Vascular Access for Therapeutic Plasma Exchange

Abstract: Adequate venous access is an essential component of therapeutic plasma exchange (TPEX). The simplest kind of venous access is venipuncture of antecubital veins, but this technique may be limited by venous size or scarring following the procedure, requiring the placement of a specialized vascular access device (VAD). VADs provide reliable central venous access and may remain in place for several weeks or months, depending on the VAD and the venous site chosen. Their use, however, is potentially limited by the risk of complications. We discuss indications for insertion, choice of catheter and access site, and complications of VAD placement for TPEX.     

Accidental Occupational Farm Fatalities in North Carolina: 1984 to 1988

Development of interventions to prevent accidental occupational fatalities requires the prior identification of those at risk and the circumstances surrounding the injuries. A survey of unintentional farm fatalities was conducted using medical examiner reports (RIME) and death certificates (MECD) to identify deaths due to agricultural occupational injuries in North Carolina from 1984 through 1988. Of 393 cases, 123 met the criteria "farmer" listed as occupation on the RIME/MECD and/or "victim" in a rural area performing a farming task when injured. A second aim of this study was to use an existing data base to achieve maximum accuracy in identifying true cases of work-related farm fatalities.
A fatality rate of 41/100,000 agricultural workers was found; the National Institutes of Occupational Safety and Health's National Traumatic Occupational Fatality study criteria would have identified only 57 percent of these. Victims were characterized as middle age (53 years), white (76%), male (100%), full-time farmers (65%). Injury occurred during harvest season on Monday or Tuesday (47%) between 2 and 6 p.m. (54%). Death was pronounced at the scene (74%), with probable cause listed as tractor (62%). Injury location and land elevation were also related, with the mountain region having twice the fatality rate as the coastal plains region.     

Validity in hermeneutic phenomenological inquiry: towards an ethics of evaluation.

This article explores the relationship of ethics to validity in hermeneutic phenomenological inquiry. First, the authors present a brief overview of the various discourses on validity in qualitative research that have been variously applied to hermeneutic phenomenological inquiry. Next, they examine how relational ethics is a presence to bear within this form of inquiry. Finally, they offer a set of ethical reflections to help the researcher engage in a process of ethical questioning during each step of the research process.     

Mood Matters: Negative Mood Induction Activates Dysfunctional Attitudes in Women Vulnerable to Depression

Cognitive theory holds that dysfunctionalattitudes are important risk factors for depression.Critics have questioned this view, noting that, althoughdysfunctional attitudes are elevated in depression, they are not evident in vulnerable individualswho are asymptomatic. To deal with this criticism,Miranda and Persons (1988) have advanced the mood-statedependent hypothesis, which suggests that cognitive vulnerability factors are indeed present invulnerable individuals, but remain dormant untilactivated by negative mood. To test this hypothesis, 33women with and 67 women without histories of depression reported dysfunctional attitudes before andafter a film negative mood induction. As predicted,vulnerable subjects who reported increased negative moodreported increased dysfunctional attitudes.Unexpectedly, nonvulnerable subjects who reported increasednegative mood reported decreased dysfunctionalattitudes. These findings support the mood-statedependent hypothesis, and suggest that a deficit in theability to regulate negative emotions may be animportant feature of vulnerability todepression.     

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.     

Cardio-respiratory measures following isocapnic voluntary hyperventilation

In some individuals, breathing is greater than at rest following voluntary hyperventilation. Most previous investigations have employed short hyperventilation periods; here we examine the time course of cardio-respiratory measures before, during, and after a 5-min voluntary hyperventilation, maintaining isocapnia throughout. We examined the possible co-involvement of the cardiovascular system; hypothesising that post-hyperventilation hyperpnoea results from an increase in autonomic arousal. In four subjects (two males, two females) of 18 (nine males, nine females) we observed a post-hyperventilation hyperpnoea, characterised by a slow decline of ventilation toward resting levels with a time constant of 109.0 +/- 16.1s. By contrast, heart rate, and systolic and diastolic blood pressure were unchanged from rest during and after voluntary hyperventilation for all subjects. We concluded that males and females were equally likely to exhibit post-hyperventilation hyperpnoea, and suggest that they may be characterised by an increased resting heart rate and the choice of breathing frequency to increase ventilation during the voluntary hyperventilation. We further concluded that post-hyperventilation hyperpnoea is rare, but when present is a strong and lasting phenomenon, and that it is not the result of an increased autonomic arousal.