Application of control chart statistics to blood pressure measurement variability in the primary care setting.

This study was undertaken as an interdisciplinary effort in response to a frequently frustrating clinical problem of interpreting variable blood pressure measurements under uncertain conditions of quality control. The method is an application of the Shewhart Control Chart analysis to blood pressure measurement in adults in an academic nursing center. The natural variability found in a series of blood pressure readings is measured and described after a pilot study to eliminate examiner, equipment, and time interval variability. Results revealed that there was a significant drop from the first systolic reading to subsequent readings. A three standard deviation limit will be met if the range between the second and third systolic reading does not exceed 13 and the range between the second and third diastolic readings does not exceed 11. Thus for recognition and management of measurement variability, three blood pressure measurements 1 minute apart should be taken as a routine, and the average of the second and third reading recorded. The positive impact on clients, providers, and interdisciplinary research colleagues in changing measurement technique to achieve greater quality in clinical practice is discussed. Limitations and recommendations are presented.

Plating medium pH as a factor in apparent survival of sublethally stressed yeasts.

Sublethally stressed cells of 9 of 10 species of yeast were recovered at maximum levels when potato dextrose agar was adjusted to approximately pH 8. The optimum for candida utilis was at approximately pH 10. At pH 3.5, as commonly employed with media selective for yeasts and molds, recovery of heat-stressed organisms ranged from essentially the same as at optimum pH to levels of 1% or less of the maximum count. The extent to which this may be of practical significance in assessing the microbiological quality of food products remains to be determined.

The effects of speed on the in vivo activity and length of a limb muscle during the locomotion of the iguanian lizard Dipsosaurus dorsalis.

The caudofemoralis muscle is the largest muscle that inserts onto the hindlimb of most ectothermic tetrapods, and previous studies hypothesize that it causes several movements that characterize the locomotion of vertebrates with a sprawling limb posture. Predicting caudofemoralis function is complicated because the muscle spans multiple joints with movements that vary with speed. Furthermore, depending on when any muscle is active relative to its change in length, its function can change from actively generating mechanical work to absorbing externally applied forces. We used synchronized electromyography, sonomicrometry and three-dimensional kinematics to determine in vivo caudofemoralis function in the desert iguana Dipsosaurus dorsalis for a wide range of speeds of locomotion from a walk to nearly maximal sprinting (50-350 cm s(-1)). Strain of the caudofemoralis increased with increasing tail elevation and long-axis rotation and protraction of the femur. However, knee extension only increased caudofemoralis strain when the femur was protracted. The maximum and minimum length of the caudofemoralis muscle and its average shortening velocity increased from the slowest speed up to the walk-run transition, but changed little with further increases in speed. The times of muscle shortening and lengthening were often not equal at higher locomotor speeds. Some (20-25 ms) activity occurred during lengthening of the caudofemoralis muscle before footfall. However, most caudofemoralis activity was consistent with performing positive mechanical work to flex the knee shortly after foot contact and to retract and rotate the femur throughout the propulsive phase.

Interaction of pH and NaCl on enumeration of heat-stressed Staphylococcus aureus.

The effect of pH level and NaCl concentrations, alone and in combination, on the enumeration of unstressed and heat-stressed cells of three strains of Staphylococcus aureus was determined. A definite narrowing of the optimum pH range for enumeration of both unstressed and heat-stressed cells was observed as the NaCl concentration was increased from 0.0 to 7.5%. Counts of unstressed cells diminished only slightly with increases in NaCl, whereas heat-stressed cells showed a marked sensitivity to NaCl concentrations of 4% and above, regardless of the pH level. Because of this sensitivity to NaCl, recoveries were far poorer than with unstressed cells at NaCl concentrations of 4% and above.

Effect of stress on blood leucocyte and milk somatic cell counts in dairy cows.

Blood and milk samples from Holstein cows were examined for total blood leucocyte count, differential blood leucocyte count, milk quality test, and somatic cell count in milk while the cows were stressed by corticotropin injection, confinement in a heat-humidity chamber, or environmental-heat stress by exposure during the hot summer months of June through November in southern Arizona. All three stressing conditions resulted in a moderate blood leucocytosis. Modest increases in somatic cell counts of milk were associated with corticotropin injection and environmental-heat stress. Positive correlations were recorded between blood leucocytes and somatic cell counts of milk in mastitis-free cows injected with corticotropin and between percent blood neutrophils and somatic cell counts of milk in environmental-heat stressed cows with no evidence of current mastitis.

Multicenter evaluation of a patient-administered test for blood cholesterol measurement.

BACKGROUND: In order to assess accuracy of a newly developed, noninstrumented, self-administered fingerstick test that measures cholesterol levels in whole blood, the AccuMeter Cholesterol Self-Test was evaluated for home-use by untrained consumers in a multicenter study. METHODS: A total of 486 untrained adult volunteers of varying age, occupation, and educational background were recruited at four sites. Participants received written instructions provided in the kit, access to a telephone "800" number for additional help, and, if necessary, a short instructional video available to consumers on request. Fingerstick cholesterol results obtained by untrained volunteers were compared with paired venous serum results obtained by the Abell-Kendall cholesterol reference method. After application of exclusion criteria, 79.0% (384/486) of subjects had AccuMeter fingerstick results available for comparison with the reference method. RESULTS: Results obtained with the AccuMeter test correlated well with the Abell-Kendall results (r = 0.91). There was a mean overall bias for the AccuMeter of -0.116 +/- 0.528 mmol/liter (-2.2%), with a mean absolute bias of 0.398 +/- 0.367 mmol/liter (7.6%). Biases at the National Cholesterol Education Program cutpoints of 5.20 and 6.20 mmol/liter were -2.2 and -2.5%, respectively. Subjects with high-risk total cholesterol values (> or = 6.20 mmol/liter) were correctly classified 80.0% of the time, with an additional 18.8% placed in the borderline category (5.20-6.20 mmol/liter); 1.2% were inappropriately placed in the desirable category. No subjects were placed in the high-risk category by the AccuMeter test if they had a desirable cholesterol value by the reference method, while 9.8% were placed in this category if they were in fact borderline. CONCLUSIONS: This test appears to be a useful addition to available options in the effort to increase awareness of cholesterol as a heart disease risk factor. A large portion of untrained consumers were able to perform the AccuMeter Cholesterol Self-Test and obtain comparable results to the reference method. This test for the first time allows consumers to determine their own cholesterol values, with a reasonably good degree of accuracy.