Effect of Age on Propofol-BIS Response

Objective: Recently, reports appeared of an 88-yr-old octogenarian exhibiting bispectral index (BIS) value of 46 before anesthesia induction, and a 91-yr-old nonagenarian fully conscious at BIS value of 52 after propofol anesthesia recovery. BIS algorithm was heuristically derived from a database of mostly "relatively fit, young healthy" volunteers. To date there are no studies precisely quantifying BIS response to propofol concentrations among different age groups.

Methods: Investigators set Propofol estimated plasma concentrations (Cp) to gradually reach 3.5 microg·mL-1 over 3.5 min in 80 patients, five male and five female, divided by age decades from vicenarian (20-29 yr) to nonagenarians (90-99 yr). BIS values were fitted against Cp in our newly devised logistic model and traditional sigmoid Emax model. Raw BIS electroencephalography and measured propofol arterial samples determined whether changes are pharmacodynamic or pharmacokinetic asserted.

Propofol link to FDA site at FDA's Drugs@FDA web site. https://www.accessdata.fda.gov/scripts/cder/drugsatfda: http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm

Inclusion criteria

80 patients, five male and five female, divided by age decades from vicenarian (20-29 yr) to nonagenarians (90-99 yr)

Exclusion criteria

Patients with liver disease