 2.62; 95% CI, 1.65 to 4.16 in validation cohort). In patients with the highest risk, mild hypotension ranges (mean arterial pressure 55 to 59 mmHg) were associated with acute kidney injury (adjusted odds ratio, 1.34; 95% CI, 1.16 to 1.56). Compared with absolute hypotension, relative hypotension demonstrated weak associations with acute kidney injury not replicable in the validation cohort. CONCLUSIONS: Adult patients undergoing noncardiac surgery demonstrate varying associations with distinct levels of hypotension when stratified by preoperative risk factors. Specific levels of absolute hypotension, but not relative hypotension, are an important independent risk factor for acute kidney injury.

Intraoperative hyperglycemia is independently associated with infectious complications after non-cardiac surgery.

BACKGROUND: Perioperative hyperglycemia and its associated increase in morbidity and mortality have been well studied in the critical care and cardiac surgery literature. However, there is little data regarding the impact of intraoperative hyperglycemia on post-operative infectious complications in non-cardiac surgery. METHODS: All National Surgery Quality Improvement Program patients undergoing general, vascular, and urological surgery at our tertiary care center were reviewed. After integrating intraoperative glucose measurements from our intraoperative electronic health record, we categorized patients as experiencing mild (8.3-11.0 mmol/L), moderate (11.1-16.6 mmol/L), and severe (≥ 16.7 mmol/L) intraoperative hyperglycemia. Using multiple logistic regression to adjust for patient comorbidities and surgical factors, we evaluated the association of hyperglycemia with the primary outcome of postoperative surgical site infection, pneumonia, urinary tract infection, or sepsis within 30 days. RESULTS: Of 13,954 patients reviewed, 3150 patients met inclusion criteria and had an intraoperative glucose measurement. 49% (n = 1531) of patients experienced hyperglycemia and 15% (n = 482) patients experienced an infectious complication. Patients with mild (adjusted odds ratio 1.30, 95% confidence interval [1.01 to 1.68], p-value = 0.04) and moderate hyperglycemia (adjusted odds ratio 1.57, 95% confidence interval [1.08-2.28], p-value = 0.02) had a statistically significant risk-adjusted increase in infectious complications. The model c-statistic was 0.72 [95% confidence interval 0.69-0.74]. CONCLUSIONS: This is one of the first studies to demonstrate an independent relationship between intraoperative hyperglycemia and postoperative infectious complications. Future studies are needed to evaluate a causal relationship and impact of treatment.

Retrospective observational evaluation of postoperative oxygen saturation levels and associated postoperative respiratory complications and hospital resource utilization.

INTRODUCTION: The clinical importance of postoperative episodic hypoxemia is still unclear, and therefore largely under-studied. As a result, there is limited understanding of its relationship with early postoperative respiratory complications (PRC, defined as intubation within three days of surgery) and hospital resource utilization. MATERIALS AND METHODS: This single center study was performed using a retrospective observational design. We described population based definitions of desaturation from continuous SpO2 monitoring data captured in the post anesthesia care unit (PACU), namely median SpO2 in PACU, duration of desaturation below median, nadir desaturation, and length of oxygen therapy relative to PACU duration. These measures were evaluated against the occurrence of early PRC in logistic regression models. Measures that were independently associated with early PRC were accepted as the primary study exposures. Stratified logistic regression models were planned if significant interaction occurred with high risk surgical procedures. Models were adjusted by including several patient conditions, procedural, and anesthesia risk factors. Propensity matching on desaturation occurrence was planned to evaluate the relationship with postoperative resource utilization. RESULTS: Among 125,740 patients included in the univariate analyses, 351 patients (0.3%) developed early PRC. Nadir desaturation <89% [14.3% of patients; adjusted odds ratio 2.02; 95% CI 1.52, 2.68; p<0.001] and PACU oxygen therapy requirements greater than 60 min [adjusted odds ratio 1.92 (>60 min) to 3.04 (>90 min); p<0.001] were identified as independent predictors of early PRC occurrence. A modest interaction was observed between desaturation and higher surgical risk. Propensity matching for postoperative oxygen requirement was performed in 37,354 matched patients. Matched analysis demonstrated significant increase in day of surgery charges, respiratory charges, total charges, hospital length of stay, reintubation and use of invasive or non-invasive ventilatory support. CONCLUSIONS: In summary, we report that prolonged PACU oxygen therapy and nadir desaturation <89% in PACU as captured in a retrospective database are independently associated with early PRC. This study describes resource implications of PACU desaturation in a large academic medical center in North America.

