Dean B Andropoulos

Baylor College of Medicine, Houston, Texas, United States

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Publications (75)165.83 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective:To quantify cerebrovascular autoregulation as a function of gestational age (GA) and across the phases of the cardiac cycle.Study design:The present study is a hypothesis-generating re-analysis of previously published data. Premature infants (n=179) with a GA range of 23 to 33 weeks were monitored with umbilical artery catheters and transcranial Doppler insonation of the middle cerebral artery for 1-h sessions over the first week of life. Autoregulation was quantified by three methods, as a moving correlation coefficient between: (1) systolic arterial blood pressure (ABP) and systolic cerebral blood flow (CBF) velocity (Sx); (2) mean ABP and mean CBF velocity (Mx); and (3) diastolic ABP and diastolic CBF velocity (Dx). Comparisons of individual and cohort cerebrovascular pressure autoregulation were made across GA for each aspect of the cardiac cycle.Results:Systolic, mean and diastolic ABP increased with GA (r=0.3, 0.4 and 0.4; P<0.0001). Systolic CBF velocity was pressure-passive in infants with the lowest GA, and Sx decreased with advancing GA (r=-0.3; P<0.001), indicating increased capacity for cerebral autoregulation during systole during development. By contrast, Dx was elevated, indicating dysautoregulation, in all subjects and showed minimal change with advancing GA (r=-0.06; P=0.05). Multivariate analysis confirmed that both GA (P<0.001) and 'effective cerebral perfusion pressure' (ABP minus critical closing pressure (CrCP); P<0.01) were associated with Sx.Conclusion:Premature infants have low and usually pressure-passive diastolic CBF velocity. By contrast, the regulation of systolic CBF velocity by pressure autoregulation developed in this cohort between 23 and 33 weeks GA. Elevated effective cerebral perfusion pressure derived from the CrCP was associated with dysautoregulation.Journal of Perinatology advance online publication, 10 July 2014; doi:10.1038/jp.2014.122.
    Journal of perinatology: official journal of the California Perinatal Association 07/2014; · 1.59 Impact Factor
  • Society of Pediatric Anesthesia/Congenital Cardiac Anesthesia Society Annual Meeting, Fort Lauderdale, FL; 03/2014
  • Society for Pediatric Anesthesia/Congenital Cardiac Anesthesia Society Annual Meeting, Fort Lauderdale, FL; 03/2014
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    ABSTRACT: Adverse neurodevelopmental outcomes are observed in up to 50% of infants after complex cardiac surgery. We sought to determine the association of perioperative anesthetic exposure with neurodevelopmental outcomes at age 12 months in neonates undergoing complex cardiac surgery and to determine the effect of brain injury determined by magnetic resonance imaging (MRI). Retrospective cohort study of neonates undergoing complex cardiac surgery who had preoperative and 7-day postoperative brain MRI and 12-month neurodevelopmental testing with Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). Doses of volatile anesthetics (VAA), benzodiazepines, and opioids were determined during the first 12 months of life. From a database of 97 infants, 59 met inclusion criteria. Mean ± sd composite standard scores were as follows: cognitive = 102.1 ± 13.3, language = 87.8 ± 12.5, and motor = 89.6 ± 14.1. After forward stepwise multivariable analysis, new postoperative MRI injury (P = 0.039) and higher VAA exposure (P = 0.028) were associated with lower cognitive scores. ICU length of stay (independent of brain injury) was associated with lower performance on all categories of the Bayley-III (P < 0.02). After adjustment for multiple relevant covariates, we demonstrated an association between VAA exposure, brain injury, ICU length of stay, and lower neurodevelopmental outcome scores at 12 months of age. These findings support the need for further studies to identify potential modifiable factors in the perioperative care of neonates with CHD to improve neurodevelopmental outcomes.
