Customised format floating itemized list

Question

I'd like to add floating itemized lists in a format illustrated below:

More specifically, I would like

1. The title above rather than below the float, with bold font for title and horizontal line beneath
2. No bullets
3. First level items italicised, no indent; Second level items Roman, no indent; Third level items Roman; indented one tab stop; with a blank line of space between groups of first level items
4. Also, if in a two column formatted document, the list is to only occupy one column of the document

Ideally, I'd like to set up all the formatting in the preamble, then whenever I have a floating list of this type to insert, I could just create it by listing the \items in a similar way to making a regular itemized list.

I suspect it is possible to do this using \table, but will be rather long-winded.

Is it possible to customise the \itemize command to easily produce floating lists of this type?

Is there an add-in package which is like \itemize but has greater options for customisation, that might be able to produce a list of this type?

Answer 1

I don't think you need itemized lists, but a (modified) tabular environment.

\documentclass{article}
\usepackage{booktabs,caption}
\captionsetup[table]{position=top}

\newcommand{\category}{%
  \ifstarted\addlinespace\fi
  \global\startedtrue
  \global\categorytrue
  \itshape}
\newcommand{\main}{\ifcategory\global\categoryfalse\else\addlinespace\fi}
\newcommand{\sub}{\quad}
\newif\ifstarted
\newif\ifcategory
\newenvironment{itemtabular}
 {\global\startedfalse\global\categoryfalse\tabular}
 {\endtabular}

\begin{document}
\begin{table}
\centering
\caption{Low tidal volumes in pressure preset modes}
\begin{itemtabular}{@{}l@{}}
\toprule
\category Patient factors \\
\main Asynchronous breathing \\
\main Decreased compliance \\
\sub Development of pneumothorax \\
\sub Pulmonary pathology \\
\category Equipment causes \\
\main Ventilator settings\\
\sub Inadequate preset pressure \\
\bottomrule
\end{itemtabular}
\end{table}
\end{document}