/**
  * Handle event PAM / DEC / PDQ / SWF message
  *
  * @param CExchangeHL7v2     $exchange_hl7v2 Exchange HL7v2
  * @param CHL7v2MessageXML   $dom_evt        DOM Event
  * @param CHL7Acknowledgment $ack            Acknowledgment
  * @param array              $data           Nodes data
  *
  * @return null|string
  */
 static function handleEvent(CExchangeHL7v2 $exchange_hl7v2, CHL7v2MessageXML $dom_evt, CHL7Acknowledgment $ack, $data = array())
 {
     $newPatient = new CPatient();
     $newPatient->_eai_exchange_initiator_id = $exchange_hl7v2->_id;
     $data = array_merge($data, $dom_evt->getContentNodes());
     return $dom_evt->handle($ack, $newPatient, $data);
 }