Overview
Continuous measurement of vital signs such as heart rate, respiratory rate, and blood oxygen saturation (SpO2) is essential for effective care. The ability to measure multiple parameters simultaneously makes multiparameter patient monitors increasingly important.
Electronic patient monitors use noninvasive sensors attached to the patient to acquire and display physiological data. One key challenge for multiparameter monitors is maintaining high performance while achieving compact size and low power consumption.
Design Summary
Many bedside monitors are large, immobile, and connected to patients with numerous wires, which limits their use in mobile care and home-care settings. This has driven demand for compact multiparameter monitors that connect wirelessly to the patient and transmit data wirelessly or via cable to phones, tablets, or computers.
Texas Instruments (TI) offers a multiparameter vital-signs front-end reference design that targets compact, low-cost, and low-power operation by integrating the front-end components required to acquire vital-sign data.
The design acquires parameters such as ECG, SpO2, heart rate, and respiratory rate using AFE4403 and ADS1292R biosensing front-end integrated circuits. It can be combined with a software-configurable pacemaker detection module reference design to support pacing pulse detection and can connect up to three temperature sensors (TMP117) with 0.1 degrees Celsius accuracy to measure skin temperature. Standard wet ECG electrodes are used for ECG measurement, and a transmissive finger-clip sensor can be used for SpO2. Raw data are transmitted by an onboard MSP432P401 microcontroller over an isolated universal asynchronous receiver-transmitter (UART) interface at 460.8 Kbps to a backend processor or PC. Power can be supplied via a standard USB port or a USB-chargeable lithium-ion battery.
Graphical User Interface
The graphical user interface (GUI) displays acquired waveforms with a 5-second scroll interval and applies basic filtering to remove noise such as common-mode interference from power and lighting. Figure 2 shows the ECG measurements, respiration, SpO2, heart rate (beats per minute), respiratory rate (breaths per minute), SpO2 percentage, and temperature values displayed on a PC.
Figure 3 shows ECG, photoplethysmogram (PPG), pacemaker activity, heart rate, and temperature sensor data captured on a computer. When a pacing pulse is detected, the pacemaker activity is indicated, as shown by the top trace in Figure 3.
Figure 3: GUI showing ECG, PPG, pacemaker, heart rate, and skin temperature
Conclusion
The reference design provides a compact, low-power platform for evaluating collaborating devices. It includes design guidelines, schematics, layout, and a bill of materials to support quick evaluation and accelerate product development. The design also facilitates real-time acquisition of vital-sign parameters.
