$re = '/(?i)\bw(?:eigh)?t\b.{1,25}?\b(?<!\d/)(\d+(?:\.\d+)?)(?!/?\d)\s*(\w+)/m';
$str = 'Weight Measured: 80.7 kg 11/27/1900 24:59:00
Pulse 64 \\F\\ Temp 37.3?C (99.1 ?F) \\F\\ Wt 101.2 kg (223 lb)
Weight as of 11/11/1900 72.2 kg (159 lb 1.6 oz)
Resp. rate 16, height 177.8 cm (5\' 10"), weight 84.7 kg (186 lb|
11.2 oz)
And one extra weight example 100lbs';
preg_match_all($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