FIRST AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT AND WAIVER

E XHIBIT 10.1

F IRST A MENDMENT TO A MENDED AND R ESTATED C REDIT A GREEMENT

AND W AIVER

T HIS F IRST A MENDMENT TO A MENDED AND R ESTATED C REDIT A GREEMENT AND W AIVER (this “Amendment” ) is entered into as of August 5, 2008, between N ATUS M EDICAL I NCORPORATED , a Delaware corporation ( “Borrower” ), and W ELLS F ARGO B ANK , N ATIONAL A SSOCIATION ( “Bank” ).

R ECITALS

W HEREAS Borrower is currently indebted to Bank pursuant to the terms and conditions of the Amended and Restated Credit Agreement, dated as of November 28, 2007 (as amended, modified or supplemented prior to the date hereof, the “Credit Agreement” ), between Borrower and Bank;

W HEREAS Bank and Borrower have agreed to certain changes in the terms and conditions set forth in the Credit Agreement and have agreed to amend the Credit Agreement to reflect such changes;

W HEREAS Borrower has informed Bank that it has, in violation of the aggregate $10,000,000 limitation set forth in clause (e) of the definition of “Permitted Investments,” invested approximately $16,200,000 in Subsidiaries formed or acquired after the Closing Date and acquisitions of assets of other Persons constituting business units of such Person (the “ Investment Default ”);

W HEREAS Borrower has requested that Bank waive the Investment Default;

W HEREAS Borrower has informed Bank that is has acquired all of the equity interests in Sonamed (as such term is defined in the Credit Agreement as amended by this Amendment) and, Sonamed did not execute a Guaranty or security agreement within the required timeframes set forth in Section 6.12 (the “ Sonamed Default ”); and

W HEREAS Borrower has requested that Bank waive the Sonamed Default;

N OW , THEREFORE , for valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Bank has agreed to provide a waiver for the Investment Default and a waiver for the Sonamed Default subject to the terms and conditions provided herein and Bank and Borrower hereby agree that the Credit Agreement shall be amended as follows; provided that nothing contained herein shall terminate any security interests, guaranties, subordinations or other documents in favor of Bank, all of which shall remain in full force and effect unless expressly amended hereby:

Section 1. Definitions . Each capitalized term used but not otherwise defined herein has the meaning assigned to it in the Credit Agreement.

Section 2. Amendments to Credit Agreement . Subject to Section 4 hereof, the Credit Agreement is hereby amended as follows:

(a) The following definitions in Section 1.1 of the Credit Agreement are hereby amended and restated in their entirety to read as follows:

“ Applicable Rate ” means, from time to time, with respect to any Base Rate Loan, or LIBOR Loan, or with respect to the Unused Commitment Fees payable pursuant to Section 2.7(a), as the case may be, the applicable rate per annum set forth below (expressed in basis points) under the caption “LIBOR Spread,” “Base Rate Spread” or “Unused Commitment Fee Rate,” as the case may be, based upon, subject to Section 2.6(d), the Leverage Ratio as set forth in the most recent Compliance Certificate received by Bank pursuant to Section 5.1(b)(vii) or Section 6.3(d), as applicable:

“ Interest Payment Date ” means: (a) with respect to (i) a LIBOR Loan, the last day of each Interest Period applicable thereto; provided that, if any such Interest Period exceeds three months, the date that falls three months after the beginning of such Interest Period shall also be an Interest Payment Date; and (ii) a Base Rate Loan, the last Business Day of each calendar month; and (b) in the case of Revolving Credit Loans, the Revolving Credit Maturity Date.

“ Interest Period ” means, as to each LIBOR Loan, the period commencing on the date such LIBOR Loan is disbursed or converted to or continued as a LIBOR Loan and ending on the date one, two, three or six months thereafter, as selected by Borrower in its related Loan Notice; provided that: (a) any Interest Period that would otherwise end on a day that is not a Business Day shall be extended to the next succeeding Business Day unless such Business Day falls in another calendar month, in which case such Interest Period shall end on the next preceding Business Day; (b) any Interest Period that begins on the last Business Day of a calendar month (or on a day for which there is no numerically corresponding day in the calendar month at the end of such Interest Period) shall end on the last Business Day of the calendar month at the end of such Interest Period; and (c) no Interest Period for any Revolving Credit Loan shall extend beyond the Revolving Credit Maturity Date.

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“ Loan ” means any Revolving Credit Loan.

“ Loan Documents ” means this Agreement, the Revolving Line of Credit Note, the Security Agreement, the Guaranties, and each other contract, instrument and document required by or delivered to Bank in connection with this Agreement.

“ Material Adverse Effect ” means a material adverse effect on (i) the business operations or financial condition of Borrower and its Subsidiaries taken as a whole, (ii) the ability of Borrower to repay all debt, principal, interest, expenses and other amounts owed to Bank by Borrower pursuant to this Agreement, the Revolving Line of Credit Note and the other Loan Documents, or to otherwise perform its material obligations under the Loan Documents, or (iii) Borrower’s interest in, or the value, perfection or priority of Bank’s security interest or lien in, the collateral described in Section 2.10 hereof.

“ Note ” means the Amended and Restated Revolving Line of Credit Note.

“ Permitted Investments ” means:

(a) Investments by Borrower existing as of the Closing Date and listed on Schedule 1.1-B ;

(b) Investments by Borrower in (i) marketable direct obligations issued or unconditionally guaranteed by the United States or any agency or any state thereof maturing within one year from the date of acquisition thereof, (ii) commercial paper maturing no more than one year from the date of creation thereof and currently having rating of at least A-2 or P-2 from either Standard & Poor’s Corporation or Moody’s Investors Service, (iii) Bank’s certificates of deposit maturing no more than one year from the date of investment therein, (iv) Bank’s money market accounts, and (v) in conformance with Borrower’s “Investment Policy,” as in effect on the Closing Date (or as amended from time to time, subject to the approval of Bank), a copy of which has previously been provided to Bank;

(c) Investments by Borrower consisting of the endorsement of negotiable instruments for deposit or collection or similar transactions in the ordinary course of business of Borrower;

(d) Investments by Borrower consisting of deposit accounts in which Bank has a first priority perfected security interest;

(e) Investments, in the aggregate not to exceed $10,000,000.00, by Borrower (i) in Subsidiaries formed or acquired after the Amendment Closing Date, so long as Borrower has 100% control of such Subsidiary immediately following the effectiveness of such acquisition, and/or (ii) constituting the purchase or other acquisition (in one transaction or a series of transactions) of assets of another Person that constitute a business unit;

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(f) Investments by Borrower not to exceed at any time $250,000.00 in the aggregate consisting of (i) travel advances and employee relocation loans and other employee loans and advances in the ordinary course of business, and (ii) loans to employees, officers or directors relating to the purchase of equity securities of Borrower pursuant to employee stock purchase plans or agreements approved by Borrower’s board of directors;

(g) Investments (including debt obligations) by Borrower not to exceed $50,000.00 in the aggregate outstanding at any time received in connection with the bankruptcy or reorganization of customers or suppliers and in settlement of delinquent obligations of, and other disputes with, customers or supplie