People Material Design Data Table in AngularJS with Firebase data using promises

I am trying to use this AngularJS module to create a table with information stored in Firebase. The problem is that I do not get the table to be populated with the data obtained in Firebase. At the time of loading the page, the progress bar appears, but when it finishes receiving Firebase information and the progress bar end, nothing is shown in the table. It remains as you can see in the following image, it also shows how the information is loaded, since it is being printed by the console.

The table has the following structure:

 <md-table-container>
  <table md-table md-row-select="options.rowSelection" multiple="{{options.multiSelect}}" ng-model="selected" md-progress="promise">
    <thead md-head md-order="query.order" md-on-reorder="cargarPacientes">
    <tr md-row>
      <th md-column md-order-by="nombre"><span>Nombre</span></th>
      <th md-column md-order-by="type"><span>Fecha Nacimiento</span></th>
    </tr>
    </thead>
    <tbody md-body>
    <tr md-row md-select="paciente" md-on-select="logItem" md-auto-select="options.autoSelect" ng-repeat="paciente in pacientes.data | filter: filter.search | orderBy: query.order | limitTo: query.limit : (query.page -1) * query.limit">
      <td md-cell>{{paciente.nombre + " " + paciente.apellido}}</td>
      <td md-cell>{{paciente}}</td>
    </tr>
    </tbody>
  </table>
</md-table-container>

And the code with which I access Firebase to get the information is:

$scope.pacientes = cargarPacientes();

  function cargarPacientes() {
    var deferred = $q.defer();
    $scope.promise = deferred.promise;
    let pacientesMostrar = {};
    let pacientes = [];
    let database = firebase.database();
    let pacientesRef = database.ref('pacientes');
    $timeout (function () {
      pacientesRef.once('value').then(function(paciente) {
        paciente.forEach(function (pacienteHijo) {
          let childData = pacienteHijo.val();
          childData['key'] = pacienteHijo.key;
          pacientes.push(childData);
        });
        pacientesMostrar['count'] = pacientes.length;
        pacientesMostrar['data'] = pacientes;
        console.log(pacientesMostrar);
        deferred.resolve();
        return pacientes;
      }, function (error) {
        console.error(error);
        deferred.reject();
      });

    }, 2000);
  };

I am not sure that you are using the promises correctly, or that you are correctly assigning the information obtained from Firebase to the variable $scope.pacientes . The expected behavior is that of the following demo .