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Biomedical subjects

R A Minns

Publications and source records attributed to R A Minns.

At least 19 recordsLinked to original sources
PubMed2005

Critical thresholds of intracranial pressure and cerebral perfusion pressure related to age in paediatric head injury.

BACKGROUND: The principal strategy for managing head injury is to reduce the frequency and severity of secondary brain insults from intracranial pressure (ICP) and cerebral perfusion pressure (CPP), and hence improve outcome. Precise critical threshold levels have not been determined in head injured children. OBJECTIVE: To create a novel pressure-time index (PTI) measuring both duration and amplitude of insult, and then employ it to determine critical insult thresholds of ICP and CPP in children. METHODS: Prospective, observational, physiologically based study from Edinburgh and Newcastle, using patient monitored blood pressure, ICP, and CPP time series data. The PTI for ICP and CPP for 81 children, using theoretical values derived from physiological norms, was varied systematically to derive critical insult thresholds which delineate Glasgow outcome scale categories. RESULTS: The PTI for CPP had a very high predictive value for outcome (receiver operating characteristic analyses: area under curve = 0.957 and 0.890 for mortality and favourable outcome, respectively) and was more predictive than for ICP. Initial physiological values most accurately predicted favourable outcome. The CPP critical threshold values determined for children aged 2-6, 7-10, and 11-15 years were 48, 54, and 58 mm Hg. respectively. CONCLUSIONS: The PTI is the first substantive paediatric index of total ICP and CPP following head injury. The insult thresholds generated are identical to age related physiological values. Management guidelines for paediatric head injuries should take account of these CPP thresholds to titrate appropriate pressor therapy.

Adolescent↗
PubMed2005

Which paediatric head injured patients might benefit from decompression? Thresholds of ICP and CPP in the first six hours.

Severe head injury in childhood continues to be associated with considerable mortality and morbidity. Early surgical decompression may be beneficial and the objective of this study was to examine the relationship between age-related thresholds of mean intracranial pressure (ICP) and cerebral perfusion pressure (CPP) over the first 6 hours and age outcome in paediatric head injury patients. A total of 209 head injured children admitted to five UK hospitals were studied. Patients aged 2 to 16 years were included if they had a minimum of six hours of invasive pressure monitoring. Mean values of ICP and CPP over this period were calculated and compared to those with independent (good recovery and moderate disability) and poor outcome (severe disability, and death) for different age groups. There were 148 children with independent outcome (92 good recovery, 56 moderately disabled), and 61 with poor outcome (30 severely disabled, 31 deaths). There was a significant difference between those with independent compared to poor outcome in relation to ICP (p < 0.001) and CPP (p < 0.001). Patients were divided into three groups according to age. The sensitivity of ICP and CPP in predicting outcome was similar for all groups but the specificity differed between groups. At a CPP of 50 mmHg the specificity varied between the age groups (2 to 6 years: 0.47, 7 to 10 years: 0.28 and 11 to 16 years: 0.10) and similarly for an ICP of 25 mmHg (2 to 6 years: 0.53, 7 to 10 years: 0.44 and 11 to 16 years: 0.38). Younger children may be able to tolerate lower perfusion pressures and still have an independent outcome. Our threshold values for young children are likely to be important in the identification of patients who might benefit from new treatments such as surgical decompression.

Adolescent↗
PubMed2005

Quantification of secondary CPP insult severity in paediatric head injured patients using a pressure-time index.

This paper describes and validates a new Cumulative Pressure-Time Index (CPT) which takes into account both duration and degree of cerebral perfusion pressure (CPP) derangement and determines critical thresholds for CPP, in a paediatric head injury dataset. Sixty-six head-injured children, with invasive minute-to-minute intracranial pressure (ICP) and blood pressure monitoring, had their pre-set CPP derangement episodes (outside the normal range) identified in three childhood age-bands (2-6, 7-10, and 11-16 years) and global outcome assessed at six months post injury. The new cumulative pressure-time index more accurately predicted outcome than previously used summary measures and by varying the threshold CPP values, it was found that these physiological threshold values (< or = 48, < or = 52 and < or = 56 mmHg for 2-6, 7-10, and 11-16 years respectively) best predicted brain insult in terms of subsequent mortality and morbidity.

