This study is designed to compare the effects of two bolus doses of intravenous remifentanil given prior to the emergence of anesthesia:

• on the incidence of perioperative coughing
• on the time needed for the emergence of a desflurane-based anesthesia
• on the incidence of sore throat after extubation.

The investigators hypothesis is that the use of a higher remifentanil bolus dose (0.5 mcg/kg) given prior to emergence of a desflurane-based anesthesia will reduce the incidence of perioperative coughing when compared to a lower dose of remifentanil (0.25 mcg/kg).

Emergence is an important period of general anesthesia during which several problems can occur. Coughing, hypertension, tachycardia and agitation have been observed during emergence of general anesthesia.

Most patients will cough during emergence. Different techniques and drugs have been studied to reduce coughing during emergence.

There is some evidence supporting the administration of intravenous opioids prior to emergence of general anesthesia to reduce perioperative coughing, agitation and haemodynamic stimulation. However, depending on the type of opioids given, this may delay the emergence from anesthesia. The effect of a remifentanil infusion given in combination with isoflurane as the volatile agent has been shown to reduce the incidence of perioperative coughing without delaying the emergence of anesthesia. The effect of a small bolus of remifentanil given prior to emergence to prevent perioperative coughing has yet to be studied.

Desflurane is a newer volatile agent allowing early recovery from anesthesia. This agent has led to earlier discharge and more rapid resumption of normal activities after surgery. However, an incidence of coughing around 70% has been reported after a desflurane-based anesthesia.

This study will compare the effects of two bolus doses of remifentanil (0.25 mcg/kg to 0.5 mcg/kg) when given prior to emergence to prevent perioperative coughing after a desflurane-based anesthesia.

Inclusion Criteria:

• Patients aged 18-80 years
• Physical status 1-3
• Patients undergoing elective surgery under general anesthesia requiring endotracheal intubation (excluding head and neck surgery)

Exclusion Criteria:

• Current use of ACE inhibitors
• Chronic cough
• Asthma or severe pulmonary disease
• Pulmonary tract infection
• Anticipated difficult intubation
• Current use of opioids
• Current use of cough medicine
• Contraindication to remifentanil
• Pregnancy
• Symptomatic cardiac, renal or hepatic disease