Frequency of inadequate neuromuscular blockade during general anesthesia.

STUDY OBJECTIVE: We used electronic health record data to define frequency of inadequate intraoperative neuromuscular blockade (NMB). DESIGN: Retrospective observational study using electronic health record data. SETTING: Operating room in a tertiary care academic hospital. PATIENTS: A total of 129,209 adult patients with American Society of Anesthesiologists physical status 1 to 5 undergoing general anesthesia in an outpatient or inpatient setting who received nondepolarizing NMB. We excluded patients intubated before arrival to the operating room, patients undergoing a liver transplant or cardiac surgery, and patients who remained intubated at the end of the operation. INTERVENTIONS: None. MEASUREMENTS: The primary outcomes were inadequate NMB defined by (1) documentation of patient movement and (2) documentation of surgical request for additional NMB, followed by NMB agent administration. MAIN RESULTS: A total of 1261 patients (1.0%) demonstrated either intraoperative movement (369 or 0.29%) or prompted surgical request for additional NMB agent (921 or 0.71%). Trend analysis showed a variation in the annual rate of inadequate NMB, with an increase from 2004 to 2013 for criteria 1 and 2. CONCLUSIONS: Nearly 1% of all general anesthetic procedures involving NMB exhibit inadequate relaxation resulting in procedural interruption. These data suggest that current use of neuromuscular blocking drugs and NMB monitoring expose patients to inadequate blockade. The risk of this phenomenon warrants further study.

Arterial Pressure Variation in Elective Noncardiac Surgery: Identifying Reference Distributions and Modifying Factors.

BACKGROUND: Assessment of need for intravascular volume resuscitation remains challenging for anesthesiologists. Dynamic waveform indices, including systolic and pulse pressure variation, are demonstrated as reliable measures of fluid responsiveness for mechanically ventilated patients. Despite widespread use, real-world reference distributions for systolic and pulse pressure variation values have not been established for euvolemic intraoperative patients. The authors sought to establish systolic and pulse pressure variation reference distributions and assess the impact of modifying factors. METHODS: The authors evaluated adult patients undergoing general anesthetics for elective noncardiac surgery. Median systolic and pulse pressure variations during a 50-min postinduction period were noted for each case. Modifying factors including body mass index, age, ventilator settings, positioning, and hemodynamic management were studied via univariate and multivariable analyses. For systolic pressure variation values, effects of data entry method (manually entered vs. automated recorded) were similarly studied. RESULTS: Among 1,791 cases, per-case median systolic and pulse pressure variation values formed nonparametric distributions. For each distribution, median values, interquartile ranges, and reference intervals (2.5th to 97.5th percentile) were, respectively, noted: these included manually entered systolic pressure variation (6.0, 5.0 to 7.0, and 3.0 to 11.0 mmHg), automated systolic pressure variation (4.7, 3.9 to 6.0, and 2.2 to 10.4 mmHg), and automated pulse pressure variation (7.0, 5.0 to 9.0, and 2.0 to 16.0%). Nonsupine positioning and preoperative ß blocker were independently associated with altered systolic and pulse pressure variations, whereas ventilator tidal volume more than 8 ml/kg ideal body weight and peak inspiratory pressure more than 16 cm H2O demonstrated independent associations for systolic pressure variation only. CONCLUSIONS: This study establishes real-world systolic and pulse pressure variation reference distributions absent in the current literature. Through a consideration of reference distributions and modifying factors, the authors' study provides further evidence for assessing intraoperative volume status and fluid management therapies.

