PREMIER PURCHASING PARTNERS, L.P. AMENDMENT NUMBER # 3 TO GROUP PURCHASING AGREEMENT CONTRACT #: PP-NS-347 Product Category: Pulse Oximeters Price Additions, Product Deletions, Price Decrease, Price Correction

Exhibit 10.33

*** Text Omitted and Filed Separately

Confidential Treatment Requested

Under 17 C.F.R. §§ 200.80(b)(4)

and 17 C.F.R. 24b-2

PREMIER PURCHASING PARTNERS, L.P.

AMENDMENT NUMBER # 3 TO GROUP PURCHASING AGREEMENT

CONTRACT #: PP-NS-347

Product Category: Pulse Oximeters

Price Additions, Product Deletions, Price Decrease, Price Correction

This Amendment Number 3 (“Amendment”), is entered into effective August 15, 2007 (the “Effective Date”), and shall amend and modify the Group Purchasing Agreement (Contract #: PP-NS-347) by and between Premier Purchasing Partners, L.P. (“Purchasing Partners”), and Masimo Americas (“Seller”), dated effective March 1, 2006 (the “Agreement”), as follows:

1. Addition of Products. Effective as of the Effective Date, Exhibit A-3 Price Lists to the Agreement is hereby amended to add the Products set forth in Schedule 1 hereto. The price of such Products and other pertinent information concerning such Products is also set forth in Schedule I hereto.

2. Deletion of Products. Effective as of the Effective Date, Exhibit A-3 Price Lists to the Agreement is hereby amended to add the Products set forth in Schedule 2 hereto. The price of such Products and other pertinent information concerning such Products is also set forth in Schedule 2 hereto.

3. Price Decreases. Effective as of the Effective Date, Exhibit A-3 Price List to the Agreement is hereby amended to decrease the prices for the Products listed in the attached Schedule 3.

4. Price Corrections. Effective as of the Effective Date, Exhibit A-3 Price List to the Agreement is hereby amended to correct the prices to match the QTY/UOM for the Products listed in the attached Schedule 4.

5. Other Terms and Conditions. All other terms and conditions of the Agreement shall remain in full force and effect.

This Amendment is hereby executed as of the Effective Date by the parties’ authorized representatives set forth below.

PREMIER PURCHASING PARTNERS, L.P.

AMENDMENT NUMBER # 3 TO GROUP PURCHASING AGREEMENT

CONTRACT #: PP-NS-347