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At least 19 recordsLinked to original sources

Influences of phasic changes in systemic blood pressure on intracranial pressure.

In acute experiments on lambs, the effects of short-lasting induced modifications in arterial and venous systemic blood pressure on intracranial pressure have been studied. Haemodynamic changes have been provoked by increasing the cardiac venous return, by increasing or decreasing the arterial resistance and by stimulating the vagus nerve. Intracranial pressure modifications have been demonstrated to depend essentially on arterial influences. A direct venous influence is apparent only when the central venous pressure is increased, as occurs in the case of increased venous cardiac return.

Animals

Anesthesia and subarachnoid intracranial pressure.

Intracranial pressure (ICP) was continuously monitored by the Richmond technic of Vries and Becker in 17 patients undergoing elective craniotomy. This method entails the placement, underlocal anesthesia, of a hollow screw through the cranium into the subarachnoid space. The screw was connected to a Statham P23Db pressure transducer with heavy vinyl tubing and with pressures recorded on a Beckman Dynograph. The effects of 3 anesthetic technice-halothane, enflurane, and nitrous oxide-narcotic-relaxant-on ICP during induction and maintenance were compared with preinduction control pressures. Control ICP in awake, lightly premedicated patients was 15 plus or minus 10 torr. Mask inductions with halothane and enflurane consistently caused significant increases in ICP from preinduction levels in the absence of excitement or airway obstruction. Induction with nitrous oxide-narcotic-relaxant did not increase ICP. Decreases in ICP following barbiturate administration were noted. Addition of halothane and enflurane to the inspired mixture of patients controlled and hyperventilated with nitrous oxide and oxygen caused consistent increases in ICP. With control hyperventilation (Paco2 25 plus or minus 5 torr), the ICP did not return toward preinduction values within 5 minutes with enflurane and halothane.

Anesthesia, Inhalation

Effect of positive end-expiratory pressure on intracranial pressure in dogs.

Application of positive end-expiratory pressure to dogs with noncardiogenic pulmonary edema increased intracranial pressure (measured as cerebrospinal fluid pressure) and decreased cerebral perfusion pressure. The magnitude of these changes depended on the amount of end-expiratory pressure applied and the lung compliance.

Animals

Effects of positive end-expiratory pressure on intracranial pressure and compliance in brain-injured patients.

Hypoxic pulmonary disorders and head injuries associated with increased intracranial pressure (ICP) frequently co-exist. Positive end-expiratory pressure (PEEP) improves hypoxemia but has been reported to impede cerebral venous return, potentially causing a further increase in ICP. This study examined the effects of PEEP on ICP at different levels of brain compliance. continuous ICP recordings were obtained after insertion of Scott cannulas to the lateral ventricles of seven comatose patients. Brain compliance was assessed by calculation of the pressure volume index. Patients were maintained in a 30 degrees head-up position. Maintenance of PEEP to levels of 40 cm H2O pressure for as long as 18 hours did not increase ICP in patients with either normal or low intracranial compliance, and did not increase ICP in the absence of pulmonary disease. Central venous pressure and pulmonary artery wedge pressure increased proportionately as PEEP was increased. No consistent changes were found in blood pressure recordings, nor were there any reductions in cardiac output found during the studies. Abrupt discontinuation of PEEP did not result in increased ICP except for a transient rise on two occasions when respiratory secretions became copious and the patients were inadequately ventilated. Improved oxygenation in two patients as a result of PEEP was concomitant with improved intracranial compliance and neurological status. In patients with brain injuries, PEEP improves arterial oxygenation without increasing ICP as previously supposed. Consequently, PEEP is a valuable form of therapy for the comatose patient with pulmonary disorders such as pneumonia or pulmonary edema.

Adult

On the uses of intracranial pressure monitoring.

Intracranial pressure monitoring with an intra-ventricular catheter, an external transducer and a continuous chart recorder was undertaken in 15 patients with acute brain damage and in six patients suspected of suffering from long-standing raised intracranial pressure. In the acute cases, monitoring was useful in the diagnosis of raised intracranial pressure and in the assessing of the efficacy of its treatment. In the chronic cases, the clinical suspicion of raised pressure was confirmed or refuted without doubt. Complications were minimal, and the method was judged to be of considerable value in selected cases.

Adolescent

Systemic vascular responses to increased intracranial pressure. 3. Effects of individual balloon inflations on intracranial pressure and the systemic circulation.

The effects of discrete increases in the volume of an artificial space-occupying lesion on intracranial pressures and the systemic circulation were studied in six anaesthetised and artificially ventilated dogs. Each increase in volume, accompanied by an increase in supratentorial intracranial pressure, a decrease in supratentorial perfusion pressure, and an increase in transtentorial pressure gradient, induced alterations in the systemic circulation. There were a decrease in heart rate, marked alterations in the arrhythmia index, and increases in stroke volume and systemic vascular resistance. A period of transient systemic hypertension was noted to accompany each discrete increase in intracranial pressure.

