Causes of Suboptimal Preoxygenation Before Tracheal Intubation in Elective and Emergency Abdominal Surgery

Optimal preoxygenation (PO) prior to tracheal intubation reduces the risk of arterial desaturation and prolongs the period of safe apnoea. The common methods of PO are mask ventilation with 100% O 2 for 3–5 minutes or, alternatively, asking the patient to take eight deep breaths in a minute. Our study group conducted a prospective study to assess the impact of the most common risk factors on PO and to compare the efficiency of PO in patients undergoing elective and emergency abdominal surgery without premedication. PO was performed using mask ventilation with 6 l/min of 100% oxygen for 5 minutes. End-tidal oxygen (EtO 2 ) was documented in 30-second increments. We found that optimal PO (EtO 2 > 90%) was not achieved by almost half of the patients (46%) and that this was more common in the elective surgery group. Effective PO was not impacted by any of the evaluated risk factors for suboptimal oxygenation. Despite these findings, we believe that the identification of potential risk factors is crucial in the pre-anaesthesia stage, given the benefits of optimal PO.