Noninvasive measurements of central arterial pressure and distensibility by arterial applanation tonometry with a generalized transfer function: implications for nursing.

Decreased distensibility of large arteries is a strong indicator of cardiovascular risk. Measurements of arterial distensibility can be made noninvasively with the use of an arterial applanation pressure tonometer with a generalized transfer function. This article reviews (1) the concept of arterial distensibility and its relation to pulse wave amplitude, velocity, and reflection; (2) epidemiologic evidence that large-artery stiffness increases cardiovascular risks; and (3) the estimation of arterial distensibility with the use of noninvasive techniques, with an emphasis on measuring pulse wave velocity and calculating the aortic augmentation index. Finally, it addresses the application of arterial applanation tonometry in nursing research and practice.

Ambulatory blood pressure monitoring: measurement implications for research.

Although blood pressure (BP) is a frequently used variable in nursing studies, measurements are likely to be inaccurate for a variety of reasons: incorrect technique, operator error, and environmental factors. Ambulatory BP monitoring (ABPM) reduces measurement error, is relatively easy to use, and yields many more BP parameters than do clinic BP measurements. The cost of equipment for ABPM ranges from $2,500 to $5,000 per monitor and from $2,000 to $3,000 for computer software. A research assistant can easily be trained to follow a standardized procedure. Researchers have used ABPM to study normal BP patterns, complications of hypertension, effects of antihypertensive drugs, and the prognosis of cardiovascular events. This article provides the nurse researcher with an introduction to this technology and an overview of information gained from ambulatory blood pressure monitoring.

The effect of biofeedback in hypertension.

The purpose of this study was to determine the effectiveness of biofeedback in the treatment of stages 1 and 2 essential hypertension via meta-analytical methods. A utilization-focused integrative review was limited to adult randomized clinical trials, and study groups were categorized into biofeedback, active control, and inactive control. Both biofeedback and active control treatments resulted in a reduction in systolic blood pressure (SBP) and diastolic blood pressure (DBP). Only biofeedback (with related cognitive therapy and relaxation training) showed a significantly greater reduction in both SBP (6.7 mm Hg) and DBP (4.8 mm Hg) when compared with inactive control treatments. Nurses in practice settings should consider biofeedback therapy for their hypertensive clients.

Use of microneurography to evaluate sympathetic activity in hypertension: a brief review.

Muscle sympathetic nerve activity (MSNA) is an important variable in the study of autonomic activity in both normotensive and hypertensive subjects. It is measured directly from the peroneal nerve using microneurography. The technique is complex and difficult to learn, but yields accurate and direct information about sympathetic nerve impulses. MSNA provides not only greater reproducibility than other measures of sympathetic activity, but also a clearer and more consistent reflection of changes in sympathetic activity caused by changes in the subject's status or disease. This technique has been used primarily in basic research settings studying stress and hypertension. It has much potential to enhance our understanding of sympathetic nervous system activity and its role in applied psychophysiology and biofeedback.

Insights learned from teaching pathophysiology on the World Wide Web.

This article describes a one-credit, graduate level pathophysiology module taught using the World Wide Web. Student outcomes are compared to those of students who took the same module in a traditional classroom setting. Although the majority of the graduate students were not Web literate, they became more comfortable with this instructional medium over time. A comparison of the Web-based instruction with the traditional format, both directed by the same instructor, showed no significant differences in student performance on a multiple choice examination.

Acute renal failure. Recognition and prevention.

Acute renal failure remains a devastating syndrome associated with a high mortality rate. Accurate and rapid etiologic diagnosis is critical, since it may be possible to stop the injurious process and prevent further progression of renal insufficiency. To do this, one must understand and differentiate among the three broad categories of disorders that can cause acute renal failure-prerenal, postrenal, and intrarenal processes. This article compares and contrasts these three categories in regard to causes and predisposing factors, history and physical examination, urinalysis, and urine chemistries. Treatment focuses on correcting prerenal and postrenal factors; treating acute complications, such as hyperkalemia, hyponatremia, acidosis, and pulmonary edema; optimizing cardiac output and renal blood flow; and adjusting doses of drugs consistent with renal failure.

Detecting i.v. infiltrations using a Venoscope.

This research evaluates the Venoscope for its ability to detect infiltrations when present (sensitivity) and to detect the absence of infiltrations when not present (specificity), and compares these findings with those obtained via ultrasonography. Health adult volunteers were randomly assigned to receive or not receive an intentionally made 5-ml normal-saline infiltration. The Venoscope had a sensitivity of .92-.93 and a specificity of .89-1.0. Ultrasound had a sensitivity of .92-.93 and a specificity of .22-.25. The Venoscope, which is simple and easy to use, is a valid indicator of the presence and absence of i.v. infiltrations.

Renal regulation of extracellular fluid volume and osmolality.

In order for our body cells to function properly, they must be surrounded in extracellular fluid that is relatively constant with regard to osmolality. The kidneys, in concert with neural and endocrine input, regulate the volume and osmolality of the extracellular fluid by altering the amount of sodium and water excreted. This is accomplished primarily though alterations in sodium and water reabsorption, the mechanisms of which differ within each nephron segment.

The minimum discard volume: accurate analysis of peripheral hematocrit.

