Patients with severe chronic lung disease, acute hypoxemic respiratory failure, or an SpO
2 < 100% after pre-oxygenation are at increased risk for hypoxemia during intubation [
9]. Providing positive pressure ventilation for these high-risk patients during pre-oxygenation and between induction and laryngoscopy can help prevent hypoxemia [
10,
11]. The primary concern regarding positive pressure ventilation in this setting is aspiration. For patients at high risk for hypoxemia and low risk for aspiration (e.g., those without vomiting, hematemesis, or hemoptysis), we pre-oxygenate with non-invasive bilevel positive airway pressure (BiPAP) ventilation with 100% FiO
2 for 5 min whenever feasible [
10]. For patients at high risk for hypoxemia and high risk for aspiration, we pre-oxygenate with 60 l per minute of 100% FiO
2 via high-flow nasal cannula or with supplemental oxygen via standard face mask and nasal cannula [
12,
13]. The recent PreVent trial found that positive pressure bag-mask ventilation between induction and laryngoscopy reduced severe hypoxemia during tracheal intubation in the ICU [
11]. The PreVent trial excluded patients with very high risk for aspiration (e.g., vomiting, hematemesis, hemoptysis). Therefore, for patients with very high risk of aspiration, we provide supplemental oxygen alone without positive pressure after induction, whereas for patients at high risk for hypoxemia and without high-risk features for aspiration, we provide positive pressure ventilation with either BiPAP or bag-mask ventilation between induction and laryngoscopy.
Severe hypotension during intubation can lead to cardiac arrest and death. Mechanisms that contribute to peri-intubation hypotension include vasodilation from induction medications, decreased sympathetic tone from sedation, and decreased venous return from increased intrathoracic pressure with positive pressure ventilation. We attempt to reverse pre-existing hypotension prior to intubation by administering blood products for hemorrhagic shock and intravenous fluids and vasopressors for distributive shock. Additionally, we commonly administer phenylephrine 100 mcg by IV push to treat peri-intubation hypotension. For patients at risk for hypotension during intubation [
14], we use ketamine for induction and avoid other agents more likely to contribute to hypotension, understanding that data supporting this practice are incomplete [
15]. For patients without pre-procedure hypotension, whether prophylactically administering an intravenous fluid bolus or a vasopressor prior to induction prevents cardiovascular collapse remains the subject of ongoing research (NCT03026777). Currently, we do not routinely administer prophylactic fluids or vasopressors prior to induction in patients who are not hypotensive. Immediately after intubation, we set the mechanical ventilator to preserve ventilatory compensation for metabolic acidosis and avoid tidal volumes > 6 ml/kg of ideal body weight.