Abstract: A connector assembly couples signal lines for an optical catheter by providing a guided releasable latching mechanism that ensures optimal alignment with only a single vertical dimension under control. A receptacle carrying a first signal line defines a channel for receiving a plug carrying a second signal line. A spring-loaded pawl on the receptacle locks to a retaining bracket on the plug when the plug slides into the channel, imparting a retaining force on the plug, the force having a first component normal to channel and a second component parallel to the channel to maintain the first and second signal lines in optimal alignment. The retaining bracket may include a sloped edge to allow for easy release of the pawl in the presence of a release force. The release force may be set to allow disconnection of the assembly without affecting catheter installation or causing patient discomfort.

Abstract: A cardiovascular parameter such as cardiac output is estimated from a current pressure waveform data set without needing to directly measure blood flow or arterial compliance. The general shape of an input flow waveform over one beat-to-beat cycle is assumed (or computed), and then the parameters of a flow-to-pressure model, if not pre-determined, are determined using system identification techniques. In one embodiment, the parameters thus determined are used to estimate a current peripheral resistance, which is used not only to compute an estimate of the cardiovascular parameter, but also to adjust the shape of the input flow waveform assumed during at least one subsequent beat-to-beat cycle. Another embodiment does not require computation of the peripheral resistance and still another embodiment computes a flow estimate from an optimized identification of the parameters defining the assumed input flow waveform.

Abstract: An expansion frame system for deploying medical devices in a patient's body cavity. The system typically includes an inner wire disposed within a lumen of an outer wire. Distal ends of the inner and outer wires are attached to a substantially circular frame at first and second points. During use, the outer wire is displaced relative to the inner wire, causing the circular frame to rotate about an axis perpendicular to the line defined by the first and second points. Medical devices, such as a filter, a stent, an occluder or a manometer, can be mounted on the circular frame. The diameter of the expansion frame can be varied to achieve optimal contact with the luminal wall of the body cavity. Methods of using the expansion frame system for temporary or permanent placement of a medical device is disclosed.

Abstract: A medical blood pressure transducer that provides an identifier to a monitor that conveys characteristics of the transducer. The monitor can use the information to decide whether to function, or in calibration of the system. The transducer may be part of a disposable blood pressure monitoring system, and may include two transducers closely-spaced to provide two separate but identical outputs. In this way, the transducer may be connected to both a patient monitor and a cardiac output monitor at the same time measurements from a single line can be simultaneously supplied to two separate monitoring devices (for example a patient monitor and a cardiac output monitor). The identifier for the transducer may be circuitry, specifically a resistance/capacitance (RC) combination that possesses a characteristic time constant.

Abstract: In one embodiment the present invention provides a wireless communication system for medical sensor data. This communications system includes a portable unit that connects to a wireless sensor and a monitor unit that connects to a sensor monitor. Once activated, the units will self organize into a wireless communication structure controlled by the portable unit. As other pairs of units activate, they can self-organize their transmissions by joining an existing network or by creating new networks.

Abstract: A method of creating a sensor that may include applying a first conductive material on a first portion of a substrate to form a reference electrode and depositing a first mask over the substrate, the first mask having an opening that exposes the reference electrode and a second portion of the substrate. The method may also include depositing a second conductive material into the opening in the first mask, the second conductive material being in direct contact with the reference electrode and depositing a second mask over the second conductive material, the second mask having an opening over the second portion of the substrate, the opening exposing a portion of the second conductive material, which forms a working surface to receive a fluid of interest.

Abstract: One or more cardiovascular parameters is estimated as a function of the arterial pressure waveform, in particular, using at least one statistical moment of pressure waveform having an order greater than one. Arterial compliance, the exponential pressure decay constant, vascular resistance, cardiac output, and stroke volume are examples of cardiovascular parameters that can be estimated using various aspects of the invention. In one embodiment of the invention, not only are the first four moments (mean, standard deviation, skewness, and kurtosis) of the pressure waveform used to estimate the cardiovascular parameter(s) of interest, but also heart rate, statistical moments of a set of pressure-weighted time values, and certain anthropometric patient measurements such as age, sex, body surface area, etc.

Abstract: An introducer having an elongate tubular member and a device connector releasably attached to a proximal end of the tubular member. The introducer allows exchange of medical instruments, such as a blood filter and cardioplegia catheter, through a single lumen. An obturator having a retractable blade for making incision on a tissue is insertable through the lumen of the introducer. Methods of using the obturator and the introducer for introducing medical device(s) into body cavity, such as a vessel or cardiac tissue, are also disclosed.

