Jonathan P. Wanderer

Intraoperative protective mechanical ventilation and risk of postoperative respiratory complications: hospital based registry study

Objective To evaluate the effects of intraoperative protective ventilation on major postoperative respiratory complications and to define safe intraoperative mechanical ventilator settings that do not translate into an increased risk of postoperative respiratory complications. Design Hospital based registry study. Setting Academic tertiary care hospital and two affiliated community hospitals in Massachusetts, United States. Participants 69 265 consecutively enrolled patients over the age of 18 who underwent a non-cardiac surgical procedure between January 2007 and August 2014 and required general anesthesia with endotracheal intubation. Interventions Protective ventilation, defined as a median positive end expiratory pressure (PEEP) of 5 cmH2O or more, a median tidal volume of less than 10 mL/kg of predicted body weight, and a median plateau pressure of less than 30 cmH2O. Main outcome measure Composite outcome of major respiratory complications, including pulmonary edema, respiratory failure, pneumonia, and re-intubation. Results Of the 69 265 enrolled patients 34 800 (50.2%) received protective ventilation and 34 465 (49.8%) received non-protective ventilation intraoperatively. Protective ventilation was associated with a decreased risk of postoperative respiratory complications in multivariable regression (adjusted odds ratio 0.90, 95% confidence interval 0.82 to 0.98, P=0.013). The results were similar in the propensity score matched cohort (odds ratio 0.89, 95% confidence interval 0.83 to 0.97, P=0.004). A PEEP of 5 cmH2O and median plateau pressures of 16 cmH2O or less were associated with the lowest risk of postoperative respiratory complications. Conclusions Intraoperative protective ventilation was associated with a decreased risk of postoperative respiratory complications. A PEEP of 5 cmH2O and a plateau pressure of 16 cmH2O or less were identified as protective mechanical ventilator settings. These findings suggest that protective thresholds differ for intraoperative ventilation in patients with normal lungs compared with those used for patients with acute lung injury.

Epidemiology of obstetric-related ICU admissions in Maryland: 1999-2008*.

Objective:To define the prevalence, indications, and temporal trends in obstetric-related ICU admissions. Design:Descriptive analysis of utilization patterns. Setting:All hospitals within the state of Maryland. Patients:All antepartum, delivery, and postpartum patients who were hospitalized between 1999 and 2008. Interventions:None. Measurements and Main Results:We identified 2,927 ICU admissions from 765,598 admissions for antepartum, delivery, or postpartum conditions using appropriate International Classification of Diseases, 9th Revision, Clinical Modification codes. The overall rate of ICU utilization was 419.1 per 100,000 deliveries, with rates of 162.5, 202.6, and 54.0 per 100,000 deliveries for the antepartum, delivery, and postpartum periods, respectively. The leading diagnoses associated with ICU admission were pregnancy-related hypertensive disease (present in 29.9% of admissions), hemorrhage (18.8%), cardiomyopathy or other cardiac disease (18.3%), genitourinary infection (11.5%), complications from ectopic pregnancies and abortions (10.3%), nongenitourinary infection (10.1%), sepsis (7.1%), cerebrovascular disease (5.8%), and pulmonary embolism (3.7%). We assessed for changes in the most common diagnoses in the ICU population over time and found rising rates of sepsis (10.1 per 100,000 deliveries to 16.6 per 100,000 deliveries, p = 0.003) and trauma (9.2 per 100,000 deliveries to 13.6 per 100,000 deliveries, p = 0.026) with decreasing rates of anesthetic complications (11.3 per 100,000 to 4.7 per 100,000, p = 0.006). The overall frequency of obstetric-related ICU admission and the rates for other indications remained relatively stable. Conclusions:Between 1999 and 2008, 419.1 per 100,000 deliveries in Maryland were complicated by ICU admission. Hospitals providing obstetric services should plan for appropriate critical care management and/or transfer of women with severe morbidities during pregnancy.

