AnesthesiaHub
TutorialsPlaybookOralsDrugsCalcsEmergencySubsQ-BankResourcesAIBookmarks
OR Playbook
Step 4 · Monitoring

Monitors — What to Attach & In What Order

Pulse ox first. The sequence the ASA standard monitors go on before you induce.

6 min read

The TL;DR

  • Standard ASA monitors before EVERY anesthetic: pulse ox, NIBP, ECG, capnography, temperature.
  • Pulse oximeter goes on FIRST — it's your earliest, continuous warning and gives an audible tone.
  • Cycle a baseline blood pressure before you give any drug.
  • Capnography becomes meaningful once the airway is in — it's your #1 confirmation of tube placement.
  • Don't induce until you have a pulse ox tracing, a baseline BP, and an ECG rhythm on the screen.

01Why order matters

You attach monitors in an order that gets you a safety signal as fast as possible, with the least disruption to the patient. The pulse oximeter is first because it's continuous, audible, and the earliest warning of trouble. Everything else builds from there.

Don't push induction drugs until you can see a pulse-ox waveform, a baseline blood pressure, and an ECG rhythm.
arm board1Pulse oximeterfirst — earliest warning, audible tone2NIBP cuffother arm · cycle a baseline3ECG leads5-lead · RA/LA/RL/LL/V4Capnography+ temp, BIS, TOFadded once airway is inPre-induction monitors, in order →
swipe diagram horizontally →
The pre-induction sequence: pulse ox → NIBP → ECG, with capnography added once the airway is placed.

02The sequence

  1. Pulse oximeter (finger). First on. Gives you SpO₂ and a beat-to-beat tone — you'll hear a desaturation or loss of pulse before you look up.
  2. NIBP cuff (the other arm from the pulse ox so the cuff cycling doesn't drop the SpO₂ signal). Cycle a baseline immediately.
  3. ECG — 3 or 5 leads. White-on-right, smoke (black) over fire (red); 5-lead adds brown (V) on the chest. Confirm a rhythm.
  4. Capnography — connected to the circuit; becomes your money signal the instant the airway goes in (sustained EtCO₂ = you're in the trachea).
  5. Temperature — probe placed after induction (esophageal/nasal) for anything beyond a short case.
  6. Add-ons as indicated: BIS/processed EEG (TIVA, high awareness risk), nerve stimulator (TOF) for paralytics, arterial line for beat-to-beat BP.
Pearls
  • Put the BP cuff and pulse ox on OPPOSITE arms — same-arm cuff cycling makes the SpO₂ drop out every few minutes.
  • An audible pulse-ox tone is a hands-free monitor — keep the volume up; pitch falls as saturation falls.
Common mistakes
  • Inducing before a baseline BP is on the screen — you've lost your reference for the rest of the case.
  • Forgetting that capnography only confirms the tube AFTER intubation, not before.
In this guide
Previous
Drawing Up & Labeling Drugs
Next
Transferring the Patient (Bed → OR Table)