Abstract: An apparatus for the measurement of at least one analyte in the blood of a patient, which includes a light source generating broadband light and a light-transmission arrangement having a plurality of transmitting fibers is positioned for simultaneously transmitting multiple wavelengths of the broadband light from the light source to the blood of the patient. The measurement apparatus further includes an optical fiber arrangement having a plurality of light detector fibers for leading multi-wavelength light, in spectrally unseparated form, transmitted through, or reflected from, the blood and a light detection arrangement for receiving the multi-wavelength light in its spectrally unseparated form from the optical fiber arrangement, for spectrally decomposing the received light, and for determining amplitudes of selected wavelengths of the decomposed light.

Abstract: Ventricular stroke volume variation (SVV) is estimated as a function of the standard deviation of arterial blood pressure value measured over each of at least two cardiac cycles, preferably over each of the cardiac cycles in a computation interval covering a full respiratory cycle. In one embodiment, maximum and minimum standard deviation values are determined over the computation interval. SVV is then estimated proportional to the ratio of the difference between the maximum and minimum standard deviation values and the mean of the standard deviation values. In another embodiment, SVV is then estimated proportional to the ratio of the standard deviation of the standard deviation values and the mean standard deviation over the entire computation interval. A pre-processing arrangement for improving reliability of estimates of more general cardiac or hemodynamic parameters is also disclosed and involves smoothing with an approximating function, and sampling and low-pass filtering at an adjustable rate.

Abstract: Devices and methods for filtering blood. The devices generally comprise a mesh for filtering blood flowing within a blood vessel, particularly within an artery such as the aorta, a structure adapted to open and close the mesh within the blood vessel, and a means to actuate the structure. The methods generally include the steps of introducing a mesh into a blood vessel to entrap embolic material, and removing the mesh and the entrapped foreign matter from the blood vessel.

Abstract: Methods for measuring the total hemoglobin of whole blood include measuring reflective light at multiple wavelengths within the visible spectrum, calculating light absorbance at each of the multiple wavelengths, performing a comparison in a change in like absorbance between the multiple wavelengths, and/or relating the comparison to total hemoglobin. A system for measuring total hemoglobin of whole blood may include at least one light source, a catheter, optical fibers, at least one photodetector, data processing circuitry, and/or a display unit.

Abstract: A blood sampling device for allowing a fluid pressure measurement and a fluid sample to be taken from a patient, having an inlet port configured to receive blood from the patient, an outlet port configured to be coupled to a monitoring channel having an infusion fluid, a sampling port configured for extraction of blood from the patient, a sampling channel configured to self-flush, after extraction, the blood with the infusion fluid, and an auxiliary channel for self-flushing the sampling channel.

Abstract: A balloon arterial cannula and methods for filtering blood. The devices generally include a mesh for filtering blood flowing within a blood vessel, particularly within an artery such as the aorta, a structure adapted to open and close the mesh within the blood vessel, a means to actuate the structure, and a balloon occluder which typically includes a flexible material enclosing a chamber. The methods generally include the steps of introducing a mesh into a blood vessel to capture embolic material, adjusting the mesh, if necessary, during the course of filtration, inflating the balloon occluder to occlude the vessel upstream of the mesh, and thereafter deflating the balloon occluder and removing the mesh and the captured foreign matter from the blood vessel. Additionally, visualization techniques are used to ensure effective filtration.

Abstract: A method for monitoring blood oxygen saturation (SO2) includes the steps of calculating an estimate of SO2 in the blood and correcting the estimate by a scaling factor. A preferred embodiment of the method includes the steps of transmitting light containing a plurality of wavelengths into the blood; measuring a remitted spectrum over the plurality of wavelengths; calculating a measured blood absorption spectrum from the remitted spectrum; estimating local rates of change in the measured blood absorption spectrum at a plurality of the wavelengths; and calculating the estimate of SO2 as a function of absolute values of the local rates of change of the measured blood absorption spectrum.

Abstract: Cardiac stroke volume (SV) of a subject is estimated as a function of a value derived from a measured arterial pressure waveform. The value may be the standard deviation, or a function of the difference between maximum and minimum pressure values, or a function of either the maximum value of the first time derivative or the absolute value of the minimum of the first time derivative of the pressure waveform, or both, or a function of the magnitude of one or more spectral components of the pressure waveform at a frequency corresponding to the heart rate. Cardiac output is then estimated as the product of the subject's heart rate and SV, scaled by a calibration constant. Arterial pressure may be measured invasively or non-invasively.

Abstract: A method for monitoring oxygenation of blood includes the steps of transmitting light containing a plurality of wavelengths into blood and measuring a remitted spectrum over the plurality of-wavelengths. A measured blood absorption spectrum is then calculated from the remitted spectrum and local rates of change in the measured blood absorption spectrum are estimated at a plurality of the wavelengths, including at least one isobestic wavelength. An estimate of blood oxygen saturation (SO2) is calculated as a function of absolute values of the local rates of change of the measured blood absorption spectrum.