Was wondering if anyone knew what was causing this warning and what I could do to fix it. PHP 7.2.

Code:
[17-May-2019 15:02:26 America/Chicago] Request URI: /ipn_main_handler.php, IP address: 
#1  require(/home/dentalplanet/www.dentalplanet.com/includes/init_includes/init_database.php) called at [/home/dentalplanet/www.dentalplanet.com/includes/autoload_func.php:48]
#2  require(/home/dentalplanet/www.dentalplanet.com/includes/autoload_func.php) called at [/home/dentalplanet/www.dentalplanet.com/includes/application_top.php:170]
#3  require(/home/dentalplanet/www.dentalplanet.com/includes/application_top.php) called at [/home/dentalplanet/www.dentalplanet.com/ipn_main_handler.php:114]
--> PHP Warning: Use of undefined constant USE_PCONNECT - assumed 'USE_PCONNECT' (this will throw an Error in a future version of PHP) in /home/dentalplanet/www.dentalplanet.com/includes/init_includes/init_database.php on line 23.
Thank you,