Dexmedetomidine Produces Similar Alterations in the Determinants of Left Ventricular Afterload in Conscious Dogs before and after the Development of Pacing-induced Cardiomyopathy

Background: The authors tested the hypothesis that intravenous dexmedetomidine produces alterations in left ventricular (LV) afterload that are deleterious to cardiac performance in conscious dogs with pacing-induced cardiomyopathy.

Methods: Dogs (n = 8) were fitted with instruments for long-term measurement of LV and aortic blood pressure, aortic blood flow, and subendocardial segment length and received dexmedetomidine (1.25, 2.5, and 5 [micro sign]g/kg) in a cumulative manner before and after 19 +/- 3 (mean +/- SEM) days of rapid LV pacing. LV afterload was measured with aortic input impedance [Zin ([Greek small letter omega]) and quantified with a three-element Windkessel model. Hemodynamics and Zin ([Greek small letter omega]) were assessed under control conditions and 5 and 60 min after administration of each dose.

Results: Dexmedetomidine caused early and late decreases in heart rate, the maximum rate of increase of LV pressure, mean aortic blood flow, and stroke volume in dogs before and after pacing. Dexmedetomidine caused similar early increases in total arterial resistance and decreases in total arterial compliance in dogs before and after pacing. Early dexmedetomidine-induced increases in resistance and decreases in compliance caused similar reductions in mean aortic blood flow in cardiomyopathic compared with healthy dogs. Resistance and compliance returned to control values, and characteristic aortic impedance decreased late after dexmedetomidine in healthy dogs. In contrast, resistance remained elevated late after dexmedetomidine in dogs with dilated cardiomyopathy.     

Transposition of the great arteries and isolated origin of the sinus node artery

We report the cases of 2 newborns who underwent at 7 days of age an arterial switch operation for transposition of the great arteries with a rare coronary anomaly: the left and right coronary arteries originated with a single ostium from sinus 1 and the sinus node artery had an isolated origin from sinus 2. The sinus node artery was reimplanted into the new aorta in both patients. Both babies were discharged in sinus rhythm. Preserving the vascularization of the sinus node may avoid the occurrence of postoperative atrial rhythm disturbances.     

Advancing Nursing Practice with a Unit-based Clinical Expert

Objective: To explore patterns in the practice of nursing and patient outcomes.
Design: Qualitative field research.
Population, Sample, Setting: Populations were critical care nurses and critically ill adult patients in the 10-bed medical critical care unit of a 900-bed teaching hospital. A convenience-purposive sample of 27 nurses and 31 patients was studied in 1985.
Methods: Six months of participant observation, unstructured interviews, and the constant comparison method of grounded theory.
Findings: Markedly different patterns were found in expert and nonexpert practice. The substantive theory of conversion helped explain how the majority of nonexpert nurses advanced their practice. The metaphor of catalyzed conversion captures how a unit-based expert nurse serves as a catalyst to advance the practice of nonexperts. Presence, defined as the way of being within a given clinical context, differentiated nurses.
Conclusions: (a) Expert and nonexpert practices are substantively different, (b) Expert and nonexpert practice results in different patient outcomes, (c) Conversion helps explain changes in nonexpert practice.
Clinical Implications: A unit-based expert nurse can increase patient-focused care.     

Speech-language pathology and dysphagia: A brief historical perspective

In the past decade, speech-language pathologists have taken a leading role in the management of services for patients with oropharyngeal dysphagia. This article presents the historical perspective of this role, the rationale for assuming the responsibility, and suggests directions for continued involvement.     

A Psychosociocultural Perspective, Part 2

Building on the foundation of understanding and comprehensive assessment of battered women, this article addresses service planning and intervention. Strategies are approached within the framework of a Crisis Paradigm developed from field research with battered women and their families. They include mechanisms such as support groups which link crisis service to the long-term needs of battered women, and systematic approaches to removing the obstacles which keep women victimized. An Assessment and Service Planning Guide (ASPG) is proposed for inclusion in routine health care of abused women. The article concludes with strategies for preventing violence at interpersonal and societal levels.     

