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An EMS monitor, also called an EMS cardiac monitor or monitor/defibrillator, is the single ambulance unit that combines heart-rhythm monitoring with defibrillation and, depending on the configuration, 12-lead ECG, pacing, pulse oximetry, capnography and blood pressure measurement. It is used by advanced life support (ALS) crews. This guide maps each module to the FDA regulation that defines it and to what the 2020 national ambulance equipment list requires at basic (BLS) and advanced (ALS) level.
What is an EMS monitor?
An EMS monitor is the ALS ambulance’s cardiac device. The 2020 joint position statement on essential ground-ambulance equipment describes it as “a device capable of performing automatic and/or manual defibrillation, cardiac rhythm monitoring (in at least three leads), 12 lead ECG acquisition, and transcutaneous pacing”. “EMS cardiac monitor” and “EMS monitor” name the same device class. Who uses it: paramedics and other ALS clinicians on ground ambulances, and the agencies and medical directors who equip them.
It is not the same as an automated external defibrillator (AED). The same list requires an AED with adult and pediatric or combination pads at BLS level, and the monitor/defibrillator at ALS level. For the device-level difference see manual defibrillator vs AED.
What modules does an EMS monitor have?
The modules below are the ones named in the national list and in FDA device regulations. Which of them a given unit carries is set by the configuration the agency buys, so treat the table as a map of functions, not a spec sheet.
| Module | FDA regulation and class | What the regulation says |
|---|---|---|
| Cardiac rhythm monitoring | 21 CFR 870.2300 cardiac monitor, Class II | A device used to measure the heart rate from an analog signal; it may sound an alarm when the heart rate falls outside preset upper and lower limits. |
| Defibrillation (low energy) | 21 CFR 870.5300 DC-defibrillator, Class II | Delivers into a 50 ohm test load a shock of a maximum of 360 joules; may synchronize with the ECG or operate asynchronously. |
| Defibrillation (high energy) | 21 CFR 870.5300, Class III (premarket approval) | Devices delivering more than 360 joules into a 50 ohm test load. |
| Pulse oximetry (SpO2) | 21 CFR 870.2700 oximeter, Class II | Transmits radiation at a known wavelength through blood and estimates blood oxygen from the light returned or scattered. |
| Capnography (EtCO2) | 21 CFR 868.1400 carbon dioxide gas analyzer, Class II | Measures the concentration of carbon dioxide in a gas mixture; helps determine ventilatory, circulatory and metabolic status; techniques include infrared absorption. |
| Noninvasive blood pressure (NIBP) | 21 CFR 870.1130 noninvasive blood pressure measurement system, Class II | Provides a signal from which systolic, diastolic, mean, or any combination of the three pressures can be derived; sensors sit on the body surface. |
The national list names 12-lead ECG acquisition and transcutaneous pacing as ALS functions. For the ECG side in a clinic setting see what an ECG machine is, and for a worn device see what a wearable defibrillator is.
How does FDA regulate the defibrillator part?
21 CFR 870.5300 splits DC-defibrillators by output. A low-energy unit, one that delivers a maximum of 360 joules into a 50 ohm test load, is Class II and subject to performance standards. A high-energy unit, above 360 joules into the same load, is Class III and needs premarket approval. The regulation text does not name EMS use; it defines the device class, not the ambulance configuration.
What does the national ambulance list require at BLS and ALS level?
