<PAGE>


                                                                   EXHIBIT 10.18


                               SEVERANCE AGREEMENT

         This SEVERANCE AGREEMENT ("Agreement") is made and entered into by and
between U.S. MedSys Corp. ("Company") and Kenton Sieckman ("Sieckman").

         WHEREAS, Sieckman has served as a director of Company and its
subsidiaries;

         WHEREAS, Company and Sieckman desire to terminate Sieckman's seats on
the board of directors of the Company and its subsidiaries, upon mutually
acceptable terms and to settle any and all differences, claims and potential
claims arising out of Sieckman's resignation of his seats on the board of
directors of the Company and its subsidiaries;

         NOW THEREFORE, in consideration of the mutual promises and other
consideration contained herein and intending to be legally bound, the parties
agree as follows:

         1. Severance. Sieckman hereby resigns, effective on the date of the
closing date of the Securities Purchase Agreement between Rangeley Corporation
and Montague Investments, Inc. (the "Resignation Date"), from the following
positions: (i) a director of Company; and (ii) a director of any of Company's
subsidiaries.

         2. Consideration Provided to Sieckman. On the Resignation Date,
Sieckman will not be owed, and Company shall not pay, any cash amount as
compensation, remuneration or reimbursement.

Sieckman presently holds an option, originally granted on November 3, 2003, to
purchase 250,000 shares of common stock of the Company at a purchase price of
$.25 per share, that may be exercised on a "cashless exercise" basis (as fully
described in the Grant of Option issued to Sieckman). On the Resignation Date,
Company shall adjust the purchase price of the option to a price per share that
will result in the issuance of exactly 175,000 shares of common stock on a
cashless exercise basis, and Sieckman shall exercise the option on such basis
and Company shall issue 175,000 shares of common stock to Sieckman. It is
understood that, for purposes of Rule 144 of the Securities Act of 1933, as
amended, Sieckman's holding period will be deemed to have commenced on November
3, 2003.

         3. Sieckman's Release of All Claims. In consideration of this
Agreement, including, but not limited to, the mutual, binding promises contained
herein, and intending to be legally bound thereby, Sieckman, on behalf of
himself, his executors, legatees, devisees, administrators successors, and
assigns, does hereby irrevocably, forever and unconditionally release and
forever discharge Company and each of its past, present and future stockholders,
agents, directors, officers, executives, representatives, attorneys, and its
predecessors, successors, parents, affiliates, insurers, heirs, executors,
administrators and assigns, and all persons acting by, through, under or in
concert with any of them (collectively referred to herein as the "Released
Parties"), of and from any and all actions, causes of action, suits, debts,
judgments, charges and expenses (including attorneys' and paralegal fees and
costs at all levels of dispute resolution), of any nature whatsoever, asserted
or unasserted, known or unknown, ("Claims"), which Sieckman ever had, now has,
or hereafter may have against the Released Parties, in any way arising out of or
related to Sieckman's Claims for compensation or remuneration through the
Resignation Date.

In expansion of the foregoing release, Sieckman releases and forever discharges
any and all Claims he may have had against such Released Parties in any way
arising out of or related to discrimination on any basis prohibited by statute,
public policy or otherwise, including those under the Age


Page 1 of 5
<PAGE>


Discrimination in Employment Act of 1967, 29 U.S.C. 621 et seq., Title VII of
the Civil Rights Act of 1964 ("Title VII"), 42 U.S.C. 2000 et seq., 2101 et
seq., the Americans with Disabilities Act ("ADA") 42 U.S.C. 1201 et seq., the
federal Family and Medical Leave Act, 29 U.S.C. 2601 et seq., and the Executive
Retirement Income Security Act of 1974, 29 U.S.C. 1001 et seq., and as any or
all of the foregoing are or may be amended.

Expanding the foregoing releases further still, Sieckman releases Released
Parties of and from any and all Claims for wrongful discharge of any kind
(including in violation of public policy and constructive discharge).

         4. Company's Release of all Claims. As part of the consideration for
Sieckman entering into this Agreement, Company for and on behalf of itself and
all of its past, present and future subsidiaries, parent corporations,
affiliates, directors, officers, executives, representatives, attorneys,
insurers, heirs, executors, administrators, assigns, and agents, and all persons
acting by, through, under or in concert with any of them, does hereby
irrevocably, forever and unconditionally release and forever discharge Sieckman,
his personal representatives, heirs, legatees, devisees, administrators,
successors, assigns, and future employers, and all persons acting by, through,
under or in concert with any of them (collectively referred to herein as the
"Released Parties"), of and from any and all Claims which Company ever had, now
has, or hereafter may have against the Released Parties, in any way arising out
of or related to Sieckman's service and/or capacity with Company or any of its
subsidiaries or affiliated entities or the termination of his services and/or
capacities with Company and its subsidiaries and affiliated entities.