Psychological sequelae of surgery in a prospective cohort of patients from three intraoperative awareness prevention trials.

BACKGROUND: Elective surgery can have long-term psychological sequelae, especially for patients who experience intraoperative awareness. However, risk factors, other than awareness, for symptoms of posttraumatic stress disorder (PTSD) after surgery are poorly defined, and practical screening methods have not been applied to a broad population of surgical patients. METHODS: The Psychological Sequelae of Surgery study was a prospective cohort study of patients previously enrolled in the United States and Canada in 3 trials for the prevention of intraoperative awareness. The 68 patients who experienced definite or possible awareness were matched with 418 patients who denied awareness based on age, sex, surgery type, and awareness risk. Participants completed the PTSD Checklist-Specific (PCL-S) and/or a modified Mini-International Neuropsychiatric Interview telephone assessment to identify symptoms of PTSD and symptom complexes consistent with a PTSD diagnosis. We then used structural equation modeling to produce a composite PTSD score and examined potential risk factors. RESULTS: One hundred forty patients were unreachable; of those contacted, 303 (88%) participated a median of 2 years postoperatively. Forty-four of the 219 patients (20.1%) who completed the PCL-S exceeded the civilian screening cutoff score for PTSD symptoms resulting from their surgery (15 of 35 [43%] with awareness and 29 of 184 [16%] without). Nineteen patients (8.7%; 5 of 35 [14%] with awareness and 14 of 184 [7.6%] without) both exceeded the cutoff and endorsed a breadth of symptoms consistent with the Diagnostic and Statistical Manual Fourth Edition diagnosis of PTSD attributable to their surgery. Factors independently associated with PTSD symptoms were poor social support, previous PTSD symptoms, previous mental health treatment, dissociation related to surgery, perceiving that one's life was threatened during surgery, and intraoperative awareness (all P ≤ 0.017). Perioperative dissociation was identified as a potential mediator for perioperative PTSD symptoms. CONCLUSIONS: Events in the perioperative period can precipitate psychological symptoms consistent with subsyndromal and syndromal PTSD. We not only confirmed the high rate of postoperative PTSD in awareness patients but also identified a significant rate in matched nonawareness controls. Screening surgical patients, especially those with potentially mediating risk factors such as intraoperative awareness or perioperative dissociation, for postoperative PTSD symptoms with the PCL-S is practical and could promote early referral, evaluation, and treatment.

Alerting thresholds for the prevention of intraoperative awareness with explicit recall: a secondary analysis of the Michigan Awareness Control Study.

BACKGROUND: Intraoperative awareness with explicit recall is a potentially devastating complication of surgery that has been attributed to low anaesthetic concentrations in the vast majority of cases. Past studies have proposed the determination of an adequate dose for general anaesthetics that could be used to alert providers of potentially insufficient anaesthesia. However, there have been no systematic analyses of appropriate thresholds to develop population-based alerting algorithms for preventing intraoperative awareness. OBJECTIVE: To identify a threshold for intraoperative alerting that could be applied for the prevention of awareness with explicit recall. DESIGN: Secondary analysis of a randomised controlled trial (Michigan Awareness Control Study). SETTING: Three hospitals at a tertiary care centre in the USA. PATIENTS: Unselected patients presenting for surgery under general anaesthesia. INTERVENTIONS: Alerts based on end-tidal anaesthetic concentration or bispectral index values. MAIN OUTCOME MEASURES: Using case and outcomes data from the primary study, end-tidal anaesthetic concentration and bispectral index values were analysed using Youden's index and c-statistics derived from a receiver operating characteristic curve to determine a specific alerting threshold for the prevention of awareness. RESULTS: No single population-based threshold that maximises sensitivity and specificity could be identified for the prevention of intraoperative awareness, using either anaesthetic concentration or bispectral index values. The c-statistic for anaesthetic concentration was 0.431 ±â€Š0.046, and 0.491 ±â€Š0.056 for bispectral index values. CONCLUSION: We could not derive a single population-based alerting threshold for the prevention of intraoperative awareness using either anaesthetic concentration or bispectral index values. These data indicate a need to move towards individualised alerting strategies in the prevention of intraoperative awareness. TRIAL REGISTRATION: Primary trial registration (Michigan Awareness Control Study) ClinicalTrials.gov identifier: NCT00689091.

