Effects of altering O2 delivery on VO2 of isolated, working muscle

1976 ◽  
Vol 230 (2) ◽  
pp. 327-334 ◽  
Author(s):  
DH Horstman ◽  
M Gleser ◽  
J Delehunt
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Muscle Blood Flow ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Hemoglobin Concentration ◽  
Arterial Oxygen ◽  
Vo2 Max ◽  
Before And After ◽  
O2 Delivery

Maximal oxygen consumption (VO2 max) and muscle blood flow (Q max) were measured in an isolated gracilis muscle preparation before and after alteration in perfusion pressure (BP), arterial oxygen saturation (SaO2), and hemoglobin concentration (Hb). Q varied directly with BP and inversely with Hb (viscosity) but was unaffected by changes in arterial SaO2. VO2 max varied directly with oxygen delivery under all conditions. These results indicate that VO2 max is normally limited by oxygen delivery rather than any intrinsic limiting of oxygen consumption of the muscle.

scholarly journals Does recombinant human Epo increase exercise capacity by means other than augmenting oxygen transport?

2008 ◽  
Vol 105 (2) ◽  
pp. 581-587 ◽  
Author(s):  
C. Lundby ◽  
P. Robach ◽  
R. Boushel ◽  
J. J. Thomsen ◽  
P. Rasmussen ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Uptake ◽  
Oxygen Delivery ◽  
Maximal Oxygen Consumption ◽  
Hemoglobin Concentration ◽  
Arterial Oxygen ◽  
Peak Exercise ◽  
Healthy Humans ◽  
Human Erythropoietin ◽  
Oxygen Carrying Capacity

This study was performed to test the hypothesis that administration of recombinant human erythropoietin (rHuEpo) in humans increases maximal oxygen consumption by augmenting the maximal oxygen carrying capacity of blood. Systemic and leg oxygen delivery and oxygen uptake were studied during exercise in eight subjects before and after 13 wk of rHuEpo treatment and after isovolemic hemodilution to the same hemoglobin concentration observed before the start of rHuEpo administration. At peak exercise, leg oxygen delivery was increased from 1,777.0 ± 102.0 ml/min before rHuEpo treatment to 2,079.8 ± 120.7 ml/min after treatment. After hemodilution, oxygen delivery was decreased to the pretreatment value (1,710.3 ± 138.1 ml/min). Fractional leg arterial oxygen extraction was unaffected at maximal exercise; hence, maximal leg oxygen uptake increased from 1,511.0 ± 130.1 ml/min before treatment to 1,793.0 ± 148.7 ml/min with rHuEpo and decreased after hemodilution to 1,428.0 ± 111.6 ml/min. Pulmonary oxygen uptake at peak exercise increased from 3,950.0 ± 160.7 before administration to 4,254.5 ± 178.4 ml/min with rHuEpo and decreased to 4,059.0 ± 161.1 ml/min with hemodilution ( P = 0.22, compared with values before rHuEpo treatment). Blood buffer capacity remained unaffected by rHuEpo treatment and hemodilution. The augmented hematocrit did not compromise peak cardiac output. In summary, in healthy humans, rHuEpo increases maximal oxygen consumption due to augmented systemic and muscular peak oxygen delivery.

Oxygen transport in the critically ill

2016 ◽  
Author(s):  
Stephan M. Jakob ◽  
Jukka Takala
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Saturation ◽  
Oxygen Transport ◽  
Oxygen Delivery ◽  
Arterial Oxygen Saturation ◽  
Lactate Concentration ◽  
Mixed Venous Oxygen Saturation ◽  
Arterial Oxygen ◽  
Venous Oxygen Saturation ◽  
Mixed Venous

Adequate oxygen delivery is crucial for organ survival. The main determinants of oxygen delivery are cardiac output, haemoglobin concentration, and arterial oxygen saturation. The adequacy of oxygen delivery also depends on oxygen consumption, which may vary widely. Mixed venous oxygen saturation reflects the amount of oxygen not extracted by the tissues, and therefore provides useful information on the relationship between oxygen delivery and oxygen needs. If not in balance, tissue hypoxia may ensue and arterial lactate concentration increases. This occurs at higher oxygen delivery rates in acute compared with chronic diseases where metabolic adaptions often occur. Arterial and mixed venous oxygen saturation are related to each other. The influence of mixed venous saturation on arterial saturation increases with an increasing intrapulmonary shunt. This chapter discusses interactions between the components of oxygen transport and how they can be evaluated. Various methods for measuring tissue oxygenation and oxygen consumption are also presented, together with their limitations.

