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PubMed1993

Interpretive research methodology: broadening the dialogue.

This article expands the dialogue on interpretive research methodology, locating this set of approaches within a broad historical and interdisciplinary context. Several of the most commonly held misconceptions in nursing, particularly those related to the meanings and derivations ascribed to "grounded theory," "symbolic interactionism," and "ethnography," are examined. The interpretive research approaches not only have gained broader acceptance across disciplines, but also have shifted in more radical and often less structured directions during the past decade. Several pivotal areas of these ongoing shifts are analyzed for their relevance to nursing research: the influence of critical and feminist theory and postmodernism, the ambiguity inherent in both every-day life and the research enterprise, the importance of locating the researcher, power and status inequities, the problematic aspects of language, meaning, and representation, and the emphasis on reflexivity and context as constitutive of meaning.

Anthropology, Cultural↗
PubMed1989

Four digital algorithms for activation detection from unipolar epicardial electrograms.

The reproducibility of activation detection by each of four algorithms used to calculate maximum derivatives was tested on two sequential paced beats of right ventricular unipolar epicardial electrograms which represented either local activation of the right ventricle alone or synchronous activation of both ventricles. The methods were evaluated by comparing the shape of the two beats aligned on their selected activation times, i.e., the time at which the maximum negative deflection occurred, the differences in activation intervals for the two beats, and the effect on the activation time of superimposing distant events on local activation. The 17-point second-order data fit algorithm performed slightly better than the first-order difference, three-point Lagrange derivative, and five-point second-order data fit algorithms except that activation time selection by the 17-point technique was slightly, but significantly, delayed by the superposition of distant potentials. The 17-point second-order data fit technique is therefore recommended for use in detecting activation unless computation time is a major consideration. In that case, the five-point second-order data fit technique, which uses only four data values for each computation, can be used with only slight decreases in accuracy.

Algorithms↗
PubMed1992

Extraintestinal amebiasis.

Extraintestinal involvement is a dreaded complication of amebiasis, with a reported mortality rate of 7%-14%. The authors retrospectively studied 188 patients with extraintestinal amebiasis confirmed by means of clinical, surgical, and radiologic criteria over a 45-month period. Ultrasonography (US) was the mainstay of radiologic investigation. Liver abscess was present in 183 patients (97%); five patients (3%) had other organ involvement but a normal liver. The majority of liver abscesses were in the right lobe. US is recommended for the diagnosis and follow-up of patients with extraintestinal amebiasis. It is noninvasive, simple, easily reproducible, and less expensive than computed tomography. Portable models can be taken into remote areas of the less-developed world.

Adult↗
PubMed1993

Low-energy endocardial defibrillation using an axillary or a pectoral thoracic electrode location.

BACKGROUND: A significant proportion of patients receiving endocardial defibrillation lead systems must accept either high defibrillation thresholds (DFTs) with lower safety margins or lead implantation by thoracotomy. We examined the feasibility of achieving universal application of endocardial leads and lower defibrillation energy requirements by optimizing the lead system location in conjunction with biphasic shocks. METHODS AND RESULTS: Two defibrillation catheter electrodes were positioned in the right ventricle and superior vena cava. Thoracic patch electrodes were placed at three sites (apical, pectoral, and axillary). Fifteen-joule, 10-J, and 5-J bidirectional simultaneous biphasic shocks were delivered across three different triple electrode configurations (right ventricle, superior vena cava, and patch) after inducing ventricular fibrillation (VF), and DFT was determined. All patients in whom VF was reproducibly inducible (14 patients) could be reproducibly defibrillated at 15 J at one or more patch electrode locations. Fifteen-joule shocks were effective at three thoracic electrode locations in 12 patients and at two electrode locations in 6 patients. The lowest mean single-shock DFT was 8.1 +/- 3.8 J. In 4 patients, ventricular flutter was reproducibly induced and reverted at 15 J in all patients. Mean DFT for the axillary location was 8.3 +/- 3.5 J and was significantly lower than apical (12.8 +/- 5.6 J, P = .008) and pectoral (11.6 +/- 4.1 J, P < .04) patch locations. The probability of success was significantly higher at 10 J with axillary location (78% of patients, P < .03 compared with both other sites) and at 15 J (P < .05 compared with the apical location). Low-energy endocardial defibrillation (< or = 10 J) was feasible in 10 of 14 tested patients at more than 1 thoracic electrode location at 10 J, whereas only 1 of 7 successful patients could be reverted at more than 1 electrode location at 5 J (P < .02). CONCLUSIONS: The use of axillary or pectoral patch lead location can allow endocardial defibrillation with biphasic shocks at energies < or = 15 J in this lead configuration. Virtually universal application of endocardial defibrillation lead systems can be predicted from these data. Reduction in maximum pulse generator output to < or = 25 J using these two thoracic electrode locations with bidirectional shocks can be feasible and maintain an adequate safety margin and permit thoracic pulse generator implantation. Lowering endocardial defibrillation energy < 10 J requires increasing specificity of thoracic electrode location.

