Medical Monitor

Medical Monitor

A medical monitor, also referred to as a physiological monitor or display, is an electronic medical device utilized for medical monitoring purposes. It presents the monitored data, and may have the capability to transmit this data on a monitoring network. Physiological data are continually displayed on a CRT or LCD screen as data channels along the time axis. These data may be accompanied by numerical readouts of computed parameters, such as maximum, minimum, and average values, as well as pulse and respiratory frequencies.

The evolution of medical monitors is closely tied to the development of digital signal processing (DSP) technology. DSP technology offers advantages such as miniaturization, portability, and the ability for multi-parameter monitoring, allowing the tracking of numerous vital signs simultaneously.

Common parameters monitored by medical monitors include pulse oximetry (measuring the saturated percentage of oxygen in the blood, known as SpO2, often measured by an infrared finger cuff), ECG (electrocardiograph of the QRS waves of the heart, with or without an accompanying external heart pacemaker), blood pressure (invasively through an inserted blood pressure transducer assembly, or noninvasively with an inflatable blood pressure cuff), and body temperature through an adhesive pad containing a thermoelectric transducer.

Additional parameters that can be measured and displayed include cardiac output (via an invasive Swan-Ganz catheter), capnography (CO2 measurements, referred to as EtCO2 or end-tidal carbon dioxide concentration), and respiration (via a thoracic transducer belt, an ECG channel, or via EtCO2, known as AWRR or airway respiratory rate), among others.

Digital medical monitors feature automated numeric readouts of peak and/or average parameters displayed on the screen, along with the ability to set high/low alarm levels. These alarms alert staff when a parameter exceeds or falls below set limits, often using audible signals.

Many models of multi-parameter monitors are network-able, meaning they can send their output to a central ICU monitoring station. This allows a single staff member to observe and respond to several bedside monitors simultaneously. Ambulatory telemetry can also be achieved by portable, battery-operated models that transmit data via a wireless connection.

Some digital patient monitors, especially those used in EMS services, incorporate a defibrillator into the patient monitor itself. These monitor/defibrillators typically have the capabilities of an ICU monitor, along with manual (and often semi-automatic AED) defibrillation capability. This is particularly useful for EMS services and for patient transport between facilities. Additionally, monitor defibrillators may have specialized monitoring parameters such as waveform capnography, invasive BP, and Masimo Rainbow SET pulse oximetry. Examples of monitor defibrillators include the Lifepak 12, 15, and 20 made by Physio Control, the Philips Heartstart MRx, and the E Series and R Series by ZOLL Medical.