EXHIBIT 4.1

SONOSITE, INC.,

as Issuer

and

WELLS FARGO BANK, NATIONAL ASSOCIATION,

as Trustee

SECOND SUPPLEMENTAL INDENTURE

Dated as of March 29, 2012

3.75% Convertible Senior Notes Due 2014

SECOND SUPPLEMENTAL INDENTURE dated as of March 29, 2012 (the “Second Supplemental Indenture”) between SonoSite, Inc., a Washington corporation, as issuer (the “Company”), and Wells Fargo Bank, National Association, a national banking association, as trustee (the “Trustee”).

W I T N E S S E T H :

WHEREAS, the Company and the Trustee has heretofore entered into an Indenture dated as of July 16, 2007 (the “Base Indenture”), providing for the issuance by the Company from time to time of its senior debt securities evidencing its unsecured and unsubordinated indebtedness (the “Securities”);

WHEREAS, the Company and the Trustee has heretofore entered into a First Supplemental Indenture dated as of July 16, 2007 (the “First Supplemental Indenture” and the Base Indenture, as supplemented by the First Supplemental Indenture, the “Indenture”), providing for the issuance by the Company of its 3.75% Convertible Senior Notes Due 2014 (the “Notes”);

WHEREAS, the Company, FUJIFILM Holdings Corporation, a Japanese corporation (“FUJIFILM”), and Salmon Acquisition Corporation, a Delaware corporation and an indirect wholly-owned subsidiary of FUJIFILM (“Merger Sub”), have entered into an Agreement and Plan of Merger dated December 15, 2011 (the “Merger Agreement”);

WHEREAS, at a special meeting held on March 29, 2012, the shareholders of the Company approved a merger (the “Merger”) under which Merger Sub merged with and into the Company with the Company as the surviving corporation;

WHEREAS, pursuant to the Merger Agreement, at the effective time of the Merger, each share of common stock, par value $0.01 per share of the Company (“Common Stock”) (except for shares held in the treasury of the Company or owned by FUJIFILM or Merger Sub or any direct or indirect subsidiary of FUJIFILM, Merger Sub or the Company or shares for which appraisal rights are properly demanded) was automatically cancelled and converted into the right to receive $54.00 in cash, without interest thereon (the “Merger Consideration”);

WHEREAS, Section 6.05 of the First Supplemental Indenture provides that upon any consolidation, merger or combination to which the Company is a party, the Company and the Trustee shall enter into a supplemental indenture providing that the Notes shall be convertible into the kind and amount of shares of stock, securities or other property or assets (including cash) receivable upon such consolidation, merger or combination by a holder of a number of shares of Common Stock issuable upon conversion of such Notes immediately prior to such consolidation, merger or combination;

WHEREAS, pursuant to Section 11.02 of the First Supplemental Indenture, the Company and the Trustee may enter into this Second Supplemental Indenture without the consent of any Holders;

WHEREAS, the Board of Directors of the Company has resolved to authorize the execution and delivery of this Second Supplemental Indenture pursuant to a Board Resolution; and

WHEREAS, all other acts and things necessary to make the execution of this Second Supplemental Indenture have in all respects been duly authorized;

NOW, THEREFORE, THIS SECOND SUPPLEMENTAL INDENTURE WITNESSETH:

(a) Capitalized terms used but not defined herein shall have the respective meanings assigned to them in the Indenture;

(b) Terms defined both herein and in the Indenture shall have the meanings assigned to them herein; and

(c) Provisions of this Second Supplemental Indenture that conflict with or are otherwise inconsistent with provisions of the Indenture shall be deemed to supersede and amend the Indenture for all purposes with respect to the Notes.

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[signature page follows]

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IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental Indenture to be duly executed as of the date first written above.

Signature Page to Second Supplemental Indenture