Spiroergometrische Leistungsdiagnostik vor und nach Blutspende

Blood withdrawal acutely impairs cardiac filling, output and aerobic capacity in proportion to induced hypovolemia in middle-aged and older women

Blood donation entails acute reductions of cardiorespiratory fitness in healthy men. Whether these effects can be extrapolated to blood donor populations comprising women remains uncertain. The purpose of this study was to comprehensively assess the acute impact of blood withdrawal on cardiac function, central hemodynamics and aerobic capacity in women throughout the mature adult lifespan. Transthoracic echocardiography and O2 uptake were assessed at rest and throughout incremental exercise (cycle ergometry) in healthy women (n = 30, age: 47-77 yr). Left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (Q̇) and peak O2 uptake (V̇O2peak), and blood volume (BV) were determined with established methods. Measurements were repeated following a 10% reduction of BV within a week period. Individuals were non-smokers, non-obese and moderately fit (V̇O2peak = 31.4 ± 7.3 mL·min-1·kg-1). Hematocrit and BV ranged from 38.0 to 44.8% and from 3.8 to 6.6 L, respectively. The standard 10% reduction in BV resulted in 0.5 ± 0.1 L withdrawal of blood, which did not alter hematocrit (P = 0.953). Blood withdrawal substantially reduced cardiac LVEDV and SV at rest as well as during incremental exercise (≥10% decrements, P ≤ 0.009). Peak Q̇ was proportionally decreased after blood withdrawal (P < 0.001). Blood withdrawal induced a 10% decrement in V̇O2peak (P < 0.001). In conclusion, blood withdrawal impairs cardiac filling, Q̇ and aerobic capacity in proportion to the magnitude of hypovolemia in healthy mature women. Novelty: The filling of the heart and therefore cardiac output are impaired by blood withdrawal in women. Oxygen delivery and aerobic capacity are reduced in proportion to blood withdrawal.

Iron supplementation limits the deleterious effects of repeated blood donation on endurance sport performance but not on iron status

BACKGROUND

Every day, blood banks worldwide face the challenge of ensuring an adequate blood supply. Iron deficiency is by far the most common cause of deferral of blood donors. The aim of the present study was to determine the effect of iron supplementation after repeated blood donation on iron status and physiological performance.

MATERIALS AND METHODS

Forty-four moderately trained and iron-replete subjects were randomly divided into a whole blood donation (n=36) and a placebo donation (n=8) group. One third of the donation group received no iron supplementation, whereas one third received 20 mg iron and one third received 80 mg iron daily for 28 days. The subjects were intended to make three donations 3 months apart, and recovery of endurance capacity, assessed by an incremental maximal cycling test, and haematological parameters was monitored up to 28 days after each donation.

RESULTS

Negative effects of repeated blood donation were found for markers of iron storage, markers of functional iron and/or iron metabolism regulation, and physiological markers. Iron supplementation did not affect iron storage but did limit, at the highest dose of 80 mg, the effect of blood donations on functional iron and/or iron metabolism regulation, and at both 20 and 80 mg the negative effects on maximal power output and peak oxygen consumption.

DISCUSSION

Iron supplementation limited the deleterious effects of repeated blood donation on endurance sport performance but not on decline in iron status in iron-replete young men. These results underline the importance of iron supplementation to minimise the deleterious effects of blood donation on physiological functions, and the necessity to optimise the supplementation strategy to preserve iron status.

Replicating measurements of total hemoglobin mass (tHb-mass) within a single day: precision of measurement; feasibility and safety of using oxygen to expedite carbon monoxide clearance