Low chemoresponsiveness and inadequate hyperventilation contribute to exercise-induced hypoxemia

1995 ◽  
Vol 79 (2) ◽  
pp. 575-580 ◽  
Author(s):  
C. A. Harms ◽  
J. M. Stager
Keyword(s):  
Oxygen Consumption ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Co2 Production ◽  
Arterial Oxygen ◽  
Ventilatory Parameters ◽  
Exercise Induced ◽  
End Tidal

Is inadequate hyperventilation a cause of the exercise-induced hypoxemia observed in some athletes during intense exercise? If so, is this related to low chemoresponsiveness? To test the hypothesis that exercise-induced hypoxemia, inadequate hyperventilation, and chemoresponsiveness are related, 36 nonsmoking healthy men were divided into hypoxemic (Hyp; n = 13) or normoxemic (Nor; n = 15) groups based on arterial oxygen saturation (SaO2; Hyp < or = 90%, Nor > 92%) observed during maximum O2 uptake (VO2max). Men with intermediate SaO2 values (n = 8) were only included in correlation analysis. Ventilatory parameters were collected at rest, during a treadmill maximal oxygen consumption (VO2max) test, and during a 5-min run at 90% VO2max. Chemoresponsiveness at rest was assessed via hypoxic ventilatory response (HVR) and hypercapnic ventilatory response (HCVR). VO2max was not significantly different between Nor and Hyp. SaO2 was 93.8 +/- 0.9% (Nor) and 87.7 +/- 2.0% (Hyp) at VO2max. End-tidal PO2 and the ratio of minute ventilation to oxygen consumption (VE/VO2) were lower while PETCO2 was higher for Hyp (P < or = 0.01). End-tidal PO2, end-tidal PCO2, and VE/VO2 correlated (P < or = 0.05) to SaO2 (r = 0.84, r = -0.70, r = 0.72, respectively), suggesting that differences in oxygenation were due to differences in ventilation. HVR and HCVR were significantly lower for Hyp. HVR was related to VE/VO2 (r = 0.43), and HCVR was related to the ratio of VE to CO2 production at VO2max (r = 0.61)

Splanchnic Oxygen Consumption Is Impaired during Severe Acute Normovolemic Anemia in Anesthetized Humans

2006 ◽  
Vol 105 (1) ◽  
pp. 37-44 ◽  
Author(s):  
Mali Mathru ◽  
Daneshvari R. Solanki ◽  
Lee C. Woodson ◽  
J Sean Funston ◽  
Orthan Ozkan ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Oxygen Delivery ◽  
Biochemical Markers ◽  
Anaerobic Metabolism ◽  
Hemoglobin Concentration ◽  
Whole Body ◽  
Before And After ◽  
Normovolemic Anemia ◽  
Splanchnic Oxygen ◽  
Beta Hydroxybutyrate

