Age-specific cerebral perfusion pressure thresholds and survival in children and adolescents with severe traumatic brain injury*

OBJECTIVES

Evidence-based traumatic brain injury guidelines support cerebral perfusion pressure thresholds for adults at a class 2 level, but evidence is lacking in younger patients. The purpose of this study is to identify the impact of age-specific cerebral perfusion pressure thresholds on short-term survival among patients with severe traumatic brain injury.

DESIGN

Institutional review board-approved, prospective, observational cohort study.

SETTING

Level I or II trauma centers in New York State.

PATIENTS

Data on all patients with a postresuscitation Glasgow Coma Score less than 9 were added in the Brain Trauma Foundation prospective New York State TBI-trac database.

MEASUREMENTS AND MAIN RESULTS

We calculated the survival rates and relative risks of mortality for patients with severe traumatic brain injury based on predefined age-specific cerebral perfusion pressure thresholds. A higher threshold and a lower threshold were defined for each age group: 60 and 50 mm Hg for 12 years old or older, 50 and 35 mm Hg for 6-11 years, and 40 and 30 mm Hg for 0-5 years. Patients were stratified into age groups of 0-11, 12-17, and 18 years old or older. Three exclusive groups of CPP-L (events below low cerebral perfusion pressure threshold), CPP-B (events between high and low cerebral perfusion pressure thresholds), and CPP-H (events above high cerebral perfusion pressure threshold) were defined. As an internal control, we evaluated the associations between cerebral perfusion pressure events and events of hypotension and elevated intracranial pressure. Survival was significantly higher in 0-11 and 18 years old or older age groups for patients with CPP-H events compared with those with CPP-L events. There was a significant decrease in survival with prolonged exposure to CPP-B events for the 0-11 and 18 years old and older age groups when compared with the patients with CPP-H events (p = 0.0001 and p = 0.042, respectively). There was also a significant decrease in survival with prolonged exposure to CPP-L events in all age groups compared with the patients with CPP-H events (p< 0.0001 for 0- to 11-yr olds, p = 0.0240 for 12- to 17-yr olds, and p < 0.0001 for 18-yr old and older age groups). The 12- to 17-year olds had a significantly higher likelihood of survival compared with adults with prolonged exposure to CPP-L events (< 50 mm Hg). CPP-L events were significantly related to systemic hypotension for the 12- to 17-year-old group (p = 0.004) and the 18-year-old and older group (p < 0.0001). CPP-B events were significantly related to systemic hypotension in the 0- to 11-year-old group (p = 0.014). CPP-B and CPP-L events were significantly related to elevated intracranial pressure in all age groups.

CONCLUSIONS

Our data provide new evidence that cerebral perfusion pressure targets should be age specific. Furthermore, cerebral perfusion pressure goals above 50 or 60 mm Hg in adults, above 50 mm Hg in 6- to 17-year olds, and above 40 mm Hg in 0- to 5-year olds seem to be appropriate targets for treatment-based studies. Systemic hypotension had an inconsistent relationship to events of low cerebral perfusion pressure, whereas elevated intracranial pressure was significantly related to all low cerebral perfusion pressure events across all age groups. This may impart a clinically important difference in care, highlighting the necessity of controlling intracranial pressure at all times, while targeting systolic blood pressure in specific instances.

Outcome prediction model for severe traumatic brain injury

Aim

Treatment of severe traumatic brain injury is aided by better prediction of outcomes. The purpose of the present study was to develop and validate a prediction model using retrospective analysis of prospectively collected clinical data from two tertiary critical care medical centers in Japan.

Methods

Data were collected from 253 patients with a Glasgow Coma Scale score of <9. Within 24 h of their admission, 15 factors possibly related to outcome were evaluated. The dataset was randomly split into training and validation datasets using the repeated random subsampling method. A logistic regression model was fitted to the training dataset and predictive accuracy was assessed using the validation data.

Results

The best model included the variables age, pupillary light reflex, extensive subarachnoid hemorrhage, intracranial pressure, and midline shift. The estimated area under the curve for the model development data was 0.957, with a 95% confidence interval of 0.926-0.987, and that for validation data was 0.947, with a 95% confidence interval of 0.909-0.980.

Conclusion

Our predictive model was shown to have high predictive value. It will be useful for review of treatment, family counseling, and efficient allocation of resources for patients with severe traumatic brain injury.

