Exhibit 3.4.1

                                  AMENDMENT TO
                        AGREEMENT OF LIMITED PARTNERSHIP

                                       OF

                         EMERGENCY MEDICAL SERVICES L.P.

      This Amendment to Agreement of Limited Partnership of Emergency Medical
Services L.P., dated as of February 10, 2005 (the "AGREEMENT"), dated November
27, 2005.

      Capitalized terms not defined herein have the respective meanings set
forth in the Agreement.

                                    RECITALS

      In order to obtain an offering permit from the Department of Corporations
of the State of California to register the Class B Units (the "PERMIT"), the
Partnership has agreed to amend the Agreement as provided herein.

                                    AMENDMENT

      Effective on the issuance of the Permit:

      1.    Section 4.4(b) of the Agreement is amended and restated to read in
            its entirety as follows:

            (i) Except as provided in this Section 4.4(b), holders of the Class
            B Units shall not be entitled to any vote on any matter requiring
            the vote of the Limited Partners hereunder.

            (ii) On the 90th day after the date the Permit is issued, and only
            if the Partnership has not then completed an initial public offering
            of the equity interests of the Partnership (or a successor,
            including any entity that becomes the holding company of the
            Partnership) (an "IPO") within such 90-day period, then, on such
            90th day, the holders of the Class B Units shall be entitled to vote
            on any matter requiring the vote of the Limited Partners hereunder
            except as provided in clause (iii) of this Section 4.4(b).

            (iii) In no event shall the holders of the Class B Units have the
            right to vote on any reorganization or recapitalization to be
            effected in connection with, or furtherance of, an IPO, provided
            that, as a result of such reorganization or recapitalization, the
            Class B Units are exchanged for the same securities as are offered
            to the public in the IPO (it being understood that such exchange may
            be deferred until the registration statement with respect to the
            securities to be issued in the exchange is declared effective under
            the Securities Act of 1933).

      2.    Section 13.1 is amended and restated to read in its entirety as
            follows:

            This Agreement represents the entire agreement among the parties
            with respect to its subject matter and cannot be changed or
            terminated except by an instrument in writing signed by the General
            Partners and Limited Partners holding more than 50% of the Class A
            Units outstanding or, if the holders of the Class B Units are
            entitled to vote as provided in Section 4.4(b)(ii), then by an
            instrument in writing signed by the General Partners and Limited
            Partners holding more than 50% of the Percentage Interests. If,
            notwithstanding the provisions of Section 8.1, the General Partner,
            in its sole discretion, seeks the consent



            of the Limited Partners to any action, such consent shall require
            only an instrument or instruments in writing signed by Limited
            Partners holding more than 50% of the Class A Units outstanding.

      The foregoing sets forth the entire amendment to the Partnership
Agreement. Except as modified specifically by this Amendment, the Agreement
remains in full force and effect.

            IN WITNESS WHEREOF, the parties have executed this Amendment as of
the day and year first above written.

                                        GENERAL PARTNER:


                                        EMSC, Inc.

                                        By: /s/ Todd Zimmerman
                                            ------------------------------------
                                            Name:  Todd Zimmerman
                                            Title: Secretary

                                        LIMITED PARTNERS:


                                        ONEX PARTNERS LLC


                                        By: /s/ Donald F. West
                                            ------------------------------------
                                            Name:  Donald F. West
                                            Title: Director

                                        By: /s/ Robert M. Le Blanc
                                            ------------------------------------
                                            Name:  Robert M. Le Blanc
                                            Title: Director

                                        ONEX US PRINCIPALS LP

                                        By: Onex American Holdings GP LLC,
                                            its General Partner


                                        By: /s/ Donald F. West
                                            ------------------------------------
                                            Name:  Donald F. West
                                            Title: Representative

       [Signature Page to Amendment to Agreement of Limited Partnership of
                        Emergency Medical Services L.P.]




                                        EMS EXECUTIVE INVESTCO LLC

                                        By: /s/ DONALD F. WEST
                                            ------------------------------------
                                            Name:  DONALD F. WEST
                                            Title: DIRECTOR

                                        ONEX EMSC CO-INVEST LP

                                        By: Onex Partners GP LP, its General
                                            Partner
                                        By: Onex Partners Manager LP, its Agent
                                        By: Onex Partners Manager GP Inc., its
                                            General Partner


                                        By: /s/ Robert M. Le Blanc
                                            ------------------------------------
                                            Name:  Robert M. Le Blanc
                                            Title: Managing Director

                                        By: /s/ Donald F. West
                                            ------------------------------------
                                            Name:  Donald F. West
                                            Title: Vice President

                                        ONEX PARTNERS LP

                                        By: Onex Partners GP LP, its General
                                            Partner
                                        By: Onex Partners Manager LP, its Agent
                                        By: Onex Partners Manager GP Inc., its
                                            General Partner


                                        By: /s/ Robert M. Le Blanc
                                            ------------------------------------
                                            Name:  Robert M. Le Blanc
                                            Title: Managing Director


                                        By: /s/ Donald F. West
                                            ------------------------------------
                                            Name:  Donald F. West
                                            Title: Vice President

       [Signature Page to Amendment to Agreement of Limited Partnership of
                        Emergency Medical Services L.P.]