Kevin K. Tremper

Concordia University–Ann Arbor, Ann Arbor, Michigan, United States

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Publications (223)914.71 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Intraoperative electrocardiographic monitoring is considered a standard of care. However, there are no evidence-based algorithms for using intraoperative ST segment data to identify patients at high risk for adverse perioperative cardiac events. Therefore, we performed an exploratory study of statistical measures summarizing intraoperative ST segment values determine whether the variability of these measurements was associated with adverse postoperative events. We hypothesized that elevation, depression, and variability of ST segments captured in an anesthesia information management system are associated with postoperative serum troponin elevation. We conducted a single-institution, retrospective study of intraoperative automated ST segment measurements from leads I, II, and III, which were recorded in the electronic anesthesia record of adult patients undergoing noncardiac surgery. The maximum, minimum, mean, and SD of ST segment values were entered into logistic regression models to find independent associations with myocardial injury, defined as an elevated serum troponin concentration during the 7 days after surgery. Performance of these models was assessed by measuring the area under the receiver operator characteristic curve. The net reclassification improvement was calculated to quantify the amount of information that the ST segment values analysis added regarding the ability to predict postoperative troponin elevation. Of 81,011 subjects, 4504 (5.6%) had postoperative myocardial injury. After adjusting for patient characteristics, the ST segment maximal depression (e.g., lead I: odds ratio [OR], 1.66; 95% confidence interval [CI], 1.26-2.19; P = 0.0004), maximal elevation (e.g., lead I: OR, 1.70; 95% CI, 1.34-2.17; P < 0.0001), and SD (e.g., lead I: OR, 0.16; 95% CI, 0.06-0.42; P = 0.0002) were found to have statistically significant associations with myocardial injury. Increased SD was associated with decreased risk when accounting for the maximal amount of ST segment depression and elevation and for patient characteristics. The ST segment summary statistics model had fair discrimination, with an area under the receiver operator characteristic curve of 0.71 (95% CI, 0.68-0.73). Addition of ST segment data produced a net reclassification improvement of 0.0345 (95% CI, 0.00016-0.0591; P = 0.0474). Analysis of automated ST segment values obtained during anesthesia may be useful for improving the prediction of postoperative troponin elevation.
    Anesthesia and analgesia 05/2015; DOI:10.1213/ANE.0000000000000803 · 3.47 Impact Factor
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    ABSTRACT: An educational intervention was implemented at the University of Michigan starting in 2008, in which anesthesiology interns complete a dedicated month-long didactic rotation in evidence-based medicine (EBM) and research methodology. We sought to assess its utility. Scores on a validated EBM test before and after the rotation were compared and assessed for significance of improvement. A survey was also given to gauge satisfaction with the quality of the rotation and self-reported improvement in understanding of EBM topics. Fourteen consecutive interns completed the research rotation during the study period. One hundred percent completed both the pre- and postrotation test. The mean pretest score was 7.78 ± 2.46 (median = 7.5, 0-15 scale, and interquartile range 7.0-10.0) and the mean posttest score was 10.00 ± 2.35 (median = 9.5, interquartile range 8.0-12.3), which represented a statistically significant increase (P = 0.011, Wilcoxon signed-rank test). All fourteen of the residents "agreed" or "strongly agreed" that they would recommend the course to future interns and that the course increased their ability to critically review the literature. Our findings demonstrate that this can be an effective means of improving understanding of EBM topics and anesthesiology research.
    Anesthesiology Research and Practice 01/2015; 2015:1-4. DOI:10.1155/2015/623959
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    ABSTRACT: 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.