Adolescent↗
PubMed2004

Age-related differences in intracranial pressure and cerebral perfusion pressure in the first 6 hours of monitoring after children's head injury: association with outcome.

OBJECTIVES: Severe head injury in childhood is associated with considerable mortality and morbidity. In this study we determined age-related differences in the relationship between outcome and intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in the first 6 h of monitoring in a large cohort of head-injured children. METHODS: Two hundred and thirty-five head-injured children (admitted to five UK hospitals over a 15-year period) in whom intracranial pressure monitoring was clinically indicated were studied. RESULTS: Patients were divided into three age groups (2-6, 7-10 and 11-16 years). The sensitivity of ICP and CPP were similar. Differences were found in the specificity of ICP and CPP for each group and these were more marked for CPP. For a specificity of 50% the pressures were 53, 63 and 66 mmHg for the three age groups. CONCLUSIONS: There are age-related differences in the specificity of intracranial pressure and cerebral perfusion pressure in relation to outcome. These differences may be important in the clinical management of head-injured children. Thus cerebral perfusion pressures of 53, 63 and 66 mmHg should be the minimum to strive for in these three age groups respectively.

Adolescent↗
PubMed2004

Inner calvarial erosion from traumatic subdural haematoma in infancy.

CASE REPORT: This is a report of a case of a subdural haematoma in infancy of possible non-accidental aetiology with raised pericerebral pressure, which we postulate has eroded the inner table of the cranial bones and resulted in leakage of marrow precursor cells into the extradural space. RESULT: Subdural tapping via the fontanelle has created a channel allowing subsequent ingress of nucleated red cell precursors into the subdural space. This addition to the subdural collection has prolonged its course necessitating subduro-peritoneal shunting.

Erythrocytes↗
PubMed2003

Graphical display of variability and inter-relationships of pressure signals in children with traumatic brain injury.

A prospective observational study was undertaken to examine time series ICU data of pressure variables (mean arterial pressure (MAP), intracranial pressure (ICP) and cerebral perfusion pressure (CPP)) and relate their variability (SD) to outcome, together with simple graphical displays which could be useful at the ICU bedspace. Forty-three children (aged < 1-15 years) were admitted to the intensive care unit for Regional Neurosurgical Service, Edinburgh, following traumatic brain injury (TBI). The standard deviations from 221,291 validated pressure data measurements (representing three variables) were calculated for the duration of ICP monitoring (and in 48 h epochs from the time of injury). Data were displayed on polygraphs, and several well-defined 'patterns' were described. The standard deviations of MAP, ICP and CPP for the total duration of monitoring were found to be significantly related to survival (p = 0.003, <0.001 and 0.005, respectively), while the SD of ICP alone was strongly related to global recovery (p = 0.008) in the first 48 h post-injury. Patterns in 104 epochs (each of 48 h) were identified. Ninety-two were of the type I (MAP > CPP > ICP) pattern and 12 were of the non-type I pattern. Glasgow Outcome Scale scores at 12 months were significantly related to the dichotomized pattern type (Fisher's exact test p < 0.001 for both alive versus dead and independent versus dependent outcomes). Only one patient with type I pattern died in this series. While variability of ICP during the first 48 h post-injury is predictive of the outcome, the pattern behaviour of three pressure signals gives useful outcome prediction information throughout monitoring. These displays may help interpret some of the plethora of data produced at the bedside.

Accidental Falls↗
PubMed2003

Long-term risks and benefits of a separate CSF access device with ventriculoperitoneal shunting in childhood hydrocephalus.

