Mark R Rigby

Medical Center of Central Georgia, Macon, Georgia, United States

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Publications (22)102.99 Total impact

  • Mark R Rigby
    Pediatric Critical Care Medicine 11/2010; 11(6):752-4. · 2.35 Impact Factor
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    ABSTRACT: Hyperglycemia is associated with increased morbidity and mortality in critically ill patients and strict glycemic control has become standard care for adults. Recent studies have questioned the optimal targets for such management and reported increased rates of iatrogenic hypoglycemia in both critically ill children and adults. The ability to provide accurate, real-time continuous glucose monitoring would improve the efficacy and safety of this practice in critically ill patients. The aim of our study is to determine if a continuous, interstitial glucose monitor will correlate with blood glucose values in critically ill children. We evaluated 50 critically ill children age 6 weeks to 16 years old with a commercially available continuous glucose monitor (CGM; Medtronic GuardianĀ®). CGM values and standard blood glucose (BG) values were compared. During the study, no changes in patient management were made based on CGM readings alone. Forty-seven patients had analyzable CGM data. A total of 1,555 CGM and routine BG measurements were compared using Clarke error grid and Bland-Altman analysis. For all readings, 97.9% were within clinically acceptable agreement. The mean absolute relative difference between CGM and BG readings was 15.3%. For the 1,555 paired CGM and BG measurements, there is a statistically significant linear relationship between CGM values and BG (P < .0001). A high degree of clinical agreement existed in three subpopulation analyses based on age, illness severity, and support measures. This included some of our smallest patients (that is, < 12 months old), those who required vasopressors, and those who were treated for critical illness hyperglycemia. In one of the largest studies to date, in a highly vulnerable ICU population, CGM values have a clinically acceptable correlation with the BG values now used diagnostically and therapeutically. Our data contest the theoretical concerns posed by some regarding CGM use in the ICU. The existing medical evidence may now support a role for CGM devices in the identification and management of hyperglycemia in diverse ICU settings.
    Critical care (London, England) 10/2010; 14(5):R176. · 4.72 Impact Factor
  • Mark R Rigby
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    ABSTRACT: In a relatively short time, advances in both basic science and clinical medicine have revolutionized the way we understand disease processes and suggested novel approaches that may be able to be used to treat or cure some of the most relevant human afflictions. In type 1 diabetes, one unintended consequence of this has been the polarization of the investigational groups (i.e., immunologists and endocrinologists) interested in developing novel therapies for this condition. This review will examine how and why such polarization exists, and why past and current approaches to develop critically needed translational investigators may be falling short. Despite significant efforts to increase the number of individuals trained in both basic science and clinical medicine, the number of academic physician-scientists is on the decline. Increased demands from academic institutions coupled with severe difficulty in securing extramural funding are probably playing important roles in this concerning trend. Type 1 diabetes will continue to be a significant strain on individuals, their families and society until a cure is found. More than ever, there is a critical need to support appropriately trained translational investigators who can best facilitate bringing the promise of basic research to clinical reality.
    Current opinion in endocrinology, diabetes, and obesity 02/2010; 17(2):131-42. · 3.77 Impact Factor
  • Mark R Rigby, Catherine M Preissig
    Pediatric Critical Care Medicine 01/2010; 11(1):163. · 2.35 Impact Factor
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    Catherine M Preissig, Mark R Rigby
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    ABSTRACT: Hyperglycemia is common in critically ill patients and is associated with increased morbidity and mortality. Strict glycemic control improves outcomes in some adult populations and may have similar effects in children. While glycemic control has become standard care in adults, little is known regarding hyperglycemia management strategies used by pediatric critical care practitioners. We sought to assess both the beliefs and practice habits regarding glycemic control in pediatric intensive care units (ICUs) in the United States (US). We surveyed 30 US pediatric ICUs from January to May 2009. Surveys were conducted by phone between the investigators and participating centers and consisted of a 22-point questionnaire devised to assess physician perceptions and center-specific management strategies regarding glycemic control. ICUs included a cross section of centers throughout the US. Fourteen out of 30 centers believe all critically ill hyperglycemic adults should be treated, while 3/30 believe all critically ill children should be treated. Twenty-nine of 30 believe some subsets of adults with hyperglycemia should be treated, while 20/30 believe some subsets of children should receive glycemic control. A total of 70%, 73%, 80%, 27%, and 40% of centers believe hyperglycemia adversely affects outcomes in cardiac, trauma, traumatic brain injury, general medical, and general surgical pediatric patients, respectively. However, only six centers use a standard, uniform approach to treat hyperglycemia at their institution. Sixty percent of centers believe hypoglycemia is more dangerous than hyperglycemia. Seventy percent listed fear of management-induced hypoglycemia as a barrier to glycemic control at their center. Considerable disparity exists between physician beliefs and actual practice habits regarding glycemic control among pediatric practitioners, with few centers reporting the use of any consistent standard approach to screening and management. Physicians wishing to practice glycemic control in their critically ill pediatric patients may want to consider adopting center-wide uniform approaches to improve safety and efficacy of treatment.
