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EXHIBIT 28.11

|                                                   |                                       |  |                      
|-------------------------------------------------- | ------------------------------------- |  | ---------------------
|(DEPARTMENT OF HEALTH & HUMAN SERVICES U.S.A LOGO) | DEPARTMENT OF HEALTH & HUMAN SERVICES |  | Public Health Service

| |                             
| | ----------------------------
| | Food and Drug Administration
| | 9200 Corporate Boulevard    
| | Rockville MD 20850          

Mr. Kevin McCulloh
Vice President, Engineering
Chad Therapeutics, Incorporated
21622 Plummer Street
Chatsworth, California 91311

|                                                         
|---------------------------------------------------------
|Re: K020475                                              
|Trade/Device Name: Chad Therapeutics OXYPNEUMATIC CYPRESS
|Model 511                                                
|Regulation Number: 868.5905                              
|Regulation Name: Non-continuous Ventilator               
|Regulatory Class: II                                     
|Product Code: NFB                                        
|Dated: May 10, 2002                                      
|Received: May 14, 2002                                   

Dear Mr. McCulloh:

We have reviewed your Section 510(k) premarket notification of intent to market
the device referenced above and have determined the device is substantially
equivalent (for the indications for use stated in the enclosure) to legally
marketed predicate devices marketed in interstate commerce prior to May 28,
1976, the enactment date of the Medical Device Amendments, or to devices that
have been reclassified in accordance with the provisions of the Federal Food,
Drug, and Cosmetics Act (Act) that do not require approval of a premarket
approval application (PMA). You may, therefore, market the device. subject to
the general controls provisions of the Act. The general controls provisions of
the Act include requirements for annual registration, listing of devices, good
manufacturing practice, labeling, and prohibitions against misbranding and
adulteration.

If your device is classified (see above) into either class II (Special
Controls) or class III (PMA), it may be subject to such additional controls.
Existing major regulations affecting your device can be found in the Code of
Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish
further announcements concerning your device in the Federal Register.

Please be advised that FDAs issuance of a substantial equivalence
determination does not mean that FDA has made a determination that your device
complies with other requirements of the Act or any Federal statutes and
regulations administered by other Federal agencies.





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Page 2  Mr. McCulloh

You must comply with all the Acts requirements, including, but not limited to:
registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); good
manufacturing practice requirements as set forth in the quality
systems (QS)
regulation (21 CFR Part 820); and if applicable, the electronic product
radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.

This letter will allow you to begin marketing your device as described in your
Section 510(k) premarket notification. The FDA finding of substantial
equivalence of your device to a legally marketed predicate device results in a
classification for your device and thus, permits your device to proceed to the
market.

If you desire specific advice for your device on our labeling regulation (21
CFR Part 801 and additionally 21 CFR Part 809.10 for in vitro diagnostic
devices), please contact the Office of Compliance at (301) 594-4646.
Additionally, for questions on the promotion and advertising of your device,
please contact the Office of Compliance at (301) 594-4639. Also, please note
the regulation entitled, Misbranding by reference to premarket notification
(21 CFR Part 807.97). Other general information on your responsibilities under
the Act may be obtained from the Division of Small Manufacturers, International
and Consumer Assistance at its toll-free number (800) 638-2041 or (301)
443-6597 or at its Internet address http: //www.fda.gov/cdrh/dsma/dsmamain.html

| |  |                
| |  | ---------------
| |  | Sincerely your,

| |  | (-s- ILLEGIBLE)                              
| |  | ---------------------------------------------
| |  | for Timothy A. Ulatowski                     
| |  | Director                                     
| |  | Division of Anesthesiology, General Hospital,
| |  | Infection Control and Dental Devices         
| |  | Office of Device Evaluation                  
| |  | Center for Devices and                       
| |  | Radiological Health                          

Enclosure





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Page 1 of 1

510 (k) Number (If Known):K020475

Device Name:Chad Therapeutics OXYPNEUMATIC CYPRESS Model 511.

Indications for Use:

The Chad Therapeutics OXYPNEUMATIC CYPRESS Model 511 is intended for
prescription use only, to be used as part of a portable oxygen delivery system
for patients that require supplemental oxygen in their home and for ambulatory
use.

(PLEASE DO NOT WRITE BELOW THIS LINE- CONTINUE ON ANOTHER PAGE IF NEEDED)



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Concurrence of CDRH, Office of Device Evaluation (ODE)

|                        |  |    |  |                         
|----------------------- |  | -- |  | ------------------------
|Prescription Use
     ü |  | OR |  | Over-The-Counter-Use    
|(Per 21 CRF 801.109)    |  |    |  | (Optional Format 1-2-96)

| |  |                                       
| |  | --------------------------------------
| |  | (-s- ILLEGIBLE)                       
| |  |                                       
| |  | (Division Sign-Off)                   
| |  | Division of Dental, Infection Control,
| |  | and General Hospital Devices          
| |  | 510(k) Number K020475