TY - JOUR
T1 - Chemoreceptor responsiveness at sea level does not predict the pulmonary pressure response to high altitude
AU - Hoiland, Ryan L.
AU - Foster, Glen E.
AU - Donnelly, Joseph
AU - Stembridge, Mike
AU - Willie, Chris K.
AU - Smith, Kurt J.
AU - Lewis, Nia C S
AU - Lucas, Samuel J.E.
AU - Cotter, Jim D.
AU - Yeoman, David J.
AU - Thomas, Kate N.
AU - Day, Trevor A.
AU - Tymko, Mike M.
AU - Burgess, Keith R.
AU - Ainslie, Philip N.
PY - 2015/7/1
Y1 - 2015/7/1
N2 - BACKGROUND: The hypoxic ventilatory response (HVR) at sea level (SL) is moderately predictive of the change in pulmonary artery systolic pressure (PASP) to acute normobaric hypoxia. However, because of progressive changes in the chemoreflex control of breathing and acid-base balance at high altitude (HA), HVR at SL may not predict PASP at HA. We hypothesized that resting oxygen saturation as measured by pulse oximetry (Spo2) at HA would correlate better than HVR at SL with PASP at HA. METHODS: In 20 participants at SL, we measured normobaric, isocapnic HVR (L/min · -%Spo2 -1) and resting PASP using echocardiography. Both resting Spo2 and PASP measures were repeated on day 2 (n = 10), days 4 to 8 (n = 12), and 2 to 3 weeks (n = 8) after arrival at 5,050 m. These data were also collected at 5,050 m in life-long HA residents (ie, Sherpa [n = 21]). RESULTS: Compared with SL, Spo2 decreased from 98.6% to 80.5% (P <.001), whereas PASP increased from 21.7 to 34.0 mm Hg (P <.001) after 2 to 3 weeks at 5,050 m. Isocapnic HVR at SL was not related to Spo2 or PASP at any time point at 5,050 m (all P >05). Sherpa had lower PASP (P <.01) than lowlanders on days 4 to 8 despite similar Spo2. Upon correction for hematocrit, Sherpa PASP was not different from lowlanders at SL but was lower than lowlanders at all HA time points. At 5,050 m, although Spo2 was not related to PASP in lowlanders at any point (all R2 ≤ 0.05, P >50), there was a weak relationship in the Sherpa (R2 = 0.16, P =.07). CONCLUSIONS: We conclude that neither HVR at SL nor resting Spo2 at HA correlates with elevations in PASP at HA.
AB - BACKGROUND: The hypoxic ventilatory response (HVR) at sea level (SL) is moderately predictive of the change in pulmonary artery systolic pressure (PASP) to acute normobaric hypoxia. However, because of progressive changes in the chemoreflex control of breathing and acid-base balance at high altitude (HA), HVR at SL may not predict PASP at HA. We hypothesized that resting oxygen saturation as measured by pulse oximetry (Spo2) at HA would correlate better than HVR at SL with PASP at HA. METHODS: In 20 participants at SL, we measured normobaric, isocapnic HVR (L/min · -%Spo2 -1) and resting PASP using echocardiography. Both resting Spo2 and PASP measures were repeated on day 2 (n = 10), days 4 to 8 (n = 12), and 2 to 3 weeks (n = 8) after arrival at 5,050 m. These data were also collected at 5,050 m in life-long HA residents (ie, Sherpa [n = 21]). RESULTS: Compared with SL, Spo2 decreased from 98.6% to 80.5% (P <.001), whereas PASP increased from 21.7 to 34.0 mm Hg (P <.001) after 2 to 3 weeks at 5,050 m. Isocapnic HVR at SL was not related to Spo2 or PASP at any time point at 5,050 m (all P >05). Sherpa had lower PASP (P <.01) than lowlanders on days 4 to 8 despite similar Spo2. Upon correction for hematocrit, Sherpa PASP was not different from lowlanders at SL but was lower than lowlanders at all HA time points. At 5,050 m, although Spo2 was not related to PASP in lowlanders at any point (all R2 ≤ 0.05, P >50), there was a weak relationship in the Sherpa (R2 = 0.16, P =.07). CONCLUSIONS: We conclude that neither HVR at SL nor resting Spo2 at HA correlates with elevations in PASP at HA.
U2 - 10.1378/chest.14-1992
DO - 10.1378/chest.14-1992
M3 - Article
C2 - 25501858
AN - SCOPUS:84937566605
VL - 148
SP - 219
EP - 225
JO - CHEST (Official publication of the American College of Chest Physicians)
JF - CHEST (Official publication of the American College of Chest Physicians)
SN - 0012-3692
IS - 1
ER -