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Biomedical subjects

M Numoto

Publications and source records attributed to M Numoto.

36 records · Page 2Linked to original sources
PubMed1983

A new method for measuring cerebrospinal fluid flow in shunts.

An implantable device for measurement of cerebrospinal fluid (CSF) flow in a ventriculoperitoneal shunt tube has been developed. The unit is energized by an extracorporeal high-frequency generator (200 KHz), and electrolysis creates bubbles in the shunt tube. Velocity of bubble flow is detected by a pair of ultrasonic Doppler probes placed a certain distance apart on the skin surface and in parallel with the implanted tube. The CSF flow rate is calculated taking into account velocity and tube diameter, and is expressed in ml/min. The unit consists of a coil with a capacitor, a silicon diode to rectify the high frequency, and a Zener diode to regulate maximum output voltage of 20 V. The output is fed to a pair of platinum electrodes placed inside the unit's tunnel through which the CSF flows. These components are molded in epoxy resin and coated with medical-grade silicone rubber. In animal experiments, CSF flow rates ranging from 0.033 to 1.0 ml/min could be measured by this flowmeter. Clinically, CSF flow has been measured to date in several cases. In two cases of communicating hydrocephalus occurring after the onset of cerebrovascular disease, and in which the CSF flow was continuously monitored for 24 hours, the flow rate ranged between 0.05 and 0.78 ml/min. The CSF flow rate fluctuates in a 24-hour period, increasing in the morning, especially between 12 midnight and 6 a.m., which suggests a circadian rhythm.

Aged↗
PubMed1983

[CSF dynamics following shunt operation, with special reference to the diurnal changes of CSF circulation].

The purpose of this study is to study the pathophysiology of the cerebrospinal fluid (CSF) formation and circulation after a ventriculoperitoneal shunt operation. With the CSF flowmeter we developed, the CSF flow rate in the shunt tube has been measured non-traumatically over a 24-hour period in six patients. These include both communicating and noncommunicating hydrocephalus patients with ages ranging from 20 to 70. There were three cases of ruptured intracranial aneurysm, one cerebral contusion, one hypertensive brain stem hemorrhage and one occlusion of the aqueduct sylvius. Intraventricular pressure was continuously recorded for 24 hours prior to the shunt operation in each case, and the pressure changes were compared with the measured CSF flow rates in the shunt tube. The flow rate fluctuated between 0.05 ml/min and 1.2 ml/min with the supine position and high flow rates were detected in the early morning. Each case showed its own rhythm of CSF flow fluctuation during a 24-hour period, and the changes were compatible with the intraventricular pressure. It is suggested that there may be a relationship between these changes and an increased cerebral blood volume during the REM sleep stage.

Adult↗
PubMed1982

[A device to measure CSF flow in a shunt tube and its clinical application].

An implantable device for measurement of cerebrospinal fluid (CSF) flow in a shunt tube has been developed. The unit is energized by an extracorporeal high frequency generator (200 kHz), and electrolysis creates bubbles in the shunt tube. Bubble flow velocity is detected as reflected sound using a pair of ultrasonic Doppler probes (Saneisokkuki Doppler Flowmeter Type 1935) placed apart on the skin surface and in parallel with the tube. CSF flow is expressed in ml/min. by calculating velocity and tube diameter. The unit consists of a coil with a 200 kHz capacitor, a silicon diode to rectify the high frequency, and a Zener diode to regulate maximum output voltage of 20 V. The output is fed to a pair of platinum electrodes inside the unit's tunnel through which the CSF flows. The unit is moulded in epoxy resin and coated with medical grade silicon rubber. In vitro, CSF flow rates ranging from 0.033 ml/min to 1.0 ml/min. could be measured by this flowmeter model. In vivo, however, it was difficult to detect a flow rate of less than 0.006 ml/min. To measure the slower flow rate, a so-called bubble-detecting-tube made from an 11 cm stainless steel tube coated with silicon rubber is centrally inserted between the two ends of the separated shunt tube. The bubble flow velocity is detected by a tissue impedance detector's pair of probes placed apart on the skin surface. Clinically, CSF flow was measured in three cases of hydrocephalus (two cases of normal pressure hydrocephalus and one case of pineal tumor with non-cummunicating hydrocephalus). The flow rates were found to be, respectively, 0.10 ml/min., 0.063 ml/min., and 0.20 ml/min. The merits of the unit include its ability to repeatedly measure CSF flow at short intervals, and also to measure dynamic CSF flow under various conditions.

Adolescent↗
PubMed1976

[Intracranial pressure monitoring apparatus for clinical use balanced pressure sensors].

Three types of pressure sensors, (1) electric pressure switch, (2) fiber optic pressure switch and (3) pressure indicating bag for intracranial pressure monitoring which were developed by the author are described. Advantages and disadvantages between them are also discussed. The electric pressure switch is relatively simple in construction but has a possibility of producing micro-shock hazard in case of accidental electric leakage. The fiber optic pressure switch is the safest for the micro shock but its structure is rather complicated and fragile. The pressure indicating bag is simple to make and durable to use. However, it has a hydrostatic effect.

Fiber Optic Technology↗
PubMed1975

[A method for the continuos recording of intracraneal pressure].

91 patients with acute head injuries, hydrocephalus, cerebral infarction, subarachnoid hemorrhage, encephalitis, intracerebral hemorrhage, or carbon monoxide intoxication have been so monitored by using the Numoto pressure switch by a method herein described. The main advantage has been the knowledge of the level of intracranial pressure at any given time and the early detection of a rising pressure when this phenomenon occurred. There were no complications except for 3 cases of infection. Two of these cases were minor purulent collections only at the site of exit of the tube in the scalp. One patient with a compound wound, cerebral laceration, and intracerebral hematoma developed a wound infection and brain abscess which required drainage.

Brain Concussion↗
PubMedDate not supplied

Brain tissue pO2 and pCO2 levels before and after cerebral revascularization.

Microvascular surgical techniques have made possible the improvement of cerebral blood flow, as demonstrated by angiography and by regional cerebral blood flow research. In this study, simultaneous mass spectrometer determinations of brain tissue and blood pO2 and pCO2 levels were used to evaluate the effectiveness of common carotid-supraclinoid carotid anastomoses (CC-SCA) in dogs. With blood pCO2 maintained at a constant level, the baseline brain tissue pO2 and pCO2 levels were recorded. During the CC-SCA procedure, which involved brain retraction and temporary vascular occlusion, brain tissue pO2 levels fell to 40% of baseline and pCO2 levels rose by 35%. Following restoration of flow via the anastomosis, the brain tissue pO2 and pCO2 levels again reached baseline.

Animals↗
PubMedDate not supplied

A non-invasive CSF flowmeter.

A new non-invasive method for quantitative measurement of cerebrospinal fluid (CSF) flow in the ventriculo-peritoneal shunt tubing, used in hydrocephalus, has been developed. It is an implantable device which produces a bubble in the shunt tubing by electrolysis. This bubble is then detected in the tubing by an electrode arrangement using electric impedance or ultrasonically using a Doppler probe. The energy for electrolysis is supplied by extracorporeal high-frequency transmission. The CSF flow rate is calculated by the velocity of bubble flow in the tubing. CSF flow rates, ranging from 0.01 to 1.00 ml/min, have been measured in animal experiments with statistically good accuracy. In 11 clinical cases a flow range of between 0.01 and 1.93 ml/min have been observed.

Animals↗