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PubMed2004

Prediction of intracranial pressure from noninvasive transocular venous and arterial hemodynamic measurements: a pilot study.

INTRODUCTION: Continuous measurement of intracranial pressure (ICP) requires the invasive placement of epidural, parenchymal, or intraventricular devices. For critical single-point assessments, lumbar puncture may not always be practical. An accurate, reliable, portable and noninvasive method to estimate absolute ICP remains an elusive goal. The arteries that perfuse and the vein that drains the orbit are exposed to the ambient ICP while coursing through the cerebrospinal fluid or optic nerve. METHODS: The venous outflow pressure (VOP) of the central retinal vein was measured using occlusion in six intensive care patients treated for acute hydrocephalus or brain hemorrhage and in whom transducers of intracranial pressure could provide standardized continuous output. A novel adaptation of the Balliart ophthalmodynamometer was developed for use. Simultaneously, the central retinal (CRA) and ophthalmic (OA) arterial flow velocities were recorded using color Doppler imaging technique. Repeat noninvasive measurements were performed at various ICPs, (n=22 independently collected observations). Linear regression and correlation testing were performed to evaluate these variables for ICP predictability. RESULTS: The VOP increased linearly with ICP (r=0.87). The arterial pulsatility indices for both OA and CRA decreased inversely with ICP (r=0.66). An empiric index combining both venous and arterial parameters (VOP/Gosling Pulsatility Index [GPI]) was significantly more correlated with absolute ICP than either parameter alone (r=0.95, p<0.005, ICP=0.29+0.74 [VOP/GPI(OA)]). CONCLUSION: The feasibility to estimate ICP from transocular sonographic and dynamometric data is suggested by these preliminary data. Retinal arterial properties are important in modeling the effect of ICP on the venous outflow pressure. Our pilot results serve as a basis on which to conduct a larger prospective and blinded study.

Adult↗
PubMed1994

Experimental analysis of brain surface elastance in cats.

Brain surface elastance, defined as the pressure needed to compress the cortex 3 mm, was measured using the ophthalmodynamometer in six cats using three burr holes (frontal, parietal, and occipital) on each side. An intracranial mass was then used to compress the right side for 3 hours, and cardiac arrest was induced after the mass was removed. Elastance was measured four times: before insertion of the mass, 10 and 70 minutes after removal of the mass, and 60 minutes after cardiac arrest. The results showed that: brain surface elastance does not change between sides, but varies among regions with the parietal region having the highest elastance; elastance increases after compression by an intracranial mass, but not after cardiac arrest; and stiff brain tends to restore poorly. Elastance is apparently increased by the formation of edema. Measuring brain elastance may be useful in predicting brain restoration subsequent to removal of mass lesions.

Animals↗
PubMed1983

Ocular pneumoplethysmography in carotid-cavernous sinus fistulas.

Pulsatile exophthalmos in association with carotid-cavernous sinus fistulas has been well defined anatomically, by angiography. This paper presents the physiological assessment of this entity, as measured with ocular pneumoplethysmography (OPG-Gee). The abnormal arteriovenous communication lowers resistance to arterial flow. This is characterized by a lowered ophthalmic systolic pressure and an increased ocular blood flow. The OPG readily documents the physiological result of therapeutic intervention.

Arteriovenous Fistula↗
PubMed1983

Ocular pneumoplethysmography in head-injured patients.

Severe head injury is frequently associated with multiple trauma. In the comatose patient, endotracheal intubation and ventilator support are often required, if there is associated dyssynchronous spontaneous effort. The latter is managed with therapeutic (drug) paralysis. An elaborate life-support and monitoring system coupled with controlled paralysis limits the mobility of the patient for diagnostic procedures, and a continuing reevaluation of neurological status is difficult. Under these circumstances the ocular pneumoplethysmograph provides a simple rapid noninvasive assessment of ocular blood flow, and this reflects cerebral blood flow and alterations in brain compliance. Alterations in the therapeutic regimen can be based on these observations.

Brain Injuries↗
PubMed1982

Noninvasive neurovascular tests for carotid artery disease.

