Rapid sequence induction (RSI) is a well-known procedure to maintain a safe and rapid airway in patients especially at risk of aspiration. Propofol and rocuronium are generally used agents for RSI. However, the difficult airway scenarios are always valid for these patients, even without predictive signs of difficult airway. Therefore, it is important to decrease the rocuronium dose used in RSI to achieve a rapid recovery of a neuromuscular conduction with the aid of a reversal agent in case of difficult airway. The short acting opioids such as remifentanil may be helpful to reduce the dose of rocuronium in RSI.

Rapid sequence induction is a widely used anesthesia technique to achieve a safe airway control. However, the difficult airway may be expected in these patients as in the others. In the difficult airway situation, cholinesterase inhibitors and sugammadex may be used for the reversal. However, sugammadex is not always available due to its cost in every hospital. In addition to this, it is well-known that cholinesterase inhibitors do not work well in case of deep neuromuscular block. In consideration of these informations, the recovery of the neuromuscular block gain an importance in patients undergoing RSI with difficult airway. Therefore, decreasing the dosage of non-depolarizing neuromuscular agent may be helpful in case of the difficult airway situations. With the aim of decreasing the neuromuscular blocker dosage, opioid analgesics especially remifentanil is preferred combined with propofol to decrease the hemodynamic response to laryngoscopy and intubation. A recent study demonstrated that after induction of anesthesia with remifentanil and propofol, ED50 of rocuronium for acceptable intubation conditions was 0.20 mg/kg. In another study, the authors showed that the administration sequence of propofol and remifentanil for target controlled anesthesia affect the onset time of rocuronium due to change in cardiac output. The authors concluded that the prior administration of remifentanil decreased the cardiac output and delayed the onset time of rocuronium.

The investigators hypothesized that prior administration of remifentanil compared to propofol may increase the ED50 and ED95 of rocuronium for acceptable intubation conditions in RSI.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status I-II patients
• patients scheduled for elective surgery

Exclusion Criteria:

• suspected or known difficult airway
• a significant renal or hepatic dysfunction
• a known neuromuscular disease
• hypertension
• a known allergy to one of the drugs used in general anesthesia
• a body mass index lower than 18.5 kg/m2 or higher than 30 kg/m2
• intake of any medication that might interact with rocuronium
• patient refusal