    Pediatric Anesthesia 03/2014; 24(3):266-74. · 2.44 Impact Factor
  • American Society of Anesthesiologists, San Francisco, California; 10/2013
  • American Society of Anesthesiologists Annual Meeting, San Francisco, CA; 10/2013
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    ABSTRACT: The purpose of this study was to assess the utility of preoperative head ultrasound scan (HUS) in a cohort of newborns also under going preoperative MRI as part of a prospective research study of brain injury in infants having surgery for congenital heart disease(CHD). A total of 167 infants diagnosed with CHD were included in this 3-center study. None of the patients had clinical signs or symptoms of preoperative brain injury, and all patients received both HUS and brain MRI before undergoing surgical intervention. HUS and MRI results were reported by experienced neuroradiologists who were blinded to any specific clinical details of the study participants. The findings of the individual imaging modes were compared to evaluate for the presence of brain injury. Preoperative brain injury was present on HUS in 5 infants(3%) and on MRI in 44 infants (26%) (P , .001). Four of the HUS showed intraventricular hemorrhage not seen on MRI, suggesting false-positive results, and the fifth showed periventricular leukomalacia. The predominant MRI abnormality was white matter injury (n = 32). Other findings included infarct (n = 16) and hemorrhage (n = 5). Preoperative brain injury on MRI was present in 26% of infants with CHD, but only 3% had any evidence of brain injury on HUS.Among positive HUS, 80% were false-positive results. Our findings suggest that routine HUS is not indicated in asymptomatic term or near-term neonates undergoing surgery for CHD, and MRI may bea preferable tool when the assessment of these infants is warranted.
    PEDIATRICS 06/2013; 131(6):e1765-70. · 4.47 Impact Factor
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    ABSTRACT: The frequency--response of pressure autoregulation is not well delineated, therefore, the optimal frequency of ABP modulation for measuring autoregulation is unknown. We hypothesized that cerebrovascular autoregulation is band--limited and delineated by a cutoff frequency for which ABP variations induce cerebrovascular reactivity. Neonatal swine (n=8) were anesthetized using constant minute ventilation while PEEP was modulated between 6 and 0.75 cycles per minute (min(--1)). The animals were hemorrhaged until ABP was below the lower limit of autoregulation (LLA) and PEEP modulations were repeated. Vascular reactivity was quantified at each frequency according to the phase lag between ABP and intracranial pressure (ICP) above and below the LLA. Phase differences between ABP and ICP were small for frequencies > 2 min(-1), with no ability to differentiate cerebrovascular reactivity between ABPs above or below the LLA. For frequencies < 2 min(--1), ABP and ICP showed phase shift when measured above LLA, and no phase shift when measured below LLA (above vs. below LLA at 1 min(-1): 156° [139°-174°] vs. 30° [22°--50°]; p<0.001 by two---way ANOVA for both frequency and state of autoregulation). Data taken above LLA fit a Butterworth high---pass filter model with a cutoff frequency at 1.8 min(-1) (95% C.I. 1.5---2.2). Cerebrovascular reactivity occurs for sustained ABP changes lasting 30 seconds or longer. The ability to distinguish intact and impaired autoregulation was maximized by a 60--second wave (1 min(--1)), which was 100% sensitive and 100% specific in this model.
    Journal of Applied Physiology 05/2013; · 3.48 Impact Factor
  • Erin A Gottlieb, Dean B Andropoulos
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    ABSTRACT: PURPOSE OF REVIEW: To summarize recent publications emphasizing the changes in the population of patients with congenital heart disease and trends in the anesthetic and perioperative care of these patients presenting for noncardiac procedures. RECENT FINDINGS: It has been reported that children with congenital heart disease presenting for noncardiac surgery are at an increased anesthetic risk. This risk has become better defined. The patients at highest risk are infants with a functional single ventricle and patients with suprasystemic pulmonary hypertension, left ventricular outflow tract obstruction or dilated cardiomyopathy. Familiarity with the physiology and perioperative implications of the stages of single ventricle palliation is critical. The anesthetic approach, monitoring, conduct of surgery and postoperative care and outcomes are variable in this patient population. Recent literature reflects the growing number of children with ventricular assist devices and the management of these patients for noncardiac procedures. Cardiac imaging modalities provide diagnostic information, and strategies for reducing anesthetic risk for these procedures are of great interest. Pharmacologic trends and the application of technology are reviewed. SUMMARY: The identification of high-risk patients, multidisciplinary decision-making and planning and careful anesthetic management and monitoring are critical for optimizing outcomes in children with congenital heart disease presenting for noncardiac procedures.
