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.

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