Animals

Systemic vascular responses to increased intracranial pressure. 1. Effects of progressive epidural ballon expansion on intracranial pressure: and systemic circulation.

This paper details the results of experimental studies, on 16 dogs with artificially-induced intracranial space-occupying lesions, of the systemic vascular responses and the intracranial pressure changes (both in the supratentorial and infratentorial compartments) induced by increasing intracranial pressure. The changes produced were divided into two phases such that phase 1 detailed the alterations observed from the start of the balloon inflation up to the initiation of the systemic pressor response. Phase 2 recorded those alterations which occurred during, and immediately after, the period of systemic hypertension (see Fitch et al., 1977). The changes observed during phase 1, and presented in this communication, were those of increasing intracranial pressures and decreasing mean arterial pressure and heart rate. These alterations were associated with decreases in supratentorial perfusion pressure and increases in transtentorial pressure gradient and arrhythmia index.

Animals

Effect of positive end expiratory pressure ventilation on intracranial pressure in man.

THsi study was designed to define the effect of positive end expiratory pressure (PEEP) ventilation on intracranial pressure (ICP). In 25 patients with severe head trauma with and without associated pulmonary injury the following parameters were simultaneously monitored under mechanical ventilation with and without PEEP:ICP, arterial blood pressure, central venous pressure, arterial blood gases, and cardiac rate. In addition, the volume-pressure response (VPR) was evaluted in each patient to assess cerebral elastance. The results indicate a significant increase in ICP with the application of PEEP only in the 12 patients who manifested increased cerebral elastance by VPR. Half of this latter group manifested impairment of cerebral perfusion pressure to levels less than 60 mm Hg. Return to baseline CIP levels was observed with termination of PEEP. No significantly consistent changes in other parameters were noted.

Humans

Intracranial pressure increase and changes in microcirculation of the pial and iridial vessels in correlation to EEG, ECG, and arterial blood pressure.

Controlled intracranial pressure increase was produced in 120 female albino rats by infusing homologous blood and saline solution into the cisterna magna. The behaviour of the brain current, cardiovascular system, and microcirculation of the iridial and pial vessels immediately after pressure increase was examined simultaneously. A direct correlation could be demonstrated between the decrease in brain electrical potentials and the intracranial pressure applied at a time of maximal cardiovascular stimulation. Different pathological mechanisms have been put forward, one of these being identified as pial arteriolospasms. Acting together with other factors these spasms might be responsible for the rapid drop in electrical activity of the brain current potentials.

Animals

Raised intracranial pressure and cerebral blood flow. 5. Effects of episodic intracranial pressure waves in primates.

The effects of episodic waves of intracranial pressure on cerebral blood flow were studied in primates. Six pressure waves each of 20 minutes' duration and ranging from 50 to 100 mmHg in magnitude were induced in baboons, at intervals of 30 minutes, in an attempt to simulate clinical plateau waves. With pressure waves up to 75 mmHg, cerebral blood flow remained at control levels despite falling cerebral perfusion pressures. Between the initial pressure waves a marked hyperaemia developed, with cerebral blood flow increasing by as much as 100%, and this appeared to be a means whereby adequate flow was maintained during pressure waves. Later pressure waves, up to 100 mmHg, eventually reduced blood flow below control levels, although moderately high flows were maintained during periods of very low perfusion pressure. Brain metabolism was affected by eht episodic pressure waves, although no consistent change was seen.

Acetoacetates

[Effects of solcoseryl on the cerebral blood flow, intracranial pressure, systemic blood pressure and EEG in acute intracranial hypertensive cats (author's transl)].

The experiment was performed on 86 cases under intraperitoneal pentobarbital anesthesia. One balloon was placed in the extradural space of right frontal region, and the other balloon was placed in the left extradural space and the intracranial pressure was measured. A needle was stereotaxically inserted into the subcortical area in order to measure the cerebral blood flow. Systemic blood pressure was recorded by inserting a catheter into the femoral artery, and electrocorticogram was also recorded. An expanding intracranial lesion was made by inflating the extradural balloon with physiological saline. The animals were arbitrarily divided into two groups.: 1) light or moderate groups which intracranial pressure before the injection of drug was below 400 mmH2O. 2) severe groups above 400 mmH2O. After the maintenance of the pressure, Solcoseryl was infused intravenously. The investigation was focused to observe whether Solcoseryl reveales any potent effect on cerebral blood flow, intracranial pressure, systemic blood pressure and on electroencephalogram in acute intracranial hypertension. Results 1) Intravenous injection of Solcoseryl had the effect of lowering intracranial pressure in the light or moderate and severe groups. Particularly, dose of 80 mg/kg showed the marked effect, though with a rebound phenomenon in the light or moderate groups. Furthermore, the effect was more marked and lasting by drip infusion of Solcoseryl and also by intravenous injection of Solcoseryl after pretreatment with hydrocortisone, and at this time no rebound phenomenon was recognized. 2) Solcoseryl had the effect of increasing the cerebral blood flow accompained with the lowering of intracranial pressure. 3) Systemic blood pressure was transiently lowered by the injection of Solcoseryl 20 mg/kg or 80 mg/kg and recovered immediately. 4) Solcoseryl had no effect on electroencephalogram in the severe groups. Conclusion On the basis of these results, it is rational to conclude that Solcoseryl could be superior agent render to lower intracranial pressure and to improve cerebral blood flow in acute intracranial hypertension.

