PubMed · 7751123
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M H Montenegro, R J Simmons. 1995. Ghost cell glaucoma.. https://doi.org/10.1097/00004397-199503510-00012
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BACKGROUND: A minority of blood donors are Rh(D)-negative, and Rh(D)-negative red blood cell (RBC) products are often overutilized. As such, Rh(D)-negative RBCs may be difficult to maintain in blood bank inventory. STUDY DESIGN AND METHODS: We changed our blood bank laboratory policy to approve non-alloimmunized Rh(D)-negative patients to receive Rh(D)-positive RBCs for routine transfusion under defined criteria. Those criteria included Rh(D)-negative males (all ages) and females (aged >50 years) who were designated as do not resuscitate (DNR), either with or without intubation, in the electronic medical record. RESULTS: From August 15, 2024 through August 15, 2025, a total of 204 Rh(D)-negative patients met the above criteria and were approved to receive routine Rh(D)-positive RBC transfusions. Within that group, 23 patients received Rh(D)-positive RBCs. The remaining patients either did not require transfusion or were issued Rh(D)-negative RBC units. Since implementing this practice, a total of 68 Rh(D)-negative units were conserved during this time frame. Notably, 28 of the 68 units (41%) were type O, Rh(D)-negative. DISCUSSION: Rh(D)-positive RBCs can be routinely given to non-alloimmunized Rh(D)-negative patients who are not at risk for developing hemolytic disease of the fetus and newborn (HDFN). By creating clear guidelines for the routine administration of Rh(D)-positive RBCs to patients who are not at risk for HDFN, the inventory of Rh(D)-negative RBC units can be directed to those patients who would most benefit from this limited resource.
Laser treatment of port wine stains has often been modelled assuming that blood is distributed homogeneously over the dermal volume, instead of enclosed within discrete vessels. The purpose of this paper is to analyse the consequences of this assumption. Due to strong light absorption by blood, fluence rate near the centre of the vessel is much lower than at the periphery. Red blood cells near the centre of the vessel therefore absorb less light than those at the periphery. Effectively, when distributed homogeneously over the dermis, fewer red blood cells would produce the same absorption as the actual number of red blood cells distributed in discrete vessels. We quantified this effect by defining a correction factor for the effective absorbing blood volume of a single vessel. For a dermis with multiple vessels, we used this factor to define an effective homogeneous blood concentration. This was used in Monte Carlo computations of the fluence rate in a homogeneous skin model, and compared with fluence rate distributions using discrete blood vessels with equal dermal blood concentration. For realistic values of skin parameters the homogeneous model with corrected blood concentration accurately represents fluence rates in the model with discrete blood vessels. In conclusion, the correction procedure simplifies the calculation of fluence rate distributions in turbid media with discrete absorbers. This will allow future Monte Carlo computations of, for example, colour perception and optimization of vascular damage by laser treatment of port wine stain models with realistic vessel anatomy.
A 46-year-old man presented with right upper quadrant pain with a clinical suspicion of cholelithiasis and was referred for an abdominal ultrasound (US). On US evaluation, the liver and gallbladder were normal. Incidentally noted a homogeneous, well demarcated, hyperechoic, 5-cm mass in the inferior portion of the spleen. A subsequent Tc-99m labeled RBC scan showed a 5-cm photopenic area in the inferior portion of the spleen on perfusion and early blood pool images. Subsequent filling in on delayed images with slightly increased uptake relative to surrounding splenic tissue was seen on the final images (85 min). Splenic hemangiomas are rare neoplasms, although they still represent the most common primary neoplasm of the spleen. The incidence of splenic hemangiomas ranges from 0.03-14% in autopsy studies.