Incidence and risk factors of hypoxaemia after preoxygenation at induction of anaesthesia

Abstract

Background: The incidence of hypoxaemia related to airway management is still a matter of concern. Our aim was to determine the factors that contribute to hypoxaemia during induction of anaesthesia after a standardised preoxygenation procedure. Methods: The study was a multicentre and prospective observational trial. It evaluated the incidence of hypoxaemia at induction of anaesthesia in adult patients. The primary endpoint was the incidence of hypoxaemia defined as pulse oximetry of arterial oxyhaemoglobin saturation (SpO 2) <95%. Results: Of 2398 patients, hypoxaemia was observed in 158 (6.6%). We identified five preoperative independent risk factors: chronic obstructive pulmonary disease, hypertension, anticipated difficult mask ventilation and difficult tracheal intubation, and emergency surgery. There were also three pre-induction independent risk factors: difficult preoxygenation, difficult mask ventilation, and difficult tracheal intubation. We found a high negative predictive value of preoperative risk factors for difficult mask ventilation of 0.96 (0.95e0.96), and for difficult tracheal intubation (0.95 [0.94e0.96]). A total of 723 patients (30%) experienced difficult preoxygenation (FeO 2 <90% at the end of preoxygenation). Male sex, chronic obstructive pulmonary disease, hypertension, emergency surgery, and predictable difficult mask ventilation were independent patient risk factors for difficult preoxygenation. Conclusions: Difficult mask ventilation and difficult tracheal intubation are risk factors for hypoxaemia at induction of general anaesthesia. Difficult preoxygenation was observed in 30% of patients and was also identified as a risk factor for hypoxaemia. This suggests that techniques improving preoxygenation should be implemented in daily practice.

Apnoeic oxygenation for emergency anaesthesia of pre-hospital trauma patients

“…Although apnoeic oxygenation is unlikely to make a difference to the majority of trauma patients who are straightforward to oxygenate and easy to intubate, it has the potential to reduce the frequency, incidence, and duration of hypoxia in the minority of patients who are already hypoxic or require a longer time to intubate. Difficult pre-oxygenation is a risk factor for subsequent hypoxia, and up to 30% of patients can remain hypoxic, defined as SpO 2 < 90%, after 5 min of pre-oxygenation [29], so apnoeic oxygenation is potentially very beneficial in the group of patients most vulnerable to hypoxia. A recent study comparing bag-mask ventilation to no ventilation during intubation of critically ill patients reported higher oxygen saturations and a lower incidence of severe hypoxemia in the bag-mask ventilation group [30].…”

Incidence and risk factors for maternal hypoxaemia during induction of general anaesthesia for non-elective Caesarean section: a prospective multicentre study

“…Indeed, a recent prospective observational multicentre study reported an incidence of hypoxaemia and severe hypoxaemia of 6.6% and 1.4% at the time of GA induction among adult non-obstetric patients. 12 However, in the context of rapid sequence induction, up to 13% of patients experienced hypoxaemia in the operating room and in a pre-hospital setting. 12,13 Furthermore, physiological changes associated with pregnancy induce a reduced respiratory residual capacity and an increase in overall oxygen consumption exposing the pregnant women to an increased risk of hypoxaemia.…”

Decision making affecting the diagnosis of hypoxaemia in a pug

“…Hypoxaemia is the most common cause of perianaesthetic death in people, claiming some 70 per cent of all fatalities 4. The incidence of hypoxaemia during human anaesthesia is between 6 per cent and 7 per cent,5 6 with 70 per cent of episodes occurring at induction or emergence 5. In dogs and cats, the incidence may be as low as 0.5 per cent 7.…”