Erythropoietin downregulates red blood cell clearance, increasing transfusion efficacy in severely anemic recipients.

Red blood cells (RBC) transfusion is used to alleviate symptoms and prevent complications in anemic patients by restoring oxygen delivery to tissues. RBC transfusion efficacy, that can be measured by a rise in hemoglobin (Hb) concentration, is influenced by donor-, product-, and recipient-related characteristics. In some studies, severe pre-transfusion anemia is associated with a greater than expected Hb increment following transfusion but the biological mechanism underpinning this relationship remains poorly understood. We conducted a prospective study in critically ill patients and quantified Hb increment following one RBC transfusion. In a murine model, we investigated the possibility that, in conjunction with the host erythropoietic response, the persistence of transfused donor RBC is improved to maintain a highest RBC biomass. We confirmed a correlation between a greater Hb increment and a deeper pre-transfusion anemia in a cohort of 17 patients. In the mouse model, Hb increment and post-transfusion recovery were increased in anemic recipients. Post-transfusion RBC recovery was improved in hypoxic mice or those receiving an erythropoiesis-stimulating agent and decreased in those treated with erythropoietin (EPO)-neutralizing antibodies, suggesting that EPO signaling is necessary to observe this effect. Irradiated recipients also showed decreased post-transfusion RBC recovery. The EPO-induced post-transfusion RBC recovery improvement was abrogated in irradiated or in macrophage-depleted recipients, but maintained in splenectomized recipients, suggesting a mechanism requiring erythroid progenitors and macrophages, but which is not spleen-specific. Our study highlights a physiological role of EPO in downregulating post-transfusion RBC clearance, contributing to maintain a vital RBC biomass to rapidly cope with hypoxemia.

SURPRISING ERYTHROCYTOSIS RESOLUTION AFTER MYOMECTOMY: MYOMATOUS ERYTHROCYTOSIS SYNDROME.

Myomatous erythrocytosis syndrome (MES) is a rare gynaecological condition associated with the presence of a uterine fibroid and isolated polycythaemia. The main characteristic of MES is that haemoglobin returns to a normal level after removal of the myoma. MES is poorly known and still not fully understood. This case report describes the history of a patient with MES with surprising erythrocytosis resolution after myomectomy. LEARNING POINTS: A case of myomatous erythrocytosis syndrome with a normal erythropoietin level is described, adding to the scarce literature; the mediator responsible for the erythrocytosis is not yet known.This is a rare presentation of a common condition: erythrocytosis and uterine fibroids are frequent in the general population but are only anecdotally correlated.Delayed diagnosis led to unnecessary aggressive treatment with the aim of reducing the haematocrit level to below 45%.

Pharmacodynamics of rocuronium in sickle cell patients.

BACKGROUND: Sickle cell disease is the most widespread genetic disease in the world. The chronic organ damage due to this disease could lead to variability of responses to the anaesthetic drugs. We analysed the pharmacodynamics response of rocuronium to sickle cell patients. METHODS: We observed and compared the onset time and clinical duration (time to recovery first twitch) of 0.6 mg kg-1 of rocuronium using a TOFscan® monitor, as well as the time before the first incremental dose (time to recovery second twitch), in a group of 22 homozygous sickle cell patients and a group of 23 controls, all programmed for laparoscopic surgical procedures. RESULTS: The onset time of rocuronium was longer in sickle cell patients [mean ± SD (extremes)], [6.3 ± 2.1 (1.8-10) min] than in the control group [2.5 ± 0.6 (1.4-3.5) min] (P < 0.01). The clinical duration was shorter in sickle cell patients [19.2 ± 7.1 (13-41) min] when compared to the control group [28.9 ± 6.9 (21-48) min] (P < 0.01). The time before the first incremental dose was shorter in the sickle cell patients group [27.7 ± 7.9 (19-49) min] compared to the control group [39.9 ± 8.7 (30-56) min] (P < 0.01). CONCLUSION: The onset time of rocuronium was significantly longer with a shorter duration of action in patients with sickle cell disease versus the general population.