    European Journal of Anaesthesiology 07/2014; 32(5). DOI:10.1097/EJA.0000000000000123 · 2.94 Impact Factor
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    ABSTRACT: Heart failure (HF) is an important risk factor for perioperative morbidity and mortality. While these patients are at high risk for cardiac adverse events, there are few current data describing the types of noncardiac complications that occur in this population. We performed a multicenter cohort study of patients undergoing noncardiac surgery from 2005 to 2010 as part of the American College of Surgeons National Surgical Quality Improvement Program. A HF cohort (HF that is new or worsening within 30 days of surgery) was compared with a control cohort that was matched regarding other surgical risk factors. Five thousand ninety-four patients with worsening preoperative HF were compared with an otherwise similar cohort of patients without worsening preoperative HF. Worsening preoperative HF was associated with increased risk of 30-day all-cause mortality (relative risk [RR] 2.08; 95% confidence interval [CI], 1.75-2.46; P < 0.001) and increased risk of morbidity (any recorded postoperative complication) (RR 1.54; 95% CI, 1.40-1.69; P < 0.001). HF patients had increased risk of developing renal failure (RR 1.85; 95% CI, 1.37-2.49; P < 0.001), need for mechanical ventilation longer than 48 hours (RR 1.81; 95% CI, 1.52-2.15; P < 0.001), pneumonia (RR 1.73; 95% CI, 1.44-2.08; P < 0.001), cardiac arrest (RR 1.69; 95% CI, 1.29-2.21; P < 0.001), unplanned intubation (RR 1.68; 95% CI, 1.41-1.99; P < 0.001), renal insufficiency (RR 1.64; 95% CI, 1.10-2.44; P = 0.014), sepsis (RR 1.43, 95% CI, 1.24-1.64; P < 0.001), and urinary tract infection (RR 1.29; 95% CI, 1.06-1.58; P = 0.011). The incidence of myocardial infarction in the sample was similar between the 2 groups (RR 1.07; 95% CI, 0.75-1.52; P = 0.719). Worsening preoperative HF is associated with a significant increase in postoperative morbidity and mortality when controlling for other comorbidities. Although these likely have a multifactorial etiology, patients are much more likely to suffer from respiratory, renal, and infectious complications than cardiac complications.
    Anesthesia and analgesia 04/2014; 119(3). DOI:10.1213/ANE.0000000000000116 · 3.47 Impact Factor
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    ABSTRACT: We describe a pilot study investigating the airway techniques used in the anesthetic management of subglottic stenosis. We searched the electronic clinical information database of the University of Michigan Health System for cases of subglottic stenosis in patients undergoing surgery. Demographics, airway techniques, incidence of hypoxemia, and technique failure were extracted from 159 records. A lower incidence of hypoxemia was found between the 4 most commonly used techniques and the less common techniques. We detected no difference in outcome between individual techniques. This study suggests a larger prospective multicenter study is required to further investigate these outcomes in patients with subglottic stenosis.
    Anesthesia and analgesia 12/2013; 117(6):1352-1354. DOI:10.1213/ANE.0b013e3182a6d1ab · 3.47 Impact Factor
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    ABSTRACT: 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. 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. 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]). 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.
    Anesthesiology 09/2013; 119(6). DOI:10.1097/ALN.0000435832.39353.20 · 5.88 Impact Factor
  • Survey of Anesthesiology 08/2013; 57(4):192-193. DOI:10.1097/01.SA.0000431228.86571.a8
  • Kevin K Tremper
    Anesthesiology 07/2013; 119(6). DOI:10.1097/ALN.0b013e3182a17ced · 5.88 Impact Factor
  • Anesthesia and analgesia 06/2013; 116(6):1390. · 3.47 Impact Factor
  • Anesthesia & Analgesia 06/2013; 116(6):1390-1390. DOI:10.1213/ANE.0b013e31828f8ebe · 3.47 Impact Factor
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    ABSTRACT: Background: Numerous risk factors have been identified for perioperative stroke, but there are conflicting data regarding the role of β adrenergic receptor blockade in general and metoprolol in particular. Methods: The authors retrospectively screened 57,218 consecutive patients for radiologic evidence of stroke within 30 days after noncardiac procedures at a tertiary care university hospital. Incidence of perioperative stroke within 30 days of surgery and associated risk factors were assessed. Patients taking either metoprolol or atenolol were matched based on a number of risk factors for stroke. Parsimonious logistic regression was used to generate a preoperative risk model for perioperative stroke in the unmatched cohort. Results: The incidence of perioperative stroke was 55 of 57,218 (0.09%). Preoperative metoprolol was associated with an approximately 4.2-fold increase in perioperative stroke (P < 0.001; 95% CI, 2.2-8.1). Analysis of matched cohorts revealed a significantly higher incidence of stroke in patients taking preoperative metoprolol compared with atenolol (P = 0.016). However, preoperative metoprolol was not an independent predictor of stroke in the entire cohort, which included patients who were not taking β blockers. The use of intraoperative metoprolol was associated with a 3.3-fold increase in perioperative stroke (P = 0.003; 95% CI, 1.4-7.8); no association was found for intraoperative esmolol or labetalol. Conclusions: Routine use of preoperative metoprolol, but not atenolol, is associated with stroke after noncardiac surgery, even after adjusting for comorbidities. Intraoperative metoprolol but not esmolol or labetalol, is associated with increased risk of perioperative stroke. Drugs other than metoprolol should be considered during the perioperative period if β blockade is required.