    Current opinion in anaesthesiology 04/2013;
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    ABSTRACT: New noninvasive methods for monitoring cerebrovascular pressure reactivity coupled with a blood-based assay for brain-specific injury in preterm infants could allow early diagnosis of brain injury and set the stage for improved timing and effectiveness of interventions. Using an adaptation of near-infrared spectroscopy, we report a case of a very low birth weight infant undergoing hemoglobin volume index monitoring as a measure of cerebrovascular pressure reactivity. During the monitoring period, this infant demonstrated significant disturbances in cerebrovascular pressure reactivity that coincided with elevation of serum glial fibrillary acidic protein and new findings of brain injury on head ultrasound. This case report demonstrates the potential of emerging noninvasive monitoring methods to assist in both detection and therapeutic management to improve neurologic outcomes of the very low birth weight neonate.
    PEDIATRICS 03/2013; 131(3):e950-4. · 4.47 Impact Factor
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    ABSTRACT: OBJECTIVES: Neonates undergoing complex congenital heart surgery have a significant incidence of neurologic problems. Erythropoietin has antiapoptotic, antiexcitatory, and anti-inflammatory properties to prevent neuronal cell death in animal models, and improves neurodevelopmental outcomes in full-term neonates with hypoxic ischemic encephalopathy. We designed a prospective phase I/II trial of erythropoietin neuroprotection in neonatal cardiac surgery to assess safety and indicate efficacy. METHODS: Neonates undergoing surgery for D-transposition of the great vessels, hypoplastic left heart syndrome, or aortic arch reconstruction were randomized to 3 perioperative doses of erythropoietin or placebo. Neurodevelopmental testing using the Bayley Scales of Infant and Toddler Development III was performed at age 12 months. RESULTS: Fifty-nine patients received the study drug. Safety profile, including magnetic resonance imaging brain injury, clinical events, and death, was not different between groups. Three patients in each group died. Forty-two patients (22 in the erythropoietin group and 20 in the placebo group; 79% of survivors) returned for 12-month follow-up. In the group receiving erythropoietin, mean Cognitive Scale scores were 101.1 ± 13.6, Language Scale scores were 88.5 ± 12.8, and Motor Scale scores were 89.9 ± 12.3. In the group receiving placebo, Cognitive Scale scores were 106.3 ± 10.8 (P = .19), Language Scores were 92.4 ± 12.4 (P = .33), and Motor Scale scores were 92.6 ± 14.1 (P = .51). CONCLUSIONS: Safety profile for erythropoietin administration was not different than placebo. Neurodevelopmental outcomes were not different between groups; however, this pilot study was not powered to definitively address this outcome. Lessons learned suggest optimized study design features for a larger prospective trial to definitively address the utility of erythropoietin for neuroprotection in this population.
