SpO2 drops to 88% — suction, check tube; recovers. Monitoring: pulse oximetry (SpO2 — 95–100% — <90% — hypoxia: limitations — poor perfusion, nail polish; respond — FiO2, airway), capnography (EtCO2 — 35–45 — confirms intubation — flatline — esophageal; rising — hypoventilation), hemodynamic (ECG — arrhythmia; NIBP — 3–5min; arterial — beat-to-beat; CVP; temperature; urine — 0.5mL/kg/h). Respond — hypotension — fluids/vasopressor; bradycardia — atropine. Monitors watch — you act.