Clinical Focus

  • Pediatric Critical Care Medicine
  • Pediatric Cardiac Critical Care

Academic Appointments

Professional Education

  • Board Certification: American Board of Pediatrics, Pediatrics (2012)
  • Fellowship: Boston Children's Hospital (2015) MA
  • Board Certification: American Board of Pediatrics, Pediatric Critical Care Medicine (2014)
  • Fellowship: Boston Children's Hospital (2014) MA
  • Residency: Boston Children's Hospital (2011) MA
  • Medical Education: University of Massachusetts Medical School (2008) MA

All Publications

  • Neurosurgical intervention in children with ventricular assist devices: A single center case series review. Paediatric anaesthesia Yu, J., Murray, J., Ramamoorthy, C., Chen, S., Lee, S., Ryan, K., Maeda, K., Navaratnam, M. 2021


    BACKGROUND: The incidence of neurological complications related to ventricular assist devices (VAD) remains high and includes life-threatening conditions such as intracranial hemorrhage or ischemic stroke. Although no definitive management guidelines exist, operative interventions may be required for major neurological injuries.AIMS: This case series describes the perioperative management of children at a single center who underwent neurosurgical procedures for major intracranial bleeds or ischemic strokes whilst on VAD support.METHODS: A database review identified all pediatric VAD patients who underwent a neurosurgical procedure for an intracranial hemorrhage or ischemic stroke from April 2014 to January 2020. Data regarding patient characteristics, preoperative medical management, intraoperative anesthetic management, and postoperative outcomes were collected using retrospective chart review.RESULTS: Ninety VADs were implanted in 78 patients. Five neurosurgical interventions were performed: 4 for intracranial hemorrhages and 1 for an ischemic stroke. All 4 patients with hemorrhages were receiving anticoagulation at the time of their event and the 3 patients on warfarin received emergent reversal with prothrombin concentrate complex and vitamin K. Three patients also received pre-procedural platelet transfusions. Two of the 5 procedures were emergent bedside external ventricular drain placements and 3 were surgical operations. All 3 patients who underwent operative procedures received invasive hemodynamic monitoring and were supported with a combination of inotropes and afterload reduction. One patient required a massive blood product transfusion. The 2 patients who underwent external ventricular drain placement had no further surgical interventions and died from the severity of their neurological injuries. All 3 patients who underwent operative procedures survived to transplantation and discharge home.CONCLUSIONS: Perioperative concerns for the anesthesiologist include VAD hemodynamic management, bleeding, VAD thrombosis, and prevention of secondary brain injury. A systematic, multidisciplinary approach to management is paramount to attain favorable outcomes.

    View details for DOI 10.1111/pan.14287

    View details for PubMedID 34478592

  • Evaluation of Seizure Risk in Infants After Cardiopulmonary Bypass in the Absence of Deep Hypothermic Cardiac Arrest. Neurocritical care Levy, R. J., Mayne, E. W., Sandoval Karamian, A. G., Iqbal, M., Purington, N., Ryan, K. R., Wusthoff, C. J. 2021


    BACKGROUND: Guidelines recommend evaluation for electrographic seizures in neonates and children at risk, including after cardiopulmonary bypass (CPB). Although initial research using screening electroencephalograms (EEGs) in infants after CPB found a 21% seizure incidence, more recent work reports seizure incidences ranging 3-12%. Deep hypothermic cardiac arrest was associated with increased seizure risk in prior reports but is uncommon at our institution and less widely used in contemporary practice. This study seeks to establish the incidence of seizures among infants following CPB in the absence of deep hypothermic cardiac arrest and to identify additional risk factors for seizures via a prediction model.METHODS: A retrospective chart review was completed of all consecutive infants≤3months who received screening EEG following CPB at a single center within a 2-year period during 2017-2019. Clinical and laboratory data were collected from the perioperative period. A prediction model for seizure risk was fit using a random forest algorithm, and receiver operator characteristics were assessed to classify predictions. Fisher's exact test and the logrank test were used to evaluate associations between clinical outcomes and EEG seizures.RESULTS: A total of 112 infants were included. Seizure incidence was 10.7%. Median time to first seizure was 28.1h (interquartile range 18.9-32.2h). The most important factors in predicting seizure risk from the random forest analysis included postoperative neuromuscular blockade, prematurity, delayed sternal closure, bypass time, and critical illness preoperatively. When variables captured during the EEG recording were included, abnormal postoperative neuroimaging and peak lactate were also highly predictive. Overall model accuracy was 90.2%; accounting for class imbalance, the model had excellent sensitivity and specificity (1.00 and 0.89, respectively).CONCLUSIONS: Seizure incidence was similar to recent estimates even in the absence of deep hypothermic cardiac arrest. By employing random forest analysis, we were able to identify novel risk factors for postoperative seizure in this population and generate a robust model of seizure risk. Further work to validate our model in an external population is needed.

