Propofol for Pediatric Tracheal Intubation With Deep Anesthesia During Sevoflurane Induction

The purpose of this study is to determine the amount of propofol required to achieve 50% of patients obtaining a perfect ("excellent") intubation score of 5 on the Steyn modification of the Helbo-Hansen Intubation Score, when placing a tracheal tube in children 1-6 years and 6-12 years (division of age groups at 6th birthday) of age, under a specific induction and ventilation sequence as specified in this study design.

The practice of tracheal intubation of children without neuromuscular blockade (TIWNB) is widespread in pediatric anesthesia practices. There are several different methods reported for TIWNB, most of which involve administration of an inhaled anesthetic in combination with an intravenous adjunctive medication. The technique of administering propofol IV, immediately after IV placement, after a sevoflurane induction is perhaps the most popular method for pediatric TIWNB in the United States and worldwide (personal communication, and personal practice of this technique). At the time this study was proposed, nobody had studied this technique, and therefore nobody had quantified the amount of propofol needed in this context, or considered that the amount may differ according to the time sevoflurane has been administered at the moment propofol is given. This study divides patients into two age categories, with the first age group starting at the 1 year birthday and going up to the 6th year birthday, and the second age group going from the 6th year birthday up to the 12th birthday. The study also divides participants according to time that they have received sevoflurane from the start of anesthetic induction until intravenous access is achieved and propofol immediately administered. That amount of time varies in clinical practice due to variable difficulty obtaining pediatric intravenous access, and the amount of propofol may vary according to the amount of sevoflurane administered (time administered) because depth of anesthesia will increase with increasing duration of sevoflurane administration. The purpose of this study is to determine for both age groups the amount of propofol required to achieve 50% of patients obtaining a perfect intubation score of 5 on the Steyn modification of the Helbo-Hansen Intubation Score (HH Score), when placing a tracheal tube after various time periods of administration of sevoflurane. The 3 different time windows for sevoflurane administration prior to the propofol bolus will be 2-4 minutes, 4-6 minutes, and 6-8 minutes, starting the time clock at the start of anesthetic induction and ending at the moment the propofol is given. The study therefore has 6 separate groups (2 age groups x 3 time period groups) each of which utilizes a Dixon's Up and Down Method, moving up or down on the amount of propofol administered according to the result of the previous patient in each group (HH Score of 5 labeled "excellent intubation" indicates allocation of predetermined (0.3 mg/kg) incrementally smaller amount of propofol and \>5 labeled as "not-excellent intubation" an increase of 0.3 mg/kg of propofol. Linear regression will be used for each of the 6 groups to determine the amount of propofol required to achieve 50% perfect intubation, with 95% confidence intervals also calculated.

Eligibility Criteria:
Inclusion Criteria:

* Informed consent / assent
* Ages 1-11 years (12 - 132 months)
* American Society of Anesthesiology (ASA) physical status 1 or 2, which implies that the patient has no comorbidity that limits daily function.
* Scheduled for non-emergent surgery/ procedure under general anesthesia in which the anesthesia team intends to place an endotracheal tube
* Expected routine intubation according to physical exam and history
* Weight under 50 kg

Exclusion Criteria:

* Requires neuromuscular blocking agents
* Emergent surgery / procedure
* Expected difficult intubation
* ASA physical status 3 or 4
* Weight over 50 kg
* Age under 12 months or over 132 months
* Allergy to study drugs to be used