The University of Toronto head injury treatment study: a prospective, randomized comparison of pentobarbital and mannitol

Thiopental infusion in the treatment of intracranial hypertension complicating fulminant hepatic failure

Intracranial hypertension complicating fulminant hepatic failure has a mortality in excess of 90% in the presence of renal failure if not rapidly responsive to mannitol and ultrafiltration. Based on data which suggest that barbiturates can be of value in controlling the intracranial hypertension of head injury, intravenous thiopental was assessed in 13 patients with fulminant hepatic failure. All had developed acute renal failure complicated by intracranial hypertension unresponsive to other modes of therapy and were likely by all published criteria to have little chance of survival. The dosage of thiopental was adjusted incrementally until intracranial pressure, measured by extradural transducers, fell to within normal limits or adverse hemodynamic changes occurred. The intracranial pressure was reduced, in each case, by 185 to 500 mg (median: 250 mg) thiopental given over 15 min, and in eight cases continuing infusion achieved stable normal intracranial pressure and cerebral perfusion pressure. Five of the patients made a complete recovery and there were only three deaths from intracranial hypertension. Side effects were few and included minor hypotension controlled by dose reduction. The response of otherwise intractable intracranial hypertension and the 38% survival rate was remarkable for a group of patients with such a poor prognosis.

Severe traumatic brain lesions in Sweden. Part 2: Impact of aggressive neurosurgical intensive care

During a 6 year period (1977-1982), 425 patients were treated in the Department of Neurosurgery, University Hospital of Lund, for severe traumatic brain lesions (coma greater than 6 hours). From 1983 a more aggressive management protocol was introduced including early recording of intracranial pressure (ICP) and 162 patients were included in the study 1983-1984. A dangerous increase in ICP in spite of adequate surgical treatment and moderately controlled hyperventilation was the incentive for barbiturate coma therapy in selected patients. In the first part of the study overall mortality was 48% whereas 39% of the patients reached good recovery/moderate disability 6 months after injury. During the second part of the study the corresponding figures were 35% and 54%, respectively (in both cases p less than or equal to 0.01). In the group of patients with focal intracranial mass lesions mortality decreased from 59% to 46% (p less than or equal to 0.05) and good recovery/moderate disability increased from 30% to 42% (p less than or equal to 0.05). Improvement in outcome was even more pronounced in patients with no-mass lesions, mortality decreased from 30% to 12% and good recovery/moderate disability increased from 56% to 80% (p less than or equal to 0.05 and p less than or equal to 0.01, respectively). No change occurred in age distribution or in the types of intracranial lesions that could explain these improvements. It is concluded that aggressive neurosurgical intensive care significantly improves outcome in patients with severe traumatic brain lesions.

High-dose barbiturate control of elevated intracranial pressure in patients with severe head injury

In a five-center study, 73 patients with severe head injury and elevated intracranial pressure (ICP) were randomly assigned to receive either a regimen that included high-dose pentobarbital or one that was otherwise similar but did not include pentobarbital. The results indicated a 2:1 benefit for those treated with the drug with regard to ICP control. When patients were stratified by prerandomization cardiac complications, the advantage increased to 4:1. A multiple logistic model considering treatment and selected baseline variables indicated a significant positive treatment effect of barbiturates, a significant effect of time from injury to randomization, and an interaction of treatment with cardiovascular complications. However, of 925 patients potentially eligible for randomization, only 12% met ICP randomization criteria. The results support the hypothesis that high-dose pentobarbital is an effective adjunctive therapy, but that it is indicated in only a small subset of patients with severe head injury.

Cerebral blood flow, vasoreactivity, and oxygen consumption during barbiturate therapy in severe traumatic brain lesions

Mean hemispheric cerebral blood flow (CBF) and intracranial pressure (ICP) were measured in 19 severely head-injured patients treated with barbiturate coma. The CBF was calculated from the clearance of tracer substance monitored by extracranial scintillation detectors after intravenous administration of xenon-133. In 11 of the patients cerebral arteriovenous oxygen differences were measured simultaneously. In all patients the effects of pronounced hyperventilation were recorded prior to initiation of barbiturate treatment. A normal CBF response to hyperventilation (delta CBF/delta PaCO2 greater than or equal to 1) was obtained in eight patients. In these patients induction of barbiturate coma was accompanied by physiological decreases in CBF and in the calculated cerebral metabolic rate of oxygen (CMRO2); they also exhibited a rapid and lasting decrease in ICP. A decreased or an abolished CO2 reactivity was recorded (delta CBF/delta PaCO2 less than 1) in 11 patients. In 10 of these 11 patients the physiological decreases in CBF and CMRO2 were not obtained during barbiturate treatment and the decrease in ICP was transitory. This study demonstrates a correlation between cerebral vasoreactivity, physiological effects of barbiturate therapy, and clinical outcome.

