<PAGE>
                                                                    Exhibit 10.4

                                 GENERAL RELEASE

          For good and valuable consideration the receipt and sufficiency of
which is hereby acknowledged, the undersigned party ("Releasor") hereby agrees
as follows:

          1. Release. Releasor releases BCC Acquisition II LLC and its
predecessor entities, affiliates and subsidiaries (collectively "BCCAII"), and
its past and present shareholders, employees and former employees, agents,
directors, officers, attorneys, predecessors, successors, assigns, heirs,
executors, administrators, and all other persons, firms, corporations,
associations, partnerships, or entities having any legal relationship to BCCAII
(collectively, "Releasees"), from any and all claims, demands and causes of
action of any kind or nature, whether known or unknown or suspected or
unsuspected to Releasor, which Releasor now owns or holds, or has at any time
before this owned or held against any of them relating to, arising out of, or in
any way connected with BCCAII.

          2. California Civil Code Section 1542. It is Releasor's intention that
Releasor's execution of this Agreement will forever bar any released claims,
demand, cause of action, charge and grievance related to BCCAII and the
Releasees. Because this is Releasor's intention, Releasor expressly waives any
and all rights and benefits conferred upon Releasor by the provisions of Section
1542 of the California Civil Code. Section 1542 provides:

          "A GENERAL RELEASE DOES NOT EXTEND TO CLAIMS WHICH THE CREDITOR DOES
NOT KNOW OR SUSPECT TO EXIST IN HIS FAVOR AT THE TIME OF EXECUTING THE RELEASE,
WHICH IF KNOWN BY HIM MUST HAVE MATERIALLY AFFECTED HIS SETTLEMENT WITH THE
DEBTOR."

          3. Remedies, Attorney Fees, Binding Arbitration. Releasor will not
bring any action against BCCAII or the Releasees with respect to any claims,
demands or causes of action released pursuant to in this Agreement. In the event
Releasor brings any such action: (a) BCCAII will be entitled to all lawful
remedies; and (b) all other provisions of this Agreement will remain in full
force and effect. In the event of any dispute arising out of or related to this
Agreement, the parties agree to enter into binding arbitration under the
commercial rules of the American Arbitration Association. The location for such
arbitration shall be Minneapolis, Minnesota. The governing law shall be
Minnesota law. The prevailing party shall be entitled to recover reasonable
attorney's fees and costs.

          4. Enforceability. If any term or provision of this Agreement is held
to be invalid or unenforceable, the remaining terms or provisions of this
Agreement will continue to be valid and will be performed, construed and
enforced to the fullest extent permitted by law, and the invalid or
unenforceable term will be deemed amended and limited in accordance with the
intent of the parties, as determined from the face of the Agreement, to the
extent necessary to permit the maximum enforceability or validation of the term
or provision.

          5. Headings. Paragraph headings are for the convenience of the parties
only.

<PAGE>

          IN WITNESS WHEREOF, Releasor has executed and delivered this General
Release as of the day and year set forth below.

Date: _____________, 2005

                                        DIAMETRICS MEDICAL, INC.


                                        By: /s/ W. Glen Winchell
                                            ------------------------------------
                                        Name: W. Glen Winchell
                                        Its: Sr. Vice President of Finance
                                             and CFO