TY - JOUR
T1 - Hypoxia-induced intrapulmonary arteriovenous shunting at rest in healthy
AU - Laurie, Steven S.
AU - Yang, Ximeng
AU - Elliott, Jonathan E.
AU - Beasley, Kara M.
AU - Lovering, Andrew T.
PY - 2010/10
Y1 - 2010/10
N2 - Intrapulmonary arteriovenous (IPAV) shunting has been shown to occur at rest in some subjects breathing a hypoxic gas mixture [fraction of inspired oxygen (FIO2 = 0.12] for brief periods of time. In the present study we set out to determine if IPAV shunting could be induced at rest in all subjects exposed to hypoxia for 30 min. Twelve subjects (6 women) breathed four levels of hypoxia (FIO2 = 0.16, 0.14, 0.12, and 0.10) for 30 min each in either an ascending or descending order with a 15-min normoxic break between bouts. Saline contrast echocardiography was used to detect IPAV shunt and a shunt score (0 -5) was assigned based on contrast in the left ventricle with a shunt score ≥ 2 considered significant. Pulmonary artery systolic pressure (PASP) was determined using Doppler ultrasound. The total number of subjects demonstrating shunt scores ≥ 2 for FIO2 0.16, 0.14, 0.12, and 0.10 was 1/12, 7/12, 9/12, and 12/12, respectively. Shunt scores were variable between subjects but significantly greater than normoxia for FIO2O2 0.12 and 0.10. Shunt scores correlated with peripheral measurements of arterial oxygen saturation (SpO2) (rw =-0.67) and PASP (r w = 0.44), despite an increased shunt score but no increase in PASP while breathing an FIOO2 = 0.12. It is unknown how hypoxia induces the opening of IPAV shunts but these vessels may be controlled via similar mechanisms as systemic vessels that vasodilate in response to hypoxia. Despite intersubject variability our results indicate significant IPAV shunting occurs at rest in all subjects breathing an FIO2 = 0.10 for 30 min.
AB - Intrapulmonary arteriovenous (IPAV) shunting has been shown to occur at rest in some subjects breathing a hypoxic gas mixture [fraction of inspired oxygen (FIO2 = 0.12] for brief periods of time. In the present study we set out to determine if IPAV shunting could be induced at rest in all subjects exposed to hypoxia for 30 min. Twelve subjects (6 women) breathed four levels of hypoxia (FIO2 = 0.16, 0.14, 0.12, and 0.10) for 30 min each in either an ascending or descending order with a 15-min normoxic break between bouts. Saline contrast echocardiography was used to detect IPAV shunt and a shunt score (0 -5) was assigned based on contrast in the left ventricle with a shunt score ≥ 2 considered significant. Pulmonary artery systolic pressure (PASP) was determined using Doppler ultrasound. The total number of subjects demonstrating shunt scores ≥ 2 for FIO2 0.16, 0.14, 0.12, and 0.10 was 1/12, 7/12, 9/12, and 12/12, respectively. Shunt scores were variable between subjects but significantly greater than normoxia for FIO2O2 0.12 and 0.10. Shunt scores correlated with peripheral measurements of arterial oxygen saturation (SpO2) (rw =-0.67) and PASP (r w = 0.44), despite an increased shunt score but no increase in PASP while breathing an FIOO2 = 0.12. It is unknown how hypoxia induces the opening of IPAV shunts but these vessels may be controlled via similar mechanisms as systemic vessels that vasodilate in response to hypoxia. Despite intersubject variability our results indicate significant IPAV shunting occurs at rest in all subjects breathing an FIO2 = 0.10 for 30 min.
KW - Altitude
KW - Hypoxemia
KW - Pulmonaryartery pressure
KW - Saline contrast echocardiography
UR - http://www.scopus.com/inward/record.url?scp=78149329871&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78149329871&partnerID=8YFLogxK
U2 - 10.1152/japplphysiol.00150.2010
DO - 10.1152/japplphysiol.00150.2010
M3 - Article
C2 - 20689088
AN - SCOPUS:78149329871
SN - 8750-7587
VL - 109
SP - 1072
EP - 1079
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 4
ER -