    View details for DOI 10.1007/s12028-021-01313-1

    View details for PubMedID 34322828

  • Mid-Term Outcomes After Unifocalization Guided by Intraoperative Pulmonary Flow Study. World journal for pediatric & congenital heart surgery Goodman, A., Ma, M., Zhang, Y., Ryan, K. R., Jahadi, O., Wise-Faberowski, L., Hanley, F. L., McElhinney, D. B. 2021; 12 (1): 76–83


    BACKGROUND: Repair of tetralogy of Fallot (TOF) with major aortopulmonary collateral arteries (MAPCAs) requires unifocalization of pulmonary circulation, intracardiac repair with the closure of the ventricular septal defect, and placement of a right ventricle (RV) to pulmonary artery (PA) conduit. The decision to perform complete repair is sometimes aided by an intraoperative flow study to estimate the total resistance of the reconstructed pulmonary circulation.METHODS: We reviewed patients who underwent unifocalization and PA reconstruction for TOF/MAPCAs to evaluate acute and mid-term outcomes after repair with and without flow studies and to characterize the relationship between PA pressure during the flow study and postrepair RV pressure.RESULTS: Among 579 patients who underwent unifocalization and PA reconstruction for TOF/MAPCAs, 99 (17%) had an intraoperative flow study during one (n = 91) or more (n = 8) operations to determine the suitability for a complete repair. There was a reasonably good correlation between mean PA pressure at 3 L/min/m2 during the flow study and postrepair RV pressure and RV:aortic pressure ratio. Acute and mid-term outcomes (median: 3.8 years) after complete repair in the flow study patients (n = 78) did not differ significantly from those in whom the flow study was not performed (n = 444). Furthermore, prior failed flow study was not associated with differences in outcome after subsequent intracardiac repair.CONCLUSIONS: The intraoperative flow study remains a useful adjunct for determining the suitability for complete repair in a subset of patients undergoing surgery for TOF/MAPCAs, as it is reasonably accurate for estimating postoperative PA pressure and serves as a reliable guide for the feasibility of single-stage complete repair.

    View details for DOI 10.1177/2150135120964427

    View details for PubMedID 33407027

  • Compassionate Deactivation of Pediatric Ventricular Assist Devices: A Review of 14 Cases. Journal of pain and symptom management Hollander, S. A., Kaufman, B. D., Bui, C. n., Gregori, B. n., Murray, J. M., Sacks, L. n., Ryan, K. R., Ma, M. n., Rosenthal, D. N., Char, D. n. 2021


    Compassionate deactivation (CD) of ventricular assist device (VAD) support is a recognized option for children when the burden of therapy outweighs the benefits.To describe the prevalence, indications, and outcomes of CD of children supported by VADs at the end of life.Review of cases of CD at our institution between 2011-2020. To distinguish CD from other situations where VAD support is discontinued, patients were excluded from the study if they died during resuscitation (including ECMO), experienced brain or circulatory death prior to deactivation, or experienced a non-survivable brain injury likely to result in imminent death regardless of VAD status.Of 24 deaths on VAD, 14 (58%) were CD. Median age was 5.7 (IQR 0.6, 11.6) years; 6 (43%) had congenital heart disease; 4 (29%) were on a device that can be used outside of the hospital. CD occurred after 40 (IQR: 26, 75) days of support; none while active transplant candidates. CD discussions were initiated by the caregiver in 6 (43%) cases, with the remainder initiated by a medical provider. Reasons for CD were multifactorial, including end-organ injury, infection, and stroke. CD occurred with endotracheal extubation and/or discontinuation of inotropes in 12 (86%) cases, and death occurred within 10 (IQR: 4, 23) minutes of CD.CD is the mode of death in more than half of our VAD non-survivors and is pursued for reasons primarily related to noncardiac events. Caregivers and providers both initiate CD discussions. Ventilatory and inotropic support is often withdrawn at time of CD with ensuing death.