Aged↗
PubMed2004

Controlled contrast transcranial Doppler and arterial blood gas analysis to quantify shunt through patent foramen ovale.

BACKGROUND AND PURPOSE: A right-to-left shunt can be identified by contrast transcranial Doppler ultrasonography (c-TCD) at rest and/or after a Valsalva maneuver (VM) or by arterial blood gas (ABG) measurement. We assessed the influence of controlled strain pressures and durations during VM on the right-to-left passage of microbubbles, on which depends the shunt classification by c-TCD, and correlated it with the right-to-left shunt evaluation by ABG measurements in stroke patients with patent foramen ovale (PFO). METHODS: We evaluated 40 stroke patients with transesophageal echocardiography-documented PFO. The microbubbles were recorded with TCD at rest and after 4 different VM conditions with controlled duration and target strain pressures (duration in seconds and pressure in cm H2O, respectively): V5-20, V10-20, V5-40, and V10-40. The ABG analysis was performed after pure oxygen breathing in 34 patients, and the shunt was calculated as percentage of cardiac output. RESULTS: Among all VM conditions, V5-40 and V10-40 yielded the greatest median number of microbubbles (84 and 95, respectively; P<0.01). A significantly larger number of microbubbles were detected in V5-40 than in V5-20 (P<0.001) and in V10-40 than in V10-20 (P<0.01). ABG was not sensitive enough to detect a shunt in 31 patients. CONCLUSIONS: The increase of VM expiratory pressure magnifies the number of microbubbles irrespective of the strain duration. Because the right-to-left shunt classification in PFO is based on the number of microbubbles, a controlled VM pressure is advised for a reproducible shunt assessment. The ABG measurement is not sensitive enough for shunt assessment in stroke patients with PFO.

Adult↗
PubMedDate not supplied

Wrist kinematics during pitching. A preliminary report.

A computerized hand and wrist motion analysis system was modified to capture data at a rate of up to 1000 Hz. Using this system, wrist flexion and extension data were collected on five right-handed professional pitchers (75 pitches). A wrist position versus time graph was generated for each pitch. The pitch data produced a reproducible analysis of motion for the majority of the pitches regardless of pitcher. Based on the graphic display of data points, four phases of wrist motion during a pitch were identified. The first phase is the cocking phase, or the motion of the wrist as it moves into maximum extension. This is then followed by the most explosive phase, the acceleration phase, which represents ball propulsion. At ball release, the wrist progresses through flexion and there is a consistent decrease in wrist velocity, known as the deceleration phase. Finally, there is the recovery phase, or the return of the wrist toward neutral. Average values for wrist range of motion, length of phase, and angular velocity (degrees per second) were calculated for each phase of the pitch. This study represents a major step toward quantifying motion of the wrist during a pitch. The ability to quantify this motion may prove valuable in the assessment of throwing athletes after injury and rehabilitation.

Acceleration↗
PubMed2001

New CT index to quantify arterial obstruction in pulmonary embolism: comparison with angiographic index and echocardiography.

