Relationship between whole blood base excess and CO2 content in vivo

Loeppky, Jack A.; Fletcher, E.R.; Roach, Robert C.; Luft, Ulrich C.

doi:10.1016/0034-5687(93)90060-n

Cited by 21 publications

(18 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rise in LA as percent of VO 2 max was similar in both studies. The close inverse relationship between LA rise and HCO 3 − as percent of VO 2 max when PIO 2 is acutely reduced has been confirmed in other studies (3,18,24). Also, the similarity of the rise in LA Fig.…”

Section: Discussionsupporting

confidence: 65%

See 1 more Smart Citation

V_ESTPD as a measure of ventilatory acclimatization to hypobaric hypoxia

Loeppky

Sheard

Salgado

et al. 2016

Physiology International

View full text Add to dashboard Cite

This study compared the ventilation response to an incremental ergometer exercise at two altitudes: 633 mmHg (resident altitude = 1,600 m) and following acute decompression to 455 mmHg (≈4,350 m altitude) in eight male cyclists and runners. At 455 mmHg, the V E STPD at RER <1.0 was significantly lower and the V E BTPS was higher because of higher breathing frequency; at VO 2 max, both V E STPD and V E BTPS were not significantly different. As percent of VO 2 max, the V E BTPS was nearly identical and V E STPD was 30% lower throughout the exercise at 455 mmHg. The lower V E STPD at lower pressure differs from two classical studies of acclimatized subjects (Silver Hut and OEII), where V E STPD at submaximal workloads was maintained or increased above that at sea level. The lower V E STPD at 455 mmHg in unacclimatized subjects at submaximal workloads results from acute respiratory alkalosis due to the initial fall in HbO 2 (≈0.17 pHa units), reduction in PACO 2 (≈5 mmHg) and higher PAO 2 throughout the exercise, which are partially pre-established during acclimatization. Regression equations from these studies predict V E STPD from VO 2 and P B in unacclimatized and acclimatized subjects. The attainment of ventilatory acclimatization to altitude can be estimated from the measured vs. predicted difference in V E STPD at low workloads after arrival at altitude.

show abstract

Section: Discussionsupporting

confidence: 65%

“…The resulting equation utilized in Table II (11) and base excess (BE) for fully oxygenated whole blood (18). Table II indicates that the average reduction of H + during exercise at 455 mmHg compared to 633 mmHg is ≈7 nmol/L, contributing to offset the chemoreceptor hypoxic drive.…”

Section: Discussionmentioning

confidence: 99%

V_ESTPD as a measure of ventilatory acclimatization to hypobaric hypoxia

Loeppky

Sheard

Salgado

et al. 2016

Physiology International

View full text Add to dashboard Cite

show abstract

“…• Arterial O 2 : Content based on Hb (hemoglobin concentration) = 15 g%, arterial PO 2 = PAO 2 , saturation = standard dissociation curve [21] at pHa (arterial pH, the negative log of H + in arterial blood) calculated to maintain whole blood base excess (BE) equal to baseline [22], where a pHa value of 7.420 was assumed.…”

Section: Total Gas Stores Model With Blood Flow and Volume Redistribumentioning

confidence: 99%

“…Table 1 shows the compartmental and total gas stores calculated for the three exercise conditions from the flow and volume redistribution model. Because lactate, bicarbonate concentration (HCO 3 -), and BE changes are linearly related [22], we incorporated a decrease in whole blood BE of 4 mmol/L estimated from other studies (see "Discussion") during the 5th min after cuff deflation to account for circulating lactate. The values from the total stores model from Table 1 are indicated in Figure 4 in relation to the 5 min-integrated stores changes obtained from measured gas exchange (Figure 2).…”

Section: Whole Body Co 2 Smentioning

confidence: 99%

Effects of acute leg ischemia during cycling on oxygen and carbon dioxide stores

Loeppky¹

2008

JRRD

View full text Add to dashboard Cite

Abstract-This study estimated changes in whole body oxygen stores (O 2 s) and carbon dioxide stores (CO 2 s) during steady state exercise with leg ischemia induced by leg cuff inflation. Six physically fit subjects performed 75 W steady state exercise for 15 min on a cycle ergometer. After 5 min of exercise, cuffs on the upper and lower legs were inflated to 140 mmHg. Cuffs were deflated after 5 min and exercise continued for another 5 min. O 2 uptake and CO 2 output significantly increased during the first 30 s after inflation, significantly decreased between 60 and 90 s, and then rose linearly until deflation. and significantly increased further after cuff deflation, peaking between 30 and 60 s and then returned to near baseline exercise levels. Modelestimated changes in total O 2 s and CO 2 s were compared with time-integrated store changes from and . During 5 min after cuff deflation, and exceeded the model-estimated change in stores by 273 and 697 mL, respectively. These results reflect the O 2 cost repayment of the anaerobic component and lactate buffering to neutralize circulating metabolites caused by the preceding ischemia.

show abstract

“…All compartments were assumed to be well-mixed with the movement of gases in the respiratory system and blood in the pulmonary circulation being primarily through bulk axial convection (considered one-dimensional ignoring all radial variations). Blood was considered as a uniform, single-phase medium with instantaneous chemical reactions; hence species contents were related to the equilibrium tensions using empirical dissociation curves (15,28,32,41) (refer to Appendix C for details). Mixed venous inlet blood gas tensions were held constant throughout the simulations and physiological shunting of blood was ignored.…”

Section: Model Developmentmentioning

confidence: 99%