Person:
Mueller, Ariel

Profile Picture

Email Address

AA Acceptance Date

Birth Date

Research Projects

Organizational Units

Job Title

Last Name

Mueller

First Name

Ariel

Name

Mueller, Ariel
Author's Publications: search.filters.isAuthorOfPublication.7addb013-53dc-466c-b635-eaefc5e78b3b

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Publication
    Preoperative asymptomatic leukocytosis and postoperative outcome in cardiac surgery patients
    (Public Library of Science, 2017) Mahmood, Eitezaz; Knio, Ziyad O.; Mahmood, Feroze; Amir, Rabia; Shahul, Sajid; Mahmood, Bilal; Baribeau, Yanick; Mueller, Ariel; Matyal, Robina
    Background: Despite showing a prognostic value in general surgical patients, preoperative asymptomatic elevated white blood cell (WBC) count is not considered a risk factor for cardiac surgery. Whereas there is sporadic evidence of its value as a preoperative risk marker, it has not been looked at methodically as a specific index of outcome during cardiac surgery. Using a national database we sought to determine the relationship between preoperative WBC count and postoperative outcome in cardiac surgical patients. Methods: Cardiac surgeries were extracted from the 2007–2013 American College of Surgeons National Surgical Quality Improvement Program database. Leukocytosis was defined by a preoperative WBC count greater than 11,000 cells/μL. A univariate analysis compared the incidence of adverse outcomes for patients with and without leukocytosis. A multivariate logistic regression model was constructed in order to test whether leukocytosis was an independent predictor of morbidity and mortality. Results: Out of a total of 10,979 cardiac surgery patients 863 (7.8%) had preoperative leukocytosis. On univariate analysis, patients with leukocytosis experienced greater incidences of 30-day mortality, wound complications, and medical complications. Wound complications included surgical site infection as well as wound dehiscence. The medical complications included all other non-surgical causes of increased morbidity and infection leading to urinary tract infection, pneumonia, ventilator dependence, sepsis and septic shock. After stepwise model adjustment, leukocytosis was a strong predictor of medical complications (OR 1.22, 95% CI: 1.09–1.36, p = 0.002) with c-statistic of 0.667. However, after stepwise model adjustment leukocytosis was not a significant predictor of 30-day mortality and wound complications. Conclusion: Preoperative leukocytosis is associated with adverse postoperative outcome after cardiac surgery and is an independent predictor of infection-related postoperative complications.
  • Thumbnail Image
    Publication
    Shock subtypes by left ventricular ejection fraction following out-of-hospital cardiac arrest
    (BioMed Central, 2018) Anderson, Ryan J.; Jinadasa, Sayuri; Hsu, Leeyen; Ghafouri, Tiffany Bita; Tyagi, Sanjeev; Joshua, Jisha; Mueller, Ariel; Talmor, Daniel; Sell, Rebecca E.; Beitler, Jeremy R.
    Background: Post-resuscitation hemodynamic instability following out-of-hospital cardiac arrest (OHCA) may occur from myocardial dysfunction underlying cardiogenic shock and/or inflammation-mediated distributive shock. Distinguishing the predominant shock subtype with widely available clinical metrics may have prognostic and therapeutic value. Methods: A two-hospital cohort was assembled of patients in shock following OHCA. Left ventricular ejection fraction (LVEF) was assessed via echocardiography or cardiac ventriculography within 1 day post arrest and used to delineate shock physiology. The study evaluated whether higher LVEF, indicating distributive-predominant shock physiology, was associated with neurocognitive outcome (primary endpoint), survival, and duration of multiple organ failures. The study also investigated whether volume resuscitation exhibited a subtype-specific association with outcome. Results: Of 162 patients with post-resuscitation shock, 48% had normal LVEF (> 40%), consistent with distributive shock physiology. Higher LVEF was associated with less favorable neurocognitive outcome (OR 0.74, 95% CI 0.58–0.94 per 10% increase in LVEF; p = 0.01). Higher LVEF also was associated with worse survival (OR 0.81, 95% CI 0.67–0.97; p = 0.02) and fewer organ failure-free days (β = – 0.67, 95% CI – 1.28 to − 0.06; p = 0.03). Only 51% of patients received a volume challenge of at least 30 ml/kg body weight in the first 6 h post arrest, and the volume received did not differ by LVEF. Greater volume resuscitation in the first 6 h post arrest was associated with favorable neurocognitive outcome (OR 1.59, 95% CI 0.99–2.55 per liter; p = 0.03) and survival (OR 1.44, 95% CI 1.02–2.04; p = 0.02) among patients with normal LVEF but not low LVEF. Conclusions: In post-resuscitation shock, higher LVEF—indicating distributive shock physiology—was associated with less favorable neurocognitive outcome, fewer days without organ failure, and higher mortality. Greater early volume resuscitation was associated with more favorable neurocognitive outcome and survival in patients with this shock subtype. Additional studies with repeated measures of complementary hemodynamic parameters are warranted to validate the clinical utility for subtyping post-resuscitation shock. Electronic supplementary material The online version of this article (10.1186/s13054-018-2078-x) contains supplementary material, which is available to authorized users.
  • Thumbnail Image
    Publication
