Algorithms utilizing peripheral blood hematopoietic progenitor cell counts in lieu of some CD34+ cell counts predict successful peripheral blood stem cell collections with substantial time and cost savings.

BACKGROUND AND OBJECTIVES: Hematopoietic progenitor cell (HPC) counts from Sysmex hematology analyzers have been shown to correlate with peripheral blood (PB) CD34+ cell counts by flow cytometry. Algorithms utilizing HPC counts to guide stem cell collections have been proposed but rarely tested. This study describes the development and validation of algorithms utilizing HPC and PB CD34+cell counts to predict adequate peripheral blood stem cell (PBSC) collections for chemomobilized and cytokine-mobilized individuals. MATERIALS AND METHODS: Utilizing a test set of 83 PB samples from chemomobilized or cytokine-mobilized PBSC collection patients, PB CD34+ counts were correlated with HPC counts and a receiver operating characteristic curve was constructed. Cut-offs of ≤0.5 HPC/µl and ≥7 HPC/µl were established to maximize sensitivity and specificity for using HPC to predict PB CD34+ ≥ 10 cells/µl. These cut-offs were subsequently validated using a separate prospective validation set of 88 HPC/CD34+ cell sample pairs. RESULTS: Using the algorithms, all patients in the prospective validation data set achieved adequate collections of ≥1 × 106 CD34+ cells/kg, and a 67% reduction in the number of CD34+ cell counts performed was achieved. This lead to a direct cost savings of at least $18,700 USD over a 21-month period (88% reduction in direct costs). CONCLUSION: Use of the algorithms provides significant time and cost savings for the laboratory while accurately predicting (i) timing of PBSC collections to obtain adequate CD34+ product yields for chemomobilized patients and (ii) when to administer plerixafor to cytokine-mobilized patients to improve the likelihood of achieving adequate collections.

External fixation of upper limb fractures: the effect of pin offset on fixator stability.

A Shearer fracture fixator was applied to a hardwood model using various pin configurations and load-displacement curves were obtained from compressive and bending loads. The results show that offsetting the pins by 60 degrees increases rigidity by a factor of 4-5.

Pin-hole shear stresses generated by conical and standard external fixation pins.

Pin-hole shear stresses generated by tapered (conical) and untapered (standard) external fixator pins were compared using a photoelastic technique. The results show that shear stresses progressively increase as a conical pin is inserted but remain the same for the standard pin irrespective of the depth of insertion.

Comparison of the stresses generated at the pin-bone interface by standard and conical external fixator pins.

The stresses generated at the pin-bone interface by external fixator pins have been compared using finite element analysis. The results show that higher stresses are generated by conical pins compared with standard pins of the same diameter. This raises the possibility that the rate of pin loosening may be higher for conical pins.

Bending stiffness of conical and standard external fixator pins.

The bending stiffnesses of a conical and a standard external fixator pin have been compared. The pins were inserted into pilot holes in a piece of teak hardwood and loads of different magnitudes were applied at a fixed moment arm. Force-deflection curves were obtained for each pin, and stiffness (newtons per metre) and percentage stiffness reduction were calculated for each pilot hole size. The results show that deflection increased (i.e. stiffness decreased) with increasing force or diameter of pilot hole. This loss of stiffness was linear for the standard pin but was bimodal for the conical pin.

An investigation of the bending stiffness of and the plane stresses generated by a flanged external fixator pin.

In an attempt to reduce pin loosening, a flanged external fixator pin has been designed and its bending stiffness has been compared with that of a standard pin. The pins were inserted into pilot holes previously drilled into a piece of teak hardwood. Loads of different magnitudes were applied at a fixed moment arm and force-deflection curves were obtained. Thereafter, percentage stiffness increase was calculated for each pilot hole size. The results show that the addition of a collar to the external fixator pin increases its stiffness and its ability to resist bending forces. In a parallel study, the stresses generated at the pin-bone interface by this pin and a standard pin were compared using finite element analysis techniques. The results show that the flange significantly reduced the stresses generated at the pin-bone interface. In addition, stresses were dissipated over a wider area.

Factors which may increase stresses at the pin-bone interface in external fixation: a finite element analysis study.

The pin-bone interface of the external fixation system has been studied using a finite element mode. The maximum stresses were observed in the near 'cortex' adjacent to the site of entry of the pin. This location coincides with the area where loosening is usually first observed radiologically. Other results indicate that the stress values are significantly increased by using deep threads and by using stainless steel instead of titanium.