    Critical care (London, England) 01/2010; 14(1):R11. · 4.72 Impact Factor
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    ABSTRACT: Despite advances in the field of lung transplantation, the median survival after lung transplant remains below 5 years. Early rejection is a risk factor for the development of chronic rejection. In animal models of transplant tolerance, regulatory T cells (Tregs) can prevent the establishment of rejection. This study was designed to explore the dynamics of Tregs focally and systemically in lung transplant recipients. Sequential surveillance bronchoscopy results were available in 51 patients with at least four sequential samples recovered from each patient at defined times posttransplant. In 36 individuals, a complete year of follow-up data for BAL was analyzed. In 33 of these individuals had a complete year of follow-up data for peripheral blood monocyte cell specimens were also analyzed. Lung lavage cells were recovered from each bronchoscopy and corresponding blood draw and subjected to polychromatic flow cytometry. The percentage of CD4 lymphocytes, which expressed the intracellular transcription factor FoxP3 was recorded at each point. At each time point, lung biopsy specimens were scored for rejection. Lung Treg frequency was significantly more variable than blood Treg frequency. Treg frequency in the lung was increased in the aftermath of acute rejection. In contrast, lung Treg frequency declined sequentially in patients demonstrating continued quiescence. Mean BAL Treg level integrated over the first transplant year correlated inversely with the degree of acute cellular rejection. In contrast, blood Treg levels demonstrated no correlation with lung pathology. Lung Tregs increase in the setting of acute cellular rejection, whereas declining levels of BAL Tregs correlates with immunologic quiescence.
    Transplantation 09/2009; 88(4):521-7. · 3.78 Impact Factor
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    ABSTRACT: This study aimed to determine the prevalence of hyperglycemia among pediatric postoperative cardiac patients, its impact on outcomes, and whether hyperglycemia can be controlled effectively in this population. A retrospective chart review of 100 postoperative patients admitted to the authors' pediatric cardiac intensive care unit (ICU) was conducted. Patients were evaluated for incidence of hyperglycemia, defined as blood glucose (BG) level exceeding 7.7 mmol/l (140 mg/dl), and outcomes. The evaluation also included 20 different postoperative patients with a BG level exceeding 7.7 mmol/l (140 mg/dl) who received management with insulin via the authors' pediatric-specific glycemic control protocol. The BG control and hypoglycemic rates in this cohort were assessed. The prevalence of hyperglycemia was 84%. The hyperglycemic patients had higher inotrope scores, longer hospital stays, more mechanical ventilation days, and higher mortality rates than those without hyperglycemia. For the patients with hyperglycemia managed via the authors' pediatric-specific glycemic control protocol, 62% of all BG values were within the authors' goal range, and less than 4% of BG values were less than 3.3 mmol/l (60 mg/dl). No patient had a BG level lower than 2.2 mmol/l (40 mg/dl) during glycemic management. Severe hyperglycemia is prevalent among postoperative pediatric cardiac patients and correlates with morbidity and mortality. Hyperglycemia may be controlled effectively in these patients using a pediatric-specific glycemic control protocol without increasing the incidence of hypoglycemia.
