Fig. 1. Decision tree for muscle relaxant choice and airway management. The difficult ventilation grading scale is the following: Grade I, ventilation without the need for an oral airway; grade II, ventilation requiring an oral airway; grade III, difficult and unstable ventilation requiring an oral airway and two providers, or an oral airway and one provider, using mechanical ventilation (pressure-controlled mode); and grade IV, impossible ventilation. GEB = gum elastic bougie.