Hemoglobin concentration ([Hb]) is a function of total hemoglobin mass (tHb-mass) and plasma volume. [Hb] may fall by dilution due to plasma volume expansion and changes in the perioperative period may therefore correlate poorly with blood loss. A simple, reliable, repeatable way to measure plasma volume and tHb-mass would have substantial clinical utility. The "optimized carbon monoxide re-breathing method" (oCOR) meets these criteria. However, it is recommended that a minimum of 12 h (when breathing room air) is left between repeat measurements. Twenty-four subjects underwent 3 days of testing. Two oCOR tests were performed (T1 and T2), 3 h apart, with a different CO clearance method employed between tests aiming to keep the carboxyhemoglobin level below 10%. The primary aim was to ascertain whether tHb-mass testing could be safely repeated within 3 h if carboxyhemoglobin levels were actively reduced by breathing supplemental oxygen (PROCA ). Secondary aims were to compare two other clearance methods; moderate exercise (PROCB ), or a combination of the two (PROCC ). Finally, the reliability of the oCOR method was assessed. Mean (SD) tHb-mass was 807.9 ± (189.7 g) (for T1 on day 1). PROCA lowered the carboxyhemoglobin level from the end of T1 (mean 6.64%) to the start of T2 (mean 2.95%) by a mean absolute value of 3.69%. For PROCB and PROCC the mean absolute decreases in carboxyhemoglobin were 4.00% and 4.31%, respectively. The fall in carboxyhemoglobin between T1 and T2 was greatest in PROCC ; this was statistically significantly lower than that of PROCA (P = 0.0039) and PROCB (P = 0.0289). The test-retest reliability for the measurement of total hemoglobin mass was good with a mean typical error (TE) of 2.0%. The oCOR method is safe and can be repeated within 3 h when carbon monoxide is suitably cleared between tests. Using oxygen therapy alone adequately achieves this.

Effect of Repeated Whole Blood Donations on Aerobic Capacity and Hemoglobin Mass in Moderately Trained Male Subjects: A Randomized Controlled Trial

Background

The aims of the present study were to investigate the impact of three whole blood donations on endurance capacity and hematological parameters and to determine the duration to fully recover initial endurance capacity and hematological parameters after each donation.

Methods

Twenty-four moderately trained subjects were randomly divided in a donation (n = 16) and a placebo (n = 8) group. Each of the three donations was interspersed by 3 months, and the recovery of endurance capacity and hematological parameters was monitored up to 1 month after donation.

Results

Maximal power output, peak oxygen consumption, and hemoglobin mass decreased (p < 0.001) up to 4 weeks after a single blood donation with a maximal decrease of 4, 10, and 7%, respectively. Hematocrit, hemoglobin concentration, ferritin, and red blood cell count (RBC), all key hematological parameters for oxygen transport, were lowered by a single donation (p < 0.001) and cumulatively further affected by the repetition of the donations (p < 0.001). The maximal decrease after a blood donation was 11% for hematocrit, 10% for hemoglobin concentration, 50% for ferritin, and 12% for RBC (p < 0.001). Maximal power output cumulatively increased in the placebo group as the maximal exercise tests were repeated (p < 0.001), which indicates positive training adaptations. This increase in maximal power output over the whole duration of the study was not observed in the donation group.

Conclusions

Maximal, but not submaximal, endurance capacity was altered after blood donation in moderately trained people and the expected increase in capacity after multiple maximal exercise tests was not present when repeating whole blood donations.

Electronic supplementary material

The online version of this article (doi:10.1186/s40798-016-0067-7) contains supplementary material, which is available to authorized users.

Latest developments in peri-operative monitoring of the high-risk major surgery patient

Peri-operative monitoring technology has made great strides in the last 20 years with the introduction of minimally invasive devices to measure inter alia stroke volume, cardiac output, depth of anaesthesia and cerebral and tissue oxygen monitoring. Despite these technological advances, peri-operative management of the high risk major surgery patient has remained virtually unchanged. The vast majority of patients undergo a pre-operative assessment which is neither designed to quantify functional capacity nor predict outcome. Anaesthetists then usually monitor these patients using the same technology (e.g. pulse oximetry (SpO2), invasive systemic BP and CVP, end tidal carbon dioxide (etCO2) and anaesthetic agent monitoring) that was available in the early 1980s. Conventional intra-operative management can result in occult low levels of blood flow and oxygen delivery that lead to complications that only occur days or weeks following surgery and give false re-assurance to the anaesthetist that he or she is doing a "good job". Post-operative management then often takes place in an environment with reduced levels of both monitoring equipment and staff expertise. It is perhaps not surprising that outcome still remains poor in high-risk patients.(1) In this review, we will briefly describe the role of peri-operative optimization, some of the available monitors and indicate how their combined use might be beneficial in managing the high-risk surgical patient. We believe that although there is now evidence to suggest that the use of individual new monitors (such as assessment of fluid status, depth of anaesthesia, tissue oxygenation and blood flow) can influence outcome, it will only be their combination that will radically improve the peri-operative management and outcome of high-risk surgical patients. It is a matter of some urgency that large scale, prospective and collaborative studies be designed, funded and executed to prove or disprove this hypothesis.