New Medical Device and Irrigation Solution Exhibits Promising Results
in the Removal of Bacterial Colonization in Chronic Sinus and Ear
Infections

Study of New Technique Presented at Spring Meeting of the American
Rhinologic Society

MINNEAPOLIS - April 30, 2007 - Results of a laboratory study presented
on Thursday, April 26 at the spring meeting of the American Rhinologic
Society (ARS) suggest that pressurized irrigation of the sinuses in
conjunction with a specially designed irrigation solution may offer
new options to reduce bacteria associated with chronic rhinosinusitis
(CRS).

The study, presented by Martin Desrosiers, M.D., associate clinical
professor in the Department of Otolaryngology and Allergy at Montreal
General Hospital, McGill University in Montreal, Canada, showed a
large reduction of very robust and highly adherent bacterial colonies
in a laboratory model.  Two strains of bacteria, pseudomonas
aeruginosa and staphylococcus aureus, were clinically isolated from
CRS patients who had poor outcomes following functional endoscopic
sinus surgery (FESS).  Authors of the study also received the ARS
Basic Science Research Award, which was presented to them at the ARS
conference.

The bacterial strains were grown into robust bacterial colonies and
treated with a variety of commonly used therapies including
antibiotics and hypertonic saline. These existing therapies were
compared to static and pressurized application of a new irrigation
solution under development at Medtronic. Of the S aureus and
pseudomonas bacterial colonies grown in this model, respectively
99.98% and 99.999% of the bacteria were removed by the pressurized
application.

Traditional Treatment, Emerging Theories and Product Development
Established theory among Ear, Nose, and Throat (ENT) surgeons is that
CRS and chronic otitis media with effusion (COME) are inflammatory
disorders. Traditional treatments include surgery to ventilate
affected areas in an attempt to reduce or eliminate inflammation.
However, recent research suggests that CRS and COME are actually
chronic infections1, and that the chronic inflammation which
accompanies them is a byproduct of the diseases rather than the
underlying cause. Specifically, certain strains of bacteria are highly
resistant to host defenses and antibiotic treatment, and, as the
bacterial colonies persist, they produce toxins that cause chronic
inflammation. Based on this mechanism, Medtronic began developing new
treatment options for the disruption and removal of bacterial
colonies.

Mechanical disruption is one of the best mechanisms for removal of
bacterial colonies, and the effect is often enhanced with a detergent.
A common example would be brushing one's teeth. Cavities in the teeth
are caused by bacterial colonies in the mouth. Thoroughly brushing the
teeth with toothpaste serves to remove the bacterial colonies and
prevent decay.

Special irrigation devices for ENT under development by Medtronic
adopt a similar approach for the treatment of CRS and COME.  Patent
applications have been filed on a system that irrigates the nose with
pressure, analogous to that used in the dentist's office or in the
treatment of chronic orthopedic wounds.  To assist in the treatment,
Medtronic scientists developed and evaluated a large variety of
irrigating solutions. A citric acid zwitterionic surfactant provided
the best results during internal testing. A patent application has
been filed on the surfactant also.

Study Results Suggest Improved Efficacy in Bacterial Removal
Researchers at McGill University in Montreal, Montana State and
Medtronic collaborated to test the effectiveness of pressurized
irrigation with the citric acid zwitterionic surfactant irrigating
solution.

Bacteria isolated from failed surgical patients at McGill were sent to
Montana State, grown into robust bacterial colonies, and treated with
a number of static and dynamic irrigation solutions. Commonly used
controls were compared to static and pressurized applications of the
Medtronic surfactant.  Control groups included many of the currently
used irrigation solutions, including antibiotics (tobramycin and
doxycycline), and salt water (isotonic and hypertonic saline).

When applied statically, none of the controls had any material effect
on the bacterial colony. Conversely, dynamic application of saline
reduced the number of bacteria 99.4% in both types of bacterial
colonies. Static application of the surfactant reduced the number of
bacteria in the colonies of S aureus and pseudomonas 99.66% and 99.87%
respectively. The best results were achieved when surfactant was
applied under pressure, where 99.98% and 99.999% of S aureus and
pseudomonas were removed equaling a four- (10,000x) and five-
(100,000x) log reduction, respectively.

Looking Forward
Given the positive results of the laboratory study, Medtronic is
initiating a number of studies to further evaluate this technology.
Several living tissue and safety studies are scheduled to start in the
near future with subsequent submission for review by the FDA