Abstract
The majority of patients with intrapulmonary right-to-left shunting due to pulmonary arteriovenous malformations exhibit good maximum exercise capacity (>70% predicted) despite profound arterial oxygen desaturation. We studied seven such patients to assess tissue oxygen delivery during steady-state exercise. From rest to exercise [50 ± 7 (SE) W] arterial saturation fell from 80 ± 3 to 74 ± 3%, and mean right-to-left shunt increased slightly from 31 ± 4 to 34 ± 5% (P = NS). Minute ventilation was high for oxygen uptake, and the ventilatory equivalent was raised (174 ± 19% predicted) and was correlated with shunt size (r = 0.93). The majority of the patients maintained pulmonary alveolar blood flow within the predicted range for their power output, but total cardiac output was increased to 142 ± 11% predicted due to flow through the shunt. Consequently, on exercise, oxygen delivery per unit oxygen consumption [2.3-3.3 (normal range 1.6-2.4)] and calculated mixed venous oxygen tension (27.0 ± 0.8 Torr) were preserved. Arterial PCO2 rose on exercise by 2.8 ± 1.2 Torr, in proportion to the ratio of flow through the shunt to total cardiac output (r = 0.73), but remained low (33.1 ± 1.4 Torr) in absolute terms. The high cardiac output on exercise may be facilitated by a low pulmonary vascular resistance (0.33 ± 0.08 mmHg · l- 1 · min, measured at rest), which may explain why exercise performance is better in these patients than in patients with equivalent hypoxemia from other causes.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 321-328 |
| Number of pages | 8 |
| Journal | Journal of Applied Physiology |
| Volume | 75 |
| Issue number | 1 |
| State | Published - 1993 |
| Externally published | Yes |
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Keywords
- exercise hypoxemia
- pulmonary arteriovenous malformations
- right-to-left shunt
ASJC Scopus subject areas
- Endocrinology
- Physiology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation
Cite this
Cardiopulmonary response to exercise in patients with intrapulmonary vascular shunts. / Whyte, M. K B; Hughes, J. M B; Jackson, J. E.; Peters, A. M.; Hempleman, Steven C; Moore, D. P.; Jones, H. A.
In: Journal of Applied Physiology, Vol. 75, No. 1, 1993, p. 321-328.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Cardiopulmonary response to exercise in patients with intrapulmonary vascular shunts
AU - Whyte, M. K B
AU - Hughes, J. M B
AU - Jackson, J. E.
AU - Peters, A. M.
AU - Hempleman, Steven C
AU - Moore, D. P.
AU - Jones, H. A.
PY - 1993
Y1 - 1993
N2 - The majority of patients with intrapulmonary right-to-left shunting due to pulmonary arteriovenous malformations exhibit good maximum exercise capacity (>70% predicted) despite profound arterial oxygen desaturation. We studied seven such patients to assess tissue oxygen delivery during steady-state exercise. From rest to exercise [50 ± 7 (SE) W] arterial saturation fell from 80 ± 3 to 74 ± 3%, and mean right-to-left shunt increased slightly from 31 ± 4 to 34 ± 5% (P = NS). Minute ventilation was high for oxygen uptake, and the ventilatory equivalent was raised (174 ± 19% predicted) and was correlated with shunt size (r = 0.93). The majority of the patients maintained pulmonary alveolar blood flow within the predicted range for their power output, but total cardiac output was increased to 142 ± 11% predicted due to flow through the shunt. Consequently, on exercise, oxygen delivery per unit oxygen consumption [2.3-3.3 (normal range 1.6-2.4)] and calculated mixed venous oxygen tension (27.0 ± 0.8 Torr) were preserved. Arterial PCO2 rose on exercise by 2.8 ± 1.2 Torr, in proportion to the ratio of flow through the shunt to total cardiac output (r = 0.73), but remained low (33.1 ± 1.4 Torr) in absolute terms. The high cardiac output on exercise may be facilitated by a low pulmonary vascular resistance (0.33 ± 0.08 mmHg · l- 1 · min, measured at rest), which may explain why exercise performance is better in these patients than in patients with equivalent hypoxemia from other causes.
AB - The majority of patients with intrapulmonary right-to-left shunting due to pulmonary arteriovenous malformations exhibit good maximum exercise capacity (>70% predicted) despite profound arterial oxygen desaturation. We studied seven such patients to assess tissue oxygen delivery during steady-state exercise. From rest to exercise [50 ± 7 (SE) W] arterial saturation fell from 80 ± 3 to 74 ± 3%, and mean right-to-left shunt increased slightly from 31 ± 4 to 34 ± 5% (P = NS). Minute ventilation was high for oxygen uptake, and the ventilatory equivalent was raised (174 ± 19% predicted) and was correlated with shunt size (r = 0.93). The majority of the patients maintained pulmonary alveolar blood flow within the predicted range for their power output, but total cardiac output was increased to 142 ± 11% predicted due to flow through the shunt. Consequently, on exercise, oxygen delivery per unit oxygen consumption [2.3-3.3 (normal range 1.6-2.4)] and calculated mixed venous oxygen tension (27.0 ± 0.8 Torr) were preserved. Arterial PCO2 rose on exercise by 2.8 ± 1.2 Torr, in proportion to the ratio of flow through the shunt to total cardiac output (r = 0.73), but remained low (33.1 ± 1.4 Torr) in absolute terms. The high cardiac output on exercise may be facilitated by a low pulmonary vascular resistance (0.33 ± 0.08 mmHg · l- 1 · min, measured at rest), which may explain why exercise performance is better in these patients than in patients with equivalent hypoxemia from other causes.
KW - exercise hypoxemia
KW - pulmonary arteriovenous malformations
KW - right-to-left shunt
UR - http://www.scopus.com/inward/record.url?scp=0027214489&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027214489&partnerID=8YFLogxK
M3 - Article
VL - 75
SP - 321
EP - 328
JO - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology
JF - Journal of Applied Physiology Respiratory Environmental and Exercise Physiology
SN - 8750-7587
IS - 1
ER -