    The Journal of thoracic and cardiovascular surgery 10/2012; · 3.41 Impact Factor
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    ABSTRACT: BACKGROUND: In this study we report magnetic resonance imaging (MRI) brain injury and 12-month neurodevelopmental outcomes when regional cerebral perfusion (RCP) is used for neonatal aortic arch reconstruction. METHODS: Fifty-seven neonates receiving RCP during aortic arch reconstruction were enrolled in a prospective outcome study. RCP flows were determined by near-infrared spectroscopy and transcranial Doppler monitoring. Brain MRI was performed preoperatively and 7 days postoperatively. Bayley Scales of Infant Development III was performed at 12 months. RESULTS: Mean RCP time was 71 ± 28 minutes (range, 5 to 121 minutes) and mean flow was 56.6 ± 10.6 mL/kg/min. New postoperative MRI brain injury was seen in 40% of patients. For 35 RCP patients at age 12 months, mean Bayley Scales III Composite standard scores were: Cognitive, 100.1 ± 14.6 (range, 75 to 125); Language, 87.2 ± 15.0 (range, 62 to 132); and Motor, 87.9 ± 16.8 (range, 58 to 121). Increasing duration of RCP was not associated with adverse neurodevelopmental outcomes. CONCLUSIONS: Neonatal aortic arch repair with RCP using a neuromonitoring strategy results in 12-month cognitive outcomes that are at reference population norms. Language and motor outcomes are lower than the reference population norms by 0.8 to 0.9 standard deviations. The neurodevelopmental outcomes in this RCP cohort demonstrate that this technique is effective and safe in supporting the brain during neonatal aortic arch reconstruction.
    The Annals of thoracic surgery 07/2012; · 3.45 Impact Factor
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    ABSTRACT: BACKGROUND: Expectations for outcomes after the neonatal arterial switch operation (ASO) continue to change. This cohort study describes neurodevelopmental outcomes at age 12 months after neonatal ASO, and analyzes both modifiable and nonmodifiable factors for association with adverse outcomes. METHODS: Patients who underwent an ASO (n = 30) were enrolled in a prospective outcome study, with comprehensive clinical data collection during the first 12 months of life. Brain magnetic resonance imaging was done preoperatively and 7 days postoperatively, and the Bayley Scales of Infant Development III was performed at age 12 months. RESULTS: Ten of 30 patients (33%) had preoperative magnetic resonance imaging injury; 13 of 30 patients (43%) had new postoperative magnetic resonance imaging injury. Twenty patients (67%) had Bayley Scales of Infant Development III: Cognitive Composite standard score mean was 104.8 ± 15.0, Language Composite standard score median was 90.0 (25th to 75th percentile, 83 to 94), and Motor Composite standard score mean was 92.3 ± 14.2. Best subsets multivariable analysis found associations between lower preoperative and intraoperative cerebral oxygen saturation, preoperative magnetic resonance imaging brain injury, total bypass time, and total midazolam dose and lower Bayley Scales of Infant Development III scores at age 12 months. CONCLUSIONS: At 12 months after ASO, neurodevelopmental outcome means were within normal population ranges. The new associations reported in this study between potentially modifiable perioperative factors and outcomes require investigations in larger patient cohorts. Beyond survival, which was 100% in this cohort, factors influencing quality of life including neurodevelopmental outcomes should be routinely investigated in studies of ASO patients.
    The Annals of thoracic surgery 06/2012; 94(4):1250-1256. · 3.45 Impact Factor
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    ABSTRACT: Hypotension and shock are risk factors for death, renal insufficiency, and stroke in preterm neonates. Goal-directed neonatal hemodynamic management lacks end-organ monitoring strategies to assess the adequacy of perfusion. Our aim is to develop a clinically viable, continuous metric of renovascular reactivity to gauge renal perfusion during shock. We present the renovascular reactivity index (RVx), which quantifies passivity of renal blood volume to spontaneous changes in arterial blood pressure. We tested the ability of the RVx to detect reductions in renal blood flow. Hemorrhagic shock was induced in 10 piglets. The RVx was monitored as a correlation between slow waves of arterial blood pressure and relative total hemoglobin (rTHb) obtained with reflectance near-infrared spectroscopy (NIRS) over the kidney. The RVx was compared with laser-Doppler measurements of red blood cell flux, and renal laser-Doppler measurements were compared with cerebral laser-Doppler measurements. Renal blood flow decreased to 75%, 50%, and 25% of baseline at perfusion pressures of 60, 45, and 40 mmHg, respectively, whereas in the brain these decrements occurred at pressures of 30, 25, and 15 mmHg, respectively. The RVx compared favorably to the renal laser-Doppler data. Areas under the receiver operator characteristic curves using renal blood flow thresholds of 50% and 25% of baseline were 0.85 (95% CI, 0.83-0.87) and 0.90 (95% CI, 0.88-0.92). Renovascular autoregulation can be monitored and is impaired in advance of cerebrovascular autoregulation during hemorrhagic shock.
