Management of increased intracranial pressure: a review for clinicians

Improved spatial memory, neurobehavioral outcomes, and neuroprotective effect after progesterone administration in ovariectomized rats with traumatic brain injury: Role of RU486 progesterone receptor antagonist

OBJECTIVES

The contribution of classic progesterone receptors (PR) in interceding the neuroprotective efficacy of progesterone (P4) on the prevention of brain edema and long-time behavioral disturbances was assessed in traumatic brain injury (TBI).

MATERIALS AND METHODS

Female Wistar rats were ovariectomized and apportioned into 6 groups: sham, TBI, oil, P4, vehicle, and RU486. P4 or oil was injected following TBI. The antagonist of PR (RU486) or DMSO was administered before TBI. The brain edema and destruction of the blood-brain barrier (BBB) were determined. Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and beam walk (BW) task were evaluated previously and at various times post-trauma. Long-time locomotor and cognitive consequences were measured one day before and on days 3, 7, 14, and 21 after the trauma.

RESULTS

RU486 eliminated the inhibitory effects of P4 on brain edema and BBB leakage (P<0.05, P<0.001, respectively). RU486 inhibited the decremental effect of P4 on ICP as well as the increasing effect of P4 on CPP (P<0.001) after TBI. Also, RU486 inhibited the effect of P4 on the increase in traversal time and reduction in vestibulomotor score in the BW task (P<0.001). TBI induced motor, cognitive, and anxiety-like disorders, which lasted for 3 weeks after TBI; but, P4 prevented these cognitive and behavioral abnormalities (P<0.05), and RU486 opposed this P4 effect (P<0.001).

CONCLUSION

The classic progesterone receptors have neuroprotective effects and prevent long-time behavioral and memory deficiency after brain trauma.

Forecasting intracranial hypertension using multi-scale waveform metrics

OBJECTIVE

Acute intracranial hypertension is an important risk factor of secondary brain damage after traumatic brain injury. Hypertensive episodes are often diagnosed reactively, leading to late detection and lost time for intervention planning. A pro-active approach that predicts critical events several hours ahead of time could assist in directing attention to patients at risk.

APPROACH

We developed a prediction framework that forecasts onsets of acute intracranial hypertension in the next 8 h. It jointly uses cerebral auto-regulation indices, spectral energies and morphological pulse metrics to describe the neurological state of the patient. One-minute base windows were compressed by computing signal metrics, and then stored in a multi-scale history, from which physiological features were derived.

MAIN RESULTS

Our model predicted events up to 8 h in advance with an alarm recall rate of 90% at a precision of 30% in the MIMIC-III waveform database, improving upon two baselines from the literature. We found that features derived from high-frequency waveforms substantially improved the prediction performance over simple statistical summaries of low-frequency time series, and each of the three feature classes contributed to the performance gain. The inclusion of long-term history up to 8 h was especially important.

SIGNIFICANCE

Our results highlight the importance of information contained in high-frequency waveforms in the neurological intensive care unit. They could motivate future studies on pre-hypertensive patterns and the design of new alarm algorithms for critical events in the injured brain.

Brain death and true patient care

The "brain death" standard as a criterion of death is closely associated with the need for transplantable organs from heart-beating donors. Are all of these potential donors really dead, or does the documented evidence of patients destined for organ harvesting who improve, or even recover to live normal lives, call into question the premise underlying "brain death"? The aim of this paper is to re-examine the notion of "brain death," especially its clinical test-criteria, in light of a broad framework, including medical knowledge in the field of neuro-intensive care and the traditional ethics of the medical profession. I will argue that both the empirical medical evidence and the ethics of the doctor-patient relationship point to an alternative approach toward the severely comatose patient (potential brain-dead donor). Lay Summary: Though legally accepted and widely practiced, the "brain death" standard for the determination of death has remained a controversial issue, especially in view of the occurrence of "chronic brain death" survivors. This paper critically re-evaluates the clinical test-criteria for "brain death," taking into account what is known about the neuro-critical care of severe brain injury. The medical evidence, together with the understanding of the moral role of the physician toward the patient present before him or her, indicate that an alternative approach should be offered to the deeply comatose patient.

