How do we measure (the cost of) pain relief?

ber 1999) that demonstrate little difference in dermatomal spread in CSF of fentanyl compared with morphine after intrathecal injection. Thus, the extrapolation from pigs to humans and from models of CSF and tissue kinetics to clinical effects is far from certain. In summary, the article by Ummenhofer et al. is a seminal work in intrathecal pharmacokinetics. It directly incorporates location into the pharmacokinetic model, based on observations taken at multiple points in the intrathecal space. Based on their results, we can no longer ignore the relationship between sampling site and the site of the target tissue when characterizing spinal pharmacokinetics. We also need to rethink spinal drug administration to localize drug delivery to the spinal target. The future of intrathecal pharmacokinetics is now location, location, location.