Method and apparatus for determining hematocrit
First Claim
1. Apparatus for measuring hematocrit comprising:
- peak detection means for connection to a sensor providing sensor pulses in response to blood cells in a sample, the sensor pulses each having a peak amplitude respectively corresponding to the size of a cell in response to which the sensor pulse is produced;
storage means connected to said peak detecting means for generating and storing a signal having a level indicative of the peak value sensed by said peak detecting means for each pulse;
accumulation means;
controlled switching means coupling said storage means to said accumulation means, timing means responsive to said sensor pulses for initiating a first time period in response to each sensor pulse in excess of a threshold level and providing an output for enabling said storage means to respond to the sensor pulse, said timing means further including means for establishing a second time period in response to the completion of each first time period and providing an output for closing said controlled switching means for a fixed time period during said second time period, whereby said accumulation means is incremented by an amount in correspondence with the level of the stored signal in said storage means.
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Abstract
An apparatus and method are provided for measuring hematocrit. A diluted blood sample is passed through a well-known conductivity sensor providing a sensor pulse for each sensed blood cell. Each pulse has a peak amplitude corresponding to the size of a blood cell passing through the sensor. During a first time period initiated by passing of the sensor pulse above a threshold level, the sensor pulse is coupled to peak detecting means, and a signal indicative of the level of the peak is generated and stored. The value of each stored signal is added to an integrator for a fixed period of time. The value stored by the integrator is thus indicative of hematocrit level for a known sample volume.
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Citations
14 Claims
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1. Apparatus for measuring hematocrit comprising:
- peak detection means for connection to a sensor providing sensor pulses in response to blood cells in a sample, the sensor pulses each having a peak amplitude respectively corresponding to the size of a cell in response to which the sensor pulse is produced;
storage means connected to said peak detecting means for generating and storing a signal having a level indicative of the peak value sensed by said peak detecting means for each pulse;
accumulation means;
controlled switching means coupling said storage means to said accumulation means, timing means responsive to said sensor pulses for initiating a first time period in response to each sensor pulse in excess of a threshold level and providing an output for enabling said storage means to respond to the sensor pulse, said timing means further including means for establishing a second time period in response to the completion of each first time period and providing an output for closing said controlled switching means for a fixed time period during said second time period, whereby said accumulation means is incremented by an amount in correspondence with the level of the stored signal in said storage means. - View Dependent Claims (2, 3, 4, 8, 9)
- peak detection means for connection to a sensor providing sensor pulses in response to blood cells in a sample, the sensor pulses each having a peak amplitude respectively corresponding to the size of a cell in response to which the sensor pulse is produced;
- 5. Apparatus according to cliam 4 wherein said means establishing first time period comprises a threshold amplifier coupled to the sensor providing said sensor pulses, a one shot multivibrator connected for triggering by said threshold amplifier, and gating means connected to said threshold amplifier and said one shot multivibrator for providing a timing signal having a duration equal to the longer of the output of said one shot multivibrator or said threshold amplifier.
- 11. A method of measuring hematocrit comprising the steps of detecting the peak of each sensor pulse indicating a size of a blood cell in a sample passing through a sensor, establishing a first time period equal to at least the width of a sensor pulse, generating a signal indicative of the height of the sensor pulse within the first time period and storing the signal to provide a stored signal, establishing a second time period in response to the end of said first time period and incrementing accumulation means for a fixed time period by an amount in correspondence with said stored signal.
Specification