A New Automated Technology for Cerebrospinal Fluid Cell Counts: Comparison of Accuracy and Clinical Impact of GloCyte, Sysmex XN, and Manual Methods.

OBJECTIVES: The purpose of the study was to compare the performance of GloCyte (Advanced Instruments, Norwood, MA), a new semiautomated instrument for cerebrospinal fluid cell counting, with the manual hemocytometer method and the automated Sysmex XN (Sysmex, Kobe, Japan) body fluid mode. The clinical impact of replacing the manual method with either automated method was determined. METHODS: Fifty-seven samples from 38 patients were analyzed by all three methods. Pearson correlation and Passing-Bablok regression were used to compare methods. Cytospin smears were reviewed on all samples, and clinical histories were obtained. RESULTS: There was a strong linear relationship between the manual and automated methods for WBC counts ( R = 0.988 for GloCyte; R = 0.980 for Sysmex XN). Positive bias was absent or negligible for WBC counts less than 30/µL. GloCyte and manual RBC counts were equivalent. There were no samples for which replacement of manual WBC counts by automated counts would have changed the diagnosis. Both automated methods showed improved precision for WBC counts compared with the manual method. CONCLUSIONS: Replacing manual WBC counts by GloCyte or Sysmex XN WBC counts would improve consistency of results without compromising diagnostic accuracy.

Automated cerebrospinal fluid cell counts using the Sysmex XE-5000: is it time for new reference ranges?

The main objectives of the study were to compare manual and automated WBC counts on clear cerebrospinal fluid (CSF) samples. Clear CSF samples from 200 adults and children were studied. Cell counts were performed manually using a hemocytometer and then analyzed on the Sysmex XE-5000. Descriptive statistics and Spearman correlation for nonparametric data were used for method comparison. Manual WBC counts ranged from 0 to 702 cells/µL, and Sysmex counts ranged from 0 to 629 cells/µL. The Spearman rank correlation coefficient for the entire range of data was 0.77 (P < .001); however, the correlation was weaker at the low end of the data spectrum. For manual WBC ranges of 0 to 5 cells/µL and 0 to 10 cells/µL, the corresponding Sysmex 0 to 95th percentile ranges were 0 to 23 cells/µL and 0 to 27 cells/µL, respectively. The results suggest that larger studies are necessary to determine new reference ranges for automated CSF WBC counts.

In vitro evaluation of aerosol bronchodilator delivery during mechanical ventilation: pressure-control vs. volume control ventilation.

OBJECTIVE: To determine the effect of inspiratory time and inspiratory flow pattern on albuterol delivery by aerosol during mechanical ventilation. DESIGN: A ventilator was connected to a lung model and set to deliver a tidal volume of 0.6 l, PEEP 5 cmH(2)O, and respiratory rate of 15/min. We evaluated inspiratory times of 1 and 2 s, lung mechanics of 0.05 l/cmH(2)O compliance and 50 cmH(2)O/l/s resistance, or 0.02 l/cmH(2)O compliance and 5 cmH(2)O/l/s resistance, and three inspiratory flow patterns (constant flow volume-controlled ventilation, descending ramp flow volume-controlled ventilation, and pressure-controlled ventilation). Albuterol was delivered into the ventilator circuit by a nebulizer containing 5 mg (4 ml) albuterol or a pMDI and spacer (four actuations; 360 micro g). A filter between the Y-piece and the lung model collected the aerosol, which was analyzed for albuterol by spectrophotometry. RESULTS: For the nebulizer there were significant differences in albuterol delivered for inspiratory time, flow pattern, and lung mechanics. For the pMDI there were no significant differences for the amount of albuterol delivered for inspiratory time, flow pattern, or lung mechanics. CONCLUSIONS: Albuterol delivery by nebulizer is affected by inspiratory time and inspiratory flow pattern. When a pMDI is used, the amount of albuterol delivered is not affected by inspiratory flow pattern or inspiratory time.

In vitro evaluation of aerosol bronchodilator delivery during noninvasive positive pressure ventilation: effect of ventilator settings and nebulizer position.

OBJECTIVE: Respiratory failure due to exacerbation of obstructive lung disease has been successfully treated with noninvasive positive pressure ventilation (NPPV). However, there have been no reports of factors affecting aerosol delivery during NPPV. Our objective was to determine the effect of ventilator settings and nebulizer position on albuterol delivery during NPPV. DESIGN: Bench model study. SETTING: University laboratory. SUBJECTS: None. INTERVENTIONS: A Respironics BiPAP S/T-D30 with a standard circuit was attached to a lung model simulating spontaneous breathing. Inspiratory/expiratory pressures of 10/5, 15/5, 20/5, 15/10, 20/10, and 25/10 cm H2O were tested at respiratory rates of 10 and 20/min. A nebulizer was filled with 5 mg of albuterol in 4 mL of solution, driven with 8 L/min oxygen, and placed at either a proximal (ventilator outlet) or distal (between leak port and lung model connection) position. Albuterol delivery was estimated by measuring the amount of the albuterol collected on a filter placed at the inlet of the lung model. MEASUREMENT AND MAIN RESULTS: Albuterol delivery varied from 5.2 +/- 0.4% to 24.5 +/- 1.3% of the nominal dose and was significantly affected by the position of the nebulizer, respiratory rate, and BiPAP settings (p <.001 in each case). The greatest albuterol delivery was observed with the nebulizer operating at the distal position and a respiratory rate of 20/min. At this respiratory rate and nebulizer placement, albuterol delivery increased with increasing inspiratory pressure levels and decreased as expiratory pressure levels were increased. Nebulizer flow did not affect function of the ventilator. CONCLUSIONS: At optimum nebulizer position (between the leak port and patient connection) and ventilator settings (high inspiratory pressure and low expiratory pressure), as much as 25% of the nominal albuterol dose may be delivered during NPPV.