[Incidental internal mammary lymph node biopsy in 113 cases of breast cancer undergoingfree abdominal flap breast reconstruction and its influencing factors].

Objective: The aim of the current study is to determine the clinical value of incidental internal mammary lymph node biopsy in free abdominal flap breast reconstruction using internal mammary vessels as recipient vessels and to investigate the risk factors of internal mammary lymph nodes metastasis. Methods: The clinical data of all patients who underwent free abdominal flap breast reconstruction using internal mammary vessels as recipient vessels from November 2006 to December 2015 in the Department of Breast Surgery, Fudan University Shanghai Cancer Center were reviewed in the study. The incidence of internal mammary lymph node biopsy and the rate of metastasis were analyzed. Statistical analysis was conducted to evaluate the risk factors of internal mammary lymph node metastasis. Results: A total of 113 patients met the inclusion criteria, 53 (46.9%) of whom had internal mammary lymph nodes harvested. Four of these were positive for metastatic disease, all in immediate breast reconstructions. The incidence of metastasis was 7.5% in patients who had successful internal mammary lymph node biopsies.The multi-variate Logistic regression analysis showed that invasive tumor size, tumor location and axillary lymph node metastasis were not risk factors for internal mammary lymph node metastasis (P>0.05). Conclusions: Internal mammary lymph nodes found incidentally during recipient vessel exposure may provide important information about internal mammary lymph node metastasis in free flap breast reconstruction. This approach for internal mammary lymph node biopsy reveals an appreciable success rate and is convenient in clinical practice. The size of invasive tumor and the axillary lymph node metastasis are probably associated with internal mammary lymph node positivity.

Simulation of intraluminal gas transport processes in the microcirculation.

Intraluminal resistance to gas transport between the microcirculation and tissue was neglected for a half-century following the early work of Krogh. In recent years it has come to be understood that this neglect is seriously in error. This paper reviews the background for the long period of misdirection, and progress in placing the simulation of gas transport processes on a more accurate, quantitative basis.

A theoretical model for gas transport and acid/base regulation by blood flowing in microvessels.

An investigation was made of the coupling between O2 and CO2 transport by blood flowing in microvessels. The blood was treated as two continuous coexisting phases: a red blood cell (RBC) phase and a plasma phase. The microvessel was divided into two regions: the central, RBC-rich and the outer, cell-free region. The radial distribution of RBCs and transport of various species due to bulk convection and radial diffusion were taken into account. Chemical and transport processes which were included in the model are (1) interactions of hemoglobin with O2 and CO2, (2) the Bohr and Haldane effects (the inter-dependence of O2/CO2 transport), (3) CO2 hydration-dehydration reactions, (4) buffering actions of hemoglobin and plasma proteins, and (5) anion exchange across the red cell membrane. The governing equations of the model subjected to the imposed inlet and boundary conditions were solved numerically to provide the concentration distributions of various species in blood that are important in the simultaneous gas exchange and pH regulation process. Predictions of the new model of simultaneous O2/CO2 transport by flowing blood were shown to be in excellent agreement with prior workers' experimental results from large artificial membrane tubes. A previous mathematical model which treats blood as a homogeneous continuum and uses a local chemical equilibrium approximation to describe the gas transport was shown to satisfactorily predict the amount of O2 transport for blood oxygenation accompanied by CO2 elimination. However, the previous model significantly underpredicts O2 transfer for blood deoxygenation accompanied by CO2 uptake. Furthermore, the previous model disagrees substantially with the CO2 transport results under both oxygenation and deoxygenation conditions.

A simple model for prediction of oxygen transport rates by flowing blood in large capillaries.

A simple model has been developed for simulation of oxygen transport to and from blood flowing in conduits of the diameter of arterioles and larger (greater than or equal to 20 microns). The basis is the large capillary model (LCAP) of P.K. Nair, et al. 1989 which has been validated experimentally. Detailed calculations of the oxygen concentration distribution reveal that the dominant resistance to oxygen transport is distributed in the plasma. Relatively little resistance is present within or in the immediate vicinity of the red cells. On the basis of these findings, LCAP was simplified from four simultaneous nonlinear partial differential equations (PDEs) to one PDE by (1) assuming chemical equilibrium within the red blood cells, (2) neglecting intracellular and extracellular boundary layer resistances, and (3) incorporating transport in the cell-free region adjacent to the capillary wall into the boundary conditions. The simplified model is much easier to apply mathematically to new situations. A comparison between LCAP and the simpler model shows that they give virtually the same predictions, and the predictions agree well with experimental measurements. The model is predictive in that all the parameters are determined from the literature or from independent measurements. Thus it should be useful in studies of physiological significance, as well as in design and analysis of extracorporeal blood oxygenators.