Intraoperative bispectral index monitoring and time to extubation after cardiac surgery: secondary analysis of a randomized controlled trial.

BACKGROUND: Fast track recovery is a care process goal after cardiac surgery. Intraoperative anesthetic depth may impact recovery, but the impact of brain monitoring on time to extubation and intensive care unit (ICU) length of stay after cardiac surgery has not been extensively studied. Our goal was to determine if BIS-guided anesthesia improves time to extubation compared to MAC-guided anesthesia in a cardiac surgery population. METHODS: In this secondary outcome analysis of a randomized controlled study, we analyzed 294 patients undergoing elective coronary bypass grafting, valve replacements, and bypass plus valve replacements at a single tertiary referral center between February 1, 2009 and April 30, 2010. We analyzed cardiac surgery patients that had been randomized to BIS-guided anesthesia alerts (n = 131) or MAC-guided anesthesia alerts (n = 163). The primary outcome measure was time to extubation in the BIS-guided and anesthetic concentration-guided groups. Secondary outcomes were length of stay in the ICU and total postoperative hospital length of stay. RESULTS: Valid extubation time data were available for 247 of 294 patients. The median [IQR] time to extubation was 307 [215 to 771] minutes in the BIS group and 323 [196 to 730] minutes in the anesthetic concentration group (p = 0.61). The median [IQR] ICU length of stay was 54 [29 to 97] hours versus 70 [44 to 99] hours (p = 0.11). In terms of postoperative hospital length of stay, there was no difference between the groups with median [IQR] times of 6 [5-8] days (p = 0.69) in each group. CONCLUSIONS: The use of intraoperative BIS monitoring during cardiac surgery did not change time to extubation, ICU length of stay or hospital length of stay. Data regarding BIS monitoring and recovery in an exclusively cardiac surgery population are consistent with recent effectiveness studies in the general surgical population. TRIAL REGISTRATION: ClinicalTrials.gov number NCT00689091.

Intraoperative risk factors associated with postoperative pressure ulcers in critically ill patients: a retrospective observational study.

OBJECTIVE: The risk for pressure ulcers is rarely identified in the perioperative period, and the influence of this period on risk factors has not been as rigorously studied as the postoperative period. We hypothesized that intraoperative risk factors exist, which increase the likelihood of a postoperative new-onset pressure ulcer. DESIGN: A retrospective observational study. SETTING: A large midwestern U.S. quaternary care institution. PATIENTS: A total of 2,695 adult surgical patients underwent operative procedures and received care in one of three ICUs using an electronic documentation application. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary outcome was hospital-acquired pressure ulcer categorized as stages II, III, and IV; deep tissue injury; or unstageable. Univariate analyses comparing patients with and without the outcome of pressure ulcers were conducted for each preoperative characteristic or comorbidity. Patients were matched using the logit of the propensity score based solely on their preoperative comorbidities. Adjusted associations between development of pressure ulcers and intraoperative characteristics were determined in the postmatch cohort. We identified seven independent preoperative patients' characteristics and comorbidities in our adult surgical patient sample: American Society of Anesthesiologists risk classification 4 or 5, underweight body mass index, noncardiac surgery, history of congestive heart failure, renal disease, existing airway present prior to arrival in the operating room, and age. The only significant association in the matched dataset accounting for patient preoperative variability is the use of intraoperative blood products. CONCLUSION: Postoperative pressure ulcers developed in 10.7% of critically ill patients in our study. Only intraoperative use of blood products, not operative case length, hypotension, or vasopressor use, was associated with postoperative pressure ulcer development on adjusted analysis.