ICP monitoring--current status and future directions

Continuous monitoring of intracranial pressure (ICP) is now an accepted part of neurosurgical practice, used in the management of patients with severe head injury, coma-producing subarachnoid haemorrhage, hydrocephalus, intracranial infection and following hypoxic or ischaemic insults to the brain. The pressure is measured from the lateral ventricle or from the subarachnoid space, and each neurosurgical department should establish criteria for determining what level of increased ICP should be acted upon and how it should be managed. This review favours a three stage approach: a) determining that ICP is truly elevated and correcting any immediately remediable causes, such as airway obstruction, then b) first-line measures, which consist of hyperventilation, osmotherapy and controlled CSF drainage, then c) second-line measures, consisting of short-acting anaesthetic agents--thiopentone and gammahydroxybutyrate. Future refinements of ICP monitoring will include improved understanding and better methods of measuring intracranial pressure-volume relationships and more detailed analysis of intracranial pulse pressure and the pressure waveform, its changes with mean ICP and its relationship with the arterial pressure waveform.

Clinical pharmacokinetic considerations in the treatment of increased intracranial pressure

Life-threatening increased intracranial pressure can be reversed by a variety of drugs. These compounds all have some disadvantages, producing rebound effects, severe coma or cardiovascular depression and electrolyte imbalance. However, reduction of intracranial pressure is a prerequisite for recovery and the benefits of treatment outweigh the risks. Dexamethasone is rapidly eliminated, the short half-life (about 3 hours) indicating that dosage intervals should be kept small. As yet, however, its therapeutic efficacy has not been clearly demonstrated. Therefore, an association between pharmacokinetics and pharmacodynamics cannot be established. Osmotic diuretics are the most widely used agents for reduction of intracranial pressure. Pharmacokinetics show a very close relationship to changes in serum osmolality, but there are large variations in the clearance. For the use of osmotics, the blood-brain barrier must be intact. Osmotic diuretics may lead to intracerebral oedema or to acute renal failure as serum osmolality increases. Considering the pharmacokinetics of each drug, and the dynamics of intracerebral pressure and osmolality, an intermittent, individually titrated dosage should be administered, with simultaneous monitoring of intracranial pressure. Frusemide (furosemide) can be used as an adjunct, to enhance the effect of osmotic diuretics. Its pharmacokinetics are limited by renal function, depending on age as well as on the extent of renal impairment. Altered renal elimination of concomitantly administered drugs, and electrolyte imbalances should be anticipated when diuretics are used. Barbiturates are certain to decrease intracranial pressure in humans by an as yet unknown mechanism. Their administration is recommended for patients that do not respond to conventional therapy. As barbiturates can result in deep coma, knowledge of their pharmacokinetics is of great importance for recovery. Following single doses, pentobarbitone has a relatively long elimination half-life (about 22 hours). However, after repeated administration for several days, its elimination may be enhanced due to autoinduction. Thiopentone kinetics are characterised by distribution and redistribution into deep peripheral compartments. Administration of high and frequent doses leads to considerably delayed recovery. This is not true for methohexitone, which shows comparable pharmacokinetics after single and multiple dose administration. Elimination depends on liver blood flow. Thus, recovery from methohexitone-coma is rapid. Rapid elimination is also an important characteristic of etomidate and alphaxalone/alphadolone, two non-barbiturate hypnotics.(ABSTRACT TRUNCATED AT 400 WORDS)

Minor, moderate and severe head injury

The future role of the neurosurgeon in the management of head injury is reviewed in terms of the care of patients with minor, moderate and severe head injuries. In minor head injury it is predicted that there will be increasing pressure on the neurosurgeon to undertake the management and follow-up of all patients who have sustained head injury, and this will place a considerable additional load on each neurosurgical unit. This is based on a survey of 1919 head injuries admitted in one calendar year (1981), consisting of 93 severe injuries (GCS less than 8), 210 moderate injuries (GCS 8-12), and 1616 minor injuries (GCS 13/14). In moderate injuries CT will assume a major role in detecting hematoma early and identifying contusions. There may yet be a role for steroids in these cases and there should be a greater use of neurorehabilitation, instead of the current overemphasis on the severely injured. In severe injury future efforts will be to prevent early secondary insults and to find better methods of controlling raised intracranial pressure.