Cerebral Autoregulation In Children Research Articles

Determining Optimal Mean Arterial Blood Pressure Based on Cerebral Autoregulation in Children after Cardiac Surgery.

To evaluate the feasibility of continuous determination of the optimal mean arterial blood pressure (opt-MAP) according to cerebral autoregulation and to describe the opt-MAP, the autoregulation limits, and the time spent outside these limits in children within 48h of cardiac surgery. Cerebral autoregulation was assessed using the correlation coefficient (COx) between cerebral oxygenation and MAP in children following cardiac surgery. Plots depicting the COx according to the MAP were used to determine the opt-MAP using weighted multiple time windows. For each patient, we estimated (1) the time spent with MAP outside the autoregulation limits and (2) the burden of deviation, defined as the area between the MAP curve and the autoregulation limits when the MAP was outside these limits. Fifty-one patients with a median age of 7.1 (IQR 0.7-52.0) months old were included. The opt-MAP was calculated for 94% (IQR 90-96) of the monitored time. The opt-MAP was significantly lower in neonates < 1month old. The patients spent 24% (18-31) of the time outside of the autoregulation limits, with no significant differences between age groups. Continuous determination of the opt-MAP is feasible in children within the first 48h following cardiac surgery.

Cerebral Autoregulation in Healthy Term Newborns: Brief Report

Cerebral autoregulation is a homeostatic process that maintains cerebral blood flow (CBF) across a range of mean arterial pressures (MAPs). Cerebral autoregulation can be impaired in pathologic systemic and neurological conditions and can lead to cerebral hypoperfusion or cerebral hyperperfusion from low and high MAPs, respectively. 1 Obrist W.D. Gennarelli T.A. Segawa H. Dolinskas C.A. Langfitt T.W. Relation of cerebral blood flow to neurological status and outcome in head-injured patients. J Neurosurg. 1979; 51: 292-300 Crossref PubMed Scopus (116) Google Scholar Little is known about the maturation of cerebral autoregulation after birth or whether there are sex differences in CBF at birth. One study of 16 term neonates without congenital heart disease tested autoregulation using cerebral oximeter monitoring with tilt testing and reported that cerebral autoregulation was intact between three and 10 days. 2 Tran N.N. Kumar S.R. Hodge F.S. Macey P.M. Cerebral autoregulation in neonates with and without congenital heart disease. Am J Crit Care. 2018; 27: 410-416https://doi.org/10.4037/ajcc2018672 Crossref PubMed Scopus (11) Google Scholar Sex differences in CBF have been observed in older ages. Similar to healthy adolescents aged 10 to 16 years and healthy adults, prepubertal girls between four and eight years have higher middle cerebral and basilar artery flow velocities than age-matched boys. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar ,4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar Studies report that both healthy boys and girls aged between four and 16 years have intact cerebral autoregulation and children aged two to six years have a lower limit of autoregulation (LLA) similar to adolescents and adults. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar , 4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar , 5 Vavilala M.S. Lee L.A. Lam A.M. The lower limit of cerebral autoregulation in children during sevoflurane anesthesia. J Neurosurg Anesthesiol. 2003; 15: 307-312 Crossref PubMed Scopus (78) Google Scholar This finding means that infants and young children have less cerebral autoregulatory reserve (difference between MAP and LLA) than older children. 5 Vavilala M.S. Lee L.A. Lam A.M. The lower limit of cerebral autoregulation in children during sevoflurane anesthesia. J Neurosurg Anesthesiol. 2003; 15: 307-312 Crossref PubMed Scopus (78) Google Scholar However, girls aged four to 16 years have higher normative autoregulatory indices of the basilar artery compared with age-matched boys and healthy boys aged four to 16 years have higher normative autoregulatory indices of the middle cerebral artery (MCA) compared with healthy girls; the reasons for these differences are not well understood. 3 Vavilala M.S. Kincaid M.S. Muangman S.L. Suz P. Rozet I. Lam A.M. Gender differences in cerebral blood flow velocity and autoregulation between the anterior and posterior circulations in healthy children. Pediatr Res. 2005; 58: 574-578 Crossref PubMed Scopus (92) Google Scholar ,4 Tontisirin N. Muangman S.L. Suz P. et al. Early childhood gender differences in anterior and posterior cerebral blood flow velocity and autoregulation. Pediatrics. 2007; 119: e610-e615 Crossref PubMed Scopus (62) Google Scholar In clinical practice, hypotension is commonly defined in relation to gestational age (GA), and hypotension is common in critically ill neonates. 6 Dilli D. Soylu H. Tekin N. Neonatal hemodynamics and management of hypotension in newborns. Turk Pediatri Ars. 2018; 53: S65-S75 Crossref PubMed Scopus (10) Google Scholar Obtaining normative data for female and male newborns is a requisite for further understanding CBF and cerebral autoregulation and optimizing cerebral perfusion in critically ill neonates. We explored CBF velocity and cerebral autoregulation of the anterior cerebral circulation among healthy term newborns.