Balanced Crystalloids versus Saline in the Intensive Care Unit. The SALT Randomized Trial

Rationale: Saline is the intravenous fluid most commonly administered to critically ill adults, but it may be associated with acute kidney injury and death. Whether use of balanced crystalloids rather than saline affects patient outcomes remains unknown. Objectives: To pilot a cluster‐randomized, multiple‐crossover trial using software tools within the electronic health record to compare saline to balanced crystalloids. Methods: This was a cluster‐randomized, multiple‐crossover trial among 974 adults admitted to a tertiary medical intensive care unit from February 3, 2015 to May 31, 2015. The intravenous crystalloid used in the unit alternated monthly between saline (0.9% sodium chloride) and balanced crystalloids (lactated Ringers solution or Plasma‐Lyte A). Enrollment, fluid delivery, and data collection were performed using software tools within the electronic health record. The primary outcome was the difference between study groups in the proportion of isotonic crystalloid administered that was saline. The secondary outcome was major adverse kidney events within 30 days (MAKE30), a composite of death, dialysis, or persistent renal dysfunction. Measurements and Main Results: Patients assigned to saline (n = 454) and balanced crystalloids (n = 520) were similar at baseline and received similar volumes of crystalloid by 30 days (median [interquartile range]: 1,424 ml [500‐3,377] vs. 1,617 ml [500‐3,628]; P = 0.40). Saline made up a larger proportion of the isotonic crystalloid given in the saline group than in the balanced crystalloid group (91% vs. 21%; P < 0.001). MAKE30 did not differ between groups (24.7% vs. 24.6%; P = 0.98). Conclusions: An electronic health record‐embedded, cluster‐randomized, multiple‐crossover trial comparing saline with balanced crystalloids can produce well‐balanced study groups and separation in crystalloid receipt. Clinical trial registered with www.clinicaltrials.gov (NCT 02345486).

Balanced Crystalloids versus Saline in Critically Ill Adults

BACKGROUND Comparative clinical effects of balanced crystalloids and saline are uncertain, particularly in noncritically ill patients cared for outside an intensive care unit (ICU). METHODS We conducted a single‐center, pragmatic, multiple‐crossover trial comparing balanced crystalloids (lactated Ringers solution or Plasma‐Lyte A) with saline among adults who were treated with intravenous crystalloids in the emergency department and were subsequently hospitalized outside an ICU. The type of crystalloid that was administered in the emergency department was assigned to each patient on the basis of calendar month, with the entire emergency department crossing over between balanced crystalloids and saline monthly during the 16‐month trial. The primary outcome was hospital‐free days (days alive after discharge before day 28). Secondary outcomes included major adverse kidney events within 30 days — a composite of death from any cause, new renal‐replacement therapy, or persistent renal dysfunction (defined as an elevation of the creatinine level to ≥200% of baseline) — all censored at hospital discharge or 30 days, whichever occurred first. RESULTS A total of 13,347 patients were enrolled, with a median crystalloid volume administered in the emergency department of 1079 ml and 88.3% of the patients exclusively receiving the assigned crystalloid. The number of hospital‐free days did not differ between the balanced‐crystalloids and saline groups (median, 25 days in each group; adjusted odds ratio with balanced crystalloids, 0.98; 95% confidence interval [CI], 0.92 to 1.04; P=0.41). Balanced crystalloids resulted in a lower incidence of major adverse kidney events within 30 days than saline (4.7% vs. 5.6%; adjusted odds ratio, 0.82; 95% CI, 0.70 to 0.95; P=0.01). CONCLUSIONS Among noncritically ill adults treated with intravenous fluids in the emergency department, there was no difference in hospital‐free days between treatment with balanced crystalloids and treatment with saline. (Funded by the Vanderbilt Institute for Clinical and Translational Research and others; SALT‐ED ClinicalTrials.gov number, NCT02614040.)

Real-time alerts and reminders using information systems.

Adoption of information systems throughout the hospital environment has enabled the development of real-time physiologic alerts and clinician reminder systems. These clinical tools can be made available through the deployment of anesthesia information management systems (AIMS). Creating usable alert systems requires understanding of technical considerations. Various successful implementations are reviewed, encompassing cost reduction, improved revenue capture, timely antibiotic administration, and postoperative nausea and vomiting prophylaxis. Challenges to the widespread use of real-time alerts and reminders include AIMS adoption rates and the difficulty in choosing appropriate areas and approaches for information systems support.

