A Comparison of Inhalation vs. Intravenous Induction

Hypothermia occurs with anesthetic induction due to redistribution hypothermia. Hypothermia has adverse effects and should be avoided or minimized. Intravenous propofol induction is the most common technique used for anesthetic induction. There is preliminary evidence that there is less redistribution hypothermia when anesthetic induction is achieved by inhalation induction compared to intravenous induction. There is not enough data to compel a change in practice patterns. This study will enroll a larger number of patients in order to provide stronger evidence that there is a significant difference between induction techniques on body temperature. Patients will be randomly assigned to two variation of inhalation induction techniques and two variations of intravenous induction. The effect on temperature between the four groups will be compared. Reducing the degree of hypothermia has the potential to decrease surgical infection rate as well as providing other benefits to patients.

Inclusion criteria

Elective surgery Adult, age >= 18 years old Scheduled for general anesthesia Medically fit and able to safely go any of the four anesthetic inductions in the study

Exclusion criteria

Emergency surgery, or any other aspiration risk Minor, age <18 Pregnant Febrile illness Contraindication to nasal instrumentation Allergy to propofol Malignant hyperthermia Requiring Total Invravenous Anesthesia (TIVA) Inability to oxygenate on less than 50% FiO2 Intra-cranial surgery Receiving vasoactive medications Significant valvular heart disease Unstable cardiac disease Surgery requiring prone or lateral positioning Contraindication to nitrous oxide Prisoners