Reducing Treatment Errors Through Point-of-Care Glucometer Configuration.

BACKGROUND: Blood glucose (BG) testing is the most widely performed point-of-care (POC) test in a hospital setting. Multiple adverse events reported to the Food and Drug Administration (FDA) revealed that treatment decisions may be affected by information displayed on the POC glucometer's results screen. A randomized, crossover simulation study was conducted to compare two results screen configurations for ACCU-CHEK Inform II, a POC glucometer. METHODS: Prior to the study, a heuristic evaluation of the results screen configurations and a pilot study were conducted to select the two results screen configurations for comparison. At two multicampus medical centers, 66 nurse participants experienced two computer-based simulation scenarios that asked them to interpret glucometer readings and make treatment decisions for simulated patients with 32 mg/dL BG levels and subtle symptoms of hypoglycemia. One scenario displayed a numeric value ("32 mg/dL"), and the other displayed a range abbreviation, such as "RR LO" (out of reportable range; low). Treatment errors were recorded when the participant did not treat the hypoglycemic patient with glucose or when they administered insulin. RESULTS: When ACCU-CHEK Inform II displayed an "RR LO" reading, 10.6% of participants made a treatment error, including 6.7% of participants with prior training on the meaning of an "RR LO" reading. None of the participants made a treatment error when ACCU-CHEK Inform II displayed a "32 mg/dL" reading. CONCLUSION: Displaying a numeric BG reading eliminated potentially life-threating treatment errors caused by confusing range abbreviations. Manufacturers should consider these findings during future research and development of POC glucometers.

Transmission line models to simulate the impedance of the uterine vasculature during the ovarian cycle and pregnancy.

OBJECTIVES: Changes in uterine vascular impedance may yield diagnostic insight into physiological and pathological changes in uterine vascular resistance and compliance during the ovarian cycle and pregnancy. Herein, our objectives were to develop models to simulate uterine vascular impedance in order to gain insight into the vascular size and stiffness changes that occur during ovarian cycling and pregnancy. STUDY DESIGN: Two electrical analogue transmission line models were developed and evaluated based on goodness-of-fit to experimental impedance measurements, which were obtained in nonpregnant luteal and follicular phase (NP-L and NP-F) and pregnant (P) ewes (n=4-8 per group). First, an anatomically based, multi-segment, symmetric, branching transmission line model was developed. Parameter values were calculated based on experimental measurements of size and stiffness in the first three generations of the uterine arterial tree for NP-L, NP-F and P ewes. Then, a single segment transmission line model was developed and effective parameter values were optimized to best-fit the measured impedances. RESULTS: The anatomically based multi-segment model did not yield the expected good agreement with the experimental data (R(2)<0.5 for all groups). In contrast, the impedance spectra predicted by the single segment model agreed very well with experimental data (R(2)=0.93, 0.82, and 0.84 for NP-L, NP-F and P, respectively; p<0.0001, all groups). Furthermore, the changes in the best-fit model parameters for NP-F and P compared to the NP-L were consistent with the prior literature on the effects of the ovarian cycle and pregnancy on vascular resistance and compliance. In particular, compared to NP-L, NP-F had decreased longitudinal and terminal resistance with a modest increase in compliance whereas pregnancy caused more dramatic drops in longitudinal and terminal resistance and a significant increase in compliance. CONCLUSIONS: The single segment transmission line model is a useful tool to examine changes in vascular structure and function that occur during the ovarian cycle and pregnancy.

The effects of the ovarian cycle and pregnancy on uterine vascular impedance and uterine artery mechanics.

OBJECTIVES: Uterine vascular resistance (UVR) is the ratio of systemic mean arterial pressure to mean uterine blood flow and is sensitive to changes in small arteries and arterioles. However, it provides little or no insight into changes in large, conduit arteries. Fluctuations in estrogen (E2) and progesterone (P4) levels during the ovarian cycle are thought to cause uterine resistance artery vasodilation; the effects on large arteries are unknown. Herein, our objective was to use the uterine vascular impedance, which is sensitive to changes in small and large arteries, to determine the effects of the ovarian cycle and pregnancy on the entire uterine vasculature. STUDY DESIGN: Uterine vascular perfusion pressure and flow rate were recorded simultaneously in anesthetized sheep in the nonpregnant (NP) luteal (NP-L, n=6) and follicular (NP-F, n=7) phases and in late pregnancy (CP, n=10). Impedance and metrics of impedance (input impedance Z(0), index of wave reflection R(W), characteristic impedance Z(C)) were calculated. E2 and P4 levels were measured from jugular vein blood samples. Finally, from pressure-diameter tests post-mortem, large uterine artery circumferential elastic modulus (E(Circ)) was measured. Significant differences were evaluated by two-way ANOVA or Student's t-test. RESULTS: As expected, E2:P4 was higher in the NP-F group compared to the NP-L group (p<0.05). Also as expected, UVR and Z(0) decreased in the follicular phase compared to the luteal (p<0.05), but R(W), Z(C), and E(Circ) were unaltered. Pregnancy not only substantially decreased UVR (and Z(0)) (p<0.00001) but also decreased Z(C) (p<0.001), R(W) (p<0.0001), E(Circ) (p<0.01), and pulse wave velocity (p<0.0001). CONCLUSIONS: The E2:P4 ratio mediates resistance artery vasodilatation in nonpregnant states, but has no effect on conduit artery size or stiffness. In contrast, pregnancy causes dramatic vasodilation and remodeling, including substantial reductions in conduit artery stiffness and increases in conduit artery size, which affect pulsatile uterine hemodynamics.