    View details for DOI 10.1016/j.jpainsymman.2021.01.125

    View details for PubMedID 33910026

  • Commentary: A new option for patch material on coronary artery ostium plasty JTCVS TECHNIQUES Maeda, K., Ryan, K. R. 2020; 4: 235-236
  • Commentary: A new option for patch material on coronary artery ostium plasty. JTCVS techniques Maeda, K., Ryan, K. R. 2020; 4: 235-236

    View details for DOI 10.1016/j.xjtc.2020.08.075

    View details for PubMedID 34318025

    View details for PubMedCentralID PMC8306519

  • Continuous EEG for Seizure Detection in Neonates after Cardiac Bypass without Deep Hypothermic Cardiac Arrest Levy, R., Karamian, A., Mayne, E., Iqbal, M., Purington, N., Ryan, K., Wusthoff, C. LIPPINCOTT WILLIAMS & WILKINS. 2020
  • The Use of Clevidipine for Hypertension in Pediatric Patients Receiving Mechanical Circulatory Support. Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies Wu, M. n., Ryan, K. R., Rosenthal, D. N., Jahadi, O. n., Moss, J. n., Kwiatkowski, D. M. 2020


    Limited data exist regarding the management of hypertension in pediatric patients on mechanical circulatory support. Hypertension is a known risk factor for stroke and low cardiac output in patients requiring mechanical circulatory support and a narrow therapeutic window of blood pressure is often targeted. Traditional short-acting infusions to treat hypertension, such as sodium nitroprusside, may lead to accumulation of toxic metabolites in patients with renal dysfunction. Our primary objective was to describe use of clevidipine, a continuous short-acting calcium channel blocking medication, for blood pressure control in pediatric patients on mechanical circulatory support.Single-center retrospective cohort study.A 26-bed quaternary cardiovascular ICU in a university-based pediatric hospital in California.Mechanical circulatory support patients admitted to cardiovascular ICU who received clevidipine infusions between October 1, 2016, and March 31, 2019.Clevidipine infusion.Data from a cohort of 38 patients who received a total of 45 clevidipine infusions were reviewed. The cohort had a median age of 2.7 years and included neonates. No patient had record of hypotensive events, code events, or received low-dose epinephrine or code-dosed epinephrine related to a clevidipine infusion. Median duration of clevidipine infusion was 4.1 days (1.5-9.2 d). Eleven patients transitioned from clevidipine to enteral antihypertensive agents, and 26 clevidipine infusions were administered as a single agent without sodium nitroprusside. Seven patients were switched from sodium nitroprusside to clevidipine to avoid cyanide toxicity, a majority of whom had elevated serum creatinine.In this pediatric cardiac cohort, clevidipine infusions were effective at hypertension management and were not associated with hypotensive or code events. This report details the largest cohort and longest duration of clevidipine administration within a pediatric population and did not demonstrate hypotensive events, even among neonatal populations. Clevidipine may be a reasonable cost-effective alternative antihypertensive medication compared to traditional short-acting agents.

    View details for DOI 10.1097/PCC.0000000000002562

    View details for PubMedID 32796396

  • Developments in Pediatric Ventricular Assist Device Support. World journal for pediatric & congenital heart surgery Tume, S. C., Conway, J., Ryan, K. R., Philip, J., Fortkiewicz, J. M., Murray, J. 2019: 2150135119880890


    Mechanical support devices have revolutionized the management of circulatory failure. This has been met by a dramatic increase in ventricular assist device (VAD) utilization in children over the last two decades. Previous wide gaps in experience and knowledge have significantly narrowed in the recent years. As we continue to gain experience with this technology, we face new challenges such as complex congenital circulations and small patient size. The emergence of new pharmacologic therapies and device technology offers more opportunities and requires constant adjustment in practice. As we continue to embark on this journey, constant insight is needed to refine patient selection criteria, minimize complications, and continue to push the field for safer smaller devices to accommodate these complex patient populations. In this review focused at inpatient critical care environment, we discuss the recent field developments and focus on challenging patient populations, the emergence of temporary support, management of anticoagulation, and diagnostic approach to stroke in the setting of VAD support.