Background In conscious humans, reduction in hemoglobin concentration to 5 g/dl did not produce inadequate systemic oxygenation. However, systemic measures of inadequate oxygenation may not be sufficiently sensitive to detect inadequate oxygenation in individual organs such as splanchnic organs. The authors tested the hypothesis that acute normovolemic anemia to hemoglobin less than 6.0 g/dl in anesthetized humans reduces splanchnic oxygen consumption because of diminished whole body oxygen delivery. Methods Elective spine (n = 12) and abdominal (n = 7) surgery patients underwent acute normovolemic anemia to decrease the hemoglobin concentration close to 6.0 g/dl. The authors assessed the development of supply-dependent conditions in systemic and regional vascular beds by two primary measures before and after acute normovolemic anemia: oxygen consumption and surrogate biochemical markers of anaerobic metabolism, including plasma lactate, regional lactate kinetics, and ketone body ratio. Results When hemoglobin was reduced from 13.6 +/- 1.2 to 5.9 +/- 0.3 g/dl, oxygen supply dependency occurred in the splanchnic and preportal tissues but not at the systemic level. Regional supply dependency was accompanied by biochemical markers of anaerobic metabolism. Conclusions In anesthetized humans, a reduction in hemoglobin to 5.9 g/dl by acute normovolemic anemia diminished splanchnic and preportal whole body oxygen delivery and impaired splanchnic and preportal oxygen consumption. This was accompanied by increased plasma levels of regional lactate and an increased beta-hydroxybutyrate-to-acetoacetate ratio. These findings suggest that the risk to the gastrointestinal tract during acute normovolemic anemia may be underestimated.

Acute dietary nitrate supplementation does not attenuate oxidative stress or the hemodynamic response during submaximal exercise in hypobaric hypoxia

2018 ◽  
Vol 43 (12) ◽  
pp. 1268-1274 ◽  
Author(s):  
Colin R. Carriker ◽  
Paige Rombach ◽  
Brooke M. Stevens ◽  
Roger A. Vaughan ◽  
Ann L. Gibson
Keyword(s):  
Oxidative Stress ◽  
Oxygen Consumption ◽  
Hypobaric Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Maximal Oxygen Consumption ◽  
Arterial Oxygen ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Nitrate Supplementation ◽  
Plasma Nitrite

The purpose of this study was to investigate changes in oxidative stress, arterial oxygen saturation (SaO2), blood pressure (BP), and heart rate (HR) during exercise in hypobaric hypoxia following acute dietary nitrate supplementation. Nine well-trained (maximal oxygen consumption, 60.8 ± 7.8 mL·kg−1·min−1) males (age, 29 ± 7 years) visited the laboratory on 3 occasions, each separated by 1 week. Visit 1 included a maximal aerobic cycling test and five 5-min increasing-intensity exercise bouts in a normobaric environment (1600 m). A single dose of either a nitrate-depleted placebo (PL) or a nitrate-rich beverage (NR; 12.8 mmol nitrate) was consumed 2.5 h prior to exercise during visits 2 and 3 (3500 m) in a double-blind, placebo-controlled, crossover study consisting of a 5-min cycling warm-up and 4 bouts, each 5 min in duration, separated by 4-min periods of passive rest. Exercise wattages were determined during visit 1 and corresponded to 25%, 40%, 50%, 60%, and 70% of normobaric maximal oxygen consumption. Catalase and 8-isoprostane were measured before and after exercise (immediately before and 1 h postexercise, respectively). NR increased plasma nitrite (1.53 ± 0.83 μmol·L−1) compared with PL (0.88 ± 0.56 μmol·L−1) (p < 0.05). In both conditions, postexercise (3500 m) 8-isoprostane (PL, 23.49 ± 3.38 to 60.90 ± 14.95 pg·mL−1; NR, 23.23 ± 4.12 to 52.11 ± 19.76 pg·mL−1) and catalase (PL, 63.89 ± 25.69 to 128.15 ± 41.80 mmol·min−1·mL−1; NR, 78.89 ± 30.95 to 109.96 ± 35.05 mmol·min−1·mL−1) were elevated compared with baseline resting values (p < 0.05). However, both 8-isoprostane and catalase were similar in the 2 groups (PL and NR) (p = 0.217 and p = 0.080, respectively). We concluded that an acute, pre-exercise dose of dietary nitrate yielded no beneficial changes in oxidative stress, SaO2, BP, or HR in healthy, aerobically fit men exercising at 3500 m.

scholarly journals Spleen contraction elevates hemoglobin concentration at high altitude during rest and exercise