OBJECTIVE: This study was designed to define and evaluate a specific index to quantify arterial obstruction with helical CT in acute pulmonary embolism. MATERIALS AND METHODS: Fifty-four patients (mean age, 56 years) with proven pulmonary emboli among 158 consecutive patients, who had undergone both CT and pulmonary angiography for clinically suspected pulmonary embolism, were eligible for the study. The CT obstruction index was defined as (n. d) (n, value of the proximal clot site, equal to the number of segmental branches arising distally; d, degree of obstruction scored as partial obstruction [value of 1] or total obstruction [value of 2]). We compared the CT obstruction index with pulmonary arterial obstruction on angiography (assessed by the Miller index), using linear regression, and correlated it with findings on echocardiography. Interobserver variability was determined for both CT and pulmonary angiography indexes. RESULTS: The CT obstruction index (29% +/- 17%) and the Miller index (43% +/- 25%) were well correlated (r = 0.867, p < 0.0001) with an excellent concordance between investigators for both the CT index (r = 0.944, p < 0.0001) and the Miller index (r = 0.904, p < 0.0001). A CT obstruction index greater than 40% identified more than 90% of patients with right ventricular dilatation. CONCLUSION: The degree of arterial obstruction in pulmonary embolism may be quantified by a specific CT index that appears reproducible and highly correlated to the previously described index with pulmonary angiography. Further evaluations are needed to investigate the usefulness of the CT obstruction index for stratification of patient risk and determining therapeutic options.

Angiography↗
PubMed1983

Directional preferences of bilingual children.

Effects of simultaneous acquisition of differential reading and writing habits (in English and Hebrew) on directional preferences were investigated for 72 bilingual children in Grades 1 to 6. The children reproduced series of single and multiple stimuli; horizontal directions of their responses were recorded. Increased age was accompanied by growing left-right directional preferences in response to all stimuli but Hebrew letters, for which the reversed right-left preferences appeared. These data corroborate previous findings showing effects of reading and writing habits on directional preferences.

Child↗
PubMed1996

Brain tissue pressure gradients created by expanding frontal epidural mass lesion.

A porcine model was used to study the regional intracranial pressure (ICP) differences caused by a frontal mass lesion. Intraparenchymal ICP monitors were placed in the right and left frontal lobes, right and left temporal lobes, midbrain, and cerebellum. A frontal epidural mass lesion was created by placing a balloon catheter through a burr hole into the right frontal epidural space. A computer was used to acquire data from all monitors at 50-msec intervals. The balloon was expanded by 1 cc over a period of 1 second every 5 minutes and maximum pressure immediately before and during expansion was determined for each balloon volume at each site. Prior to expansion of the mass, the morphology of the cerebellum pressure tracing was different from that seen in all supratentorial regions. Also, pressures in the midbrain, at baseline, were slightly but significantly lower than pressures in the frontal and temporal regions. During expansion of the mass, a pressure differential that increased as the size of the mass increased developed between intracranial regions. Furthermore, the regional pressures were found to vary in a consistent fashion expressed by the formula RF=LF>RT=LT>MB>CB, in which RF and LF are the right and left frontal lobes, RT and LT are the right and left temporal lobes, MR in the midbrain, and CB is the cerebellum. The study shows that an expanding epidural mass reproducibly results in a gradient of brain parenchymal pressure. This gradient results in parenchymal pressures that are significantly different in each region of the brain depending on the proximity of that region to the epidural mass. The results of this study have implications for clinical ICP monitoring and therapy.

Animals↗
PubMed1992

[Somatostatin as a modulator of vagal effects on heart rhythm].

In 11 experiments on anesthetised cats burst stimulation of peripheral cut end of right vagus nerve leads to synchronization of cardiac and vagus rhythms. Alterations of burst sequence frequency within definite limits has been synchronously reproduced by heart thus creating managed bradycardia possibility. Somatostatin (10(-8)-10(-9) M intravenously) decreases heart rate and inhibits total vagus chronotropic effect. Vagolytic effect of somatostatin caused a decrease of tonic component of the vagus chronotropic effect. On the other hand, somatostatin augmented the extent of the vagal synchronizing influences and caused enlargement of the ranges of managed bradycardia. The observed results testify to participation of the peptidergic mechanisms in genesis of vagal managed bradycardia.

Animals↗
PubMed1993

[Modulating action of neurotensin on the parasympathetic regulation of cardiac rhythm].

