Question

​​​​​​Trace the development of: Physiological Monitor.. Which includes sections on the following: ECG, SPO2, NIBP

Answer the following question:

• What did the original equipment look like? How has it changed over the years?

Answer 1

Physiologic monitors monitor vital sign parameters and inform clinicians of changes in a patient's condition through the use of alarms. They consist of multiple components, including a central station, bedside monitors, and telemetry transmitters and receivers

Physiological monitoring systems assess aspects of human performance and either respond with a corrective action, or alert a human being to do so. Physiologic monitors can measure and record temperature, heart rate, respiration, alertness, and activity.

We will consider the potential of these systems to assist in biosurveillance by equipping a “sentinel population.” A sentinel population is any group of people who are willing to participate in a monitoring scheme. Security professionals, for example, could act as the proverbial canary in the mineshaft in a variety of settings. Examples of this approach could include advance members of the president's Secret Service detail, or other executive protection forces, or security agents patrolling special events (e.g., the Republican National Convention). In the latter case, we imagine that devices worn unobtrusively by the sentinels would provide early warning of spiking fevers, tachycardia or other signs arising in a fraction of the sentinel population. The information transmitted automatically from these sentinels would be timely.

To offer this capability, the equipment worn must be able to carry out accurate measurements while withstanding, and compensating for, the activities of an active subject. For example, a thermometer worn on the body must be able to compensate for clothing, weather, and exercise.

Physiological monitoring in the ICU setting closely follows the patient's cardiac, hemodynamic, and respiratory statuses. While early physiological monitors could view one lead of the ECG and, perhaps, an invasive blood pressure, today's systems integrate a vast array of parameters into a relatively small monitoring device. A typical, full-featured, physiological monitor might contain a set of built-in monitored parameters or might have the ability to add plug-in modules to configure the unit as the clinical situation demands. Monitors located at the bedside are typically connected to monitors at a central station where one may observe the physiological status of many patients at once.

Physiologic monitors have been in regular commercial production since about 1954. Therefore, in recognition of those first 50 years, we have compiled a history of these interesting devices and present some of our guesses as to where this technology is headed. This history of physiologic monitors looks at the technical evolution of physiologic monitors which incorporate a cathode ray tube (CRT) or flat panel display and that normally would be used in a hospital setting.

The 1950s’: Early Warning Systems for “Cardiac Accidents”:

Himmelstein and Scheiner reported in a 1952 paper that in January of 1950 they began using an instrument they devised. They called it the “Cardiotachoscope” and found it useful during surgery.

Systems of the 1950’s and early 1960’s made less of a distinction between the equipment roles of monitoring and defibrillation or pacing and were often intended to be used together as a diagnostic and, especially, therapeutic whole at the bedside or in the operating room on a mobile cart. Equipment used in this sense is more closely related to what we currently find on a hospital crash-cart: a defibrillator/monitor with integrated non-invasive pacing.

The frequency response of the ECG monitor was often less than comparable electrocardiographs of the period.   This meant that detailed ECG assessment still required the electrocardiograph. The advantage of the monitor was the immediacy of the information and the ability to generate alarms.  

Most bedside type monitors often had round screens of about 5 inches in diameter.   Some had only 3-inch diameter screens. Most bedside monitors were limited to one or two waveform traces. The diameter of the screen (in inches) was often incorporated as part of the devices model number.

The 1960s’: Proliferation into Critical Care:

The 1960’s featured monitoring systems whose intended functions and configurations were surprisingly similar to more modern systems.  

The 1970s’: The Impact of Digital Electronics:

The decade of the 1970’s saw some significant improvements in the presentation of the displayed waveforms and information. This was a result of the incorporation of digital electronics and, eventually, microprocessors.

The 1980s’: Modularity and Bedside Arrhythmia Analysis:

The 1980’s witnessed further significant evolution in patient monitors. Arrhythmia analysis became available at the bedside instead of centrally.  

The 1990s’: Mobility and Connectivity:

Monitors of the 1990s’ became more flexible and efficient in their deployment and setup and began accepting and presenting data from other sources such as medical equipment and hospital departments.

The Early 21^st Century and Beyond:

Monitors of the 1990’s usually had to be configured for the type of location such as the OR versus emergency.

History :

1950: First ‘modern’ monitor reported in use.

1954: First appearance of production monitors (Cambridge cardioscope).

1956: Production monitors enter clinical use (Electrodyne PM-65).

1966: Non-circular displays and Nixie numeric indicators are employed.

1968: Heart rate included on CRT as a progress-bar indicator.

1970: The memory monitor appears which allows for a non-fade display.   Isolated inputs appear for added patient safety.

1975: LEDs employed as numeric indicators on physiologic monitors.

1978: Monitor displays include heart rate as a numeric on the CRT.

1980: Modern modular parameter modules appear.

1983: Arrhythmia analysis available at the bedside. The first color physiologic monitors appear.

1990: Transport monitors appear which could transfer the same patients’ module and cabling to a compatible bedside monitor.  Flatscreen (non-CRT) monitors appear on physiologic monitors.

1995: Some monitors can run Windows applications.

1996: Continuum of care monitors appear and parameter modules begin to be replaced by configured acquisition panels on the side of monitors.

2000: Internet connectivity at the bedside becomes available.