Effect of nasal cannula oxygen administration on oxygen concentration at facial and adjacent landmarks

An oxygen‐enriched atmosphere enhances the potential for operating‐room fires. We thus determined oxygen concentrations at various facial landmarks during oxygen administration via nasal cannulae. Thirteen supine volunteers were draped similarly to patients undergoing a cervical‐node biopsy. Oxygen was delivered in random order through nasal cannulae at rates of 2, 4, and 6 l.min−1. Oxygen concentration was measured at pre‐determined facial landmarks and also distal to the drape at non‐facial sites. At a flow of 2 l.min−1, oxygen concentrations exceeded 23% only within a few centimetres of the nasal cannula. Concentration increased as a function of flow, but rarely exceeded 26%. At all flow rates, concentrations distal to the drape were < 24%. To reduce combustion risk, ignition sources should be kept at least 10 cm from the oxygen outlet when using nasal cannula at a flow rate ≥ 4 l.min−1.