    Journal of Applied Physiology 05/2012; 113(2):307-14. · 3.48 Impact Factor
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    ABSTRACT: Anesthesiologists face a dilemma in determining appropriate dosing of anesthetic drugs in obese children. In this study we determined the dose of propofol that caused loss of consciousness in 95% (ED(95)) of obese and nonobese children as determined by loss of eye lash reflex. Forty obese (body mass index [BMI] > 95th percentile for age and gender) and 40 normal weight (BMI 25th to 84th percentile) healthy ASA 1 to 2 children ages 3 to 17 years presenting for surgical procedures were studied using a biased coin design. The primary endpoint was loss of lash reflex at 20 seconds after propofol administration. The first patient in each group received 1.0 mg/kg of IV propofol, and subsequent patients received predetermined propofol doses based on the lash reflex response in the previous patient. If the lash reflex was present, the next patient received a dose increment of 0.25 mg/kg. If the lash reflex was absent, the next patient was randomized to receive either the same dose (95% probability) or a dose decrement of 0.25 mg/kg (5% probability). The ED(95) and 95% confidence intervals (CI) were calculated using isotonic regression and bootstrapping methods respectively. The ED(95) of propofol for loss of lash reflex was significantly lower in obese pediatric patients (2.0 mg/kg, approximate 95% CI, 1.8 to 2.2 mg/kg) in comparison with nonobese patients (3.2 mg/kg, approximate 95% CI, 2.7 to 3.2 mg/kg), P ≤ 0.05. A simple approach to deciding what dose of propofol should be used for induction of anesthesia in children ages 3 to 17 years is to first establish the child's BMI on readily available gender-specific charts. Obese children (BMI >95th percentile for age and gender) require a lower weight-based dose of propofol for induction of anesthesia, than do normal-weight children.
    Anesthesia and analgesia 05/2012; 115(1):147-53. · 3.08 Impact Factor
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    ABSTRACT: Autoregulation is impaired by traumatic brain injury. Cerebral blood flow disturbances are spatially heterogeneous, but autoregulation is often reported as a global metric. We tested lateralization of autoregulatory responses in the neonatal piglet brain during hypotension early after unilateral injury. Neonatal piglets (5-7 days old) had controlled cortical impact (severe, n = 12; moderate, n = 13; sham, n = 13) and recovery for 6 hours. The lower limit of autoregulation (LLA) and static rate of autoregulation (SRoR) were determined for each subject and compared among groups and between the ipsilateral and contralateral hemispheres. The LLA was not increased by injury (sham, 34 mm Hg [29-39 mm Hg]; moderate injury, 37 mm Hg [33-41 mm Hg]; severe injury, 35 mm Hg [32-38 mm Hg]; P = .93, mean [95% confidence interval]). SRoR, when measured ipsilateral to injury and above the LLA, showed intact autoregulation and was not lower than SRoR in uninjured subjects (sham, 0.82 [0.53-1.1]; moderate injury, 1.0 [0.60-1.5]; severe, 0.91 [0.33-1.5]; P = .44). The average hemispheric LLA difference was 2.7 mm Hg, (95% limits of agreement, -7.5 to 7.0; bias, -0.25; Spearman r = 0.73; P < .0001). Ipsilateral and contralateral SRoR measurements also showed correlation in the injured groups (Spearman r = 0.85, P < .0001). LLA was not increased by controlled cortical impact, nor did SRoR measurements demonstrate ineffective autoregulation when cerebral perfusion pressure was greater than and within 10 mm Hg of the LLA. Cerebral perfusion pressure optimization, indicated by autoregulation measurements, was significantly similar in the 2 hemispheres despite severe unilateral injury.