    Predicting Mortality in Low-Income Country ICUs: The Rwanda Mortality Probability Model (R-MPM)
    (Public Library of Science, 2016) Riviello, Beth; Kiviri, Willy; Fowler, Robert A.; Mueller, Ariel; Novack, Victor; Banner-Goodspeed, Valerie M.; Weinkauf, Julia L.; Talmor, Daniel; Twagirumugabe, Theogene
    Introduction: Intensive Care Unit (ICU) risk prediction models are used to compare outcomes for quality improvement initiatives, benchmarking, and research. While such models provide robust tools in high-income countries, an ICU risk prediction model has not been validated in a low-income country where ICU population characteristics are different from those in high-income countries, and where laboratory-based patient data are often unavailable. We sought to validate the Mortality Probability Admission Model, version III (MPM0-III) in two public ICUs in Rwanda and to develop a new Rwanda Mortality Probability Model (R-MPM) for use in low-income countries. Methods: We prospectively collected data on all adult patients admitted to Rwanda’s two public ICUs between August 19, 2013 and October 6, 2014. We described demographic and presenting characteristics and outcomes. We assessed the discrimination and calibration of the MPM0-III model. Using stepwise selection, we developed a new logistic model for risk prediction, the R-MPM, and used bootstrapping techniques to test for optimism in the model. Results: Among 427 consecutive adults, the median age was 34 (IQR 25–47) years and mortality was 48.7%. Mechanical ventilation was initiated for 85.3%, and 41.9% received vasopressors. The MPM0-III predicted mortality with area under the receiver operating characteristic curve of 0.72 and Hosmer-Lemeshow chi-square statistic p = 0.024. We developed a new model using five variables: age, suspected or confirmed infection within 24 hours of ICU admission, hypotension or shock as a reason for ICU admission, Glasgow Coma Scale score at ICU admission, and heart rate at ICU admission. Using these five variables, the R-MPM predicted outcomes with area under the ROC curve of 0.81 with 95% confidence interval of (0.77, 0.86), and Hosmer-Lemeshow chi-square statistic p = 0.154. Conclusions: The MPM0-III has modest ability to predict mortality in a population of Rwandan ICU patients. The R-MPM is an alternative risk prediction model with fewer variables and better predictive power. If validated in other critically ill patients in a broad range of settings, the model has the potential to improve the reliability of comparisons used for critical care research and quality improvement initiatives in low-income countries.
  • Thumbnail Image
    Publication
    Intraoperative oxygen concentration and neurocognition after cardiac surgery: study protocol for a randomized controlled trial
    (BioMed Central, 2017) Shaefi, Shahzad; Marcantonio, Edward; Mueller, Ariel; Banner-Goodspeed, Valerie; Robson, Simon; Spear, Kyle; Otterbein, Leo; O’Gara, Brian P.; Talmor, Daniel; Subramaniam, Balachundhar
    Background: Postoperative cognitive dysfunction (POCD) is a common complication of cardiac surgery. Studies have identified potentially injurious roles for cardiopulmonary bypass (CPB) and subsequent reperfusion injury. Cognitive dysfunction has also been linked to the deleterious effects of hyperoxia following ischemia-reperfusion injuries in several disease states, but there has been surprisingly little study into the role of hyperoxia in reperfusion injury after CPB. The potential for tightly regulated intraoperative normoxia to ameliorate the neurocognitive decline following cardiac surgery has not been investigated in a prospective manner. We hypothesize that the use of a protocolized management strategy aimed towards maintenance of an intraoperative normoxic level of oxygen, as opposed to hyperoxia, will reduce the incidence of POCD in older patients undergoing cardiac surgery. Methods/Design One hundred patients aged 65 years and older undergoing non-emergency coronary artery bypass grafting surgery on cardiopulmonary bypass will be enrolled in this prospective, randomized, controlled trial. Subjects will be randomized to receive a fraction of inspired oxygen of either 35% or 100% while under general anesthesia throughout the intraoperative period. The primary outcome measure will be the incidence of POCD in the acute postoperative phase and up to 6 months. The assessment of neurocognition will be undertaken by trained personnel, blinded to study group, with the telephone Montreal Cognitive Assessment (t-MoCA) tool. Secondary outcome measures will include assessment of delirium using the Confusion Assessment Method (CAM and CAM-ICU), as well as time to extubation, days of mechanical ventilation, length of ICU and hospital stay and mortality at 6 months. With the aim of later identifying mechanistic aspects of the effect of oxygen tension, blood, urine, and atrial tissue specimens will be taken at various time points during the perioperative period and later analyzed. Discussion This trial will be one of the first randomized controlled studies to prospectively assess the relationship between intraoperative oxygen levels and postoperative neurocognition in cardiac surgery. It addresses a promising biological avenue of intervention in this vulnerable aging population. Trial registration ClinicalTrials.gov Identifier: NCT02591589, registered February 13, 2015. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-2337-1) contains supplementary material, which is available to authorized users.