Intersubject assessment of implantable antenna performance for intracranial pressure monitoring

This work focuses on the assessment of an implantable antenna performance designed for Intracranial Pressure (ICP) monitoring applications. A simplified three-layer canonical model, exclusively designed for antenna tuning inside anatomical human head, is evaluated. Inter-subject variability is studied using four different human head anatomical models which are part of the Virtual Family by Foundation for Research on Information Technologies in Society (IT'IS) and have been extensively used in the literature. Simulations are performed within MedRadio band, which is worldwide available, and has been allocated exclusively for medical applications. The results highlight the suitability of the proposed simplified model for antenna fine-tuning. Moreover, no significant detuning effects are observed among the anatomical models, as the antenna maintain sits resonance, radiation and safety performance.

Advances in Intracranial Pressure Monitoring and Its Significance in Managing Traumatic Brain Injury

Intracranial pressure (ICP) measurements are essential in evaluation and treatment of neurological disorders such as subarachnoid and intracerebral hemorrhage, ischemic stroke, hydrocephalus, meningitis/encephalitis, and traumatic brain injury (TBI). The techniques of ICP monitoring have evolved from invasive to non-invasive-with both limitations and advantages. Some limitations of the invasive methods include short-term monitoring, risk of infection, restricted mobility of the subject, etc. The invasiveness of a method limits the frequency of ICP evaluation in neurological conditions like hydrocephalus, thus hampering the long-term care of patients with compromised ICP. Thus, there has been substantial interest in developing noninvasive techniques for assessment of ICP. Several approaches were reported, although none seem to provide a complete solution due to inaccuracy. ICP measurements are fundamental for immediate care of TBI patients in the acute stages of severe TBI injury. In severe TBI, elevated ICP is associated with mortality or poor clinical outcome. ICP monitoring in conjunction with other neurological monitoring can aid in understanding the pathophysiology of brain damage. This review article presents: (a) the significance of ICP monitoring; (b) ICP monitoring methods (invasive and non-invasive); and (c) the role of ICP monitoring in the management of brain damage, especially TBI.

Contribution of estrogen receptors alpha and beta in the brain response to traumatic brain injury

OBJECT

Although there is evidence that estradiol has neuroprotective effects after traumatic brain injury (TBI) in female rats, it is unclear which estrogen receptor (ER) subtype, ERα or ERβ, mediates this effect. The authors therefore examined the roles of the different ERs in this effect. Here the authors used the ERα selective agonist propyl pyrazole triol (PPT) and the ERβ selective agonist diarylpropionitrile (DPN) alone and in combination in female rats to investigate this question.

METHODS

Before the ovariectomized animals were injured using the Marmarou TBI technique, they were randomly divided into the following 9 groups: control, sham, TBI, vehicle, E1 (physiological dose of 17-β estradiol), E2 (pharmacological dose of 17-β estradiol), PPT, DPN, and PPT+DPN. Levels of blood-brain barrier (BBB) disruption (5 hours) and water content (24 hours) were evaluated after TBI. In groups receiving drugs or vehicle, treatment was administered as a single dose intraperitoneally 30 minutes after induction of TBI.

RESULTS

Results showed that brain edema or brain water content after TBI was lower (p < 0.001) in the E2, PPT, DPN, and PPT+DPN groups than it was in the vehicle group. After trauma, the Evans blue dye content or BBB permeability was significantly higher in the TBI and vehicle groups (p < 0.001) than in the E2, PPT, DPN, and PPT+DPN groups. The inhibitory effects of PPT+DPN on brain water content, neurological scores, and Evans blue dye content were the highest for all groups. Although both PPT and DPN increased neurological scores after TBI, PPT appears to be more effective in increasing neurological scores.

CONCLUSIONS

Neuroprotective effects of estradiol on brain edema, BBB permeability, and neurological scores are mediated through both ERα and ERβ. This may suggest a therapeutic potential in the brain trauma for ER-specific agonists.

Effect of sex steroid hormones on brain edema, intracranial pressure, and neurologic outcomes after traumatic brain injury

Recent studies have reported that estrogen and progesterone have a neuroprotective effect after traumatic brain injury (TBI); however, the mechanism(s) for this effect have not yet been elucidated. The aim of the present study was to investigate the role of sex steroid hormones on changes in brain edema, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) after TBI in ovariectomized (OVX) rats. In this study, 50 female rats were divided into 5 groups: control (intact), sham, and 3 TBI groups consisting of vehicle, estrogen (1 mg/kg), and progesterone (8 mg/kg). TBI was induced by the Marmarou method, and the hormones were injected i.p. 30 min after TBI. ICP was measured in the spinal cord, and CPP was calculated by subtracting the mean arterial pressure (MAP) from ICP. The results revealed that brain water content after TBI was lower (p < 0.001) in the estrogen and progesterone groups than in the vehicle group. After trauma, ICP was significantly higher in TBI rats (p < 0.001). The ICP in the estrogen and progesterone groups decreased at 4 and 24 h after TBI compared with vehicle (p < 0.001 and p < 0.05, respectively). The CPP in the estrogen and progesterone groups increased after 24 h compared with vehicle (p < 0.001). Also after TBI, the neurological score (veterinary coma scale) was significantly higher than vehicle at 1 h (p < 0.01) and 24 h (p < 0.001) in the group treated with estrogen. In conclusion, pharmacological doses of estrogen and progesterone improved ICP, CPP, and neurological scores after TBI in OVX rats, which implies that these hormones play a neuroprotective role in TBI.

