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Old 04-19-2011, 08:12 AM
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RickI RickI is offline
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Default Tissue damage from Nitrox?

Scotty just put this up on Facebook. They were looking at Nitrox, makes you wonder if Trimix has similar effects?

"EuroPRevent: Diving May Damage Blood Vessels

By Crystal Phend, Senior Staff Writer, MedPage Today
Published: April 18, 2011
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner


GENEVA -- Repeat scuba dives appear to harm the endothelium, particularly when breathing the mix of gases popular with recreational divers, according to a small study.

With the low-nitrogen air mix called nitrox, endothelial function as measured by flow mediated dilation dropped significantly after each dive -- and didn't fully recover between dives, Emeline Van Craenenbroeck, MD, PhD, of Antwerp University Hospital in Antwerp, Belgium, and colleagues reported.

Endothelial repair mechanisms appeared activated as well in their study of 10 divers, presented here at the European Society of Cardiology's EuroPRevent meeting.

Based on the results of this small study, Van Craenenbroeck told MedPage Today that in his opinion the use of regular compressed air was safer for vessels.

Nitrox is popular because its lower nitrogen content allows divers to stay down longer and return to the surface faster with less decompression time needed, she explained."


"We already knew diving was bad for the endothelium," Van Craenenbroeck told MedPage Today, noting that one prior study suggested that endothelial function didn't return to baseline more than six days after just a single dive.

What effect these repeated dings to blood vessels function and repair mechanisms for frequent divers, such as military and professional divers, have on cardiovascular outcomes isn't known.

"There's no data on it," Van Craenenbroeck cautioned.

But she noted that it might be expected to lead to more atherosclerosis and coronary artery disease.

Still, divers have a choice in the gas mix they use and could attempt to protect their vessels by a preconditioning jog before going down into the water, since this method boosts oxygenation in soccer players and stimulates endothelial progenitor cells in healthy individuals, she suggested."

""Diving with nitrox generates less bubbles during decompression, but elicits more hyperoxia," she told attendees. "We know that the hyperoxia during diving elicits oxidative stress and subsequent endothelial dysfunction.""
Continued at:
http://networkedblogs.com/gPU1S

Related observations were published in:

"A single air dive reduces arterial endothelial function in man.
Brubakk AO, Duplancic D, Valic Z, Palada I, Obad A, Bakovic D, Wisloff U, Dujic Z.

Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway. alfb@ntnu.no

Abstract

During and after decompression from dives, gas bubbles are regularly observed in the right ventricular outflow tract. A number of studies have documented that these bubbles can lead to endothelial dysfunction in the pulmonary artery but no data exist on the effect of diving on arterial endothelial function. The present study investigated if diving or oxygen breathing would influence endothelial arterial function in man. A total of 21 divers participated in this study. Nine healthy experienced male divers with a mean age of 31 +/- 5 years were compressed in a hyperbaric chamber to 280 kPa at a rate of 100 kPa min(-1) breathing air and remaining at pressure for 80 min. The ascent rate during decompression was 9 kPa min(-1) with a 7 min stop at 130 kPa (US Navy procedure). Another group of five experienced male divers (31 +/- 6 years) breathed 60% oxygen (corresponding to the oxygen tension of air at 280 kPa) for 80 min. Before and after exposure, endothelial function was assessed in both groups as flow-mediated dilatation (FMD) by ultrasound in the brachial artery. The results were compared to data obtained from a group of seven healthy individuals of the same age who had never dived. The dive produced few vascular bubbles, but a significant arterial diameter increase from 4.5 +/- 0.7 to 4.8 +/- 0.8 mm (mean +/- s.d.) and a significant reduction of FMD from 9.2 +/- 6.9 to 5.0 +/- 6.7% were observed as an indication of reduced endothelial function. In the group breathing oxygen, arterial diameter increased significantly from 4.4 +/- 0.3 mm to 4.7 +/- 0.3 mm, while FMD showed an insignificant decrease. Oxygen breathing did not decrease nitroglycerine-induced dilatation significantly. In the normal controls the arterial diameter and FMD were 4.1 +/- 0.4 mm and 7.7 +/- 0.2.8%, respectively. This study shows that diving can lead to acute arterial endothelial dysfunction in man and that oxygen breathing will increase arterial diameter after return to breathing air. Further studies are needed to determine if these mechanisms are involved in tissue injury following diving.”"
J Physiol. 2005 Aug 1;566(Pt 3):901-6. Epub 2005 Jun 16
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