Indirect noninvasive neurovascular tests provide information on hemodynamic changes cephalad to the carotid bifurcation, whereas direct tests measure anatomic or physiologic changes at the bifurcation itself. Batteries of tests are often done and should combine both indirect and direct methods. Results with two ultrasonic techniques and digital subtraction intravenous angiography suggest a larger role for these methods. Carotid arteriography is the definitive procedure for evaluating the carotid artery, although it should only be done when carotid endarterectomy is contemplated. The relative risks and benefits of other diagnostic and therapeutic management strategies should guide the decision to do noninvasive neurovascular tests, or to proceed directly to arteriography.

Carotid Artery Diseases↗
PubMedDate not supplied

[Comparative assessment of hemodynamic risk factors of glaucomatous optic neuropathy progress].

Comparative evaluation of the significance of hemodynamic factors of risk of progress of glaucomatous optic neuropathy has been carried out: blood flow velocity, blood flow resistance, blood pressure in the orbital artery-central retinal artery system, perfusion ocular pressure in connection with stabilization of glaucomatous process, and intraocular pressure were analyzed for a period of up to 16 years. The most significant factors were blood pressure in the orbital artery-central retinal artery system and perfusion ocular pressure, but not blood flow velocity. The leading factor indicating the risk of progress of optic neuropathy in primary glaucoma is ocular perfusion pressure. Measurements of opthalmodynamometric pressure can be used for evaluation of perfusion pressure and recommended for wide clinical application for predicting the course of primary glaucoma.

Blood Flow Velocity↗
PubMed1975

[The importance of the eyelids for ophthalmodynamographic recordings-- an oscillographic study before and after total plastic reconstruction of the eyelids (authors transl)].

Ophthalmodynamography (ODG) of an empty orbit apart from a covering of atrophic skin 1mm thick revealed only one twentieth of the pluse amplitude of the contralateral normal orbital oscillographic waves. After total plastic surgical reconstruction of the lids, isolated oscillographiy of the eyelids was performed for the first time. The pulse amplitude now reached about 1/4 of that of the contralateral side. It is concluded that these reconstituted eyelids contribute at least 25% towards the volume and 25% towards the oscillographic pulse wave amplitude on performing ODG in the usual manner. These values could well be exceeded in normal lids on account of their better blood supply.

Adult↗
PubMed1975

Blood pressure and pressure amaurosis.

Susceptibility to pressure amaurosis was measured in young research subjects before and during blood pressure elevation induced by intravenous infusions of phenylephrine. Intraocular pressure elevations were produced by paralimbal suction; we measured the highest level to which intraocular pressure could be raised without obliterating perception of a slowly flickering stimulus in the nasal field of vision. Elevation of systemic blood pressure was accompanied in all subjects by a corresponding increase in the highest "safe" level of intraocular pressure. This observation confirms the commonly held hypothesis that pressure amaurosis is the result of pressure-induced neuroretinal ischemia.

Atropine↗
PubMed1975

[Orthostatic cephalic hypotension and the eye (author's transl)].

The pressure in the ophthalmic artery was measured during change of posture from the lying position to the sitting position by means of Muller's ophthalmodynamometer. In 210 healthy individuals there was a fall of average pressure between 0 and 21 percent. In 89 patients having a certainly pathological fluctuation of 25 percent or more which could not be found in the brachial pressure. Such patients did not only have general orthostatic symptoms but also various ocular symptoms.

Adolescent↗
PubMed1979

[Neurosurgical aspects of cerebral ischemia (author's transl)].

Besides purely conservative treatment and cerebrovascular surgery, the extra-intracranial bypass operation forming an end-to-end anastomosis between the superficial temporal artery and a cortical branch of the middle cerebral artery offers a neurosurgical possibility for therapy. The indications for this operation lie principally in the transitory cerebral ischemic attacks, the precursors of ischemic insults. In contrast to this the indications for the microneurosurgical vascular interventions possible in the regions supplied by the vertebral and basilar arteries cannot presently be comprehensively defined.

Arterial Occlusive Diseases↗