Patient selection for day case-eligible surgery: identifying those at high risk for major complications.

BACKGROUND: Due to economic pressures and improvements in perioperative care, outpatient surgical procedures have become commonplace. However, risk factors for outpatient surgical morbidity and mortality remain unclear. There are no multicenter clinical data guiding patient selection for outpatient surgery. The authors hypothesize that specific risk factors increase the likelihood of day case-eligible surgical morbidity or mortality. METHODS: The authors analyzed adults undergoing common day case-eligible surgical procedures by using the American College of Surgeons' National Surgical Quality Improvement Program database from 2005 to 2010. Common day case-eligible surgical procedures were identified as the most common outpatient surgical Current Procedural Terminology codes provided by Blue Cross Blue Shield of Michigan and Medicare publications. Study variables included anthropometric data and relevant medical comorbidities. The primary outcome was morbidity or mortality within 72 h. Intraoperative complications included adverse cardiovascular events; postoperative complications included surgical, anesthetic, and medical adverse events. RESULTS: Of 244,397 surgeries studied, 232 (0.1%) experienced early perioperative morbidity or mortality. Seven independent risk factors were identified while controlling for surgical complexity: overweight body mass index, obese body mass index, chronic obstructive pulmonary disease, history of transient ischemic attack/stroke, hypertension, previous cardiac surgical intervention, and prolonged operative time. CONCLUSIONS: The demonstrated low rate of perioperative morbidity and mortality confirms the safety of current day case-eligible surgeries. The authors obtained the first prospectively collected data identifying risk factors for morbidity and mortality with day case-eligible surgery. The results of the study provide new data to advance patient-selection processes for outpatient surgery.

Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy: a report from the multicenter perioperative outcomes group.

BACKGROUND: Research regarding difficult mask ventilation (DMV) combined with difficult laryngoscopy (DL) is extremely limited even though each technique serves as a rescue for one another. METHODS: Four tertiary care centers participating in the Multicenter Perioperative Outcomes Group used a consistent structured patient history and airway examination and airway outcome definition. DMV was defined as grade 3 or 4 mask ventilation, and DL was defined as grade 3 or 4 laryngoscopic view or four or more intubation attempts. The primary outcome was DMV combined with DL. Patients with the primary outcome were compared to those without the primary outcome to identify predictors of DMV combined with DL using a non-parsimonious logistic regression. RESULTS: Of 492,239 cases performed at four institutions among adult patients, 176,679 included a documented face mask ventilation and laryngoscopy attempt. Six hundred ninety-eight patients experienced the primary outcome, an overall incidence of 0.40%. One patient required an emergent cricothyrotomy, 177 were intubated using direct laryngoscopy, 284 using direct laryngoscopy with bougie introducer, 163 using videolaryngoscopy, and 73 using other techniques. Independent predictors of the primary outcome included age 46 yr or more, body mass index 30 or more, male sex, Mallampati III or IV, neck mass or radiation, limited thyromental distance, sleep apnea, presence of teeth, beard, thick neck, limited cervical spine mobility, and limited jaw protrusion (c-statistic 0.84 [95% CI, 0.82-0.87]). CONCLUSION: DMV combined with DL is an infrequent but not rare phenomenon. Most patients can be managed with the use of direct or videolaryngoscopy. An easy to use unweighted risk scale has robust discriminating capacity.

Incidence, predictors, and outcomes of perioperative stroke in noncarotid major vascular surgery.

