monitor_heartNICU Guide · 7 min read

Understanding NICU Monitors

The numbers on your baby's bedside monitor can feel like a foreign language at first. This guide explains what each one means,and what to do when an alarm sounds.

Important:Normal ranges vary by gestational age, medical condition, and hospital protocol. Always confirm your baby's specific target ranges with your NICU team. This guide is educational, not medical advice.

Oxygen saturation (SpO₂)

SpO₂ measures the percentage of hemoglobin in your baby's blood that is carrying oxygen. It is measured by a pulse oximeter,a small sensor taped to your baby's hand or foot that shines light through the skin.

Typical range
90–95% for most preemies
Target ranges vary significantly by gestational age and clinical status. Your NICU will set individualized alarm limits for your baby. Ask your nurse what your baby's specific targets are.

Why not higher? In very premature infants, oxygen saturation targets are kept below full saturation intentionally,high oxygen levels in preemies are associated with retinopathy of prematurity (ROP) and lung injury. Your team is managing a careful balance.

What causes brief drops (desaturations)? Movement, position changes, feeding, crying, suctioning, or apnea episodes. Many desaturations in stable preemies resolve on their own within seconds. Your nurse will respond if they do not.

Heart rate

Heart rate is measured continuously via electrodes on your baby's chest (the small adhesive patches with wires). It is displayed in beats per minute (bpm).

Typical range
120–180 bpm for preemies
Premature babies have naturally faster heart rates than full-term newborns. Rates outside this range briefly during activity are common.

Bradycardia ("bradys")

Bradycardia is a drop in heart rate below the alarm threshold,typically below 80–100 bpm for preemies, though your team sets specific limits. It is one of the most common events in premature infants and is often associated with apnea.

Most bradys in stable preemies self-resolve within 10–20 seconds, sometimes with gentle stimulation (rubbing the back or feet). Your nursing team is trained to respond. They are not emergencies in isolation,they are expected events that the team monitors closely.

As your baby matures, brady episodes typically decrease and eventually stop,often one of the last milestones before discharge.

Respiratory rate

Respiratory rate measures how many breaths your baby takes per minute, also tracked by the chest electrodes.

Typical range
40–60 breaths per minute
Premature babies breathe faster than older children or adults. Rates above 60 sustained may indicate respiratory distress and will be assessed by your team.

Apnea of prematurity

Apnea is a pause in breathing lasting more than 15–20 seconds, or a shorter pause accompanied by bradycardia or desaturation. It occurs because the brainstem's breathing control center is immature in premature infants.

Apnea of prematurity is treated with caffeine (yes, the same stimulant,in a precise medical dose), CPAP, or high-flow nasal cannula to keep the airway open. It typically resolves as the baby approaches 36–44 weeks corrected gestational age.

Temperature

Temperature is checked regularly, either by axillary (armpit) measurement or via a temperature probe taped to the skin for continuous monitoring.

Typical range
36.5–37.5°C (97.7–99.5°F)
Premature babies cannot regulate their own body temperature and are placed in incubators or under radiant warmers to maintain this range.

Temperature regulation is a key discharge milestone. Before going home, your baby must be able to maintain their own temperature in an open crib at room temperature for a defined period,typically 24–48 hours. This demonstrates sufficient fat stores and neurological maturity.

Blood pressure

Blood pressure is not always continuously displayed for stable preemies, but is monitored regularly via small blood pressure cuffs or,in critically ill infants,through an arterial line (a thin catheter placed in an artery).

Normal blood pressure in preemies is lower than in older children and varies significantly by gestational age and weight. Your team tracks trends rather than a single number. Low blood pressure (hypotension) in preemies is treated with IV fluids or medications called vasopressors if needed.

Understanding alarms

One of the most stressful parts of the NICU is the constant sound of alarms. Here is what to know:

  • Most alarms are not emergencies. The majority of alarms in stable NICU babies are caused by sensor displacement (baby moved, probe slipped), brief self-resolving events, or nuisance alerts from normal activity like crying or feeding.
  • Yellow alarms vs. red alarms. Most NICUs use a tiered alarm system. Yellow (advisory) alarms indicate a value outside the normal range. Red (critical) alarms indicate a value requiring immediate attention. Learn what each color means in your unit.
  • Your nursing team is always watching. Bedside nurses monitor their patients continuously. You do not need to act on alarms yourself,your job is to stay calm and let the team assess.
  • It is okay to ask about any alarm. If an alarm goes off and no one explains it, ask. "What was that alarm for?" is always a reasonable question.

Logging your baby's vitals

Keeping a log of your baby's daily vitals helps you track trends over time, ask more specific questions during rounds, and have an accurate record for outpatient providers after discharge.

Key things to log each day:

  • Typical SpO₂ range (not just peak,the range throughout the day)
  • Number of apnea or bradycardia events
  • Heart rate range
  • Daily weight
  • Temperature (if your unit takes it at set times)
  • Respiratory support level (room air, low-flow O₂, CPAP, ventilator)

Lumen NICU includes a built-in vitals tracker with all of these fields, so you can log at the bedside and review trends over days and weeks.

Track vitals alongside feedings, weight, and milestones

Lumen NICU was designed specifically for the NICU. Log SpO₂, heart rate, respiratory rate, temperature, and more,all in one private, calm app.