A Comparison of Inhalation vs. Intravenous Induction (INHvsIV)

A Comparison of the Effect on Temperature Between Patients Induced With Intravenous Propofol vs Inhalation Induction With Sevoflurane

To compart differences on the effect on core temperature between anesthetic induction with intravenous propofol versus inhalation induction with sevoflurane

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.

The intervention will be the randomized selection of anesthetic induction technique to sevoflurane in 100% oxygen and temperatures will be recorded per protocol. Age 18-55.

The intervention will be the randomized selection of anesthetic induction technique to sevoflurane in 50% oxygen and 50% nitrous oxide. Age 18-55.

The intervention will be the randomized selection of anesthetic induction technique to intravenous induction with 2.2 mg/kg propofol. Age 18-55.

The intervention will be the randomized selection of anesthetic induction technique to intravenous induction 2.2 mg/kg propofol immediately preceded by 160 mcg intravenous phenylephrine. Age 18-55.

The intervention will be the randomized selection of anesthetic induction technique to sevoflurane in 100% oxygen and temperatures will be recorded per protocol. Age >55.

The intervention will be the randomized selection of anesthetic induction technique to sevoflurane in 50% oxygen and 50% nitrous oxide. Age >55.

Standard anesthesia care will be provided after induction based on randomization. Temperatures will be monitored every 15 minutes

Percentage of patients who had at least one temperature below 36.0 degrees C in the first hour of anesthesia

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

Roth JV, Braitman LE, Hunt LH. Induction techniques that reduce redistribution hypothermia: a prospective, randomized, controlled, single blind effectiveness study. BMC Anesthesiol. 2019 Nov 6;19(1):203. doi: 10.1186/s12871-019-0866-8. Erratum In: BMC Anesthesiol. 2021 Apr 12;21(1):112.