Monitoring cerebrovascular reactivity in pediatric traumatic brain injury: comparison of three methods.

To study three different methods of monitoring cerebral autoregulation in children with severe traumatic brain injury. Prospective cohort study of all children admitted to the pediatric intensive care unit at a university-affiliated hospital with severe TBI over a 4-year period to study three different methods of monitoring cerebral autoregulation: pressure-reactivity index (PRx), transcranial Doppler derived mean flow velocity index (Mx), and near-infrared spectroscopy derived cerebral oximetry index (COx). Twelve patients were included in the study, aged 5months to 17years old. An empirical regression analyzing dependence of PRx on cerebral perfusion pressure (CPP) displayed the classic U-shaped distribution, with low PRx values (< 0.3) reflecting intact auto-regulation, within the CPP range of 50-100mmHg. The optimal CPP was 75-80mmHg for PRx and COx. The correlation coefficients between the three indices were as follows: PRx vs Mx, r = 0.56; p < 0.0001; PRx vs COx, r = 0.16; p < 0.0001; and COx vs Mx, r = 0.15; p = 0.022. The mean PRx with a cutoff value of 0.3 predicted correctly long-term outcome (p = 0.015). PRx seems to be the most robust index to access cerebrovascular reactivity in children with TBI and has promising prognostic value. Optimal CPP calculation is feasible with PRx and COx.

Continuous Monitoring of Cerebral Autoregulation in Children Supported by Extracorporeal Membrane Oxygenation: A Pilot Study.

Cerebral autoregulation (CA) impairment may pose a risk factor for neurological complications among children supported by extracorporeal membrane oxygenation (ECMO). Our first objective was to investigate the feasibility of CA continuous monitoring during ECMO treatment and to describe its evolution over time. The second objective was to analyze the association between CA impairment and neurological outcome. Observational prospective study. Twenty-nine children treated with veno-arterial or veno-venous ECMO in the PICU of Nantes University Hospital, France, and the PICU of the IRCCS Giannina Gaslini Institute in Genoa, Italy. A correlation coefficient between the variations of regional cerebral oxygen saturation and the variations of mean arterial blood pressure (MAP) was calculated as an index of CA (cerebral oxygenation reactivity index, COx). A COx > 0.3 was considered as indicative of autoregulation impairment. COx-MAP plots were investigated allowing determining optimal MAP (MAPopt) and limits of autoregulation: lower (LLA) and upper (ULA). Neurological outcome was assessed by the onset of an acute neurological event (ANE) after ECMO start. We included 29 children (median age 84days, weight 4.8kg). MAPopt, LLA, and ULA were detected in 90.8% (84.3-93.3) of monitoring time. Mean COx was significantly higher during day 1 of ECMO compared to day 2 [0.1 (0.02-0.15) vs. 0.01 (-0.05 to 0.1), p = 0.002]. Twelve children experienced ANE (34.5%). The mean COx and the percentage of time spent with a COx > 0.3 were significantly higher among ANE+ compared to ANE- patients [0.09 (0.01-0.23) vs. 0.04 (-0.02 to 0.06), p = 0.04 and 33.3% (24.8-62.1) vs. 20.8% (17.3-23.7) p = 0.001]. ANE+ patients spent significantly more time with MAP below LLA [17.2% (6.5-32.9) vs. 5.6% (3.6-9.9), p = 0.02] and above ULA [13% (5.3-38.4) vs. 4.2% (2.7-7.4), p = 0.004], respectively. CA assessment is feasible in pediatric ECMO. The first 24h following ECMO represents the most critical period regarding CA. Impaired autoregulation is significantly more severe among patients who experience ANE.

Prevalence, Evolution, and Extent of Impaired Cerebral Autoregulation in Children Hospitalized With Complex Mild Traumatic Brain Injury.

