Genetic Differences in Propofol Pharmacodynamics in Children

Study Overview
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Brief Summary
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Propofol is an extensively utilized intravenous sedative and general anesthetic. However, propofol has a narrow therapeutic index, and this means that there is only a small difference in the dose required to produce loss of consciousness and the dose required to produce potentially life-threatening effects such as loss of protective airway reflexes and cessation of spontaneous breathing. Moreover, there is substantial variation between individuals in the doses required to achieve these pharmacodynamic endpoints. Given the inexorable rise in demand for pediatric sedation and the increasing use of propofol in sedation protocols by non-anaesthesiologists, the purpose of this study is to refine the propofol dosing recommendations to account for pharmacogenomic variability to make procedural sedation safer for children. Experienced users already adjust for age and body weight. This study may enable further refinements according to sex and - novelly - ancestry.

Detailed Description
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Hypothesis: The investigators hypothesize that examination of genome-wide association study (GWAS) findings will enable the investigators to provide pharmacogenomic insights into clinically observed - and, with this study, quantified - differences in propofol requirements for loss of consciousness (LOC) and apnea in children. It is further hypothesized that the distribution of allelic variants in these pharmacogenes may differ between children of different genomic ancestry. Objectives: Primary: (i) To describe and quantify doses of propofol required to produce loss of consciousness and apnea in children of differing ages, sex and self-identified countries of origin. (ii) To identify genomic associations that may explain variability, and generate hypotheses for further study. (iii) To identify genomic ancestry and examine how pharmacogene allele variants that may explain the findings of (i) above are distributed across genomic ancestries. Secondary: To examine the correlation between self-identified countries of family origin and genomic ancestry. Methods: Prospective, non-randomized, single cohort study of two pharmacodynamic endpoints (loss of consciousness and apnea), in children requiring propofol anesthesia, with subsequent genome-wide association study (GWAS) and principal component analysis (PCA) to examine, respectively, pharmacogenomic explanations for pharmacodynamic variability and genomic ancestry.

Official Title
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Genetic Differences in Pharmacodynamic Safety Endpoints With Propofol Anaesthesia in Children

Conditions
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Anesthesia

Intervention / Treatment
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* Drug: Propofol


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥ 3 to ≤ 18 ASA physical status classification I-III Intravenous induction resulting in apnea clinically appropriate and indicated Exclusion Criteria: Age < 3 or >18 ASA physical status IV-V Propofol induction to apnea not indicated or feasible Sedative premedication Severe neurological impairment, expected to reduce propofol requirement as judged by the clinical experience of the anaesthetist Weight <3%ile or >97%ile for age

Ages Eligible for Study
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Minimum Age: 3 Years
Maximum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intravenous Propofol Infusion<br>Quantification of the dose of propofol required to produce loss of consciousness and apnea. | Drug: Propofol<br>* At T0, a propofol infusion at a rate of 1.5 mg/kg/min will be started until apnea is achieved. Loss of consciousness will be defined clinically using loss of eyelash reflex (TLOER) and tolerance of nasal cannulae (TNC), tested every 10 sec., and by a BIS <60 for 30 sec. (TBIS). Apnea will be defined as absence of end-tidal CO2 for at least 20 seconds (TAPNEA). A saliva sample with be taken under anesthesia for genome-wide association study and principal component analysis.<br>* Other names: Propofol Injection 1%;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Dose of propofol required to produce loss of consciousness | Loss of consciousness will be defined clinically when there is a loss of eyelash reflex, a tolerance of nasal cannulae, and when the Bispectral Index <60 for 30 sec. | Loss of consciousness will be expected to occur somewhere between 120-180 seconds after commencing the induction infusion. | 
| Dose of propofol required to produce apnea | Apnea will be defined as absence of end-tidal CO2 for at least 20 seconds. | Apnea will be expected to occur within 10 min after commencing the induction infusion. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Self-identified countries of family origin up to grandparents | The participant will report the countries which make up the participant's ancestral background, up to the country of origin of the grandparents. | Within 10 minutes after consent to participate. | 
| A genotyped/imputed dataset of 8 million genetic variants aggregated using SHAPEIT (v2), IMPUTE2 (v2.3.2), Phase 3 1000 Genomes Project reference panel, SNP2HLA (v1.0.2), and the Type 1 Diabetes Genetics Consortium reference panel. | Extensive genome-wide genotyping to determine genetic variants of the pathways involved in propofol biotransformation. The array captures both common and rare variation collected from large-scale sequencing projects. | Saliva sample collected immediately after apnea, within 10min of propofol infusion start. Genomic analysis will be performed post-hoc. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Propofol