Inter-beat Interval
The Inter-beat Interval (also IBI for short) refers to the millisecond interval between two consecutive R Wave peaks (two heart beats), usually in human or mammal ECG signals. Note first that the IBI is derived from the ECG, and so a stable ECG signal, and whatever signal conditioning and subject connection the ECG might require; this must be available first. Note also that the IBI is a calculated value. Some sort of algorithm must be somehow performed on the ECG signal in order to detect the R Wave peak, then accurately time the interval between two successive peaks. Some ECG data recording systems (such as our Biologs), can perform the R Wave detection and IBI interval timing as the ECG signal is actually being recorded. Otherwise, the IBI detection process must be performed, usually via a software program, after the ECG data is recorded and retrieved. Typical human IBI values range between 600 and 900 milliseconds. And the IBI is rarely constant. Respiration, psychological factors and physiological aspects can all influence the IBI.
For many years, it was Heart Rate that was used in many studies. Initially, the amount of heart beats were simply counted over a 1 minute period (or counted for, say 15 seconds, then multiplied accordingly). The accepted unit for Heart Rate (HR for short) is Beats per Minute. The instantaneous or beat-by-beat heart rate is probably a more helpful measure, but this measure also requires some sort of detection and timing algoithm. The IBI can easily be mathmatically converted into an instantaneous Heart Rate for those studies that require this. However, the IBI is considered a more exact measure.
A number of UFI instruments can be supplied that handle the ECG signal, which is the basis for the IBI. More information about UFI ECG systems can be found here. On-line (while recording) millisecond IBI detection can easily be added to ALL of these instruments as an additional channel.
We mentioned the Biolog platform above. All Biologs can include an ECG channel, with the Fetrode technology incorporated as standard. All Biologs can also both record ECG as well as detect, calculate and record IBI as well. The IBI algorithm is actually performed while the ECG data is being received and recorded! And, if the IBI is all you need, the Biolog can use the ECG channel data for IBI, and then record just the IBI. This approach allows for much longer recording time for a given memory size! And if you add a PPG (finger pulse plethysmograph) channel to the same Biolog, the Pulse Transit Time (PTT; the time it takes for a heart beat to show up in a finger, for example) can be calculated and recorded along with the IBI and everything else.
If simplicity is your game, we can supply a compact PC connected instrument focused on just IBI. Check out our EZ-IBI module. This small, 9V battery powered device includes Fetrode ECG Signal Conditioning, built-in 12 bit A-D data conversion, R Wave detection and interval timing, along with an isolated USB port! Simple PC data recording and review software is included. Three electrodes on your subject plus the EZ-IBI and a USB cable puts high resolution ECG and millisecond IBI on your computer! Thats simple!
If you still have questions, or if you don't see what you need, drop us a line, and we will see how we can help you!