2020 ◽  
Vol 120 (12) ◽  
pp. 2693-2704
Author(s):  
Erika Schagatay ◽  
Alexander Lunde ◽  
Simon Nilsson ◽  
Oscar Palm ◽  
Angelica Lodin-Sundström
Keyword(s):  
High Altitude ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Step Test ◽  
Arterial Oxygen ◽  
Spleen Volume ◽  
Spleen Contraction ◽  
Response To Exercise ◽  
Rest And Exercise

Abstract Purpose Hypoxia and exercise are known to separately trigger spleen contraction, leading to release of stored erythrocytes. We studied spleen volume and hemoglobin concentration (Hb) during rest and exercise at three altitudes. Methods Eleven healthy lowlanders did a 5-min modified Harvard step test at 1370, 3700 and 4200 m altitude. Spleen volume was measured via ultrasonic imaging and capillary Hb with Hemocue during rest and after the step test, and arterial oxygen saturation (SaO2), heart rate (HR), expiratory CO2 (ETCO2) and respiratory rate (RR) across the test. Results Resting spleen volume was reduced with increasing altitude and further reduced with exercise at all altitudes. Mean (SE) baseline spleen volume at 1370 m was 252 (20) mL and after exercise, it was 199 (15) mL (P < 0.01). At 3700 m, baseline spleen volume was 231 (22) mL and after exercise 166 (12) mL (P < 0.05). At 4200 m baseline volume was 210 (23) mL and after exercise 172 (20) mL (P < 0.05). After 10 min, spleen volume increased to baseline at all altitudes (NS). Baseline Hb increased with altitude from 138.9 (6.1) g/L at 1370 m, to 141.2 (4.1) at 3700 m and 152.4 (4.0) at 4200 m (P < 0.01). At all altitudes Hb increased from baseline during exercise to 146.8 (5.7) g/L at 1370 m, 150.4 (3.8) g/L at 3700 m and 157.3 (3.8) g/L at 4200 m (all P < 0.05 from baseline). Hb had returned to baseline after 10 min rest at all altitudes (NS). The spleen-derived Hb elevation during exercise was smaller at 4200 m compared to 3700 m (P < 0.05). Cardiorespiratory variables were also affected by altitude during both rest and exercise. Conclusions The spleen contracts and mobilizes stored red blood cells during rest at high altitude and contracts further during exercise, to increase oxygen delivery to tissues during acute hypoxia. The attenuated Hb response to exercise at the highest altitude is likely due to the greater recruitment of the spleen reserve during rest, and that maximal spleen contraction is reached with exercise.

Muscle maximal O2 uptake at constant O2 delivery with and without CO in the blood

1990 ◽  
Vol 69 (3) ◽  
pp. 830-836 ◽  
Author(s):  
M. C. Hogan ◽  
D. E. Bebout ◽  
A. T. Gray ◽  
P. D. Wagner ◽  
J. B. West ◽  
...  
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Hemoglobin Concentration ◽  
O2 Uptake ◽  
Isometric Twitch ◽  
O2 Delivery ◽  
Arterial Po2 ◽  
O2 Dissociation Curve ◽  
Total Hemoglobin Concentration

In the present study we investigated the effects of carboxyhemoglobinemia (HbCO) on muscle maximal O2 uptake (VO2max) during hypoxia. O2 uptake (VO2) was measured in isolated in situ canine gastrocnemius (n = 12) working maximally (isometric twitch contractions at 5 Hz for 3 min). The muscles were pump perfused at identical blood flow, arterial PO2 (PaO2) and total hemoglobin concentration [( Hb]) with blood containing either 1% (control) or 30% HbCO. In both conditions PaO2 was set at 30 Torr, which produced the same arterial O2 contents, and muscle blood flow was set at 120 ml.100 g-1.min-1, so that O2 delivery in both conditions was the same. To minimize CO diffusion into the tissues, perfusion with HbCO-containing blood was limited to the time of the contraction period. VO2max was 8.8 +/- 0.6 (SE) ml.min-1.100 g-1 (n = 12) with hypoxemia alone and was reduced by 26% to 6.5 +/- 0.4 ml.min-1.100 g-1 when HbCO was present (n = 12; P less than 0.01). In both cases, mean muscle effluent venous PO2 (PVO2) was the same (16 +/- 1 Torr). Because PaO2 and PVO2 were the same for both conditions, the mean capillary PO2 (estimate of mean O2 driving pressure) was probably not much different for the two conditions, even though the O2 dissociation curve was shifted to the left by HbCO. Consequently the blood-to-mitochondria O2 diffusive conductance was likely reduced by HbCO.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Volume Changes in Patients With Cystic Fibrosis