    Pediatric Cardiology 09/2009; 30(8):1098-104. · 1.20 Impact Factor
  • Catherine M Preissig, Mark R Rigby
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    ABSTRACT: To determine which children are susceptible to critical illness hyperglycemia (CIH) and whether CIH severity and duration correlate with diagnosis or illness severity. We developed a standard approach to identify and treat CIH in our medical/surgical pediatric intensive care unit. We define CIH as persistent blood glucose (BG) >140 mg/dL and titrate infused insulin to maintain BG 80 to 140 mg/dL. We conducted a retrospective analysis of patients with hyperglycemia from June 2006 through May 2007. Main outcomes were risk of development of CIH in different patient subgroups and CIH severity and duration. Average peak BG, CIH duration, and peak insulin requirements were 199 mg/dL, 6.3 days, and 0.09 units/kg/h, respectively, in patients with CIH. CIH severity and duration were highest in neurosurgical and patients with sepsis, those requiring mechanical ventilation and vasopressors, extracorporeal support, and those with highest illness severity scores. CIH severity and duration correlate with diagnosis and illness severity. Certain "risk factors" may be predictive of who develops CIH.
    The Journal of pediatrics 08/2009; 155(5):734-9. · 4.02 Impact Factor
  • Catherine Preissig, Mark Rigby
    The Lancet 05/2009; 373(9673):1423; author reply 1424. · 39.21 Impact Factor
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    ABSTRACT: To determine whether ultrasound (US) increases successful central venous catheter (CVC) placement, decreases site attempts, and decreases CVC placement complications. A prospective observational cohort study evaluating a transition by the Pediatric Critical Care Medicine service to US-guided CVC placement. Medical and surgical patients in a 21-bed quaternary multidisciplinary pediatric intensive care unit had CVCs placed by attendings, fellows, residents, and a nurse practitioner. Ninety-three patients were prospectively enrolled into the landmark (LM) group and 119 into the US group. : After collection of prospective LM data, training with US guidance was provided. CVCs were subsequently placed with US guidance. Operator information, disease process, emergent/routine, sites attempted, and complications were recorded. Procedure time was from initial skin puncture to guidewire placement. There was no difference overall in success rates (88.2% LM vs. 90.8% US, p = 0.54) or time to successful placement (median seconds 269 LM vs. 150 US, p = 0.14) between the two groups. Median number of attempts were fewer with US for all CVCs attempted (3 vs. 1, p < 0.001) as were attempts at >1 anatomical site (20.7% LM vs. 5.9% US, p = 0.001). Use of US was associated with fewer inadvertent artery punctures (8.5% vs. 19.4%, p = 0.03). Time to successful placement by residents was decreased with US (median 919 seconds vs. 405 seconds, p = 0.02). More internal jugular CVCs were placed during the US period than during the LM period (13.4% vs. 2.1%). US-guided CVC placement in children is associated with decreased number of anatomical sites attempted and decreased number of attempts to gain placement. Time to placement by residents was decreased with US, but not the time to placement by other operators. US guidance increased the use of internal jugular catheter placement and decreased artery punctures. US guidance did not improve success rates.
    Critical care medicine 04/2009; 37(3):1090-6. · 6.37 Impact Factor
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    ABSTRACT: To evaluate the success and dosing requirements of propofol in children for prolonged procedural sedation by a nonanesthesiology-based sedation service. The pediatric sedation service at this institution uses propofol as its preferred sedative, and the local guideline suggests using 3 mg/kg for induction and 5 mg kg(-1) h(-1) for maintenance sedation. Doses can be adjusted as needed to individualize successful sedation. A retrospective analysis of patients sedated for 30 minutes or longer was conducted. Patients were stratified into 4 cohorts based on age (<1 year [n = 16], 1-2 years [n = 85], 3-7 years [n = 54], and >7 years [n = 55]) and dosing patterns, success, and adverse effects were investigated. Two hundred forty-nine patients met the inclusion criteria. Mean age was 4.8 years (SD, 4.1). The mean induction dose was 3.2 mg/kg (range, 0.9-9.7), and the mean maintenance infusion was 5.2 mg kg(-1) h(-1) (range, 0.14-21.3). No differences were seen in the induction doses in the different age cohorts, yet the SD was largest in the youngest cohort compared to any other. Although no differences were seen in maintenance rates by age, the greatest SD for dosing was seen in the oldest cohort. For all ages, all sedations were successful (100%) and unanticipated adverse effects rare (<1%). Although it seems that the mean dosing of propofol does not vary significantly with age, there is greater variability in induction dosage for those younger than 1 year and in maintenance dosing for those 7 years or older. The results and general dosing parameters may assist pediatric subspecialists in using propofol for prolonged procedural sedation.