         5. Assumption of Risk of Change in Facts. Sieckman and Company
understand that the facts under which they give their releases hereunder may
prove to be different than now known or believed by them, and each accepts and
assumes the risk thereof and agrees that their releases shall remain in full
force and effect and not subject to modification, termination or rescission by
reason of any difference in facts.

         6. Covenant Not to Sue. Subject to full performance of the other
party's obligations under this Agreement, each party hereto agrees that neither
such party nor any person or entity on such party's behalf has or shall
commence, maintain or prosecute any lawsuit, complaint, action or proceeding of
any kind against the other or their respective Released Parties with respect to
any Claims released by either party. The foregoing notwithstanding, this
covenant not to sue does not extend to any claim for breach of this Agreement.

         7. Company Records; Return of Company Property. Sieckman represents
that he shall return to Company any of the following that he has in his
possession: records and business documents, whether on computer or hard copy,
and other materials (including but not limited to computer disks and tapes,
computer programs and software, office keys, correspondence, files, customer
lists, technical information, customer information, pricing information,
business strategies, sales records and copies thereof) (collectively, the
"Company Records") provided by Company and/or its predecessors, subsidiaries or
affiliates and/or obtained as a result of his position with, or in any of his
capacities with, or rendering of services for, Company and/or its predecessors,
subsidiaries or affiliates, and/or created by Sieckman while rendering services
to or for Company and/or its predecessors, subsidiaries or affiliates. Sieckman
acknowledges that all such Company Records are the property of Company. In
addition, Sieckman shall promptly return in good condition any and all physical
assets in his possession that belong to Company.

         8. Confidential Information. Sieckman acknowledges that, during his
tenure and other service with Company and/or its subsidiaries or affiliated
entities, he has had access to confidential


Page 2 of 5
<PAGE>


and other information proprietary to Company and/or its subsidiaries or
affiliated entities, including but not limited to trade secrets, operations,
customer information, customer prospects, strategic plans, inventions, business
plans, formulas processes, designs, methods, techniques, know-how, systems,
software programs, works of authorship, plans, proposals, information about
products, and other proprietary information (the "Confidential Information").
Sieckman agrees that he has not and shall not at any time disclose to any person
or entity the Confidential Information acquired during or in connection with his
position with or in rendering services to Company and/or any of its subsidiaries
and affiliates without prior written permission from Company. Sieckman agrees
that he shall keep secret the Confidential Information and all matters that have
been entrusted to him and shall not use or attempt to use any of the
Confidential Information in any manner that may injure or cause loss or may be
calculated to injure or cause loss, whether directly or indirectly, to Company
and/or its subsidiaries and affiliates.

The above restrictions shall not apply to: (i) information that at the time of
disclosure is in the public domain through no fault of Sieckman; (ii)
information received from a third party outside of Company that was disclosed
without a breach of any confidentiality obligation; (iii) information approved
for release by written authorization of Company; or (iv) information that may be
required by law or an order of any court, agency or proceeding to be disclosed;
provided, Sieckman shall provide Company with notice of any such required
disclosure once Sieckman has knowledge of it and will provide all reasonable
help to Company to obtain an appropriate protective order.

         9. Non-disparagement. Each party agrees to make no disparaging
statements, or any other communication or publication relating to the other
party that would tend to denigrate or discredit the other party, regardless of
whether such party believes the statement or communication to be true. This
provision extends to the past, present and future officers, directors, managers,
employees, shareholders, agents, consultants, advisors, accountants, attorneys,
business associates, successors and assigns of the respective parties.

         10. Non-interference. Company shall not interfere with any request by
Sieckman to publicly or privately sell any shares of common stock of Company
owned by Sieckman. Upon presentment of a request by Sieckman to Company's
transfer agent to sell or transfer shares privately, under Rule 144 of the
Securities Act of 1933, as amended, or to remove a restrictive legend under Rule
144(k), Company shall provide to the transfer agent (with a copy to Sieckman),
within two business days, of any authorization or legal opinion requested by the
transfer agent.