In 8 experiments on anaesthetised cats bursts stimulation of the peripheral cut end of right vagus nerve leads to synchronisation of cardiac and vagus rhythms. Alterations of burst sequence frequency within definite limits has been synchronously reproduced by heart thus creating managed brady-cardia possibility. Neurotensin (4.10(-8) M intravenously) accelerate heart rate and potentiate total vagal chronotropic effect. Vagotropic effect of the neurotensin is due to enlargement of the tonic component's strength in the vagal chronotropic effect. On the other hand, extent of the synchronizing vagal influences upon heart rhythm is unaffected. Mechanisms of the participation of neurotensin in organisation of the vegetative control of the cardiac rhythm are discussed.

Animals↗
PubMed1977

[Ultrasound diagnosis of the liver and gallbladder (author's transl)].

Ultrasound echography has proved a non-invasive, reproducible, harmless and, for the patient, not burdensome technique for the diagnosis of diseases of the liver and bile ducts in the right upper abdomen. Diffuse changes of the organs and disease of the bile ducts as well as cystic or tumorous solid changes in the upper abdomen are the main spheres of sonography. The use of "grey value" techniques has increased the efficiency of compound ultrasound examinations. We can expect further improvements with digital computerised evaluation of signals.

Cholelithiasis↗
PubMed1998

Development of a model of complete heart block in rats.

Atrioventricular (AV) block is a useful substrate for the study of cardiac physiology. The objective of this investigation was to develop a straightforward and reproducible model of permanent AV block in rats. Working through a sternotomy, we used an epicardial fat pad between the aortic root and the right atrial wall of the rat as a landmark for the site for injection of 70% ethanol (5-10 microl) into the myocardium 3 mm below the epicardial surface. Stable, complete heart block was produced in 23 of 28 rats (82%) with a success rate of 100% in the last 16 rats of the series. Saline injection produced no heart block in 15 rats. A separate group of 14 animals was allowed to recover. Chronic heart block was achieved in all ethanol-injected animals for up to 7 days before death. The survival rate in the recovered rats was 90% in the ethanol-injected group and 100% in the saline-injected control group. Acute hemodynamic changes following the production of heart block consisted of an increase in central venous pressure, a decrease in systolic blood pressure, a decrease in left ventricular pressure, and a decrease in change in pressure over time. Chronic hemodynamic changes demonstrated a return to baseline of the central venous pressure, a persistent decrease in systolic blood pressure, and a decrease in left ventricular pressure. After the rats were killed and the hearts were dissected, discrete areas of myocardial damage were identified histologically in the atrial septum near the AV conduction axis tissue in the ethanol-injected hearts. Complete heart block was associated only with lesions extending into the specialized muscle of the AV node or His bundle. Focal mild hemorrhage, inflammation, and damaged myocardial fibers were observed in the acute stage, whereas healing lesions were characterized by granulation tissue and fibrosis replacing conduction tissue. The simple technique described provides a reproducible model for permanent, complete heart block and the study of cardiac function.

Adipose Tissue↗
PubMed1996

Maternal effect of low temperature on handedness determination in C. elegans embryos.

C. elegans embryos, larvae, and adults exhibit several left-right asymmetries with an invariant dextral handedness, which first becomes evident in the embryo at the 6-cell stage. Reversed (sinistral) handedness was not observed among > 10,000 N2 adults reared at 16 degrees C or 20 degrees C under standard conditions. However, among the progeny of adults reproducing at 10 degrees C, the frequency of animals with sinistral handedness was increased to approximately 0.5%. Cold pulse experiments indicated that the critical period for this increase was in early oogenesis, several hours before the first appearance of left-right asymmetry in the embryo. Hermaphrodites reared at 10 degrees C and mated with males reared at 20 degrees C produced sinistral outcross as well as sinistral self-progeny, indicating that the low temperature effect on oocytes was sufficient to cause reversals. Increased frequency of reversal was also observed among animals developed from embryos lacking the egg shell. Possible mechanisms for the control of embryonic handedness are discussed in the context of these results, including the hypothesis that handedness could be dictated by the chirality of a gametic component.

Animals↗
PubMed2000

Measurement of refractive error in Native American preschoolers: validity and reproducibility of autorefraction.