    Neurosurgery 02/2012; 71(1):138-45. · 2.53 Impact Factor
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    ABSTRACT: Prevention of brain injury during congenital heart sur-gery has focused on intraoperative and perioperative neuroprotection and neuromonitoring. Many strategies have been adopted as "standard of care." However, the strength of evidence for these practices and the relation-ship to long-term outcomes are unknown. We performed a systematic review (January 1, 1990 to July 30, 2010) of neuromonitoring and neuroprotection strategies during cardiopulmonary bypass (CPB) in in-fants of age 1 year or less. Papers were graded individu-ally and as thematic groups, assigning evidence-based medicine and American College of Cardiology/American Heart Association (ACC/AHA) level of evidence grades. Consensus scores were determined by adjudication. Literature search identified 527 manuscripts; 162 met inclusion criteria. Study designs were prospective obser-vational cohort (53.7%), case-control (21.6%), randomized clinical trial (13%), and retrospective observational co-hort (9.9%). Median sample size was 43 (range 3 to 2,481).
    The Annals of Thoracic Surgery 01/2012; 94:1365. · 3.45 Impact Factor
  • Dean B. Andropoulos
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    ABSTRACT: hout exposing the patient to the risk of adverse outcomes. In a clinical model of pediatric sedation [1], the patient’s state can range from fully awake undergoing a painful procedure without sedation or analgesia to apnea, hypoxia, and death from oversedation (Fig. 4.1). Clearly, having the sedated child’s state in the goal zone is important, and objective tools to assess sedation depth are necessary to standardize depth of sedation. Additionally, having objective assessment scales available to rate a child’s readiness for discharge from a sedation recovery area is also important, as premature discharge may lead to adverse events and even death [2–4].
    12/2011: pages 35-48;
  • Dean B. Andropoulos
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    ABSTRACT: Safe sedation of pediatric patients requires a thorough understanding of the physiological differences between infants, children, adolescents, and adults. Especially in small infants, there is much less margin for any errors in diagnosis and treatment of respiratory or cardiovascular depression during sedation procedures. This chapter will review developmental aspects of respiratory, cardiovascular, central nervous system, renal, hepatic, hematologic, and temperature homeostatic systems, highlighting the differences between children and adults and emphasizing their relevance to sedation procedures in children.
    12/2011: pages 77-91;
  • Source
    Olutoyin A Olutoye, Mehernoor F Watcha, Dean B Andropoulos
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    ABSTRACT: More obese children are presenting for surgery, reflecting an increase in comorbidities requiring surgery or an increased prevalence in the community. The objectives of this study were to determine the prevalence of obesity in our pediatric surgery patient population, detect ethnic disparities amongst this cohort of obese patients and also to determine any increase in pediatric obesity related comorbidities requiring surgery. Day surgery patients between ages 3 and 17 years were prospectively studied over a 3-month period. The proportion of obese children, demographics, and surgical procedures were determined. Of the 1559 patients analyzed, 312 (20%) were obese. Close to half of this subset of children were of Hispanic descent. Adenotonsillectomy was the most common surgery; however, the case distribution of this cohort was similar to our operating room database. Prevalence of pediatric obesity in our day surgery patients therefore reflects that of the community and has not resulted in an increase in related comorbidities requiring surgery. Longitudinal studies to assess the incidence of pediatric obesity related complications will be beneficial.
    Journal of the National Medical Association 01/2011; 103(1):27-30. · 0.91 Impact Factor

Publication Stats

891 Citations
165.83 Total Impact Points


  • 1999–2014
    • Baylor College of Medicine
      • • Section of Neonatology
      • • Department of Anesthesiology
      • • Department of Pediatrics
      • • Division of Pediatric Cardiovascular Anesthesiology
      • • Section of Cardiology
      Houston, Texas, United States
  • 1999–2005
    • Texas Children's Hospital
      Houston, Texas, United States