    Pediatric emergency care 03/2009; 25(3):133-8. · 0.92 Impact Factor
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    Catherine M Preissig, Mark R Rigby
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    ABSTRACT: Hyperglycaemia is common in critical illness and associated with poor outcome. Glycaemic control using insulin may decrease morbidity and mortality. Many questions remain about the cause of critical illness hyperglycaemia (CIH). Our objective was to investigate the endocrinological basis of paediatric CIH. C-peptide and blood glucose (BG) levels were assessed in 41 children aged 2 to 18 years old who were admitted to our paediatric intensive care unit (PICU). Patients who developed CIH, defined as persistent BG above 7.7 mmol/L, were treated with insulin infusion to achieve BG levels between 4.4 and 7.7 mmol/L. C-peptide levels were compared with respect to CIH development and degree of organ failure in all patients. Respiratory and cardiovascular failure were defined as need for mechanical ventilation and need for vasoactive infusions, respectively. Clinical and laboratory parameters, including c-peptide levels, were assessed. Of 41 children enrolled, 18 had respiratory failure only, 11 had both respiratory and cardiovascular failure, and 12 had neither respiratory or cardiovascular failure. Nine patients with respiratory failure only, 10 with both respiratory and cardiovascular failure, and none with no respiratory or cardiovascular failure developed CIH. Patients with CIH and respiratory and cardiovascular failure (n = 10) had very low c-peptide levels (4.4 ng/mL) despite significantly elevated mean BG levels (10.8 mmol/L), while those with CIH and respiratory failure only had very high c-peptide levels (11.5 ng/mL) with mean BG of 9.9 mmol/L. Low endogenous insulin production in those with respiratory and cardiovascular failure was associated with rapid onset of CIH, illness severity, higher insulin requirement and longer mechanical ventilation days, PICU length of stay and CIH duration. Primary beta-cell dysfunction as defined by low endogenous c-peptide production appears to be prevalent in critically ill children with both respiratory and cardiovascular failure who develop CIH, whereas elevated insulin resistance appears to be the prominent cause of CIH in children with respiratory failure only. Our finding that beta-cell dysfunction is present in a subset of critically ill children with CIH challenges the assertion from adult studies that CIH is primarily the result of elevated insulin resistance.
    Critical care (London, England) 02/2009; 13(1):R27. · 4.72 Impact Factor
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    ABSTRACT: The extent of neuroendocrine dysfunction (NED) has not been well defined in critically ill children and likely varies significantly from that in adults. We sought to define the prevalence of neuroendocrine dysfunction in a group of children in a multidisciplinary pediatric intensive care unit and determine the relationship of neuroendocrine dysfunction with severity of illness and presence of sepsis. Prospective observational study in a pediatric intensive care unit at a referral childrens hospital. Blood samples were evaluated within 12 hrs of admission for serum cortisol, thyroid stimulating hormone, total triiodothyronine (T3), reverse triiodothyroine (rT3), free thyroxine, and arginine vasopressin. Pediatric risk of mortality, pediatric logistic organ dysfunction scores, and length of stay were calculated. Seventy-three children were enrolled over a 13-month period. Median patient age was 72 months (range, 3-228 months). Overall prevalence of absolute adrenal insufficiency ranged from 7% to 58% based on cortisol cutoff chosen. Presence of absolute adrenal insufficiency, low T3 syndrome (LT3S), or vasopressin insufficiency did not differ between septic or nonseptic patients. NED did not correlate with pediatric logistic organ dysfunction, Pediatric Risk of Mortality Score III, length of stay, or mortality. Prevalence of multiple NED was 62% (28 of 45 children), where 62% had 2 neurohormonal deficiencies and 24% had 3 neurohormonal deficiencies. NED is common in both septic and nonseptic critically ill children in a single pediatric intensive care unit. Larger scale studies are necessary to determine whether presence of NED, or specific combinations of neurohormonal dysfunction, is important in predicting outcomes or benefit of early hormonal replacement therapies in critically ill children.