PURPOSE: To examine (1) reproducibility of cycloplegic retinoscopy (C-RNS), cycloplegic autorefraction (C-Autoref), and noncycloplegic autorefraction (NC-Autoref), and (2) validity of C-Autoref and NC-Autoref compared with C-RNS in preschoolers with astigmatism. METHODS: Subjects were 36 Native American preschoolers. Three measurements of right eye refractive error were obtained with each of three methods: C-RNS (by three different retinoscopists), C-Autoref, and NC-Autoref (Nikon Retinomax K+). Vector methods (vector dioptric distance, VDD) were used in the analyses. RESULTS: Mean reproducibility was 0.41 D (SD = 0.18) for C-RNS, 0.25 D (SD = 0.17) for C-Autoref, and 0.37 D (SD = 0.21) for NC-Autoref. Mean agreement between C-Autoref and C-RNS ranged from 0.51 to 0.61 VDD (SD = 0.24 to 0.35), and ranged from 1.66 to 1.74 VDD (SD = 1.11 to 1.25) for agreement between NC-Autoref and C-RNS. Mean bias was -0.07 +0.21 x 149 and -1.33 +0.34 x 178 for C-Autoref and NC-Autoref, respectively. CONCLUSIONS: C-Autoref provided reliable and valid measurements of refractive error in young children. NC-Autoref measurements were reliable within subjects, but there was large variability in validity among subjects.

Arizona↗
PubMed1994

The reproducibility of 109Cd-based X-ray fluorescence measurements of bone lead.

We assessed the reproducibility of X-ray fluorescence-based lead measurements from multiple measurements made on a low-concentration plaster of paris phantom and in five subjects measured five times on two occasions. Over a 6-month period, 220 measurements of the same phantom were obtained and showed a standard deviation of 1.29 micrograms Pb (g plaster of paris)-1. The two sets of in vivo measurements were made 10 months apart and revealed a mean standard deviation of 3.4 micrograms Pb (g bone mineral)-1 and 5.1 micrograms Pb (g bone mineral)-1 for males and females, respectively. Our measured standard deviation exceeded by 20-30% the calculated standard deviation associated with a single measurement both in the phantom and in subjects. This indicates that some variance is introduced during the measurement process. Operator learning and consistency significantly minimized this increased variability. Measured lead concentrations of the left and right tibia in 14 subjects showed no significant differences between legs. As a result, either tibia can be sampled and compared over time. The levels of reproducibility we report here mean that X-ray fluorescence-based determinations of bone lead concentrations are reliable both over the short and long term. Thus, reasonably sized confidence intervals can be placed on detected changes in concentration and should permit acquisition of longitudinal data within a reasonable length of time.

Bone and Bones↗
PubMed2000

Assessment of acute right ventricular dysfunction induced by right coronary artery occlusion using echocardiographic atrioventricular plane displacement.

Right ventricular (RV) systolic function analysis by echocardiography has traditionally required RV endocardial border definition with subsequent tracing and is often inaccurate or impossible in technically poor studies. The atrioventricular plane displacement (AVPD) method attempts to use the descent of the tricuspid annular ring, a reflection of the longitudinal shortening of the right ventricle, as a surrogate marker for RV systolic function. We hypothesized that RV ischemia induced during right coronary artery occlusion proximal to the major right ventricular branches would result in severe right ventricular systolic dysfunction detectable by the AVPD method. During this pilot study, seven patients undergoing elective proximal RCA angioplasty had echocardiographic measurement of RV AVPD performed at baseline (i.e., immediately prior to RCA balloon inflation), during the last 30 seconds of first RCA balloon inflation, and at 1 minute after balloon deflation (recovery). Lateral and medial RV AVPD were significantly reduced from baseline values during intracoronary balloon inflation. (Lateral: 2.45 cm +/- 0.22 vs 1.77 cm +/- 0.13, P < 0.001; medial: 1.46 cm +/- 0.37 vs 1.28 cm +/- 0.32, P < 0.05). Additionally, lateral and medial RV AVPD significantly returned towards baseline values during recovery. (Lateral: 2.39 cm +/- 0.20, P < 0.001; medial: 1.58 cm +/- 0.27, P = 0.01). At baseline, all lateral RV AVPD values were > 2.0 cm, whereas during balloon inflation all were < 2.0 cm. No such clear distinction was found in medial RV AVPD values. Proximal RCA angioplasty is associated with a significant reduction in lateral and medial RV AVPD. Thus RV AVPD may serve as a marker for RV systolic dysfunction.

Acute Disease↗