Comments on the presentation of sexual distress in family planning clinics.

PIP: There is little question that the people seeking contraception are making statements regarding their sexuality. All family planning agencies are in the position to be helpful to people who are, or who might become sexually distressed. Some of the issues involved in the process of helping people identify and deal with their sexual difficulties are reviewed with focus primarily on the difficulties experienced and presented by women. Attention is directed to sexual distress in a broad sense and not merely to specific sexual dysfunctions. The clinical interview and pelvic examination offer good opportunities for identifying sexual distress. It is part of the job of physicians and nurses to check on patients' knowledge and to give permission to express sexual anxieties and uncertainties. Along with making efforts to establish that patients are knowledgeable, it is suggested that the following questions be kept in mind: 1) how does this woman feel about herself as a woman; 2) what sort of relationship(s) does she have; 3) how pleased or displeased is she with her sexual life. A woman who has experienced painful intercourse over a period of time may continue to do so after the original cause or causes have been dealt with, for this expectation becomes her reality. Such a woman may gain enormously by practicing Kegel's exercises and by gaining or regaining confidence regarding her ability to accommodate a penis without pain. through gradual and stress-free self-dilation. Samples of numerous reasons for a loss of interest in a sexual relationship are reviewed.^ieng

A finite element analysis of the effect of pin distribution on the rigidity of a unilateral external fixation system.

The effect of pin distribution on the rigidity of a unilateral external fixation system has been investigated using finite element techniques. The results show that spreading the pins out along the entire length of the bone is more stable than grouping the pins in clusters as is customary.

Monitoring fracture healing with strain gauges: the effect on strain values of strain gauge location on the pin circumference.

In an attempt to establish some principles for the use of strain gauges in monitoring fracture healing, four strain gauges were fastened onto the most proximal pin of a Shearer external fixator applied to a hardwood fracture model. Compression and bending loads were applied and the strain data were obtained. The results show that the location of the strain gauge on the circumference of the pin has a significant effect on strain values.

Effectiveness of a heat and moisture exchanger in preventing hyperpnoea induced bronchoconstriction in subjects with asthma.

The effect of a heat and moisture exchanger, a device with hygroscopic material for conditioning inspired air, on hyperpnoea induced bronchoconstriction was studied in nine non-smoking volunteers with asthma, aged 19-32 years. Each had previously shown an increase of at least 100% in specific airways resistance (sRaw) to isocapnic hyperpnoea with dry air. On two separate days the subject performed isocapnic hyperpnoea with dry air at 60-70 l min-1 for five minutes. Before, immediately after, and five minutes after completion of a test sRaw measurements were made. Heat and moisture exchangers were placed in the breathing circuit on one of the two days. All subjects had an increase in sRaw of 100% or more without the heat and moisture exchangers (average increase 300%) but were protected from bronchoconstriction with the devices in place (average increase 7%) (p less than 0.005). The exchanger's resistance to airflow was less than 1 cm H2O for flow rates of 100 l min-1. A heat and moisture exchanger designed as a facemask or mouthpiece may allow a person with asthma to exercise without the need for prophylactic drugs.

Patient work of breathing during pressure support and volume-cycled mechanical ventilation.

A computer-assisted technique based on the equation of motion of the respiratory system was used to measure inspiratory work of breathing in 11 patients during pressure support ventilation (PSV) and assisted, volume-cycled mechanical ventilation (AMV). During both modes of ventilation, patient work of breathing was calculated as the difference between the total work performed on the respiratory system (as predicted by the equation of motion) and the work performed by the ventilator. Patient work of breathing during AMV was also calculated as the difference between ventilator work measured during assisted and controlled mechanical breaths. By either method of work calculation, patient work of breathing during AMV was less than previously reported. In addition, when equal tidal volumes were delivered, there was no significant difference between the work performed by the patient during AMV and PSV. Patient work of breathing during PSV was found, however, to vary inversely with the level of pressure support. We conclude that: (1) patient work of breathing during AMV and PSV can be calculated using a computer-assisted technique based on the equation of motion of the respiratory system, and (2) depending on the amount of pressure support provided, patient work of breathing during PSV may be greater than, less than, or equal to the work performed during AMV.