BACKGROUND: Perioperative stroke is a potentially catastrophic complication of surgery. Patients undergoing vascular surgery suffer from systemic atherosclerosis and are expected to be at increased risk for this complication. We studied the incidence, predictors, and outcomes of perioperative stroke after noncarotid major vascular surgery using the American College of Surgeons National Quality Improvement Program database. METHODS: Forty-seven thousand seven hundred fifty patients undergoing noncarotid vascular surgery from 2005 to 2009 at nonVeterans Administration hospitals were identified from the American College of Surgeons National Quality Improvement Program database. An analysis of patients undergoing elective lower extremity amputation, lower extremity revascularization, or open aortic procedures was performed to determine the incidence, independent predictors, and 30-day mortality of perioperative stroke. RESULTS: The overall incidence of perioperative stroke within 30 days of surgery (n=37,927) was 0.6%. Multivariate analysis revealed that each 1-year increase in age [odds ratio 1.02, 95% confidence interval (CI) (1.01 to 1.04)], cardiac history [1.42, (1.07 to 1.87)], female sex [1.47, (1.12 to 1.93)], history of cerebrovascular disease [1.72, (1.29 to 2.29)], and acute renal failure or dialysis dependence [2.03, (1.39 to 2.97)] were independent predictors of stroke. Only 15% (95% CI, 11%-20%) of strokes occurred on postoperative day 0 or 1. Perioperative stroke was associated with a 3-fold increase in 30-day all-cause mortality [3.36, (1.77 to 6.36)] and an increased median surgical length of stay from 6 (95% CI, 2 to 28) to 13 (95% CI, 3 to 43) days (P<0.001, WMWodds 2.5, 95% CI, 2.0 to 3.2) in a matched-cohort assessment. CONCLUSION: Perioperative stroke is an important source of morbidity and mortality, as reflected by significant increases in median surgical length of stay and all-cause 30-day mortality. The independent predictors of stroke that we have identified in this population are not readily modifiable and the majority of strokes occurred after postoperative day 1. Additional studies are required to identify potentially modifiable intraoperative or postoperative risk factors of perioperative stroke.

Predictors and clinical outcomes from failed Laryngeal Mask Airway Unique™: a study of 15,795 patients.

BACKGROUND: Although the estimated risk of life-threatening adverse respiratory events during supraglottic airway device use is rare, the reported rate of events leading to failure of the airway device is 0.2-8%. Little is known about the risk-adjusted prediction of Laryngeal Mask Airway failure requiring rescue tracheal intubation and its impact on patient outcomes. METHODS: All adult patients in whom a laryngeal mask airway (LMA Unique™, uLMA™; LMA North America, Inc., San Diego, CA) was used in ambulatory and nonambulatory anesthesia settings were included. The primary outcome was uLMA™ failure, defined as an airway event requiring uLMA™ removal and tracheal intubation. The secondary outcomes were the incidence of difficult mask ventilation and unplanned hospital admissions. RESULTS: Of the 15,795 cases included in our study, 170 (1.1%) experienced the primary outcome of uLMA™ failure. More than 60% of patients with uLMA™ failure experienced significant hypoxia, hypercapnia, or airway obstruction, whereas 42% presented with inadequate ventilation related to leak. Four independent risk factors for failed uLMA™ were identified: surgical table rotation, male sex, poor dentition, and increased body mass index. A 3-fold increased incidence of difficult mask ventilation was observed in patients with uLMA™ failure. Among outpatients with uLMA™ failure, 13.7% had unplanned hospital admission, 5.6% of whom needed intensive care for persistent hypoxemia. CONCLUSIONS: The study supports the use of the uLMA™ as an effective supraglottic airway device with a relatively low failure rate. However, there are clinically relevant consequences of uLMA™ failure, as evidenced by the high rate of acute respiratory events and need for unplanned hospital admissions.

Perioperative stroke and associated mortality after noncardiac, nonneurologic surgery.

