Nine treatments of 1000 mL therapeutic phlebotomy in a subject with polycythemia: A case report.

Large-volume therapeutic phlebotomy is the mainstay of hemochromatosis treatment and offers an opportunity to investigate the hemodynamic changes during acute hypovolemia. An otherwise healthy 64-year-old male with hemochromatosis participated. On nine separate visits, 1000 mL therapeutic phlebotomy was performed. On one occasion, pre- and post-phlebotomy orthostatic challenge with 27° reverse Trendelenburg position was administered. Mean arterial pressure, heart rate, and stroke volume were measured continuously during the procedures. The patient's tolerance to the interventions was continuously evaluated. The procedures were well tolerated by the patient. Mean arterial pressure was maintained during hemorrhage and following phlebotomy in both supine and reverse Trendelenburg positions, primarily through an increase in heart rate and systemic vascular resistance. The present study found that 1000 mL therapeutic phlebotomy in a patient with hemochromatosis may be acceptably and safely used to model hemorrhage. The approach demonstrates high clinical applicability and ethically robustness in comparison with volunteer studies.

Prioritized Brain Circulation During Ergometer Cycling with Apnea and Face Immersion in Ice-Cold Water: A Case Report.

BACKGROUND: Successful cardiopulmonary resuscitation after drowning or avalanche is often attributed to hypothermia-induced decrease in metabolism, which adapts the oxygen demand to the amount supplied under cardiac compression. Four decades ago, we speculated if oxygen-sparing mechanisms like those found in marine mammals, may improve cerebral oxygenation during acute airway blockade in humans. We investigated hemodynamic changes during steady state ergometer cycling with intermittent periods of apnea and face immersion (AFI) in ice-cold water. During AFI, heart rate (HR) dropped by 58% whereas average blood velocity (ABV) determined by means of a Doppler ultrasound velocity meter (UNIDOP University of Oslo, Oslo, Norway) fell by 85% in the radial artery and rose by 67% in the vertebral artery. Similar changes occured in radial artery ABV, albeit more slowly, when the test subject only held his breath while cycling. When he breathed via a snorkel during face immersion, HR remained unchanged while radial artery ABV fell transiently and subsequently returned to its pre-immersion level. These findings later were confirmed by other investigators. Moreover, a recent study revealed that the seal even has a system for selective brain cooling during the dive. CONCLUSION: Our research has confirmed prioritized cerebral circulation during AFI in cold water. We hypothesize that these changes may improve brain oxygenation due both to greater blood flow and possibly also to faster brain cooling, as demonstrated in diving seals.

[Regulation of the iron metabolism]. / Regulering av jernbalansen.

BACKGROUND: The regulation of iron absorption has previously been considered <>. Recent research has given us interesting information on the regulation of the iron metabolism and pathological iron overload; the present article aims at providing an overview of these topics. MATERIALS AND METHODS: The article is based on a review of literature retrieved from PubMed. RESULTS: The peptide hepcidin binds to ferroportin on membranes of enterocytes, macrophages and hepatocytes. The complex is internalised and degraded and this results in decreased export of iron to the circulation, and thus a lower level of plasma iron. Hepcidin production is up-regulated in iron overload and down-regulated with iron deficiency. The liver proteins human haemochromatosis protein (HFE), transferrin receptor 2 (TfR2), haemojuvelin (HJV) and bone morphogenetic protein (BNP) are necessary regulators for activation of the hepcidin synthesis. Lack of or mutations in the genes for these proteins, e.g. the HFE mutation C282Y in primary haemochromatosis, reduces the synthesis of hepcidin. Iron regulatory proteins (IRP) may bind to iron responsive elements (IRE) of ferritin-mRNA and transferritin-mRNA and regulate the protein synthesis. INTERPRETATION: Regulation of uptake, utilization, release and storage of iron occurs at the gene level. Hepcidin is currently considered to be the <> of the iron balance. Intracellular iron balance is maintained by iron regulating proteins. Synthesis of ferritin increases with high iron levels, while synthesis of TfR1 is reduced. The opposite occurs with a low iron level.