To determine the long-term risks and benefits of a separate CSF reservoir in the management of 52 children (23 males, 29 females) with shunted hydrocephalus, a retrospective study was performed comparing the use and complications after separate reservoir insertion, with a prereservoir control period. Median age at first shunt insertion was 1 month and median age at reservoir insertion was 2 years 6 months. Median follow-up for shunt with the additional reservoir was 19 years 1 month. There was no mortality due to shunt failure nor CNS infection, and there were significantly fewer episodes of ventriculitis (p < 0.01) and shunt blockage (p < 0.0001) compared with the prereservoir period. There was no hemiplegia, epilepsy, visual, nor cognitive loss from the additional reservoir. The reservoir was used for access in 344 attendances (mean 6.62 attendances per patient) for diagnosis or treatment of raised pressure or CNS infection. It was concluded that a separate CSF reservoir is useful in the long-term management of patients with shunted hydrocephalus and is without mortality or significant increased morbidity.

Adolescent↗
PubMed2003

Traumatic brain injury in childhood: intensive care time series data and outcome.

Age-specific norms are necessary to determine potential secondary brain insult after head injury in children. We describe and quantify the secondary physiological derangement recorded in children of different ages following traumatic brain injury, and relate it to outcome at 12 months post-injury. Prospective time-series data (including intracranial pressure, arterial blood pressure, cerebral perfusion pressure, oxygen saturation, temperature and heart rate) downloaded from ICU monitors, were examined to identify abnormal (i.e. outside normal age-specific limits) recordings lasting more than 5 min. Cumulated total duration of derangement was calculated for each parameter and as a percentage of the time that the ICP monitor was in situ. Univariate and multivariate logistic regression modelling was used to evaluate predictors of outcome. Age-specificity allows realistic comparisons of physiological data among children. Duration of age-specific derangement of CPP was found to predict outcome (dead v. alive: p = 0.003 and Glasgow Outcome Score 1-3 v. 4-5, i.e. poor v. independent outcome p = 0.004).

Adolescent↗
PubMed2001

Pressure compensation in shunt-dependent hydrocephalus with CSF shunt malfunction.

This study is a retrospective analysis of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) data from 56 children with active hydrocephalus and cerebrospinal fluid (CSF) shunt malfunction. The pressures were measured from a separately sited CSF access device placed in the frontal horn of the lateral ventricle. Of the patients, 79% had an elevated ICP (mean 20+/-12 mmHg). A subgroup of patients demonstrated ten different forms of CSF-filled swelling. This group had significantly lower ICP recordings (P=0.000075) with a mean ICP of 8.5 mmHg compared with the remainder (22.9 mmHg). This pressure 'compensation' was because of additional nonphysiological accommodation of CSF volume. Overall the CPP was normal in 35% of cases despite normal ICP occurring in only 11% of cases. The CPPs were not significantly different in those with and without compensation. Measurement of ICP may not always be a reliable indicator of shunt malfunction in shunt-dependent children who present with compensatory CSF-filled spaces.

Adolescent↗
PubMed2000

Annual incidence of shaken impact syndrome in young children.

We looked at the incidence and demography of nonaccidental head injury in children in a prospective population-based study of paediatric units in Scotland during 1998-99. Shaken impact syndrome occurs with an annual incidence of 24.6 per 100000 children younger than 1 year (95% CI 14.9-38.5). Cases are more common in urban regions, and during autumn and winter months. The risk of a child suffering non-accidental head injury by age 1 year is one in 4065. These brain injuries occur almost exclusively in young infants (median age 2.2 months).

Child Abuse↗
PubMed2000

Early posttraumatic seizures in non-accidental head injury: relation to outcome.

To document the characteristics of early posttraumatic seizures (EPTS) in non-accidental head injury (NAHI), and examine their relation with outcome, a retrospective study was carried out. All children with NAHI admitted to the Royal Hospital for Sick Children, Edinburgh, since 1981 were identified. The characteristics of EPTS, EEG, and outcome were noted. Forty-four cases were identified. The average age of children at presentation was 5.9 months. Thirty-two of these children had EPTS. The median length of follow-up was 3 years. The mortality rate was six in 44 (14%). The neurodevelopmental outcome correlated significantly with the presence and severity of EPTS (Tau=0.317,p=0.017). Of survivors, 22% developed late posttraumatic epilepsy; the outcome in those with epilepsy was significantly worse than those without (p<0.0001). It was concluded that the severity of the primary brain injury dictates the severity of the EPTS and neurodevelopmental status at follow-up.