Effect of gastric dysrhythmias on postcibal motor activity of the stomach

The effect of electrical dysrhythmias on the mechanical activity of the fed stomach was investigated in 5 conscious dogs implanted with Ag-AgCl electrodes and strain gauge force transducers. Each dog was fed 1 can of ALPO^® and electromechanical activities of the stomach were recorded for the next 120 min. The results show that intraarterial boluses of met-enkephalin (75 g/kg), PGE₂ (36 g/kg), and epinephrine (36 g/kg) induced episodes of antral dysrhythmias whereas saline (1 cc) did not. The postcibal antrat motility index for the test period was not altered following saline injection, but it was reduced by 61%, 70%, and 81% following the administration of met-enkephalin, epinephrine, and PGE₂, respectively (p<0.01 vs. baseline period). During periods of normal electrical rhythm, PGE₂ and epinephrine significantly reduced the antral motility index (2.07±0.93 and 3.24±0.79, respectively) vs. saline (7.92±0.44) (p<0.05 for both drugs) whereas met-enkephalin (4.98±0.56) did not. In contrast, during episodes of dysrhythmia, met-enkephalin significantly depressed antral motility (1.70±0.74) (p<0.05 vs. periods with normal electrical rhythm) whereas neither epinephrine nor PGE₂ caused a further reduction in antral motility from what was seen during periods of normal electrical rhythm (1.84±0.72 and 1.34±0.37, respectively). We thus conclude that intraarterial administration of met-enkephalin, PGE₂, or epinephrine induce gastric dysrhythmias postcibally and depress antral contractile activity. The relaxatory effect of met-enkephalin on antral contractions is primarily due to its dysrhythmic effect whereas PGE₂ and epinephrine inhibit antral motility even when the electrical rhythm is undisturbed.This work was supported in part by the USPHS, NIH grants AM26428, AM07198, and AM34988 and the Mayo Foundation.     

Interaction between Marihuana and Ethanol: Effects on Psychomotor Performance

This is a report of the results of a placebo-controlled study in which the effects of the interaction between ethanol and marihuana on drug plasma concentrations, subjective ratings of intoxication, heart rate acceleration, and psychomotor performance were investigated. Six healthy, male, paid volunteers, moderate users of ethanol and marihuana, participated in the study. Ethanol (0.42 g/kg, 0.85 g/kg, or placebo) was administered over a 30-min interval. Fifteen minutes later the subjects smoked, in their customary manner, NIDA cigarettes containing 2.4% or 0.0004% (placebo) delta-9-tetrahydrocannabinol (THC). Each subject was tested in a single-blind, latin-square crossover design with the following six conditions: placebo ethanol/placebo marihuana; low dose ethanol/placebo marihuana; high dose ethanol/placebo marihuana; placebo ethanol/marihuana; low dose ethanol/marihuana; and high dose ethanol/marihuana. The variables measured in the study were: (a) subjective rating of ethanol and/or marihuana intoxication; (b) heart rate; (c) accuracy and latency of response in the Simulator Evaluation of Drug Impairment (SEDI) task; (d) blood ethanol concentration by gas chromatography; and (e) plasma concentration of THC by radioimmunoassay. The results indicate that the decrements due to ethanol in performance of skills necessary to drive an automobile were significantly enhanced by marihuana in an additive and perhaps synergistic manner. The administration of ethanol prior to marihuana smoking did not produce significant effects on the subjective rating of "high," heart rate acceleration, or THC plasma concentration.     

Ethanol-induced Changes in Morphology and Strength of Femurs of Rats

Chronic ingestion of ethanol resulted in ultrastructural and mechanical changes in rat femurs. Scanning electron microscopy of the distal end of the femur revealed that the trabeculae of bones from ethanol-fed rats were thinner, more columnar, and more extensive than those from control rats. Three-point bending tests of the rat femurs showed that the maximum force or so-called "strength" required to break the bone was less in ethanol- than in control-fed animals. A significant inverse correlation was observed between the strength required to break the femur and the dose of ethanol calculated on a body weight basis. For the first time our study presents quantitative proof that a relationship exists between bone strength and the consumption of ethanol in rats. The study revealed that ethanol consumption resulted in a weaker femur compared to controls. We suggest that a common mechanism may be responsible for the decreased bone strength of ethanol-fed rats and the increased incidence of fractures in human alcoholics.