Annotated explainer

Understanding the bedside monitor

The screen above the bed never stops moving, and nobody hands visitors a manual. Tap each number on the illustration to learn what it shows, and, more importantly, what it does and does not mean for you as a visitor.

1. Heart rhythm (ECG)

The moving green line is the electrical rhythm of the heart, drawn continuously from sticky pads on the chest. The large number beside it is the heart rate in beats per minute.

What this means for you: The shape wiggles and varies: that is normal. A flat moment usually means a lead came loose, not a stopped heart; the team is alerted either way and reacts instantly to anything real.

1. Heart rhythm (ECG)

The moving green line is the electrical rhythm of the heart, drawn continuously from sticky pads on the chest. The large number beside it is the heart rate in beats per minute.

For visitors: The shape wiggles and varies: that is normal. A flat moment usually means a lead came loose, not a stopped heart; the team is alerted either way and reacts instantly to anything real.

2. Oxygen saturation (SpO2)

The blue number is how full the blood's oxygen seats are, as a percentage, measured by the glowing clip on a finger or ear. The wavy line under it is the pulse detected at the clip.

For visitors: The clip is sensitive to movement and cold hands, so brief dips and dropouts are common and usually meaningless. The team sets an acceptable range for this patient and the monitor calls out if it truly drifts.

3. Blood pressure

Two numbers, for example 118/74, from a cuff that inflates now and then, or continuously from a thin line in the wrist (an arterial line). The bracketed number is the average pressure the team steers by.

For visitors: Blood pressure moves with sleep, pain, medicines and simple repositioning. In intensive care it is often actively supported, so a "good" number may reflect the support working: that is the point of the support.

4. Breathing rate

Breaths per minute, counted from the chest pads or from the ventilator. The slow yellow wave is the rise and fall of breathing.

For visitors: If a ventilator is helping, some or all breaths are the machine's work, so this number reflects the settings as much as the patient. Watching the patient look comfortable tells you more than the count.

5. Temperature

Body temperature in degrees Celsius, from a skin, ear or internal probe.

For visitors: Fevers are common in critical illness and are treated actively; a changing temperature is information for the team, not by itself good or bad news.

6. Alarm lights and sounds

Monitors beep whenever any value crosses a limit the team set for THIS patient. Different pitches mean different priorities, and every bed's alarms also sound at the central nursing station.

For visitors: Most alarms are minor: a moved sensor, a bent cable, a value wandering briefly. Staff triage the sound constantly. If the staff are calm, the alarm is not worrying them; if something matters, you will see the response immediately.

Reviewed against NHS intensive care information and ICUsteps visiting guidance.

Sources

Intensive care: what to expect NHS, 2023
Visiting someone in intensive care ICUsteps, 2020

Last reviewed: 2026-07-16

Heard a word you did not recognise? Decode it in the ICU jargon decoder, or work through the family support checklist.

1. Heart rhythm (ECG)

1. Heart rhythm (ECG)

2. Oxygen saturation (SpO2)

3. Blood pressure

4. Breathing rate

5. Temperature

6. Alarm lights and sounds

Sources

About those alarms