Actihaemyl

[Effect of xylitol on increased intracranial pressure].

Increased intracranial pressure could be lowered by means of 250 ml 40% xylite (1,2,3,4,5-pentanpentol) in 17 patients, the average dosage amounted to 1.36 mg/kg, the lowering of the pressure to 54.4 plus or minus 18.4%. The effect lasted 109.5 plus or minus 35.4 min; the maximum occurring after 50.4 plus or minus 14.8 min. With the exception of 3 patients who complained of slight gastrointestinal disturbances, no side reactions were observed. Paralleling the lowering of CSF-pressure increased diuresis occurred amounting to 400% (including the infusion volume). The maxima of diuresis and lowering of CSF-pressure concur. Simultaneously we can see a highly significant lowering of urine potassium and a slightly significant lowering of sodium within the first 2 h, which after 3 h is clearly receding. There was no significant change in the values of serum electrolytes, bilirubin and transaminases (SGOT and SGPT); the residual urea was just a little lowered. The lowering of CSF-pressure after xylite surpasses the effect of the same dosage of sorbit and fructose.

Adult

Intracranial pressure with intracerebral hemorrhages.

Intracranial pressure was recorded continuously during an average of 15 days in 17 patients suffering from primary intracerebral hemorrhage. In 12 cases the highest pressures were recorded just after the stroke; then the intracranial pressure decreased and became normal in an average of 20-30 days. Other patterns of evolution were less often observed: a rapid and lethal elevation of pressure in one case, a constantly low pressure in two, and a stagnant evolution with moderate hypertension in two others. Secondarily developing intracranial hypertension was never observed during the monitoring period. Evacuation of the clots was performed in six patients. This only slightly shortened the course of the increased intracranial pressure. It is concluded that intracerebral hematoma appears as an expanding lesion only during the time of its formation. The prognosis depends more upon the destructions by the hemorrhage than upon the increased pressure. Nevertheless, true hypertension is possible. Knowledge of intracranial pressure in the course of intracerebral hemorrhage is important in deciding whether the treatment is to be surgical or conservative. Measurements of the intracranial pressure in our practice has reduced the number of interventions, with identical or slightly improved results.

Adult

Automatic intracranial pressure regulation.

This paper emphasizes our approach to control increased ventricular fluid volume and pressure; it utilizes an improved device based upon hydrostatic pressure principles. Intracranial pressure may be maintained at any preselected value, usually 25 cm H2O. Pressure increases beyond this value will result in a venting of fluid into a calibrated reservoir. The hydrostatic column will act to cushion the surrounding ventricular mass, helping to prevent ventricular collapse. The method overcomes the hazards of techniques, using intermittent withdrawal of fluid which requires human judgment. Ventricular pressure response curves performed on a number of patients showed a marked stability with a response less than 2 mm Hg/ml. This indicates a favorable influence on the intracranial compliance. The system is completely closed and its use in 52 neurosurgical patients in over 400 patient days has not been associated with any infection problem.

Humans

[Change of intracranial pressure in neurosurgical patients by hyperventilation, positive negative pressure ventilation and PEEP (author's transl)].

The effects of a hyperventilation, positive negative pressure ventilation (PNPV) and ventilation using positive endexpiratory pressure (PEEP), on intracranial pressure (ICP) was measured in 24 patients suffering from different neurosurgical disorders. The patients were given a basic anaesthesia including muscle relaxation. The investigations showed, that hyperventilation, followed by a PCO2 of 26 and 30 torr, clearly lowered the intracranial pressure. The pressure drop was much more pronounced when the preexisting ICP was high than when it was low, due to the form of the compliance curve of the brain. PNPV also lowered intracranial pressure, but a harmful effect of this technique on lung function and structure is known. Its use is justified only for short periods and in addition to other measures for lowering ICP. The results also demonstrated that PNPV possesses limited beneficial properties with regard to the subject discussed here. Ventilation by PEEP significantly increased ICP. This technique is to be employed with caution in neurosurgery. Arterial pressure (radial artery) and central venous pressure (subclavian vein) were also recorded.

Adolescent