PEDIATRICS ◽  
1977 ◽  
Vol 59 (4) ◽  
pp. 588-594
Author(s):  
Amnon Rosenthal ◽  
Lawrence N. Button ◽  
Kon Taik Khaw
Keyword(s):  
Cystic Fibrosis ◽  
Blood Volume ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Pulmonary Involvement ◽  
Progressive Increase ◽  
Cor Pulmonale ◽  
Arterial Oxygen ◽  
Mean Corpuscular Hemoglobin ◽  
Total Blood

Simultaneous red blood cell (RBC) and plasma volume determinations were obtained in 16 patients with cystic fibrosis (CF) and moderately severe pulmonary involvement. Hypervolemia with an increase in both RBC and plasma volumes was observed. Changes in blood volume were marked when values were indexed by weight but less significant when indexed by height. Decreasing systemic arterial oxygen saturation was associated with a progressive increase in RBC mass, hematocrit value, and hemoglobin level and a decrease in mean corpuscular hemoglobin concentration. RBC and total blood volumes were highest in patients with cor pulmonale and congestive heart failure. However, the compensatory polycythemic response in patients with CF was inadequate when compared with the response to hypoxemia in patients with cyanotic congenital heart disease. The insufficient oxygen-carrying capacity may compromise tissue oxygen delivery and necessitate treatment.

scholarly journals Changes in Respiratory Parameters and Fin-Swimming Performance Following a 16-Week Training Period with Intermittent Breath Holding

2015 ◽  
Vol 49 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Vasileios Stavrou ◽  
Argyris G. Toubekis ◽  
Eleni Karetsi
Keyword(s):  
Group Performance ◽  
Swimming Performance ◽  
Arterial Oxygen Saturation ◽  
Respiratory Muscles ◽  
Arterial Oxygen ◽  
Breath Holding ◽  
Performance Time ◽  
Respiratory Parameters ◽  
Before And After ◽  
And Performance

Abstract The purpose of this study was to examine the effects of training with intermittent breath holding (IBH) on respiratory parameters, arterial oxygen saturation (SpO2) and performance. Twenty-eight fin-swimming athletes were randomly divided into two groups and followed the same training for 16 weeks. About 40% of the distance of each session was performed with self-selected breathing frequency (SBF group) or IBH (IBH group). Performance time of 50 and 400 m at maximum intensity was recorded and forced expired volume in 1 s (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF) and SpO2 were measured before and after the 50 m test at baseline and post-training. Posttraining, the respiratory parameters were increased in the IBH but remained unchanged in the SBF group (FEV1: 17 ±15% vs. -1 ±11%; FVC: 22 ±13% vs. 1 ±10%; PEF: 9 ±14% vs. -4 ±15%; p<0.05). Pre compared to post-training SpO2 was unchanged at baseline and decreased post-training following the 50 m test in both groups (p<0.05). The reduction was higher in the IBH compared to the SBF group (p<0.05). Performance in the 50 and 400 m tests improved in both groups, however, the improvement was greater in the IBH compared to the SBF group in both 50 and 400 m tests (p<0.05). The use of IBH is likely to enhance the load on the respiratory muscles, thus, contributing to improvement of the respiratory parameters. Decreased SpO2 after IBH is likely due to adaptation to hypoventilation. IBH favours performance improvement at 50 and 400 m fin-swimming.

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