Anemia en el paciente crítico y el rol de la hepcidina: entendiendo los nuevos conceptos sobre la interacción entre lesión, inflamación y anemia / Anemia in critically ill patient: role of hepcidin

La anemia es un trastorno multifactorial común en el paciente crítico, en que influyen hemodilución, aumento de pérdidas sanguíneas, inflamación y déficit de hierro, a través de una homeostasis patológica de hierro, con producción alterada de eritropoyetina y alteración de la eritropoyesis. Durante la inflamación los elevados niveles de hepcidina se correlacionan con la disminución del hierro disponible para la eritropoyesis quedando almacenado en depósitos principalmente en los macrófagos tisulares. Por el contrario cuando los niveles de hepcidina son bajos, el hierro se vuelve disponible para la eritropoyesis. La hepcidina sería un factor clave tanto en la homeostasis del hierro como en la eritropoyesis, sin embargo, nuestro conocimiento de su comportamiento en el trauma, la sepsis y otras condiciones críticas, es todavía limitado. Recientes estudios han venido a ampliar nuestra comprensión del rol de la hepcidina durante la sepsis o el síndrome de respuesta inflamatoria sistémica (SIRS). Los ensayos de hepcidina en plasma u orina aún no están ampliamente disponibles y es deseable que haya muy pronto un desarrollo permanente y una validación clínica de estos ensayos. Adicionalmente, la introducción de agonistas y antagonistas farmacológicos de la hepcidina pudieran mejorar las terapias corrientes de los desórdenes del hierro. Resumimos en este artículo información actual sobre la anemia en el paciente crítico y discutimos los avances recientes.

Anemia is a common multifactorial disorder in critically ill patients, which hemodilution influence, increased blood loss, swelling and deficit iron through a pathological iron homeostasis, with production erythropoietin altered and impaired erythropoiesis. During the inflammation high hepcidin levels correlate with decrease the iron available for erythropoiesis being stored in deposits primarily in tissue macrophages. On the contrary when hepcidin levels are low iron becomes available for erythropoiesis. Hepcidin would be a key factor in both the homeostasis as iron in erythropoiesis, however, our knowledge of behavior intrauma, sepsis and other critical conditions, is still limited. Recent studies have expanded our understanding the role of hepcidin during sepsis or response syndrome systemic inflammation (SIRS). Trials of hepcidin in plasma or urine even are not widely available and it is desirable to development and clinical validation of these tests has been published assoon is possible. Additionally, the introduction of pharmacological agonists and antagonists hepcidin could improve current therapies for disorders iron. This article summarized current information on anemia in critically ill patient and discuss recent developments.

Efeitos sistêmicos e regionais da hemodiluição isovolêmica aguda moderada e intensa / Systemic and regional effects of moderate and severe acute normovolemic hemodilution

A hemodiluição isovolêmica (HD) aguda visa minimizar os efeitos colaterais de transfusões de sangue. As células da mucosa intestinal são vulneráveis à isquemia. Foi avaliada a hipótese de que durante a HD moderada (HDM) e intensa (HDI), os parâmetros hemodinâmicos não refletem a isquêmia da mucosa gástrica. Foram utilizados 21 cães. A HD foi feita com Hetastarch 6 por cento(1:1). Foi observada diminuição do hematócrito arterial nos grupos HDM e HDI. A PAM não alterou nos 3 grupos e o DC aumentou após a HD. O PCO2-gap diminuiu apenas no grupo HDI. Pode-se concluir que tanto a HDM como a HDI tem estabilidade hemodinâmica e os parâmetros hemodinâmicos não retratam a isquêmia da mucosa gástrica / Acute normovolemic hemodilution (HD) is used to decrease side effects of blood transfusions. Intestinal mucosal cells are vulnerable to ischemia. We tested the hypothesis that during moderate (MHD) and severe (SHD) hemodilution, hemodynamic parameters do not reflect the ischemia of gastric mucosal. 21 mongrel dogs were utilized. The HD was done with 6 ppwwer cent Hetastarch (1:1). We observed a fall of the arterial hematocrit in MHD and SHD. The MAP did not change in the 3 groups and the CO elevated after the HD. The PCO2-gap rose only in the SHD group. We concluded that both MHD and SHD have hemodynamic stability and the hemodynamic parameters do not reflect ischemia of the gastric mucosal...

