A pulse oximeter may reduce power consumption in the absence of overriding conditions. Various sampling mechanisms may be used individually or in combination. Various parameters may be monitored to trigger or override a reduced power consumption state. In this manner, a pulse oximeter can lower power consumption without sacrificing performance during, for example, high noise conditions or oxygen desaturations.

Low power pulse oximeter

Congestive heart failure affects about 1 percent of adults in the United States1 and is a contributing factor in over 250,000 deaths annually.2 It is diagnosed in 400,000 Americans each year3 and is the primary diagnosis for over 900,000 hospitalizations per year.4 In 1990 the age-adjusted death rate from congestive heart failure was 106.4 per 100,000,5 more than that from breast cancer and the acquired immunodeficiency syndrome combined.6,7 The median survival after diagnosis is 1.7 years in men and 3.2 years in women, with a 5-year survival rate of less than 50 percent.8 Even though medical therapies have improved . . .

Implantable left ventricular assist devices

A non-invasive optical sensor which uses the motion signal to calculate the physiological characteristic being measured. For pulse oximetry, a least squares or a ratio-of-ratios technique can be applied to the motion signal itself. This is made possible by selecting a site on the patient where variations in motion produce signals of two wavelengths which are sufficiently correlated. In particular, it has been determined that a sensor placed on a nail, in particular a thumbnail, exhibits the characteristics of having the red and infrared signals correlated when used for pulse oximetry, and the resulting signals correlate to arterial oxygen saturation.

Motion compatible sensor for non-invasive optical blood analysis

Various “contactless” bearing mechanisms including hydrodynamic and magnetic bearings are provided for a rotary pump as alternatives to mechanical contact bearings. In one embodiment, a pump apparatus includes a pump housing defining a pumping chamber. The housing has a spindle extending into the pumping chamber. A spindle magnet assembly includes first and second magnets disposed within the spindle. The first and second magnets are arranged proximate each other with their respective magnetic vectors opposing each other. The lack of mechanical contact bearings enables longer life pump operation and less damage to working fluids such as blood.

Rotary blood pump

This article reviews third-generation blood pumps, focusing on the magnetic-levitation (maglev) system. The maglev system can be categorized into three types: (i) external motor-driven system, (ii) direct-drive motor-driven system, and (iii) self-bearing or bearingless motor system. In the external motor-driven system, Terumo (Ann Arbor, MI, U.S.A.) DuraHeart is an example where the impeller is levitated in the axial or z-direction. The disadvantage of this system is the mechanical wear in the mechanical bearings of the external motor. In the second system, the impeller is made into the rotor of the motor, and the magnetic flux, through the external stator, rotates the impeller, while the impeller levitation is maintained through another electromagnetic system. The Berlin Heart (Berlin, Germany) INCOR is the best example of this principle where one-axis control combination with hydrodynamic force achieves high performance. In the third system, the stator core is shared by the levitation and drive coil to make it as if the bearing does not exist. Levitronix CentriMag (Zurich, Switzerland), which appeared recently, employs this concept to achieve stable and safe operation of the extracorporeal system that can last for a duration of 14 days. Experimental systems including HeartMate III (Thoratec, Woburn, MA, U.S.A.), HeartQuest (WorldHeart, Ottawa, ON, Canada), MagneVAD (Gold Medical Technologies, Valhalla, NY, U.S.A.), MiTiHeart (MiTi Heart, Albany, NY, U.S.A.), Ibaraki University’s Heart (Hitachi, Japan) and Tokyo Medical and Dental University/Tokyo Institute of Technology’s disposable and implantable maglev blood pumps are also reviewed. In reference to second-generation blood pumps, such as the Jarvik 2000 (Jarvik Heart, New York, NY, U.S.A.), which is showing remarkable achievement, a question is raised whether a complicated system such as the maglev system is really needed. We should pay careful attention to future clinical outcomes of the ongoing clinical trials of the second-generation devices before making any further remarks. What is best for patients is the best for everyone. We should not waste any efforts unless they are actually needed to improve the quality of life of heart-failure patients.

Third-generation blood pumps with mechanical noncontact magnetic bearings.

A centrifugal blood pump, used for heart-lung machines or the like, comprises an impeller, a casing having a suction inlet and a delivery outlet and being equipped with a space for rotatably accommodating the impeller, and a magnetic drive means disposed outside the casing. The impeller is of a rotationally symmetric shape and has a rotary vane section and a cylindrical section equipped with a magnet means. The magnet drive means for generating a rotating magnetic field coaxially encloses the magnet means of the above-mentioned cylindrical section and rotates the impeller in cooperation with the magnet means. At least the end section of the impeller's rotation center on the rotary vane section side is supported preferably by a pivot bearing. The pivot and the bearing thereof are preferably made of ceramics.

Motor driven sealless blood pump

Most acute studies of nonpulsatile blood flow have shown effects on systemic organs There have been few long-term studies of the effects of nonpulsatile blood flow due to lack of an appropriate experimental model and, consequently, it is unknown whether mammalian physiology can adapt to chronic nonpulsatile blood flow The following case report documents the effects of chronic nonpulsatile blood flow in an alive, awake animal maintained with fibrillating ventricles for a period of 34 days

Chronic nonpulsatile blood flow in an alive, awake animal 34-day survival.

Chronic nonpulsatile blood flow.

We have developed a compact, seal-less, all-purpose centrifugal pump, the Baylor C-Gyro pump, which is intended as a long-term ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. In attaining this goal, we began with eliminating the shaft seals by adopting a pivot bearing system at the impeller shaft. In addition, a ring magnet encased in the bottom of the impeller was coupled magnetically to a driver magnet placed outside the pump housing (C1 Prototype). This first model yielded satisfactory performance in vitro with a flow rate of 8 L/min against 250 mm Hg at 2,400 rpm, and an index of hemolysis (IH) of 0.0083 g/100 L using bovine blood. In the second model, the C1 Eccentric Inlet Port Model, the inlet bearing support bar in the prototype were eliminated without reducing the prototype's performance. These designs for antithrombogenicity are being tested by the first in vivo experiment, which has lasted for more than 2 weeks.

An Ultimate, Compact, Seal‐less Centrifugal Ventricular Assist Device: Baylor C‐Gyro Pump

A seal-less centrifugal pump aiming for long-term circulatory support has been developed. In this model, shaft seals that cause thrombus formation and blood leakage were eliminated. A brushless direct current motor was incorporated as a driving unit, and pivot bearings were used to support the impeller. With reference to its motor-driven system, this pump was named the M-Gyro Pump. The first model (M1) yielded an index of hemolysis of 0.005 g/100 L using bovine blood and demonstrated satisfactory performance as a right heart assist for 2 days (4 L/min, 60 mm Hg, 1,800 rpm). The second model (M2) has been developed for left heart assist by employing a stronger motor. The pump capacity was improved to 6 L/min against 240 mm Hg at 1,800 rpm, but significant heat generation was observed. By optimization of motor efficiency, the M2 model can be improved to meet the requirements of a pump for left heart assist.

Setsuo Takatani

Papers

Motor driven sealless blood pump

Chronic nonpulsatile blood flow in an alive, awake animal 34-day survival.

Chronic nonpulsatile blood flow.

An Ultimate, Compact, Seal‐less Centrifugal Ventricular Assist Device: Baylor C‐Gyro Pump

Baylor Gyro Pump: a completely seal-less centrifugal pump aiming for long-term circulatory support.