The “Lund concept”: what it is and what it isn't

Measuring intracranial pressure by invasive, less invasive or non-invasive means: limitations and avenues for improvement

Sixty years have passed since neurosurgeon Nils Lundberg presented his thesis about intracranial pressure (ICP) monitoring, which represents a milestone for its clinical introduction. Monitoring of ICP has since become a clinical routine worldwide, and today represents a cornerstone in surveillance of patients with acute brain injury or disease, and a diagnostic of individuals with chronic neurological disease. There is, however, controversy regarding indications, clinical usefulness and the clinical role of the various ICP scores. In this paper, we critically review limitations and weaknesses with the current ICP measurement approaches for invasive, less invasive and non-invasive ICP monitoring. While risk related to the invasiveness of ICP monitoring is extensively covered in the literature, we highlight other limitations in current ICP measurement technologies, including limited ICP source signal quality control, shifts and drifts in zero pressure reference level, affecting mean ICP scores and mean ICP-derived indices. Control of the quality of the ICP source signal is particularly important for non-invasive and less invasive ICP measurements. We conclude that we need more focus on mitigation of the current limitations of today's ICP modalities if we are to improve the clinical utility of ICP monitoring.

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.

Implications of neurophysiological parameters in persons with severe brain injury with respect to improved patient outcomes: a retrospective review

PRIMARY OBJECTIVE

To determine whether neurophysiologic parameters-intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), partial brain tissue oxygenation (PbtO(2)) and pressure reactivity index (PRx, calculated)-captured during the management of traumatic brain injury (TBI) have a relationship to patient outcome.

RESEARCH DESIGN

A retrospective analysis of neurophysiologic data collected from persons under medical management of TBI per Conemaugh Memorial Medical Center (CMMC) standard treatment algorithms.

METHODS AND PROCEDURES

Nine patients' medical records that matched International Statistical Classification of Diseases and Related Health Problems (ICD-9) code for head injury and a Current Procedural Terminology (CPT) code for an ICP monitoring device or ventriculostomy were analysed on the aforementioned parameters.

MAIN OUTCOMES AND RESULTS

Statistical significance by mortality (α = 0.05) was found for ICP, CPP and PbtO(2). PRx showed a pattern of significance over the last 72 hours. The couplets (CPP & ICP) and (CPP & MAP) demonstrated significant correlations.

CONCLUSIONS

Improved autoregulation was associated with PRx values near zero. Controlling those parameters that affect PRx, namely MAP, ICP and CPP and more importantly cerebral oxygen perfusion (COP), would likely increase the probability of a better outcome while guarding against secondary insult.

Emergency department predictors of tracheostomy in patients with isolated traumatic brain injury requiring emergency cranial decompression

Object

Patients with severe traumatic brain injury (TBI) frequently require a tracheostomy for prolonged mechanical ventilation and/or pulmonary toilet. It is now proven that the earlier the procedure is done, the more beneficial it is to the patient. The present study was carried out to determine if the requirement of a tracheostomy can be predicted on arrival of a patient to the emergency department. The prediction can potentially aid in combining the procedure with cranial decompression. In this study, the authors' aim was to determine the emergency department predictors of tracheostomy in patients with isolated TBI requiring emergency cranial decompression.

Methods

The authors performed a retrospective chart review of all patients who underwent surgery for isolated TBI and required more than 4 days of mechanical ventilation. Multivariate logistic regression analysis was used for predictive indicators.

Results

In patients with isolated severe TBI, a patient age of 31–50 years, the presence of preexisting medical comorbid conditions, a delay in emergency department arrival exceeding 1.5 hours, an abnormal pupil response on arrival, and a preoperative neurological worsening during hospital stay were independent predictors of the requirement for tracheostomy. These findings were validated in a small cohort of patients and were found to be significant.

Conclusions

Requirement of a tracheostomy can be predicted in patients with severe TBI on arrival to the emergency department. These results were validated in a small cohort of patients, and it was found that the positive predictive value of requirement of tracheostomy was directly proportional to the number of predictors present. Larger prospective studies with appropriate control groups are further recommended to validate the authors' findings.