# Profile of a Multivariate Observation under Destructive Sampling—A Monte Carlo Approach to a Case of Spina Bifida

## TL;DR

Researchers used Monte Carlo simulations to estimate how a biodegradable patch for spina bifida changes in roughness over time when exposed to different fluids.

## Contribution

A novel Monte Carlo approach to estimate the roughness profile of a patch under destructive sampling conditions.

## Key findings

- Roughness profiles of the patch were estimated for 0 to 16 weeks with a 95% confidence band.
- The patch showed similar roughness profiles when exposed to amniotic fluid or phosphate-buffered saline.
- The method provides a template for future patch composition experiments.

## Abstract

A biodegradable hybrid polymer patch was invented at the University of Cincinnati to cover gaps on the skin over the spinal column of a growing fetus, characterized by the medical condition spina bifida. The inserted patch faces amniotic fluid (AF) on one side and cerebrospinal fluid on the other side. The goal is to provide a profile of the roughness of a patch over time at 0, 4, 8, 12, and 16 weeks with a 95% confidence band. The patch is soaked in a test tube filled with either amniotic fluid (AF) or phosphate-buffered saline (PBS) in the lab. If roughness is measured at any time point for a patch, the patch is destroyed. Thus, it is impossible to measure roughness at all weeks of interest for any patch. It is important to assess the roughness of a patch because the rougher the patch is, the faster the skin grows under the patch. We use a model-based approach with Monte Carlo simulations to estimate the profile over time with a 95% confidence band. The roughness profiles are similar with both liquids. The profile can be used as a template for future experiments on the composition of patches.