To examine cerebral autoregulation in children with complex mild traumatic brain injury. Prospective observational convenience sample. PICU at a level I trauma center. Children with complex mild traumatic brain injury (trauma, admission Glasgow Coma Scale score 13-15 with either abnormal head CT, or history of loss of consciousness). Cerebral autoregulation was tested using transcranial Doppler ultrasound between admission day 1 and 8. The primary outcome was prevalence of impaired cerebral autoregulation (autoregulation index < 0.4),determined using transcranial Doppler ultrasonography and tilt testing. Secondary outcomes examined factors associated with and evolution and extent of impairment. Cerebral autoregulation testing occurred in 31 children 10 years (SD, 5.2 yr), mostly male (59%) with isolated traumatic brain injury (91%), median admission Glasgow Coma Scale 15, Injury Severity Scores 14.2 (SD, 7.7), traumatic brain injury due to fall (50%), preadmission loss of consciousness (48%), and abnormal head CT scan (97%). Thirty-one children underwent 56 autoregulation tests. Impaired cerebral autoregulation occurred in 15 children (48.4%) who underwent 19 tests; 68% and 32% of tests demonstrated unilateral and bilateral impairment, respectively. Compared with children on median day 6 of admission after traumatic brain injury, impaired autoregulation was most common in the first 5 days after traumatic brain injury (day 1: relative risk, 3.7; 95% CI, 1.9-7.3 vs day 2: relative risk, 2.7; 95% CI, 1.1-6.5 vs day 5: relative risk, 1.33; 95% CI, 0.7-2.3). Children with impaired autoregulation were older (12.3 yr [SD, 1.3 yr] vs 8.7 yr [SD, 1.1 yr]; p = 0.04) and tended to have subdural hematoma (64% vs 44%), epidural hematoma (29% vs 17%), and subarachnoid hemorrhage (36% vs 28%). Eight children (53%) were discharged home with ongoing impaired cerebral autoregulation. Impaired cerebral autoregulation is common in children with complex mild traumatic brain injury, despite reassuring admission Glasgow Coma Scale 13-15. Children with complex mild traumatic brain injury have abnormal cerebrovascular hemodynamics, mostly during the first 5 days. Impairment commonly extends to the contralateral hemisphere and discharge of children with ongoing impaired cerebral autoregulation is common.

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Introduction: Intracerebral complications are the most common cause of morbidity and mortality in children with diabetic ketoacidosis (DKA). Emerging evidence suggests that ischemic injury may be a factor in the development of cerebral edema in this setting. Impairment of cerebral autoregulation may contribute to neurologic injury in DKA and this can be quantified non-invasively using transcranial Doppler ultrasound (TCD). Methods: In this prospective, observational study, we enrolled patients ≤18 years admitted to a tertiary care center pediatric intensive care unit with moderate to severe DKA (serum glucose > 200 mg/dl, pH < 7.15, bicarbonate < 15 mmol/L, and urine ketones). Within 4 hours of admission, we measured the mean flow velocities in the middle cerebral arteries and basilar artery (BA) using TCD. Cerebral autoregulation was evaluated using the transient hyperemic response ratio (THRR), with values ≥ 1.1 defined as normal. TCD was repeated after resolution of DKA. Results: 21 patients have been studied to date [median age 11 yrs (0.75-17), 52% female, median initial glucose 553 (289-553) g/dL, median initial pH 6.99 (6.8-7.13), admission GCS 14 (9-15)]. 66.67% of patients were newly diagnosed with diabetes. Cerebral autoregulation during DKA was impaired in 95% of patients [median THRR on right 0.98 (0.65-1.14), on left 0.98 (0.39-1.26)] and remained abnormal in 50% after resolution of DKA. 7 patients had acute head imaging on presentation (4 with cerebral edema, 1 also with a left basal ganglia infarct, 3 normal). Patients with clinical and imaging evidence of cerebral edema had significantly lower BA mean flow velocities than patients without cerebral edema (p = 0.03). Conclusions: Our data is the first to show prolonged impairment of cerebral autoregulation in children with DKA. They suggest that decreased cerebral blood flow and loss of autoregulation is common during DKA. Understanding these disruptions in cerebral blood flow may lead to future therapeutic targets and should be the subject of further study in hopes of improving neurologic outcomes in diabetic children.

