Transfusion
Medical > Therapy > General measures
Red blood cells transfusions
It is well known that there is a direct relationship between pulmonary vascular resistance and chronic hypoxia-induced polycytemia. Pulmonary vascular resistance rises exponentially as the hematocrit increases; significant effects have been observed when hematocrit values increase above 50% (Weisse et al., 1975, Nihill et al., 1976). The site of increased resistance is located in small pulmonary arteriols and venoules (Julien et al., 1985). The origins of the increased resistance to blood flow are increased blood viscosity and possibly a decreased availability of nitric oxide to smooth muscles cells due to higher hemoglobin concentrations (Defouilloy et al., 1998). Furthermore, it has been shown that patients with primary pulmonary hypertension have impaired blood rheology (Persson et al., 1991) when having a natural as well as a standardized hematocrit of 45 %. In severe chronic hypoxemic lung disease phlebotomy (hematocrit ¡Ü 50 %) has not been associated with adverse events, on the contrary, oxygen consumption remained stable, Frank-Starling performance, exercise tolerance and pulmonary gas exchange improved (Weisse et al., 1975, Borst et al., 1999). Taking into account the factors oxygen transport and viscosity, we know that in healthy humans the optimal hematocrit value is between 25 % and 50 % (Richardson and Guyton, 1959, Cinar et al., 1999). In conclusion, phlebotomy is recommended in patients with cor pulmonale and a hematocrit value above 50-55 % and blood transfusion are not necessary for hematocrit values above 30 %.
References
Back to > Medical > Therapy > General measures
Red blood cells transfusions
It is well known that there is a direct relationship between pulmonary vascular resistance and chronic hypoxia-induced polycytemia. Pulmonary vascular resistance rises exponentially as the hematocrit increases; significant effects have been observed when hematocrit values increase above 50% (Weisse et al., 1975, Nihill et al., 1976). The site of increased resistance is located in small pulmonary arteriols and venoules (Julien et al., 1985). The origins of the increased resistance to blood flow are increased blood viscosity and possibly a decreased availability of nitric oxide to smooth muscles cells due to higher hemoglobin concentrations (Defouilloy et al., 1998). Furthermore, it has been shown that patients with primary pulmonary hypertension have impaired blood rheology (Persson et al., 1991) when having a natural as well as a standardized hematocrit of 45 %. In severe chronic hypoxemic lung disease phlebotomy (hematocrit ¡Ü 50 %) has not been associated with adverse events, on the contrary, oxygen consumption remained stable, Frank-Starling performance, exercise tolerance and pulmonary gas exchange improved (Weisse et al., 1975, Borst et al., 1999). Taking into account the factors oxygen transport and viscosity, we know that in healthy humans the optimal hematocrit value is between 25 % and 50 % (Richardson and Guyton, 1959, Cinar et al., 1999). In conclusion, phlebotomy is recommended in patients with cor pulmonale and a hematocrit value above 50-55 % and blood transfusion are not necessary for hematocrit values above 30 %.
References
Back to > Medical > Therapy > General measures
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SSPH Research Prize 2012
Deadline for submission: April 30, 2012
Further information
Symposium "pulmonal-arterielle Hypertension im Kindesalter"
Donnerstag, 10. Mai 2012, 16.00-18.00, Bern
Further information:
5th International Congress of the Swiss Society of Pulmonary Hypertension (SSPH)
28.-29. September 2012, Thun, Congress Hotel Seepark Thun
Informationen: www.imk.ch/sgph2012
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