Physiologic monitors

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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 [1]. They initially developed out of the need for anesthesiologists to monitor patients in the operating room but quickly spread to the intensive care unit in the 1970s and throughout the hospital from there. Recently, smart devices that can be attached a patient’s body or even integrated into their garments have also been developed.


Central Station

Most modern physiologic monitors send their output to a central monitoring station for either display or evaluation. In addition, digital monitoring allows for integration of the physiological data from the patient monitor into the hospital electronic health record, using appropriate health care standards such as HL7.

Bedside Monitor

The bedside monitor displays physiological data continuously on CRT, LED or LCD screens as individual data rows along the time axis for selected physiologic criteria. These physiologic criteria usually include heart rate, respiratory rate, blood pressure, and pulse oximetry.

Telemetry Transmitter and Receiver

Sensors are placed on the patient and allow for physiologic data to be transmitted to the bedside monitor. Often multiple sensors are needed. Ambulatory telemetry is achieved by portable, wi-fi capable, battery-operated models which are worn by the patient and transmit data via a wireless data connection.


Physiologic monitors allow for early detection of vital sign deterioration and work to alert responders to critical situations. Through the use of visual and audible alarm signals, physiologic monitors alert clinicians to changes in a patient’s condition that may require immediate intervention [2].Continuous monitoring of patients in the hospital is a valuable tool to provide additional information for diagnosis and treatment to the medical and nursing staff. They allow for ongoing monitoring by medical staff even when they are tending to other patients or tasks.


Physiologic monitors are intended to prevent cardiac and respiratory arrest by generating alarms to alert clinicians to signs of instability. To minimize the probability that monitors will miss signs of deterioration, alarm algorithms are often set to maximize sensitivity, sacrificing specificity [3]. As a result, monitors generate large numbers of alarms that are either invalid or are valid but do not warrant clinical intervention.[4] In national surveys of healthcare staff, respondents report that high alarm rates interrupt patient care and lead clinicians to disable alarms.[5] Recent research has supported this, demonstrating that nurses exposed to higher numbers of alarms have slower response times to alarms.[6,7]


Smart devices can create a personal network with wireless transmission of physiologic monitoring. Any data can be sent to computer, allowing remote monitoring of real time data. There are also advantages and disadvantages to these smart devices. Advantages for these devices include early detection of vital sign deterioration, enhanced connectedness among patients and loved ones, providing reassurance to family and maintaining dignity and independence for patients, and providing clinicians with transformative real time physiologic data. In addition, they also allow for battlefield monitoring of soldiers and improvement in sports related conditioning. Disadvantages include the high expense of the devices, and similar to hospital physiologic monitors, false alarms are also a large concern. These devices must be constantly updated in order to make sure that patient data is being displayed on the device accurately. Improper data can lead to improper diagnoses, which also leads to improper care for a patient [8].

Two such devices currently being developed and tested include the LifeGuard wireless physiologic monitor and the HealthGear real time physiologic monitoring system.


The LifeGuard system is being developed by NASA to monitor the health of astronauts during space flights and extravehicular activities. Capabilities of the LifeGuard include:

  • Heart rate
  • Systolic and diastolic blood pressure
  • Activity, (3-axis acceleration)
  • ECG, (2 channels)
  • Temperature
  • Respiration rate
  • Pulse oximetry


The HealthGear system is being developed by Microsoft, it is designed to be integrated into clothing and not only collects real time data but also performs algorithmic interpretation of the data for detecting sleep apnea episodes [9].

  • Heart Rate
  • Respiration rate
  • Pulse oximetry
  • Plethysmographic signal
  • Modular format to allow addition of additional components


1. Physiologic monitoring systems. Health Devices. 2000 May;29(5):153-84. PubMed PMID: 10851651.

2. Lacker C.: Physiologic alarm management.Pennsylvania Patient Safety Advisory 8:105–108, Sep. 2011.

3. Drew BJ, Califf RM, Funk M, et al. Practice standards for electrocardiographic monitoring in hospital settings: An American Heart Association scientific statement from the councils on cardiovascular nursing, clinical cardiology, and cardiovascular disease in the young. Circulation. 2004;110:2721–46. doi:10.1161/01.CIR.0000145144.56673.59

4. Paine CW, Goel V V., Ely E, et al. Systematic Review of Physiologic Monitor Alarm Characteristics and Pragmatic Interventions to Reduce Alarm Frequency. J. Hosp. Med. 2016;11:136–44. doi:10.1002/jhm.2520.

5. Korniewicz DM, Clark T, David Y. A national online survey on the effectiveness of clinical alarms. Am J Crit Care 2008;17:36–41. doi:17/1/36 [pii]

6. Bonafide CP, Lin R, Zander M, et al. Association between exposure to nonactionable physiologic monitor alarms and response time in a children’s hospital. J Hosp Med 2015;10:345–51. doi:10.1002/jhm.2331

7. Voepel-Lewis T, Parker ML, Burke CN, et al. Pulse oximetry desaturation alarms on a general postoperative adult unit: A prospective observational study of nurse response time. Int J Nurs Stud 2013;50:1351–8. doi:10.1016/j.ijnurstu.2013.02.006

8. Tran, T. Q., Boring, R. L., Dudenhoeffer, D. D., Keller, M. D., & Anderson, T. M. (2007, August). Advantages and disadvantages of physiological assessment for next generation control room design. Retrieved September 9, 2015, from Documents/3775292.pdf

9. Emil Jovanov, Dejan Raskovic, John Price, John Chapman, Anthony Moore, Abhishek Krishnamurthy. Patient Monitoring Using Personal Area Networks of Wireless Intelligent Sensors.

10. Nuria Oliver & Fernando Flores-Mangas. HealthGear: A Real-time Wearable System forMonitoring and Analyzing Physiological .

11. Signals.

Submitted by Maya Dewan