Does transfusion using a syringe infusion pump and small-gauge needle cause hemolysis?

Hemolysis of two- and nine-day-stored sedimented red blood cells (hematocrit 65%), infused by a constant-rate syringe delivery pump through a 25-gauge needle was investigated. Fifteen-ml aliquots of blood were pumped through the system at flow rates of 10.6, 20.5, and 70 ml/hour. Plasma-free hemoglobin and potassium were measured and compared to controls. Significant red blood cell hemolysis occurred during passage through this infusion system, and the amount of hemolysis was greater with nine-day-stored cells. These cells showed more hemolysis with slower flow rates, but the two-day-stored cells were not affected by rate of flow.     

Effects of Fenwal 4C2423 transfusion microfilter on microaggregates and other constituents of stored blood

The effects of a new micropore transfusion filter (Fenwal 4C2423) on stored whole blood have been examined. Five filters were preloaded by passage of two units of outdated type specific bank blood, and the effects of filtration on a third unit, consisting of 21-day-old blood, flowing under 150 mmHg pressure, were measured. Filtration did not significantly alter red blood cell count, total hemoglobin, red blood cell fragility, plasma sodium, potassium, albumin, or globulin. Some platelets and white blood cells were removed and a small amount of hemolygis of erythrocytes (less than 0.1%) was observed. Removal of microaggregates, assessed by Coulter counting, screen filtration pressure, total screen porteins, wet and dry weights of material retained, and scanning electron microscopy, was shown to be excellent over the entire range of particle size. Comparison of the Bentley PFS-127, Fenwal 4C2417, Johnson & Johnson Intersept, Pall Ultipore, and Swank IL200 filters led to the conclusion that the Fenwal 4C2423 was both a significant improvement over the previous Fenwal design and comparable to the most efficient of these filters for both the removal of microaggregates during massive blood transfusion and for the blood flow rates obtained.     

Evaluation of ten disposable manual resuscitators

We evaluated the performance and safety of 10 disposable resuscitators -- six adult units: SPUR, Code Blue, 1st Response, Hospitak MPR, CPR Bag, and Pulmanex; and four pediatric units: CPR Bag, 1st Response, Hospitak MPR, and LSP Bag Mask. METHOD: We tested the devices against the American Society for Testing and Materials (ASTM) Standard F-920. We tested each resuscitator by using a lung model, the Bio-Tek VT-1 Ventilator Tester. RESULTS: All resuscitators met the ventilation requirements for VT and f (adult: 600 mL x 12/min; child: 300 mL x 20/min and 70 mL x 30/min) and I:E less than 1:1. Standard F-920 specifies a fractional delivered O2 concentration (FDO2) greater than or equal to 0.85 with attachments and greater than or equal to 0.40 without attachments, at oxygen flow of 15 L/min, and VE of 7.2 L (600 mL x 12/min) for adult units and VE of 6 L (300 mL x 20/min) for pediatric units. All 10 resuscitators met standard F-920 for FDO2 with attachments. Nine resuscitators met the FDO2 standard without attachments. The 10 resuscitators passed the test for valve function after contamination with simulated vomitus, at an oxygen flow of 30 L/min, and for backward leakage. Three pediatric resuscitators (1st Response, Hospitak MPR, and LSP Bag Mask) did not pass the pressure-limit requirement of 40 +/- 10 cm H2O. Four resuscitators, Hospitak MPR (adult and pediatric) and CPR Bag (adult and pediatric), were unable to pass the test for mechanical shock (a fall from a height of at least 1 meter). CONCLUSION: We conclude that only Code Blue, 1st response, Pulmanex (with tube-type reservoir), and SPUR meet ASTM Standard F-920 and are acceptable replacements for permanent resuscitators.     

The spatial distribution and temporal dynamics of brain regions activated during the perception of object and non-object patterns

Both animal and human studies suggest that the efficiency with which we are able to grasp objects is attributable to a repertoire of motor signals derived directly from vision. This is in general agreement with the long-held belief that the automatic generation of motor signals by the perception of objects is based on the actions they afford. In this study, we used magnetoencephalography (MEG) to determine the spatial distribution and temporal dynamics of brain regions activated during passive viewing of object and non-object targets that varied in the extent to which they afforded a grasping action. Synthetic Aperture Magnetometry (SAM) was used to localize task-related oscillatory power changes within specific frequency bands, and the time course of activity within given regions-of-interest was determined by calculating time-frequency plots using a Morlet wavelet transform. Both single subject and group-averaged data on the spatial distribution of brain activity are presented. We show that: (i) significant reductions in 10-25 Hz activity within extrastriate cortex, occipito-temporal cortex, sensori-motor cortex and cerebellum were evident with passive viewing of both objects and non-objects; and (ii) reductions in oscillatory activity within the posterior part of the superior parietal cortex (area Ba7) were only evident with the perception of objects. Assuming that focal reductions in low-frequency oscillations (<30 Hz) reflect areas of heightened neural activity, we conclude that: (i) activity within a network of brain areas, including the sensori-motor cortex, is not critically dependent on stimulus type and may reflect general changes in visual attention; and (ii) the posterior part of the superior parietal cortex, area Ba7, is activated preferentially by objects and may play a role in computations related to grasping.     

Mechanisms of impaired beta-adrenoceptor-induced airway relaxation by interleukin-1beta in vivo in the rat.

We studied the in vivo mechanism of beta-adrenergic receptor (beta-AR) hyporesponsiveness induced by intratracheal instillation of interleukin-1beta (IL-1beta, 500 U) in Brown-Norway rats. Tracheal and bronchial smooth muscle responses were measured under isometric conditions ex vivo. Contractile responses to electrical field stimulation and to carbachol were not altered, but maximal relaxation induced by isoproterenol (10(-6)-10(-5) M) was significantly reduced 24 h after IL-1beta treatment in tracheal tissues and to a lesser extent, in the main bronchi. Radioligand binding using [125I]iodocyanopindolol revealed a 32+/-7% reduction in beta-ARs in lung tissues from IL-1beta-treated rats, without any significant changes in beta2-AR mRNA level measured by Northern blot analysis. Autoradiographic studies also showed significant reduction in beta2-AR in the airways. Isoproterenol-stimulated cyclic AMP accumulation was reduced by IL-1beta at 24 h in trachea and lung tissues. Pertussis toxin reversed this hyporesponsiveness to isoproterenol but not to forskolin in lung tissues. Western blot analysis revealed an IL-1beta-induced increase in Gi(alpha) protein expression. Thus, IL-1beta induces an attenuation of beta-AR-induced airway relaxation through mechanisms involving a reduction in beta-ARs, an increase in Gi(alpha) subunit, and a defect in adenylyl cyclase activity.