Hospital.sol

import './MedicalRecord.sol';

contract Hospital {
  MedicalRecord public medicalRecord;

  function Hospital(address _contract) public {
    medicalRecord =  MedicalRecord(_contract);
  }

  function enterHospital(bytes32 _fullName)  public {
    medicalRecord.addAdmissionRecord(_fullName);
  }
}

MedicalRecord.sol

contract MedicalRecord {
  struct Visit {
    uint admissionDate;
    uint dischargeDate;
  }

  mapping(address => mapping(bytes32 => Visit)) visits;

  function addAdmissionRecord(bytes32 _fullName) external {
    visits[msg.sender][_fullName].admissionDate = now;
  }
}