Acute physiologic predictors of mortality and functional and cognitive recovery in hemorrhagic stroke: 1-, 3-, and 6-month assessments

This study was conducted to evaluate the prognostic values of acute physiologic parameters of mortality and functional and cognitive recovery. We studied 108 patients with hemorrhagic stroke admitted within 24 hours after stroke onset to a neurologic intensive care department. Details concerning potential physiologic predictors were collected (i.e., systolic and diastolic blood pressure, pulse rate, respiration rate, body temperature, hematocrit, Pao(2), Paco(2) and serum osmolality, pH, cholesterol, and glucose levels) at admission. As outcome variables, mortality and functional and cognitive recovery at 1, 3, and 6 months were measured. Results showed that blood pressure, serum pH, and Pao(2) on admission are significant predictors of mortality; that respiratory rate and hematocrit on admission are significant predictors of functional recovery; and that respiratory rate, Pao(2), and heart rate on admission predict cognitive recovery. It appears that the physiologic predictors of hemorrhagic stroke are remarkably dependent on outcome definitions (i.e., mortality, functional disability, or cognitive ability), but not with recovery times.

“The Use of Positive End-Expiratory Pressure in Mechanical Ventilation”

An improvement in oxygenation for patients who have acute respiratory failure using PEEP was described close to 40 years ago. Since then, a considerable amount of research has allowed clinicians to use this therapeutic modality in various ways. In patients receiving mechanical ventilation, the term positive end-expiratory pressure (PEEP) refers to pressure in the airway at the end of passive expiration that exceeds atmospheric pressure. The use of PEEP mainly has been reserved to recruit or stabilize lung units and improve oxygenation in patients who have hypoxemic respiratory failure. It has been shown that this helps the respiratory muscles to decrease the work of breathing and the amount of infiltrated-atelectatic tissues. The beneficial effects of the use of PEEP include: the improvement of oxygenation, recruitment of lung units, and improvement of compliance. Other effects can be adverse, like decreasing cardiac output, increased risk of barotrauma, and the interference with assessment of hemodynamic pressures.

Therapy of intracranial hypertension in patients with fulminant hepatic failure

Severe intracranial hypertension (IH) in the setting of fulminant hepatic failure (FHF) carries a high mortality and is a challenging disease for the critical care provider. Despite considerable improvements in the understanding of the pathophysiology of cerebral edema during liver failure, therapeutic maneuvers that are currently available to treat this disease are limited. Orthotopic liver transplantation is currently the only definitive therapeutic strategy that improves outcomes in patients with FHF. However, many patients die prior to the availability of donor organs, often because of cerebral herniation. Currently, two important theories prevail in the understanding of the pathophysiology of IH during FHF. Ammonia and glutamine causes cytotoxic cerebral injury while cerebral vasodilation caused by loss of autoregulation increases intracranial pressure (ICP) and predisposes to herniation. Although ammonia-reducing strategies are limited in humans, modulation of cerebral blood flow seems promising, at least during the early stages of hepatic encephalopathy. ICP monitoring, transcranial Doppler, and jugular venous oximetry offer valuable information regarding intracranial dynamics. Induced hypothermia, hypertonic saline, propofol sedation, and indomethacin are some of the newer therapies that have been shown to improve survival in patients with severe IH. In this article, we review the pathophysiology of IH in patients with FHF and outline various therapeutic strategies currently available in managing these patients in the critical care setting.

Postanesthesia care of the patient suffering from traumatic brain injury

Each year 1.5 million people in the United States suffer a traumatic brain injury (TBI), and many of these patients require immediate surgery. TBI patients provide additional assessment and technological challenges for perianesthesia nursing care. A major goal of PACU nursing is the prevention of secondary head injury during the postanesthesia period.