Safety of acute normovolemic haemodilution with hydroxyethyl starch during intracranial surgery.

The effect of acute normovolemic haemodilution on haemodynamics, serum osmolality and coagulation parameters was studied in 20 patients undergoing intracranial surgical procedures. After induction of anaesthesia, 740+/-153 ml of blood was collected and the same was replaced with an equal volume of 6% hexaethyl starch. Heart rate (HR), blood pressure (BP), central venous pressure (CVP) and end tidal carbon dioxide tension (Et CO2) were monitored for 45 min. Haemoglobin concentration (Hb), haematocrit (Hct), serum osmolality (Osm), bleeding time (BT), prothrombin time (PT) and platelet count were determined before and 45 min after haemodilution. Hb and Hct were significantly lower following haemodilution (13.1+/-1.8 and 10.3+/-1.7 g/dL for Hb and 38.0+/-4.6%. and 30.1+/-4.5% for Hct). There was no significant change in the HR, BP and Et CO2 throughout the study period. CVP increased marginally from 35 to 45 min but was within normal limits. There was no significant change in serum osmolality, bleeding time and prothrombin time following haemodilution. Platelet count decreased following haemodilution but the values were within normal limits. The brain relaxation, as assessed by a semiquantitative scale, was satisfactory in all cases. None of the patients developed intraoperative brain swelling. In conclusion, acute normovolemic haemodilution with hexaethyl starch is tolerated well haemodynamically. It does not cause changes in serum osmolality which can increase brain oedema. It has no adverse effect on intraoperative haemostasis. It is a safe technique to decrease homologous blood transfusion during intracranial surgery.

Seguridad del Haemaccel/Solucel en pacientes sometidos a hemodilución normovolémica intencional preoperatoria (Estudio multicéntrico internacional)

El uso de Haemaccel/Soluccel en 305 pacientes sometidos a hemodilución preoperatoria normovolémica intencional, ha sido documentada en un estudio abierto, prospectivo, multicéntrico, controlado y multinacional (doce centros en 5 países). Los hallazgos reproducen el índice bajo de efectos adversos encontrados en la literatura corriente

Cardiovascular responses to phenylephrine during acute experimental anaemia in anaesthetized cats.

Experiments were performed on anaesthetized artificially ventilated cats to study the effects of phenylephrine (PE) on cardiovascular responsiveness, before and after induction of experimental anaemia. Acute anaemia was induced by replacement of blood by dextran in three steps of 20% each of total estimated blood volume. The effect of PE (20 micrograms/kg) was investigated at four stages: control and after 1st, 2nd and 3rd exchanges of blood. Induction of anaemia produced a significant increase in heart rate (HR) and cardiac output (CO) and a decrease in right atrial pressure (RAP). No significant change in mean arterial pressure (MAP), LV dP/dt max and blood gas tension was observed. Administration of bolus dose of PE produced a rapid rise in MAP, LVdP/dt max, and a decrease in HR without a change in the RAP. The pattern of response to PE was similar after induction of acute anaemia, however the magnitude of the response was significantly reduced. The attenuation in the response to PE was related to the fall in the haematocrit (HCT) level. This shows that induction of experimental anaemia, produced an increase in CO due to an increase in HR and SV and the effect of PE on cardiovascular responsiveness was significantly attenuated. The reduced sensitivity to PE during acute anaemia could be due to many factors such as inadequate O2 supply, effect of local vasodilating agents or some other cardiotonic agents which are known to contribute to vascular responsiveness.