    Pediatric Critical Care Medicine 01/2009; 10(1):35-40. · 2.35 Impact Factor
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    ABSTRACT: Hyperglycemia is a risk factor for poor outcome in critically ill patients, and glycemic control may decrease morbidity and mortality in adults. There is limited information regarding hyperglycemia and its control in pediatric intensive care. To determine prevalence and risk factors for hyperglycemia and evaluate our approach to glycemic control in critically ill children. DESIGN, SETTING, PATIENTS, AND MAIN OUTCOMES: A pediatric-specific protocol to identify and manage hyperglycemia was developed and instituted as standard practice in our pediatric intensive care unit, and was applicable to patients >6 months and >5 kg, without end-stage liver disease or type 1 diabetes mellitus. Triggers for routine blood glucose assessment were based on supportive measures including mechanical ventilation, vasopressor/inotrope infusions, and antihypertensive infusions. Hyperglycemic patients, defined by two consecutive blood glucose readings of >140 mg/dL (7.7 mmol/L), were treated with infused insulin to maintain blood glucose levels 80-140 mg/dL (4.4-7.7 mmol/L). We performed retrospective analysis 6 months after instituting this approach. Main outcomes were prevalence and risk factors for hyperglycemia, and effectiveness of our approach to achieve glycemic control. None. One hundred forty-five of 477 patients had blood glucose actively assessed, and 74 developed hyperglycemia and were managed with insulin. This approach to identify patients with hyperglycemia had a positive predictive value of 51% and negative predictive value of 94%. Hyperglycemia prevalence was 20%. Mechanical ventilation, vasopressor/inotropic infusion, continuous renal replacement therapy, high illness severity scores, and longer lengths of stay were associated with hyperglycemia. The average blood glucose of patients with hyperglycemia was 200 mg/dL (11 mmol/L), and on average, patients were treated with insulin for 6.3 days with 2.4 units/kg/day. Blood glucose levels were <160 mg/dL (8.8 mmol/L) in 70% of insulin-treated days, 80-140 mg/dL (4.4-7.7 mmol/L) in 49% of insulin-treated days, and 4% of insulin-treated patients had any blood glucose measurements <40 mg/dL (2.2 mmol/L). Hyperglycemia is prevalent in pediatric intensive care units and may be effectively identified and managed using a protocolized approach.
    Pediatric Critical Care Medicine 10/2008; 9(6):581-8. · 2.35 Impact Factor
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    ABSTRACT: Blocking T-cell signaling is an effective means to prevent autoimmunity and allograft rejection in many animal models, yet the clinical translation of many of these approaches has not resulted in the success witnessed in experimental systems. Improved understanding of these approaches may assist in developing safe and effective means to treat disorders such as autoimmune diabetes. We studied the effect of anti-CD154 and CTLA4-Ig on diabetes development, and the requirements to induce tolerance in nod.scid mice after transfer of transgenic beta-cell reactive BDC2.5.NOD T-cells. Nod.scid recipients of diabetogenic BDC2.5.NOD cells were protected indefinitely from diabetes by a short course of combined costimulation blockade, despite the continued diabetogenic potential of their T-cells. The presence of pathogenic T-cells in the absence of disease indicates peripheral immune tolerance. T-cell maturation occurred in protected recipients, yet costimulation blockade temporarily blunted early T-cell proliferation in draining pancreatic nodes. Tolerance required preexisting regulatory T-cells (Tregs), and protected recipients had greater numbers of Tregs than diabetic recipients. Diabetes protection was successful in the presence of homeostatic expansion and high T-cell precursor frequency, both obstacles to tolerance induction in other models of antigen-specific immunity. Immunotherapies that selectively suppress effector T-cells while permitting the development of natural regulatory mechanisms may have a unique role in establishing targeted long-standing immune protection and peripheral tolerance. Understanding the mechanism of these approaches may assist in the design and use of therapies for human conditions, such as type 1 diabetes.