Placing nasogastric tubes and intracranial pressure

Recently, a new method for placing nasogastric tubes (NGT) in dysphagic patients was proposed, which uses the swallowing reflex and was therefore called 'reflex placement.' The authors describe the use of this method in a patient with a large left sided striatocapsular hemorrhage, in whom decompressive craniotomy had been performed previously. Whereas the conventional approach of placing NGT led to a massive increase of intracranial pressure (ICP) and to a decline in cerebral perfusion pressure (CPP), the new method allowed a swift placement with only minor changes of ICP and CPP. The strict avoidance of intermittent peaks of ICP constitutes a basic principle of care in patients with space occupying brain lesions. We therefore suggest that, despite the admittedly larger effort, the reflex placement of NGTs should be used in such circumstances.

LF 16-0687 Ms, a bradykinin B2 receptor antagonist, reduces brain edema and improves long-term neurological function recovery after closed head trauma in rats

Bradykinin is an endogenous inflammatory agent that enhances vascular permeability and produces tissue edema. We investigated whether LF 16-0687 Ms, a potent nonpeptide antagonist of bradykinin type-2 (B(2)) receptor, was able to reduce brain swelling and to improve the recovery of neurological function following closed head trauma (CHT) in rats. In dose-effect studies, LF 16-0687 Ms doses of 0.75-4.5 mg/kg given 1 h after trauma significantly reduced the development of edema in the injured hemisphere by a maximum of 70%. It had no effect on the brain water content of sham-operated rats. LF 16-0687 Ms also significantly improved neurological recovery evaluated by a Neurological Severity Score (NSS) based on motor, reflex, and behavioral tests. In time-window studies LF 16-0687 Ms (2.25 mg/kg) was given 1, 2, 4, and 10 h after CHT. The extent of edema was significantly reduced when LF 16-0687 Ms was given 1 h (-45%), 2 h (-52%), and 4 h (-63%) but not 10 h (-24%) after CHT. Given at any time-point, LF 16-0687 Ms significantly improved the recovery of the NSS at 24 h. In duration of treatment studies, rats tended to recover normal neurological function over 14 days after CHT. However, time to recovery was longer in severely than in moderately injured animals, unless they were treated with LF 16-0687 Ms. This study provides further evidence that blockade of bradykinin B(2) receptors represents a potential effective approach to the treatment of focal cerebral contusions.

Effect of cervical hard collar on intracranial pressure after head injury

BACKGROUND

Patients suffering head trauma are at high risk of having a concomitant cervical spine injury. A rigid cervical collar is usually applied to each patient until spinal stability is confirmed. Hard collars potentially cause venous outflow obstruction and are a nociceptive stimulus, which might elevate intracranial pressure (ICP). This study tested the hypothesis that application of a hard collar is associated with an increase in ICP.

METHODS

A prospective series of 10 head-injured patients with a postresuscitation Glasgow coma scale score of nine or less had ICP measurements before and after cervical hard collar application.

RESULTS

Nine out of 10 patients had a rise in ICP following application of the collar. The difference in pre- and postapplication ICP was statistically significant (P < 0.05).

CONCLUSIONS

Early assessment of the cervical spine in head-injured patients is recommended to minimize the risk of intracranial hypertension related to prolonged cervical spine immobilization with a hard collar.

Successful cardiopulmonary resuscitation outcome reviews

An implicit question in every pre-hospital cardiopulmonary resuscitation (CPR) scenario is 'what will be the quality of life if a save is achieved?' This issue has implications for doctrine, policy, training and post-CPR counselling of both resuscitator and victim. Post-salvage neurological syndromes in surviving victims include amnesia, personality change, cognitive loss, depression, Parkinsonian syndromes, decorticate and decerebrate states and permanent brain damage with vegetative existence. Children who are salvaged by CPR rarely have pre-existing co-morbidities; but 75% of adults have pre-existing cardiac disease, cancer or diabetes. Such, of course, continue after a successful resuscitation. In the case of children who are resuscitated from acute hypoxic insults, the quality of life is generally good and, in the specific instance of survivors from near-drowning, some 95% will lead lives relatively unmodified. Although successful CPR resuscitation rates remain low in adults, the quality of life of those who leave hospital remains generally high. CPR involves two feature subjects, the resuscitator and the victim. Just as for the victim, so too the resuscitator's life is modified by CPR and its aftermath, whether immediate salvage has been achieved or not. This review addresses these issues, as a successful CPR (dramatic as it is) is not a conclusion but the beginning of a new phase of life for both resuscitator and victim.