$re = '/([^\s:\n][^:\n]*)\s+\:\s+\[\s*([^][]*)\s+]/m';
$str = 'Date : [ 2010-01-01 XX:XX:XX ] Age : [ 22 ] Sex : [ M ] : [ XXX ]
Height(cm) : [ 145 ] Weight(kg) : [ 56.4 ] Race : [ Hispanic ]
Spirometry : [ restrictive pattern ]
Treatment response : [ Negative ]
Tissue volume : [ Normal ]
Tissue volume
[ Normal RV ]
Diffusing capacity : [ Normal capacity ]
FVC Liters : [ 2.22 ] FVC Liters : [ 67 ] FVC Liters : [ 3.35 ]
FEV1 Liters : [ 1.96 ] FEV1 Liters : [ 66 ] FEV1 Liters : [ 2.06 ]
FEV1 / FVC % : [ 58 ] FEV1 / FVC % : [ 62 ]
DLCO mL/mmHg/min : [ 21.5 ] DLCO mL/mmHg/min : [ 102 ]
DLCO Adj mL/mmHg/min : [ 21.5 ] DLCO Adj mL/mmHg/min : [ 102 ]
RV/TLC % : [ 22 ]';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php