Fw: Stents, Lasers and Silicone warning

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From: " ilena rose " <ilena@...>

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Sent: Thursday, May 09, 2002 2:18 PM

Subject: Stents, Lasers and Silicone warning

> ~~~ thank you so much Kathi <1pureheart@...> ~ you provide so much

> excellent information for the group ~~~

>

> EXCERPT:

>

> " Conclusions: At ambient oxygen concentrations [is greater than or equal

> to] 40%, silicone stents can catch fire. "

>

>

> Nd-YAG Laser Ignition of Silicone Endobronchial Stents(*).

> Author/s: A. Scherer Issue: May, 2000

>

> Study objectives: To test the incendiary characteristics of various

> silicone endobronchial stents under the impact of the Nd-YAG laser.

>

> Design: In vitro study in the laser laboratory of a

university-affiliated

> city hospital.

>

> Setting: The experiments were performed in a reaction chamber under

> controlled oxygen concentrations. The radiolucent and radiopaque Dumon

> silicone stent (Novatech; Aubagne, France) and the tracheal part of the

> Dynamic stent (Ruesch AG; Kernen, Germany) were tested. The Dumon stents

> were either clean, covered with a thin layer of blood, or mounted on fresh

> pig tracheal wall. The laser was aimed on them perpendicularly from

> distances of 1.0 cm and 0.5 cm.

>

> Interventions: Minimal oxygen concentration to allow ignition and

impact

> time for power outputs (POs) between 10 W and 80 W were determined.

>

> Measurements and results: The lowest oxygen concentration that allowed

> ignition of some stents was 40%. The clean radiolucent stent could not be

> ignited with up to 100% ambient oxygen concentration. Radiopacity,

presence

> of blood, tracheal wall, and metal, as well as higher PO and shorter

> distance of the laser probe decreased impact time to ignition. The

> radiopaque blood-covered stent was most easily ignited. For this stent,

at

> a PO of 40 W, impact time to ignition was 1.5 [+ or -] 0.2 s, and at 30 W

> was 2.6 [+ or -] 0.3 s.

>

> Conclusions: At ambient oxygen concentrations [is greater than or equal

> to] 40%, silicone stents can catch fire. Depending on the condition of the

> stent, the distance of the laser probe, and PO, ignition can occur after

> short impact times. To prevent stent ignition, oxygen concentration should

> be kept [is less than] 40%. When unusual circumstances require working

with

> higher oxygen concentrations, pulse duration needs to be limited or stent

> removal might be considered before firing the laser.

>

> (CHEST 2000; 117:1449-1454)

>

> Key words: adverse effects; burns; endoscopy; laser surgery; oxygen;

stents

>

> Abbreviations. [FIO.sub.2] = fraction of inspired oxygen; LPS = laser

> guide protection system; PO = power output; ST1 = radiolucent silicone

> stent, 1-cm distance; ST2 = radiopaque silicone stent, 1-cm distance; ST3

=

> radiolucent silicone stent with metal hoops, 1-cm distance; ST4 =

> radiolucent silicone stent, covered with blood, 1-cm distance; ST5 =

> radiopaque silicone stent, covered with blood, 1-cm distance; ST6 =

> radiolucent silicone stent, covered with soot, 1-cm distance; ST7 =

> radiolucent silicone stent, mounted on pig tracheal wall, 1-cm distance.,

> ST8 = radiopaque silicone stent, mounted on pig tracheal wall, 1-cm

> distance; ST9 = radiolucent silicone stent, mounted on pig tracheal wall,

> 0.5-cm distance; ST10 = radiopaque silicone stent, mounted on pig tracheal

> wall, 0.5-cm distance

>

> The Nd-YAG laser plays an important role in endoscopic treatment of

> endobronchial lesions. Endobronchial fires caused by combustion of

> endotracheal tubes are well-known dangers. The incendiary characteristics

> of various endotracheal tubes have been thoroughly tested.[1-5]

>

>

>