Loss of EtCO2 trace

Immediate Management (First Response - ABCDE Approach)

1. Check the Patient (Airway, Breathing, Circulation)

   • Confirm ventilation – Look for chest rise, auscultate breath sounds.

   • Check for obstruction – Ensure ETT is patent and correctly positioned.

   • Manually ventilate – Rule out ventilator failure.

   • Assess haemodynamics – Check pulse, BP, SpO₂.

2. Check Equipment & Circuit

   • Ensure the capnograph is functioning – Verify sensor and sampling line.

   • Inspect the breathing circuit – Look for kinks, leaks, disconnections.

   • Confirm presence of CO₂ in insufflation cases (e.g., laparoscopy).

---

Differential Diagnosis & Management

1. Airway & Ventilation Issues

• Causes:

  • Circuit disconnection (most common)

  • ETT/tracheostomy displacement (accidental extubation, oesophageal intubation)

  • Tube obstruction (mucous plug, kinked tube)

  • Severe bronchospasm

• Management:

  • Check and reconnect circuit if disconnected.

  • Manually ventilate using bag-valve-mask (BVM) to assess for airway resistance.

  • Confirm ETT position with auscultation, capnography, or direct laryngoscopy.

  • Suction ETT if obstruction suspected; replace if necessary.

  • Administer bronchodilators if bronchospasm is the suspected cause.

---

2. Respiratory Causes

• Causes:

  • Severe hypoventilation (opioid overdose, profound respiratory depression)

  • Pneumothorax

  • Pulmonary embolism (PE)

• Management:

  • If hypoventilation: Increase ventilatory support, consider naloxone for opioid toxicity.

  • If pneumothorax suspected: Auscultate for absent breath sounds, perform needle decompression if tension pneumothorax.

  • If PE suspected:

    • Sudden drop in EtCO₂ with hypotension is highly suggestive.

    • Increase FiO₂, provide cardiovascular support.

    • Consider thrombolysis if peri-arrest.

---

3. Cardiovascular Causes (Low Perfusion States)

• Causes:

  • Massive PE

  • Cardiac arrest (Pulseless Electrical Activity - PEA, VF, Asystole)

  • Severe hypotension or shock (anaphylaxis, massive haemorrhage)

• Management:

  • If cardiac arrest:

    • Start CPR immediately (EtCO₂ monitoring guides CPR efficacy).

    • Identify and treat reversible causes (4 Hs and 4 Ts).

  • If severe hypotension/shock:

    • Identify cause (e.g., fluid resuscitation for haemorrhage, adrenaline for anaphylaxis).

    • Administer vasopressors/inotropes if needed.

---

4. Equipment Malfunction

• Causes:

  • Capnograph disconnection or sensor failure

  • Sampling line occlusion

  • Ventilator failure

• Management:

  • Replace or reconnect the capnograph sampling line and verify function.

  • Manually ventilate to confirm issue is equipment-related.

  • Switch to an alternate ventilator or breathing system if needed.

---

Key Takeaways

• Immediate priorities: Check patient first, then circuit and equipment.

• Most common cause: Circuit disconnection or blockage —always check first.

• Critical diagnoses: Cardiac arrest, massive PE, pneumothorax—act rapidly.

• EtCO₂ is a valuable resuscitation marker: Sudden loss suggests a critical event.