Young Age as a Risk Factor for Impaired Cerebral Autoregulation after Moderate to Severe Pediatric Traumatic Brain Injury

Little is known about age and cerebral autoregulation in children with traumatic brain injury (TBI). The authors compared cerebral autoregulation between young (aged <4 yr) and older (aged > or =4 yr) children with TBI. After University of Washington's institutional review board approval, a retrospective analysis of prospectively collected data (May 2002 and June 2007) was performed. Eligibility criteria included age 16 yr or younger, moderate to severe (admission Glasgow Coma Scale score <13) TBI, TBI on computed tomography scan, and tracheal intubation. Cerebral autoregulation testing was performed within 72 h after TBI, and autoregulation was quantified using the autoregulatory index. An autoregulatory index less than 0.4 represents impaired cerebral autoregulation. The 12-month Glasgow outcome score was measured. Data are presented as mean +/- SD or range. Thirty-seven children (8.9 +/- 5.1 yr; 0.8-16 yr) were enrolled. Children younger than 4 yr had a higher incidence of impaired cerebral autoregulation (8 of 10 vs. 7 of 27; P = 0.006) and worse 12-month outcome (Glasgow outcome score 3.0 +/- 1.0 vs. 4.0 +/- 1.0; P = 0.02) than older children. Age less than 4 yr (adjusted odds ratio, 12.2; 95% confidence interval, 1.5-98.5) and low Glasgow Coma Scale score (adjusted odds ratio for higher Glasgow Coma Scale, 0.53; 95% confidence interval, 0.30-0.96) were independently associated with impaired cerebral autoregulation. Age less than 4 yr was a risk factor for impaired cerebral autoregulation, independent of TBI severity. Age-related factors may play a role in the mechanisms maintaining or worsening cerebral autoregulation in children after TBI.

Hemispheric Differences in Cerebral Autoregulation in Children with Moderate and Severe Traumatic Brain Injury

To examine hemispheric differences in cerebral autoregulation in children with traumatic brain injury (TBI). After IRB approval and consent, subjects underwent static cerebral autoregulation testing during the first 9 days after PICU admission. Cerebral autoregulation was quantified using the autoregulatory index (ARI). Forty-two (27 M:15 F) children (10 +/- 5 years) with TBI and admission Glasgow coma scale score (5 +/- 2) were enrolled. Seven (54%) of the 13 children with focal TBI and 8 (28%) of 29 children with diffuse TBI had impairment or absence of cerebral autoregulation of at least one hemisphere. In patients with isolated focal TBI, ARI was lower (0.40 +/- 0.40 vs. 0.67 +/- 0.40; P = 0.03) in the side of TBI than in the unaffected hemisphere, but cerebral autoregulation was often impaired on the side without TBI or shift (5/13) on head CT. There was no difference in ARI between hemispheres in children with diffuse TBI, with or without superimposed focal lesions (P = 0.17). Patients with bilateral intact cerebral autoregulation tended to have higher 6 month Glasgow Outcome Score (GOS) than patients with either unilateral or bilateral cerebral autoregulation impairment (GOS 4.0 +/- 0.60 vs. 3.6 +/- 0.80; P = 0.08). Hemispheric differences in cerebral autoregulation were common in children with isolated focal TBI. Absence of TBI on CT was not always associated with intact cerebral autoregulation. Patients with bilaterally intact cerebral autoregulation tended to have better outcomes.

The Lower Limit of Cerebral Autoregulation in Children during Sevoflurane Anesthesia

The Lower Limit of Cerebral Autoregulation in Children during Sevoflurane Anesthesia

Cerebral autoregulation in pediatric traumatic brain injury*

The aims of this study were to document the incidence of impaired cerebral autoregulation in children with traumatic brain injury using transcranial Doppler ultrasonography and to examine the relationship between autoregulatory capacity and outcome in children following traumatic brain injury. Prospective cohort study. Harborview Medical Center (level I pediatric trauma center) in Washington state. Thirty-six children <15 yrs old with traumatic brain injury: Glasgow Coma Scale score <9 (n = 12, group 1), Glasgow Coma Scale score 9-12 (n = 12, group 2), and Glasgow Coma Scale score 13-15 (n = 12, group 3). Cerebral autoregulation testing was conducted during extracranial surgery. Mean middle cerebral artery flow velocities were measured using transcranial Doppler as mean arterial pressure was increased to whichever variable was greater: 20% above baseline or a set value (80 mm Hg for <9 yrs and 90 mm Hg for 9-14 yrs). Autoregulatory capacity was quantified by the Autoregulatory Index. Autoregulatory Index <0.4 was considered impaired cerebral autoregulation. Discharge outcome using the Glasgow Outcome Scale score was considered good if the Glasgow Outcome Scale score was > or =4. Twenty-four (67%) of 36 children had an Autoregulatory Index > or =0.4. The incidence of impaired cerebral autoregulation was 42% (five of 12) in group 1, 42% (five of 12) in group 2, and 17% (two of 12) in group 3. Ten (42%) of the 24 children with intact cerebral autoregulation had a good outcome compared with only one of 12 (8%) children with impaired cerebral autoregulation (p =.04). Six of 12 (50%) children with impaired cerebral autoregulation had hyperemia compared with one of 24 (4%) children with intact cerebral autoregulation (p <.01). Hyperemia was associated with poor outcome (p =.01). The incidence of impaired cerebral autoregulation was greatest following moderate to severe traumatic brain injury. Impaired cerebral autoregulation was associated with poor outcome. Hyperemia was associated with impaired cerebral autoregulation and poor outcome.