BACKGROUND: Stroke is a leading cause of morbidity and mortality in the United States and occurs in the perioperative period. The authors studied the incidence, predictors, and outcomes of perioperative stroke using the American College of Surgeons National Surgical Quality Improvement Program. METHODS: Data on 523,059 noncardiac, nonneurologic patients in the American College of Surgeons National Surgical Quality Improvement Program database were analyzed for the current study. The incidence of perioperative stroke was identified. Logistic regression was applied to a derivation cohort of 350,031 patients to generate independent predictors of stroke and develop a risk model. The risk model was subsequently applied to a validation cohort of 173,028 patients. The role of perioperative stroke in 30-day mortality was also assessed. RESULTS: The incidence of perioperative stroke in both the derivation and validation cohorts was 0.1%. Multivariate analysis revealed the following independent predictors of stroke in the derivation cohort: age ≥ 62 yr, history of myocardial infarction within 6 months before surgery, acute renal failure, history of stroke, dialysis, hypertension, history of transient ischemic attack, chronic obstructive pulmonary disease, current tobacco use, and body mass index 35-40 kg/m² (protective). These risk factors were confirmed in the validation cohort. Surgical procedure also influenced the incidence of stroke. Perioperative stroke was associated with an 8-fold increase in perioperative mortality within 30 days (95% CI, 4.6-12.6). CONCLUSIONS: Noncardiac, nonneurologic surgery carries a risk of perioperative stroke, which is associated with higher mortality. The models developed in this study may be informative for clinicians and patients regarding risk and prevention of this complication.

The impact of high body mass index on postoperative complications and resource utilization in minority patients.

BACKGROUND: Obesity is disproportionately prevalent among minority patients, yet very little has been written about its effect on surgical outcome in this group. OBJECTIVE: We investigated the association of body mass index (BMI) category with perioperative complications and resource utilization. METHODS: Data from the American College of Surgeons National Surgical Quality improvement Program Participant Use Data File was used to calculate the BMI (kg/m2) of all minority patients undergoing inpatient surgery from 2005 to 2008. Patients were stratified into 4 BMI classes, ranging from normal weight to severely obese. Postoperative length of stay (LOS) was used as the main proxy for resource utilization. Stepwise logistic regression was used to calculate odds ratios for prolonged LOS after controlling for clinically relevant cofactors. RESULTS: Among 73978 patients, 28% were in the normal BMI category, 28.9% were overweight, 28.2% were obese, and 14.9% were severely obese. Morbidity and mortality distribution varied significantly by BMI category, with the highest proportion of cases occurring in the normal-BMI group and the lowest in the severely obese patients. Postoperative LOS was longer for patients in the normal-BMI group than for severely obese patients. Other markers of resource utilization also followed the same pattern with progressive decrease from normal-BMI patients to the severely obese group. CONCLUSION: Postoperative morbidity and mortality and markers of hospital resource consumption were highest in the normal-BMI patients and decreased progressively to the severely obese group. This group appears to enjoy a paradoxical protection from perioperative complications and so utilize fewer hospital resources.

Perioperative peripheral nerve injuries: a retrospective study of 380,680 cases during a 10-year period at a single institution.

BACKGROUND: Peripheral nerve injuries represent a notable source of anesthetic complications and can be debilitating. The objective of this study was to identify associations with peripheral nerve injury in a broad surgical population cared for in the last decade. METHODS: At a tertiary care university hospital, the quality assurance, closed claims, and institution-wide billing code databases were searched for peripheral nerve injuries over a 10-yr period. Each reported case was individually reviewed to determine whether a perioperative injury occurred, defined as a new sensory and/or motor deficit. The location and type of the injury were also identified. Nerve complications as a result of the surgical procedure itself were excluded, and an expert review panel assisted in the adjudication of unclear cases. Patient preoperative characteristics, anesthetic modality, and surgical specialty were evaluated for associations. RESULTS: Of all patients undergoing 380,680 anesthetics during a 10-yr period, 185 patients were initially identified as having nerve injuries, and after review, 112 met our definition of a perioperative nerve injury (frequency = 0.03%). Hypertension, tobacco use, and diabetes mellitus were significantly associated with perioperative peripheral nerve injuries. General and epidural anesthesia were associated with nerve injuries. Significant associations were also found with the following surgical specialties: Neurosurgery, cardiac surgery, general surgery, and orthopedic surgery. CONCLUSIONS: To our knowledge, this is the largest number of consecutive patients ever reviewed for all types of perioperative peripheral nerve injuries. More importantly, this is the first study to identify associations of nerve injuries with hypertension, anesthetic modality, and surgical specialty.

