A 68-year-old male with COPD is admitted to ICU with acute hypercapnic respiratory failure (pH 7.25, PaCO₂ 65 mmHg, PaO₂ 55 mmHg on O₂). He is initiated on non-invasive ventilation but deteriorates over 6 hours. Intubation is planned. Which investigation is most appropriate to confirm correct endotracheal tube placement and assess ventilation adequacy immediately after intubation?

## Confirmation of Endotracheal Tube Placement — Gold Standard **Key Point:** End-tidal CO₂ capnography (ETCO₂) is the gold standard for immediate confirmation of endotracheal tube placement in the trachea and assessment of ventilation adequacy. ### Why ETCO₂ Capnography is Best 1. **Immediate feedback** — Real-time waveform within 15 seconds of intubation 2. **High sensitivity and specificity** — Detects esophageal intubation (absent or very low ETCO₂ <15 mmHg) 3. **Dual information** — Confirms tube position AND assesses ventilation (ETCO₂ reflects alveolar ventilation) 4. **Non-invasive and rapid** — No delay unlike CXR or ABG ### Clinical Pearl **High-Yield:** In this hypercapnic patient, ETCO₂ monitoring will show: - **Presence of waveform** = tracheal placement (rules out esophageal intubation) - **ETCO₂ value** = baseline for subsequent ventilator adjustments (target PaCO₂ correction) ### Comparison with Other Investigations | Investigation | Timing | Purpose | Limitation | |---|---|---|---| | **ETCO₂ capnography** | Immediate (15 sec) | Confirm placement + assess ventilation | Requires capnograph device | | Chest X-ray | 5–10 min | Confirm depth, rule out mainstem intubation | Delayed; does not confirm tracheal vs esophageal | | ABG analysis | 5–10 min | Assess gas exchange adequacy | Delayed; does not confirm placement | | Fiberoptic bronchoscopy | 10–20 min | Direct visualization | Invasive, time-consuming, not first-line | ### ACLS/ICU Standard **Warning:** Absence of ETCO₂ waveform in a non-arrest patient strongly suggests esophageal intubation — tube must be withdrawn and repositioned. In cardiac arrest, transient absence may occur due to low pulmonary blood flow, but persistent absence warrants reintubation. [cite:Harrison 21e Ch 295]