Brain↗
PubMed1999

The relation between intracranial pressure and outcome in non-accidental head injury.

The aim of this retrospective study was to ascertain whether physiological derangement and potential secondary brain insult from raised intracranial pressure (ICP) or reduced cerebral perfusion pressure (CPP) in non-accidental head injury (NAHI) influences outcome. Any child who had a diagnosis of NAHI and had ICP monitoring or measurements during the acute illness was entered in the study. Seventeen children with an average age 5.1 months (range 1 to 20 months) were identified. Details of the acute encephalopathy, lowest mean arterial blood pressure (MAP), mean of maximum ICP measured, lowest CPP, and neurodevelopmental outcome at follow up were obtained from the hospital case notes. Seshia's (1994) outcome classification scale was used. The lowest CPP was very significantly related to outcome (P=0.0047, tau=-0.544). Mean of maximum ICP did not correlate with outcome. The lowest MAP was significantly related to outcome (P=0.039). It was concluded that the degree of secondary brain insult from reduced CPP influences outcome.

Craniocerebral Trauma↗
PubMed1999

A comparison of hip guidance with reciprocating gait orthoses in children with spinal paraplegia: results of a ten-year prospective study.

Twenty-two children with spinal paraplegia were entered into a prospective randomised study to assess the efficacy of two reciprocating orthoses and to identify any prognostic factors that might affect continuing use of the devices. Thirteen received a hip guidance orthosis (HGO) and nine a reciprocating gait orthosis (RGO). They were followed for a mean of ten years. At one year follow-up there were three statistically significant differences between the two groups at the 5% level: repairs were commoner in the RGO group, the RGO group improved in their ability to walk over difficult outdoor surfaces and the HGO group improved more in their ability to rise from a sitting to standing position. At one year follow-up there was a positive parental and child's view of the benefits of the orthoses, but by ten years only 24% of the patients were still using the orthoses. We were not able to show any definite advantage of one device over the other or any statistically significant prognostic factors for walking in the longer term with a reciprocating orthosis. We question whether or not the routine provision of these types of orthosis is justifiable when it appears that, in the longer term, the patients we studied preferred wheelchair mobility.

Adolescent↗
PubMed1999

A classification of CSF shunt malfunction.

A classification of dysfunctional shunts is proposed and clarification of the terminology discussed. This is based on experience of successive shunt malfunctions over a 3-year period with the aid of ventricular pressure measurements, imaging and clinical semiology. The classification system is both anatomical and functional.

Cerebrospinal Fluid Shunts↗
PubMed1999

Magnetic resonance imaging in acute non-accidental head injury.

Making the diagnosis of non-accidental head injury, particularly in the acute illness, can be difficult. The aim of this retrospective study was to evaluate the use of magnetic resonance imaging in the acute presentation of non-accidental head injury. Twelve cases admitted to the Royal Hospital for Sick Children, Edinburgh with a diagnosis of non-accidental head injury, and who had magnetic resonance imaging in the acute illness, were identified. The average age was 5.7 mo (range 1 to 34 mo). The mechanism of the primary injury was whiplash-shaking injury syndrome with impact in four cases and without evidence of impact in seven; in one case there was a compression injury. The magnetic resonance imaging findings reflected the pathological consequences of rotational acceleration-deceleration injury and did not differ between those cases with evidence of impact and those without. Subdural haematomas were identified in all cases; the commonest location for subdural blood was the subtemporal region. It is surprising and important that the most frequent location of subdural blood was in the subtemporal area. This is an area difficult to assess by computerized tomography. Evidence of repeated injuries was found in two cases. These findings confirm the value of magnetic resonance imaging in the acute phase of non-accidental head injury.

Acute Disease↗