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

newcommand{category}{%
  ifstartedaddlinespacefi
  globalstartedtrue
  globalcategorytrue
  itshape}
newcommand{main}{ifcategoryglobalcategoryfalseelseaddlinespacefi}
newcommand{sub}{quad}
newififstarted
newififcategory
newenvironment{itemtabular}
 {globalstartedfalseglobalcategoryfalsetabular}
 {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}