Acute neuro-endocrine profile and prediction of outcome after severe brain injury

OBJECT

The aim of the study was to evaluate the early changes in pituitary hormone levels after severe traumatic brain injury (sTBI) and compare hormone levels to basic neuro-intensive care data, a systematic scoring of the CT-findings and to evaluate whether hormone changes are related to outcome.

METHODS

Prospective study, including consecutive patients, 15-70 years, with sTBI, Glasgow Coma Scale (GCS) score ≤ 8, initial cerebral perfusion pressure > 10 mm Hg, and arrival to our level one trauma university hospital within 24 hours after head trauma (n = 48). Serum samples were collected in the morning (08-10 am) day 1 and day 4 after sTBI for analysis of cortisol, growth hormone (GH), prolactin, insulin-like growth factor 1 (IGF-1), thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), follicular stimulating hormone (FSH), luteinizing hormone (LH), testosterone and sex hormone-binding globulin (SHBG) (men). Serum for cortisol and GH was also obtained in the evening (17-19 pm) at day 1 and day 4. The first CT of the brain was classified according to Marshall. Independent staff evaluated outcome at 3 months using GOS-E.

RESULTS

Profound changes were found for most pituitary-dependent hormones in the acute phase after sTBI, i.e. low levels of thyroid hormones, strong suppression of the pituitary-gonadal axis and increased levels of prolactin. The main findings of this study were: 1) A large proportion (54% day 1 and 70% day 4) of the patients showed morning s-cortisol levels below the proposed cut-off levels for critical illness related corticosteroid insufficiency (CIRCI), i.e. <276 nmol/L (=10 ug/dL), 2) Low s-cortisol was not associated with higher mortality or worse outcome at 3 months, 3) There was a significant association between early (day 1) and strong suppression of the pituitary-gonadal axis and improved survival and favorable functional outcome 3 months after sTBI, 4) Significantly lower levels of fT3 and TSH at day 4 in patients with a poor outcome at 3 months. 5) A higher Marshall CT score was associated with higher day 1 LH/FSH- and lower day 4 TSH levels 6) In general no significant correlation between GCS, ICP or CPP and hormone levels were detected. Only ICPmax and LH day 1 in men was significantly correlated.

CONCLUSION

Profound dynamic changes in hormone levels are found in the acute phase of sTBI. This is consistent with previous findings in different groups of critically ill patients, most of which are likely to be attributed to physiological adaptation to acute illness. Low cortisol levels were a common finding, and not associated with unfavorable outcome. A retained ability to a dynamic hormonal response, i.e. fast and strong suppression of the pituitary-gonadal axis (day 1) and ability to restore activity in the pituitary-thyroid axis (day 4) was associated with less severe injury according to CT-findings and favorable outcome.

Functional outcome following rehabilitation in chronic severe traumatic brain injury patients: A prospective study

Objective:

The objective was to assess functional outcome of rehabilitation in chronic severe traumatic brain injury (TBI) in-patients.

Setting:

The study was performed at university tertiary research hospital.

Study Design:

A prospective cross-sectional study

Materials and Methods:

Forty patients (34 men) with mean age of 30.1 years (range 6--60, SD 10.8), severe TBI (Glasgow coma scale 3--8, duration of coma > 6 hours, post-traumatic amnesia> 1 day postinjury) were admitted in rehabilitation unit minimum 3 months (mean 7.7±4.6 months, range 3--22 months) following injury falling in Glasgow outcome scale (GOS) of 3. Functional recovery was assessed using the Barthel Index (BI) score and disability rating scores (DRS).

Data Analysis:

Paired Student's t-test was used for the assessment of functional recovery using mean BI scores at admission and discharge. The Wilcoxon nonparametric test was used for the assessment of functional recovery by comparing admission and discharge DRS scores.

Results:

Mean duration of stay was 30.8 days (range 18--91, SD15.6). Significant functional recovery observed in patients comparing BI and DRS scores at admission and discharge (mean BI admission 50.5±25.4, range 0--85 vs. mean discharge BI score 61.1±25.3, range 0--95, P<0.001, mean DRS admission score 7.57±4.1, range 2.5--21.0 vs. mean discharge DRS score 6.36±4.3, range 1.0-21.0, P<0.001).

Conclusion:

Patients with severe TBI continue to show functional recovery even in chronic phase with rehabilitation. They are left with significant residual physical and cognitive deficits and would require long-term care and assistance from care givers for the daily activities, as suggested by the mean DRS score at discharge.