Validation of a risk stratification index and risk quantification index for predicting patient outcomes: In-hospital mortality, 30-day mortality, 1-year mortality, and length-of-stay

Background:External validation of published risk stratification models is essential to determine their generalizability. This study evaluates the performance of the Risk Stratification Indices (RSIs) and 30-day mortality Risk Quantification Index (RQI). Methods:108,423 adult hospital admissions with anesthetics were identified (2006–2011). RSIs for mortality and length-of-stay endpoints were calculated using published methodology. 91,128 adult, noncardiac inpatient surgeries were identified with administrative data required for RQI calculation. Results:RSI in-hospital mortality and RQI 30-day mortality Brier scores were 0.308 and 0.017, respectively. RSI discrimination, by area under the receiver operating curves, was excellent at 0.966 (95% CI, 0.963–0.970) for in-hospital mortality, 0.903 (0.896–0.909) for 30-day mortality, 0.866 (0.861–0.870) for 1-yr mortality, and 0.884 (0.882–0.886) for length-of-stay. RSI calibration, however, was poor overall (17% predicted in-hospital mortality vs. 1.5% observed after inclusion of the regression constant) as demonstrated by calibration plots. Removal of self-fulfilling diagnosis and procedure codes (20,001 of 108,423; 20%) yielded similar results. RQIs were calculated for only 62,640 of 91,128 patients (68.7%) due to unmatched procedure codes. Patients with unmatched codes were younger, had higher American Society of Anesthesiologists physical status and 30-day mortality. The area under the receiver operating curve for 30-day mortality RQI was 0.888 (0.879–0.897). The model also demonstrated good calibration. Performance of a restricted index, Procedure Severity Score + American Society of Anesthesiologists physical status, performed as well as the original RQI model (age + American Society of Anesthesiologists + Procedure Severity Score). Conclusion:Although the RSIs demonstrated excellent discrimination, poor calibration limits their generalizability. The 30-day mortality RQI performed well with age providing a limited contribution.

Development and Validation of an Intraoperative Predictive Model for Unplanned Postoperative Intensive Care

Background:The allocation of intensive care unit (ICU) beds for postoperative patients is a challenging daily task that could be assisted by the real-time detection of ICU needs. The goal of this study was to develop and validate an intraoperative predictive model for unplanned postoperative ICU use. Methods:With the use of anesthesia information management system, postanesthesia care unit, and scheduling data, a data set was derived from adult in-patient noncardiac surgeries. Unplanned ICU admissions were identified (4,847 of 71,996; 6.7%), and a logistic regression model was developed for predicting unplanned ICU admission. The model performance was tested using bootstrap validation and compared with the Surgical Apgar Score using area under the curve for the receiver operating characteristic. Results:The logistic regression model included 16 variables: age, American Society of Anesthesiologists physical status, emergency case, surgical service, and 12 intraoperative variables. The area under the curve was 0.905 (95% CI, 0.900–0.909). The bootstrap validation model area under the curves were 0.513 at booking, 0.688 at 3 h before case end, 0.738 at 2 h, 0.791 at 1 h, and 0.809 at case end. The Surgical Apgar Score area under the curve was 0.692. Unplanned ICU admissions had more ICU-free days than planned ICU admissions (5 vs. 4; P < 0.001) and similar mortality (5.6 vs. 6.0%; P = 0.248). Conclusions:The authors have developed and internally validated an intraoperative predictive model for unplanned postoperative ICU use. Incorporation of this model into a real-time data sniffer may improve the process of allocating ICU beds for postoperative patients.

The changing scope of difficult airway management

To the Editor, Over the past decade, the introduction of video laryngoscopes has resulted in dramatic changes in how we secure difficult airways. Consequently, anesthesia societies worldwide are including these devices in their clinical and training guidelines (e.g., Association of Canadian University Departments of Anesthesia [ACUDA] 2010 National Curriculum for Canadian Anesthesia Residency, the 2012 Australian and New Zealand Guidelines on Equipment to Manage a Difficult Airway During Anaesthesia, and the 2013 American Society of Anesthesiologists [ASA] Practice Guidelines for Management of the Difficult Airway). Over the same time, advances in supraglottic airways (SGAs) have given practitioners additional options. While awake fibreoptic intubation (FOI) is still considered the mainstay of known difficult airway management, recent work has shown that awake video laryngoscopy and FOI may provide similar results. These technological advances (e.g., SGA and video laryngoscopy), in conjunction with guideline changes, have substantially altered the practice of general anesthesia. We report a single-institution analysis of 12 years of anesthetic records that shows a rise in the use of supraglottic airways, Eschmann Tracheal Tube Introducers (bougies), and video laryngoscopes while observing a decrease in difficult airways. This work was approved by the Institutional Review Board at Vanderbilt University (protocol 110613). Our institution utilizes the GasChart application which was developed in-house as our anesthesia informatics management system and is commercially available. Airway management within our system is documented in a structured manner where usage of a SGA, fibreoptic scope, bougie, and video laryngoscope is charted discretely. Additionally, difficulty of intubation is documented as easy, moderate, difficult, or impossible by the anesthesia provider. For this analysis, difficult intubations were defined as those documented as difficult or impossible. We identified 542,993 anesthetics in adults from March 2001 through February 2013 and analyzed airway management by quarter in the 317,509 records where placement of an endotracheal tube or SGA was documented. We created an infographic to examine J. P. Wanderer, MD (&) J. M. Ehrenfeld, MD W. S. Sandberg, MD, PhD Department of Anesthesiology, Vanderbilt University, Nashville, TN, USA e-mail: Jonathan.p.wanderer@vanderbilt.edu