    Diabetes 06/2008; 57(10):2672-83. · 7.90 Impact Factor
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    ABSTRACT: Immature dendritic cells (DC) can promote long-term transplant survival in rodents. We assessed the impact of stably immature, donor-derived DC on alloimmune reactivity in rhesus macaques. CD14 monocytes isolated from leukapheresis products of Macacca mulatta were cultured in granulocyte-macrophage colony stimulating factor plus interleukin (IL)-4+/-vitamin (vit) D3, and IL-10. Major histocompatibility complex class II and cosignaling molecule expression was determined on CD11c cells by flow cytometry. T-cell allostimulatory capacity of the DC, including DC exposed to proinflammatory cytokines, was determined in mixed leukocyte reaction. To test their influence in vivo, purified DC were infused intravenously into allogeneic recipients, either alone or followed by CTLA4Ig, 24 hr later. Proliferative responses of recipient CFSE-labeled T cells to donor or third party DC, cytokine production by stimulated T cells, and circulating alloantibody levels were determined by flow cytometry, up to 100 days postinfusion. VitD3/IL-10-conditioned, monocyte-derived DC were resistant to maturation and failed to induce allogeneic T cell proliferation in vitro. After their infusion, an increase in anti-donor and anti-third party T-cell reactivity was observed, that subsequently subsided to fall significantly below pretreatment levels (by day 56) only in animals also given CTLA4Ig. No increase in circulating immunoglobulin (Ig) M or IgG anti-donor alloantibody titers compared with pretreatment values was detected. With DC+CTLA4Ig infusion, alloreactive IL-10-producing T cells were prevalent in the circulation after day 28. Maturation-resistant rhesus DC infusion is well-tolerated. DC+CTLA4Ig infusion modulates allogeneic T-cell responses and results in hyporesponsiveness to donor and third party alloantigens.
    Transplantation 08/2007; 84(2):196-206. · 3.78 Impact Factor
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    ABSTRACT: Cyanide intoxication is an extremely rare event. We report a case of a teenager presenting with unresponsiveness, hemodynamic instability, and profound anion gap metabolic acidosis secondary to elevated lactate levels. It was later confirmed that he was a victim of cyanide poisoning. Individual case report. Pediatric intensive care unit of a tertiary care hospital. A 17-yr-old male presented with seizures, apnea, and cardiovascular collapse. His laboratory evaluation revealed extreme anion gap metabolic acidosis, elevated lactate levels, and absent arteriovenous saturation difference. The patient required inotropic support and external cardiac pacing for hemodynamic instability. Serial measurements of electrolytes and arterial and central venous blood gases were performed. When cyanide poisoning was suspected he received antidote therapy, administered initially with interval dosing and then as a continuous infusion. The antidote infusions were stopped because of a high level of resultant methemoglobinemia and the belief that all ingested cyanide had been cleared, given the time from exposure. The patient never recovered neurologic function, was declared brain dead, and became a tissue and organ donor. Cyanide poisoning is a rare and potentially fatal event. Prompt recognition of its possibility in a critically ill patient can lead to early intervention with antidote therapy and decrease the extent of morbidity and mortality.
    Pediatric Critical Care Medicine 02/2006; 7(1):79-82. · 2.35 Impact Factor
  • Pediatric Critical Care Medicine - PEDIATR CRIT CARE MED. 01/2006; 7(5).
  • Critical Care Medicine 01/2006; 34. · 6.12 Impact Factor
  • Pediatric Critical Care Medicine - PEDIATR CRIT CARE MED. 01/2006; 7(5).

Publication Stats

293 Citations
102.99 Total Impact Points

Institutions

  • 2010
    • Medical Center of Central Georgia
      Macon, Georgia, United States
    • Children's Healthcare of Atlanta
      Atlanta, Georgia, United States
    • Vanderbilt University
      • Department of Pediatrics
      Nashville, MI, United States
  • 2008–2010
    • Emory University
      • Department of Pediatrics
      Atlanta, GA, United States
  • 1992
    • University of Massachusetts Medical School
      • Program in Molecular Medicine
      Worcester, Massachusetts, United States