The Recommended Essential Equipment for BLS and ALS Ground Ambulances 2020 position statement (Lyng et al., Prehospital Emergency Care 2021;25(3):451-459) was issued jointly by the American Academy of Pediatrics, the American College of Surgeons Committee on Trauma, the Emergency Nurses Association, the EMS for Children Innovation and Improvement Center, NAEMSP and NASEMSO.
| Item | BLS ambulance | ALS ambulance |
|---|---|---|
| Defibrillation | AED with adult and pediatric or combination pads | Device capable of automatic and/or manual defibrillation |
| Rhythm monitoring, 12-lead ECG, pacing | – | Rhythm monitoring in at least three leads, 12-lead ECG acquisition, transcutaneous pacing |
| Waveform capnography | – | Continuous waveform capnography |
| Pulse oximeter | With sensors to fit neonates to adults | With sensors to fit neonates to adults |
| Blood pressure cuffs | Sizes to fit neonates to adults | Sizes to fit neonates to adults |
Quantities beyond what the list states are set at the medical director or agency level. For the rest of the ambulance inventory see EMS equipment and EMT bag contents.
How to choose: what the national list actually asks for
The selection criteria in the 2020 list are these: at ALS level the unit must cover defibrillation (automatic and/or manual), at least three-lead rhythm monitoring, 12-lead acquisition, transcutaneous pacing and continuous waveform capnography, and the pulse oximeter and blood pressure cuffs must span neonate to adult sizes. A configuration that omits one of these does not meet the ALS row as written. Other factors, such as battery life, ruggedness or software, are set by the agency and its medical director.
Safe use and handling basics
Use, pad placement, energy selection and pacing settings follow the manufacturer’s instructions for use and the agency’s protocols as set by its medical director; this page does not give operating steps. In general terms: a low-energy defibrillator is a regulated Class II device, and the monitoring and measurement modules in it are separate regulated device types with their own definitions.
Common mistakes
- Treating an AED as the ALS cardiac device. The national list distinguishes an AED (BLS) from a device that also monitors rhythm in at least three leads, acquires 12-lead ECG and paces (ALS).
- Assuming SpO2 and cuffs belong only to ALS. The list requires a pulse oximeter and blood pressure cuffs that fit neonates to adults at both levels.
- Reading the 360 joule line as a recommended setting. It is the regulatory boundary between Class II and Class III defibrillators, measured into a 50 ohm test load, not a clinical energy.
- Counting a monitor as a single regulated device. FDA defines the rhythm monitor, defibrillator, oximeter, CO2 analyzer and blood pressure system in separate regulations.
FAQ
What is an EMS cardiac monitor?
It is the EMS monitor described above: the ALS unit that monitors heart rhythm in at least three leads and, in the 2020 national list’s wording, can also defibrillate, acquire a 12-lead ECG and pace transcutaneously.
Is an EMS monitor the same as an AED?
No. The 2020 list requires an AED at BLS level and the fuller monitor/defibrillator at ALS level.
Which FDA class is the defibrillator in an EMS monitor?
Under 21 CFR 870.5300, a DC-defibrillator delivering a maximum of 360 joules into a 50 ohm test load is Class II; above 360 joules it is Class III.
Sources
- 21 CFR 870.5300 DC-defibrillator: https://www.ecfr.gov/current/title-21/part-870/section-870.5300 (checked 2026-11-01)
- 21 CFR 870.2300 Cardiac monitor: https://www.ecfr.gov/current/title-21/part-870/section-870.2300 (checked 2026-11-01)
- 21 CFR 868.1400 Carbon dioxide gas analyzer: https://www.ecfr.gov/current/title-21/part-868/section-868.1400 (checked 2026-11-01)
- 21 CFR 870.1130 Noninvasive blood pressure measurement system: https://www.ecfr.gov/current/title-21/part-870/section-870.1130 (checked 2026-11-01)
- 21 CFR 870.2700 Oximeter: https://www.ecfr.gov/current/title-21/part-870/section-870.2700 (checked 2026-11-01)
- Lyng JW et al. Recommended Essential Equipment for BLS and ALS Ground Ambulances 2020, joint position statement. Prehosp Emerg Care 2021;25(3):451-459, DOI: https://doi.org/10.1080/10903127.2021.1886382. Extracted list: https://media.emscimprovement.center/documents/EquipmentList_Extracted_from_2020_Position_Statement.pdf (checked 2026-11-01)