Supervising anesthesiologists cannot be effectively compared according to their patients' postanesthesia care unit admission pain scores.

BACKGROUND:Measurement of postoperative pain scores on arrival to the postanesthesia care unit (PACU) is a potential quality metric for supervising anesthesiologists. Our goal in this study was to determine whether rank-ordering by initial PACU numeric rating scale (NRS) pain score, as collected by nurses in a nonresearch clinical setting, could be used to compare anesthesiologists after adjusting for confounding factors. METHODS:For a large population of adult patients, the admission PACU NRS pain scores (0–10) were evaluated using proportional odds mixed effects models. Fixed effects included age, gender, race, opioids in the preoperative medication list, American Society of Anesthesiologists (ASA) physical status classification, emergency surgery, laparoscopic approach, outpatient status, anesthesiologist, and PACU nurse; surgeon and surgical procedure were included as random effects. RESULTS:A total of 26,680 initial PACU pain scores were analyzed. The PACU nurse had the largest observed association with initial PACU pain score. Compared with the nurse with the median covariate adjusted NRS score, the odds ratio (OR) for an increased reported pain score ranged from 0.16 (95% confidence interval [CI] 0.11 to 0.24) to 2.95 (95% CI 2.43 to 3.59). For anesthesiologists, the ORs for an increase in reported pain ranged from 0.60 (95% CI 0.37 to 0.99) to 1.44 (95% CI 0.98 to 2.11). Factors associated with increased pain scores were preoperative opioids, female gender, and ASA physical status 2 and 3. Lower pain scores were associated with outpatient surgery, laparoscopy, African American race, and older patients. CONCLUSIONS:There is little to no evidence to suggest that supervising anesthesiologists can be compared with one another effectively using admission PACU NRS pain scores. The confounding association of the PACU nurse eliciting the admission pain score greatly exceeded the contribution by the anesthesiologist.

Decision support using anesthesia information management system records and accreditation council for graduate medical education case logs for resident operating room assignments.

Our goal in this study was to develop decision support systems for resident operating room (OR) assignments using anesthesia information management system (AIMS) records and Accreditation Council for Graduate Medical Education (ACGME) case logs and evaluate the implementations. We developed 2 Web-based systems: an ACGME case-log visualization tool, and Residents Helping in Navigating OR Scheduling (Rhinos), an interactive system that solicits OR assignment requests from residents and creates resident profiles. Resident profiles are snapshots of the cases and procedures each resident has done and were derived from AIMS records and ACGME case logs. A Rhinos pilot was performed for 6 weeks on 2 clinical services. One hundred sixty-five requests were entered and used in OR assignment decisions by a single attending anesthesiologist. Each request consisted of a rank ordered list of up to 3 ORs. Residents had access to detailed information about these cases including surgeon and patient name, age, procedure type, and admission status. Success rates at matching resident requests were determined by comparing requests with AIMS records. Of the 165 requests, 87 first-choice matches (52.7%), 27 second-choice matches (16.4%), and 8 third-choice matches (4.8%) were made. Forty-three requests were unmatched (26.1%). Thirty-nine first-choice requests overlapped (23.6%). Full implementation followed on 8 clinical services for 8 weeks. Seven hundred fifty-four requests were reviewed by 15 attending anesthesiologists, with 339 first-choice matches (45.0%), 122 second-choice matches (16.2%), 55 third-choice matches (7.3%), and 238 unmatched (31.5%). There were 279 overlapping first-choice requests (37.0%). The overall combined match success rate was 69.4%. Separately, we developed an ACGME case-log visualization tool that allows individual resident experiences to be compared against case minimums as well as resident peer groups. We conclude that it is feasible to use ACGME case-log data in decision support systems for informing resident OR assignments. Additional analysis will be necessary to assess the educational impact of these systems.