    Anesthesiology 04/2013; 119(6). DOI:10.1097/ALN.0b013e318295a25f · 5.88 Impact Factor
  • Anesthesia and analgesia 04/2013; 116(4):949-50. · 3.47 Impact Factor
  • Anesthesia & Analgesia 04/2013; 116(4):949-950. DOI:10.1213/ANE.0b013e3182861154 · 3.47 Impact Factor
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    ABSTRACT: Background: Superiority of the modified Brice interview over quality assurance techniques in detecting intraoperative awareness with explicit recall has not been demonstrated definitively. Methods: We studied a single patient cohort to compare the detection of definite awareness using a single modified Brice interview (postoperative day 28-30) versus quality assurance data (postoperative day 1). Results: The incidence of awareness based on the modified Brice interview was 19 per 18,847 or 0.1%. Fewer awareness cases (incidence 0.02%) were detected by the quality assurance approach (P < 0.0001). Conclusion: The modified Brice interview is the preferred modality for assessing intraoperative awareness with explicit recall.
    Anesthesia and analgesia 03/2013; 116(4). DOI:10.1213/ANE.0b013e318281e9ad · 3.47 Impact Factor
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    ABSTRACT: Study Objective: To investigate whether alerting providers to errors results in improved documentation of reimbursable anesthesia care. Design: Prospective randomized controlled trial. Setting: Operating room (OR) of a university hospital. Interventions: Anesthesia cases were evaluated to determine whether they met the definition for appropriate anesthesia start time over 4 separate, 45-day calendar cycles: the pre-study period, study period, immediate post-study period, and 3-year follow-up period. During the study period, providers were randomly assigned to either a control or an alert group. Providers in the alert cohort received an automated alphanumeric page if the anesthesia start time occurred concurrently with the patient entering the OR, or more than 30 minutes before entering the OR. Measurements: Three years after the intervention period, overall compliance was analyzed to assess learned behavior. Main Results: Baseline compliance was 33% ± 5%. During the intervention period, providers in the alert group showed 87% ± 6% compliance compared with 41% ± 7% compliance in the control group (P < 0.001). Long-term follow-up after cessation of the alerts showed 85% ± 4% compliance. Conclusions: Automated electronic reminders for time-based billing charges are effective and result in improved ongoing reimbursement.