    View details for DOI 10.1177/2150135119880890

    View details for PubMedID 31663841

  • Neurodevelopmental Outcomes Among Children With Congenital Heart Disease: At-Risk Populations and Modifiable Risk Factors. World journal for pediatric & congenital heart surgery Ryan, K. R., Jones, M. B., Allen, K. Y., Marino, B. S., Casey, F., Wernovsky, G., Lisanti, A. J. 2019: 2150135119878702


    As survivable outcomes among patients with complex congenital heart disease (cCHD) have continued to improve over the last several decades, more attention is being dedicated to interventions that impact not just survival but quality of life among patients with cCHD. In particular, patients with cCHD are at risk for impaired neurodevelopmental outcomes. In this review summarizing select presentations given at the 14th Annual Pediatric Cardiac Intensive Care Society's Annual Meeting in 2019, we discuss the neurodevelopmental phenotype of patients with cCHD, patients at greatest risk of impaired development, and three specific modifiable risk factors impacting development.

    View details for DOI 10.1177/2150135119878702

    View details for PubMedID 31658880

  • Vasoplegia after pediatric cardiac transplantation in patients supported with a continuous flow ventricular assist device JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Sacks, L. D., Hollander, S. A., Zhang, Y., Ryan, K. R., Ford, M. A., Maeda, K., Murray, J. M., Almond, C. S., Kwiatkowski, D. M. 2019; 157 (6): 2433–40
  • Vasoplegia after pediatric cardiac transplantation in patients supported with a continuous flow ventricular assist device. The Journal of thoracic and cardiovascular surgery Sacks, L. D., Hollander, S. A., Zhang, Y., Ryan, K. R., Ford, M. A., Maeda, K., Murray, J. M., Almond, C. S., Kwiatkowski, D. M. 2019


    OBJECTIVE: To determine the association between continuous flow ventricular assist devices and the incidence of vasoplegia following orthotopic heart transplant in children. Moreover, to propose a novel clinical definition of vasoplegia for use in pediatric populations.METHODS: This is a single-center, retrospective cohort study set in the cardiovascular intensive care unit of a tertiary children's hospital. All patients aged 3years and older who underwent orthotopic heart transplant at Stanford Universitybetween April 1, 2014, and July 31, 2017, were included. Vasoplegia was defined by the use of vasoconstrictive medication, diastolic hypotension, preserved systolic heart function, and absence of infection or right atrial pressure or central venous pressure <5mm Hg.RESULTS: Of 44 eligible patients, 21 were supported using a continuous flow ventricular assist device. Following heart transplant, 14 patients (32%) developed vasoplegia by the study definition. Development of vasoplegia was associated with pretransplant use of a continuous flow ventricular assist device (52% vs 13%) with a relative risk of 4.02 (95% confidence interval, 1.30-12.45; P=.009). No other variables were predictive of vasoplegia in univariable analysis. Presence of vasoplegia was not associated with adverse outcomes, although there were trends towards higher incidence of acute kidney injury and increased length of hospital stays.CONCLUSIONS: Children receiving continuous flow ventricular assist device support are at increased risk for vasoplegia following orthotopic heart transplant, using a novel definition of vasoplegia. Anticipation of this complication will allow for prompt intervention, thereby minimizing hemodynamic instability and impact on patient outcomes.

    View details for PubMedID 30929985

  • An alternative cannulation approach for venovenous extracorporeal membrane oxygenation in children for long-term ambulatory support. The Journal of thoracic and cardiovascular surgery Maeda, K., Ryan, K., Conrad, C. K., Yarlagadda, V. V. 2018

    View details for PubMedID 29685584