Helium breathing provides modest antiinflammatory, but no endothelial protection against ischemia-reperfusion injury in humans in vivo.
BACKGROUND
The noble gas helium is devoid of anesthetic effects, and it elicits cardiac preconditioning. We hypothesized that inhalation of helium provides protection against postocclusive endothelial dysfunction after ischemia-reperfusion of the forearm in humans.


METHODS
Eight healthy male subjects were enrolled in this study with a crossover design. Each volunteer was randomly exposed to 15 min of forearm ischemia in the presence or absence of helium inhalation. Helium was inhaled at an end-tidal concentration of 50 vol% from 15 min before ischemia until 5 min after the onset of reperfusion ("helium conditioning"). Hyperemic reaction, a marker of nitric oxide bioavailability and endothelial function, was determined at 15 and 30 min of reperfusion on the forearm using venous occlusion plethysmography. Expression of the proinflammatory markers CD11b, ICAM-1, PSGL-1, and L-selectin (CD62L) on leukocytes and P-selectin (CD62P), PSGL-1, and CD42b on platelets were measured by flow cytometry during reperfusion.


RESULTS
Ischemia-reperfusion consistently reduced the postocclusive endothelium-dependent hyperemic reaction at 15 and 30 min of reperfusion. Periischemic inhalation of helium at 50 vol% did not improve postocclusive hyperemic reaction. Helium decreased expression of the proinflammatory marker CD11b and ICAM-1 on leukocytes and attenuated the expression of the procoagulant markers CD42b and PSGL-1 on platelets.


CONCLUSIONS
Although inhalation of helium diminished the postischemic inflammatory reaction, our data indicate that human endothelium, which is a component of all vital organs, is not amenable to protection by helium at 50 vol% in vivo. This is in contrast to sevoflurane, which protects human endothelium at low subanesthetic concentrations.
Lucchinetti
Eliana
E
Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, AB, Canada.
Wacker
Johannes
J
Maurer
Christian
C
Keel
Marius
M
Härter
Luc
L
Zaugg
Kathrin
K
Zaugg
Michael
M
D000280:Administration, Inhalation; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000503:physiopathology
D000894:Anti-Inflammatory Agents, Non-Steroidal; D006371:Helium