    Journal of clinical anesthesia 01/2013; 25(2). DOI:10.1016/j.jclinane.2012.06.020 · 1.19 Impact Factor
  • Anesthesia and analgesia 01/2013; 57(6):296-298. DOI:10.1097/01.SA.0000435539.12797.60 · 3.47 Impact Factor
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    ABSTRACT: Background: Intraoperative awareness with explicit recall occurs in approximately 0.15% of all surgical cases. Efficacy trials based on the Bispectral Index® (BIS) monitor (Covidien, Boulder, CO) and anesthetic concentrations have focused on high-risk patients, but there are no effectiveness data applicable to an unselected surgical population. Methods: We conducted a randomized controlled trial of unselected surgical patients at three hospitals of a tertiary academic medical center. Surgical cases were randomized to alerting algorithms based on either BIS values or anesthetic concentrations. The primary outcome was the incidence of definite intraoperative awareness; prespecified secondary outcomes included postanesthetic recovery variables. Results: The study was terminated because of futility. At interim analysis the incidence of definite awareness was 0.12% (11/9,376) (95% CI: 0.07-0.21%) in the anesthetic concentration group and 0.08% (8/9,460) (95% CI: 0.04-0.16%) in the BIS group (P = 0.48). There was no significant difference between the two groups in terms of meeting criteria for recovery room discharge or incidence of nausea and vomiting. By post hoc secondary analysis, the BIS protocol was associated with a 4.7-fold reduction in definite or possible awareness events compared with a cohort receiving no intervention (P = 0.001; 95% CI: 1.7-13.1). Conclusion: This negative trial could not detect a difference in the incidence of definite awareness or recovery variables between monitoring protocols based on either BIS values or anesthetic concentration. By post hoc analysis, a protocol based on BIS monitoring reduced the incidence of definite or possible intraoperative awareness compared with routine care.
    Anesthesiology 10/2012; 117(4):717-725. DOI:10.1097/ALN.0b013e31826904a6 · 5.88 Impact Factor
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    ABSTRACT: In this case report, the authors present an adverse event possibly caused by miscommunication among three separate medical teams at their hospital. The authors then discuss the hospital's root cause analysis and its proposed solutions, focusing on the subsequent hospital-wide implementation of an automated electronic reminder for abnormal laboratory values that may have helped to prevent similar medical errors.
    BMJ quality & safety 07/2012; 21(10):850-4. DOI:10.1136/bmjqs-2011-000666 · 3.99 Impact Factor
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    ABSTRACT: The purpose of this review is to present a comprehensive assessment of the anesthesia workforce during the past decade and attempt forecasting the future based on present knowledge. The supply of anesthesiologists has gradually recovered from a deficit in the mid to late 1990 s. Current entry rates into our specialty are the highest in more than a decade, but are still below the level they were in 1993. These factors along with slower surgical growth and less capital available for expanding anesthetizing locations have resulted in greater availability of anesthesiologists in the labor market. Despite these recent events, the intermediate-term outlook of a rapidly aging population and greater access of previously uninsured patients portends the need to accommodate increasing medical and surgical procedures requiring anesthesia, barring disruptive industry innovations. Late in the decade, nationwide surveys found shortages of anesthesiologists and certified registered nurse anesthetists to persist. In response to increasing training program output with stagnant surgical growth, compensation increases for these allied health professionals have moderated in the present. Future projections anticipate increased personnel availability and, possibly, less compensation for this group. It is important to understand that many of the factors constraining current demand for anesthesia personnel are temporary. Anesthesiologist supply constrained by small graduation growth combined with generation- and gender-based decrements in workforce contribution is unlikely to keep pace with the substantial population and public policy-generated growth in demand for service, even in the face of productivity improvements and innovation.
    Anesthesia and analgesia 07/2012; 115(2):407-27. DOI:10.1213/ANE.0b013e3182575b4e · 3.47 Impact Factor
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    ABSTRACT: 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. 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. 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. 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.
    Anesthesiology 04/2012; 116(6):1217-26. DOI:10.1097/ALN.0b013e318255e6ab · 5.88 Impact Factor

Publication Stats

4k Citations
914.71 Total Impact Points


  • 1997–2015
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States
  • 1987–2014
    • University of Michigan
      • Department of Anesthesiology
      Ann Arbor, Michigan, United States
  • 2004
    • Yale University
      New Haven, Connecticut, United States
  • 2003
    • Albert Einstein College of Medicine
      New York City, New York, United States
  • 1993
    • Long Beach Memorial Medical Center
      Long Beach, California, United States
  • 1983–1993
    • University of California, Irvine
      • • Department of Anesthesiology and Perioperative Care
      • • Department of Surgery
      Irvine, California, United States
  • 1981–1982
    • Harbor-UCLA Medical Center
      Torrance, California, United States
    • Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center
      Torrance, California, United States
  • 1979–1981
    • University of California, Los Angeles
      Los Ángeles, California, United States