         11. Indemnification. The indemnification(s) of Sieckman from Company
that Sieckman enjoyed by and through his position with Company, the Bylaws and
Articles of Incorporation of Company, the laws of the State of Colorado (to the
fullest extent permitted) and/or any other written instrument executed and
delivered by Company prior to the Resignation Date shall not be abridged by the
execution and delivery of this Agreement or the termination of Sieckman's
position with Company under this Agreement and the same shall survive the
execution and delivery of this Agreement, and termination of Sieckman's position
with Company under this Agreement.

         Further, Company shall protect, defend, indemnify and hold Sieckman
harmless from and against all losses, liabilities, damages, judgments, claims,
counterclaims, demands, actions, proceedings, costs and expenses (including the
advancement of legal fees for attorneys chosen by Sieckman) of every kind and
character, resulting from or relating to or arising out of Sieckman's services
provided to Company through the Resignation Date, alleged by any third-party or
any state or federal regulatory agency.


Page 3 of 5
<PAGE>


         12. Future cooperation. Sieckman agrees that he will cooperate with
Company on current and future regulatory investigations and/or litigation
matters involving Company when Company's Board of Directors reasonably
determines that the assistance of Sieckman is necessary; provided, however, that
Company provides reasonable advance written notice to Sieckman regarding such
cooperation; provided further that Company agrees to be flexible and reasonable
with respect to the scheduling of such assistance; provided further that a
reasonable fee of $100.00 per hour and any expenses incurred by Sieckman in
connection with such cooperation shall be advanced to Sieckman by Company; and
provided further that Sieckman shall not be required to provide any such
assistance if Sieckman's counsel reasonably believes such assistance would
conflict with Sieckman's ability to use one or more legal or equitable defenses
available to him but not to Company, unless Company provides adequate indemnity
to Sieckman for such conflict.

         13. Knowing and Voluntary Agreement. Each party hereto hereby
acknowledges that such party has carefully read and understands all of the
provisions and effects of this Agreement; that each is voluntarily and knowingly
entering into this Agreement free of coercion or duress; and that in agreeing to
sign this Agreement, the parties have not, except for representations, promises,
statements, or explanations made herein or in an exhibit attached hereto, relied
on any representations, promises, agreements, statements or explanations made by
any party hereto or their respective attorneys concerning the terms or effects
of this Agreement in connection with their respective decisions to execute the
same.

         14. Governing Law, Jurisdiction and Venue. This Agreement and any
controversy which might arise herefrom will in all respects be interpreted,
enforced and governed by the laws of the State of Colorado, and that in any
action, special proceeding or other proceeding that may be brought arising out
of, in connection with or by reason of this Agreement, shall be brought only in
a court of competent jurisdiction within the City and County of Denver,
Colorado.

         15. Change, Modification and Waiver. No change or modification of this
Agreement shall be valid unless it is in writing and signed by Sieckman and an
authorized officer of Company. No waiver of any provision of this Agreement
shall be valid unless it is in writing and signed by the party against whom the
waiver is sought to be enforced (in the case of Company, by an authorized
officer of Company). The failure of a party to insist upon strict performance of
any provision of this Agreement in any one or more instances shall not be
construed as a waiver or relinquishment of the right to insist upon strict
compliance with such provision in the future.

         16. Integration. This Agreement and its exhibits constitutes the entire
agreement between Company and Sieckman concerning the subject matters hereof and
supercedes all prior representations, promises and agreements, whether oral or
written, implied or otherwise with respect thereto.

         17. Severability. Any provision of this Agreement, which is adjudged to
be prohibited or unenforceable, shall be ineffective to the extent of such
prohibition or unenforceability without affecting the validity or enforceability
of the remainder of this Agreement.

         18. Attorneys Fees. In the event an action is brought for breach of or
to enforce this Agreement, including arbitration, the prevailing party shall
receive its reasonable attorneys and paralegal fees and costs at all levels of
dispute resolution involved as determined by the court or arbitrators, as the
case may be.


Page 4 of 5
<PAGE>


         19. Voiding Provision. This Agreement shall become null and void and of
no force or effect if the closing of Securities Purchase Agreement between
Rangeley Corporation and Montague Investments, Inc. does not occur.

         IN WITNESS WHEREOF, and intending to be legally bound hereby, the
parties have agreed to and executed the foregoing Severance Agreement, effective
as of the last date written below.

SIECKMAN:

/s/ Kenton Sieckman                                05/06/05
----------------------------                       -----------------------------
Kenton Sieckman                                    Date


COMPANY:

U.S. MEDSYS CORP.

/s/ George Anagnost

By:
   ------------------------


Its:     Vice President                            05/06/05
    -----------------------                        -----------------------------
                                                   Date


Page 5 of 5