Cerebral Autoregulation in Children During Sevoflurane Anaesthesia

Cerebral Autoregulation in Children During Sevoflurane Anaesthesia

The lower limit of cerebral autoregulation in children during sevoflurane anesthesia.

In adults, the lower limit of cerebral autoregulation (LLA) is generally considered to be a mean arterial pressure (MAP) of 60 mmHg. The LLA in healthy children has not been identified. The aim of this report is to describe the LLA in anesthetized children and relate it to age. Static cerebral autoregulation testing was performed in children 6 months to 14 years of age during <1 MAC sevoflurane anesthesia. Mean middle cerebral artery flow velocities (Vmca) were continuously measured using transcranial Doppler ultrasonography. MAP was increased with infusion of intravenous phenylephrine incrementally titrated to the greater of either: 1) 20% above baseline MAP or 2) 80 mmHg (<9 years), 90 mmHg (9-14 years). The LLA was defined by the point where the two linear regression lines fitting the Vmca/MAP crossed. The lower limit reserve (LLR) and autoregulatory reserve (ARR%) were defined as follows: LLR=Baseline MAP-LLA; ARR (%)=(LLR/Baseline MAP)x100. There were 13 subjects <2 years of age (group 1), 13 subjects 2 to 5 years of age (group 2), 14 subjects 6 to 9 years of age (group 3), and 13 subjects 10 to 14 years of age (group 4). Older children (groups 3 and 4) had a higher baseline MAP compared with younger children (groups 1 and 2) (82 +/- 10 mmHg vs. 70 +/- 10 mmHg, respectively; P=0.0001). However, there was no difference in LLA (59 +/- 17 mmHg vs. 60 +/- 8 mmHg; P=0.6) between older and younger children. Consequently, the LLR was greater in older children compared with younger children (25 +/- 12 mmHg vs. 12 +/- 10 mmHg, respectively; P=0.0007). Similarly, the ARR was significantly higher in older children compared with younger children (30% +/- 16% vs. 16% +/- 12%; P=0.002). In this study, we found no age-related differences in the LLA. Older children had a greater LLR and ARR compared with young children. The baseline MAP in young children may rest close to the LLA. These findings may have implications for managing hemodynamics in anesthetized children at risk for secondary brain injury.

Cerebral autoregulation in children during sevoflurane anaesthesia

Little is known about cerebral autoregulation in children. The aim of this study was to examine cerebral autoregulation in children. Cerebral autoregulation testing was performed during less than 1 MAC sevoflurane anaesthesia in children (from 6 months to 14 yr) and in adults (18-41 yr). Mean middle cerebral artery flow velocities (V(MCA)) were measured using transcranial Doppler ultrasonography. Mean arterial pressure (MAP) was increased to whichever was greater: 20% above baseline or (i) 80 mm Hg for less than 9 yr, (ii) 90 mm Hg for 9-14 yr, and (iii) 100 mm Hg for adults. Cerebral autoregulation was considered intact if the autoregulatory index was > or =0.4. There were 13 subjects less than 2 yr old (Group 1), 13 subjects 2-5 yr (Group II), 14 subjects 6-9 yr (Group III), 12 subjects 10-14 yr (Group IV), and 12 adults (Group V; control group). All subjects had an autoregulatory index > or =0.4. There was no difference in autoregulatory index between children in Groups I-IV or between children and adults. We found no age-related differences in autoregulatory capacity during low-dose sevoflurane anaesthesia. We report no differences in autoregulatory capacity between children and adults.

Cerebral blood flow and oxygen consumption in man.

Cerebral blood flow and oxygen consumption in man.