Nested Forms don't updated 🎳

examination_request_console.rb

@examination_request
=> #<ExaminationRequest:0x002ab3b2f7fd38> {
                         :id => 1,
             :procedure_type => "",
         :execultante_sector => "",
                 :patient_id => nil,
                    :user_id => nil,
    :medical_consultation_id => nil,
                 :created_at => Fri, 19 Aug 2016 14:58:07 UTC +00:00,
                 :updated_at => Fri, 19 Aug 2016 14:58:07 UTC +00:00
}

-----------------------------------------------------------------------
@examination_request.procedures
=> [
    [0] #<Procedure:0x002ab3b1d97b20> {
                            :id => 1,
             :procedure_file_id => 1,
                        :amount => 1,
        :examination_request_id => 1,
                    :created_at => Fri, 19 Aug 2016 15:05:52 UTC +00:00,
                    :updated_at => Fri, 19 Aug 2016 15:05:52 UTC +00:00
    },
    [1] #<Procedure:0x002ab3b1d979e0> {
                            :id => 2,
             :procedure_file_id => 1,
                        :amount => 10,
        :examination_request_id => 1,
                    :created_at => Fri, 19 Aug 2016 15:09:57 UTC +00:00,
                    :updated_at => Fri, 19 Aug 2016 15:09:57 UTC +00:00
    }
]

examination_request_controller.rb

def update
  if @examination_request.update_attributes(examination_request_params)
    # Também estou tentando algo como: 
    # @examination_request.procedures.update_attributes(params[:examination_request][:procedures_attributes])
    ...
    ...
end

...
  def examination_request_params
    params.require(:examination_request).permit(:procedure_type, :execultante_sector, :patient_id, :user_id, procedures_attributes: [:id, :procedure_file_id, :amount, :_destroy])
  end

examination_request_model.rb

class ExaminationRequest < ActiveRecord::Base

  has_many :procedures
  has_many :procedure_file, through: :procedures
  has_many :procedures, dependent: :destroy

  accepts_nested_attributes_for :procedures, allow_destroy: true, update_only: true
end

params.yml

 params
=> {
                   "utf8" => "✓",
                "_method" => "patch",
     "authenticity_token" => "Qtin1tWaOolJITf41POjmRT/6CcGglZzq45nOtkAFUHVVRB0MU0j2BQuf+gOee4LO3sDLdOcGckKIX2NjQachQ==",
    "examination_request" => {
               "procedure_type" => "Teste maroto",
           "execultante_sector" => "1",
                   "patient_id" => "",
                      "user_id" => "",
        "procedures_attributes" => {
            "0" => {
                "procedure_file_id" => "1",
                           "amount" => "1",
                         "_destroy" => "1",
                               "id" => "1"
            },
            "1" => {
                "procedure_file_id" => "1",
                           "amount" => "5",
                         "_destroy" => "false",
                               "id" => "2"
            }
        }
    },
                 "commit" => "Salvar",
             "controller" => "examination_requests",
                 "action" => "update",
                     "id" => "1"
}