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CARDIAC MONITOR (type of patient monitoring)

CARDIAC MONITOR
  • The most important physiological parameters monitored in the intensive care unit are heartrate and ECG produced by the heart. This is done to observe the presence of arrhythmias or to detect changes in the heart rate.
  • It is specifically useful for monitoring patients with cardiac problems.
  • It mainly shows the parameters related to heart such as ECG, Heart Rateand Blood Pressure etc.
  • These instruments are also called ‘Cardio scopes’ and comprises of:
             1)     Disposable type pre-gelled electrodes to pick up the ECG signal.
             2)     Amplifier and a CRT/LCD for the amplification and display the ECG waveform
           3)    A heart rate meter to indicate average heart rate with audible beep or flashing light    or                   both     with each beat.                                                                                                                                  4)     An alarm system to produce signal in the event of abnormalities occurring in the heart rate.
 
  • Small cardio scopes using 3” diameter cathode ray tubes are mounted on anesthesia trollies.These are called “Anesthesia monitors’’.
  • These monitors are used by the anesthetist for continuously monitoring of the ECG of anaesthetized patients. 
  • Selection of System Parameters:
  •  In a digital memory system, operating parameters should be carefully selected to maintain signal accuracy, bandwidth.
  •  The following are the important parameters:
1)Sampling rate:Most of the single channel memory display systems have a sampling rate of 250 samples/s and multi-channel display work on 180 samples/s
 
 2)Word Length:The accuracy of analog signalsdepends on the number of bits used in the conversion.
  •  The greater the number of bits per word, the greater will be the resolution.
  • Usually, an 8-bit word is chosen.


3) Memory capacity: Increasing either thesampling rate or the display time interval will increase the memory size proportionally.

 
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