Development and validation of an acute kidney injury risk index for patients undergoing general surgery: results from a national data set.

BACKGROUND: The authors sought to identify the incidence, risk factors, and mortality impact of acute kidney injury (AKI) after general surgery using a large and representative national clinical data set. METHODS: The 2005-2006 American College of Surgeons-National Surgical Quality Improvement Program participant use data file is a compilation of outcome data from general surgery procedures performed in 121 US medical centers. The primary outcome was AKI within 30 days, defined as an increase in serum creatinine of at least 2 mg/dl or acute renal failure necessitating dialysis. A variety of patient comorbidities and operative characteristics were evaluated as possible predictors of AKI. A logistic regression full model fit was used to create an AKI model and risk index. Thirty-day mortality among patients with and without AKI was compared. RESULTS: Of 152,244 operations reviewed, 75,952 met the inclusion criteria, and 762 (1.0%) were complicated by AKI. The authors identified 11 independent preoperative predictors: age 56 yr or older, male sex, emergency surgery, intraperitoneal surgery, diabetes mellitus necessitating oral therapy, diabetes mellitus necessitating insulin therapy, active congestive heart failure, ascites, hypertension, mild preoperative renal insufficiency, and moderate preoperative renal insufficiency. The c statistic for a simplified risk index was 0.80 in the derivation and validation cohorts. Class V patients (six or more risk factors) had a 9% incidence of AKI. Overall, patients experiencing AKI had an eightfold increase in 30-day mortality. CONCLUSIONS: Approximately 1% of general surgery cases are complicated by AKI. The authors have developed a robust risk index based on easily identified preoperative comorbidities and patient characteristics.

Preoperative and intraoperative predictors of cardiac adverse events after general, vascular, and urological surgery.

BACKGROUND: The authors sought to determine the incidence and risk factors for perioperative cardiac adverse events (CAEs) after noncardiac surgery using detailed preoperative and intraoperative hemodynamic data. METHODS: The authors conducted a prospective observational study at a single university hospital from 2002 to 2006. All American College of Surgeons-National Surgical Quality Improvement Program patients undergoing general, vascular, and urological surgery were included. The CAE outcome definition included cardiac arrest, non-ST elevation myocardial infarction, Q-wave myocardial infarction, and new clinically significant cardiac dysrhythmia within the first 30 postoperative days. RESULTS: Four years of data demonstrated that of 7,740 noncardiac operations, 83 patients (1.1%) experienced a CAE within 30 days. Nine independent predictors were identified (P < or = 0.05): age > or = 68, body mass index > or = 30, emergent surgery, previous coronary intervention or cardiac surgery, active congestive heart failure, cerebrovascular disease, hypertension, operative duration > or = 3.8 h, and the administration of 1 or more units of packed red blood cells intraoperatively. The c-statistic of this model was 0.81 +/- 0.02. Univariate analysis demonstrated that high-risk patients experiencing a CAE were more likely to experience an episode of mean arterial pressure < 50 mmHg (6% vs. 24%, P = 0.02), experience an episode of 40% decrease in mean arterial pressure (26% vs. 53%, P = 0.01), and an episode of heart rate > 100 (22% vs. 34%, P = 0.05). CONCLUSIONS: In comparison with current risk stratification indices, the inclusion of intraoperative elements improves the ability to predict a perioperative CAE after noncardiac surgery.