The purpose of this research is to quantify the minimum amount of blood that must be discarded from an indwelling peripheral intravenous catheter (deadspace 0.5 ml) to obtain an accurate hematocrit reading. Repeat blood sampling from nine subjects is used to develop a mathematical model (Michaelis-Menten curve) describing the mixing of the flush solution and the blood. This model is used to estimate the hematocrit when different volumes are discarded. Differences between the computed hematocrit and true hematocrit were determined for each subject. When 1.5 ml (three times the deadspace volume) is discarded, the 95% confidence interval is within 0.6% of the true hematocrit.

Cerebral palsy: a comprehensive review.

Cerebral palsy is a broad range of static, nonprogressive motor disabilities that present from birth or early childhood as a result of injury to neuromotor components of the central nervous system. Motor performance is normally coordinated via communication between the cerebral cortex, thalamus, basal ganglia, brain stem, cerebellum, spinal cord, and communicating sensori-motor pathways. This complex network lends itself to injury at many different levels. Etiologies are numerous and can occur during the prenatal, perinatal, and postnatal periods. The severity of the neurologic deficit and the clinical manifestations are varied depending on the time, location and nature of the original injury. In order to approach cerebral palsy systematically, the primary health care practitioner must be prepared to recognize neuromotor deficits, diagnose and classify the type of disorder, and implement a methodical treatment plan. The purpose of this article is to review the etiology, pathophysiology, diagnostic classification (Swedish system), clinical manifestations, and therapeutic management of cerebral palsy and prepare the advanced practice nurse to care for the individual and family.

Interactive distance education: improvisation helps bridge the gap.

In this paper, distance learning through the use of interactive duplex video and audio will be described. The major advantage of this technology is the ability to provide live, face-to-face educational access to distant or isolated students. Yet faculty are concerned about the interrelationships between the instructor and the student and among students in the distance education environment. Improvisation techniques force active participation by the students and can be used to bridge the distance.

Understanding physiology by acting out concepts.

Typically, classes in anatomy and physiology are taught via lecture and visual aids. This seems to work well for students who are primarily auditory and visual learners but not for those who learn better through kinesthetic experiences. This is the first report describing the use of improvisation to act out physiological concepts within an anatomy and physiology course. Improvisational techniques encourage active participation and allow students to personally interact with and experience difficult concepts in the classroom. In this paper, sensory modality preferences for learning will be discussed briefly. Improvisational techniques will be described, and examples of improvisations useful to convey intricate physiological concepts will be provided. Last, student responses to the use of improvisational techniques in an anatomy and physiology course will be reported.

Calcium and phosphorus derangements.

Derangements in plasma calcium and phosphorus concentrations can precipitate serious and life-threatening complications in critically ill patients. An understanding of the function and homeostasis of these ions is essential to fully comprehend the causes, clinical manifestations, and treatment of calcium and phosphorus imbalances. This article will help the critical care nurse to identify patients at risk, to recognize derangements early (while they are still mild), and to seek and monitor appropriate treatment.

Magnesium: homeostasis, imbalances, and therapeutic uses.

Magnesium plays a critical role in numerous metabolic functions, including all reactions involving adenosine triphosphate, and is thus essential for the production and use of energy. Magnesium imbalances are common in hospitalized patients, with magnesium deficiency occurring in 20% to 65% of critically ill patients. This article details the homeostatic mechanisms regulating magnesium, the functions of magnesium, and the causes, manifestations, and treatment of both hyper- and hypomagnesemia. Indications and guidelines for the therapeutic uses of magnesium are also reviewed.

Effect of elevation on intravenous extravasations.

Nursing interventions used to treat intravenous extravasations (infiltrations) generally include application of warmth or cold, elevation, and no treatment. In this article, the effect of elevation on infiltrations of 0.45% sodium chloride and 3% saline made intentionally into healthy volunteers is reported. Elevation had no effect on pain, surface area of induration, or volume of infiltrate remaining as quantified by magnetic resonance imaging. A comparison of these data with previously published findings concerning the effect of warmth versus cold on infiltrations shows that no one treatment is better overall in decreasing the symptoms or speeding re-absorption of the infiltrate.

Multiple organ failure syndrome.

Although many new areas of research are directed at the regulatory aspects of the metabolic response, the prognosis of MOF remains poor. Critical care nurses, challenged to provide a supportive environment during this life-threatening syndrome, must understand its onset, clinical patterns, and prolonged support required by patients. Such knowledge will enable critical care nurses to detect subtle changes while monitoring clinical status, and facilitate timely interventions in order to decrease the morbidity and mortality associated with MOF.

Differences among intravenous extravasations using four common solutions.

A frequent complication of intravenous therapy is extravasation (infiltration) of the infused fluid into the interstitial tissues. This study compares infiltrates intentionally made using different IV solutions regarding surface assessment and the volume of infiltrate as quantified by magnetic resonance imaging. Solutions differed significantly concerning pain, surface area of induration, and volume at the site of infiltration.

Renal physiology series: Part 5a of 8. Renal control of calcium.

Calcium is critical for many metabolic functions. While 99% of body calcium is found as part of the structure of bone and teeth, 1% found in plasma and body cells is crucial for such functions as blood clotting, nerve impulse conduction, and muscle contraction. The homeostasis of calcium is complex because the gastrointestinal tract, the bones, and the kidneys all affect calcium balance. This article reviews the functions, homeostasis, and renal handling and regulation of calcium. The major sites of renal tubular reabsorption and the presumed cellular mechanisms involved are described.

Renal physiology series: Part 5b of 8. Renal control of phosphorus and magnesium.

The kidney plays a major role in the maintenance of phosphorus and magnesium balance. The homeostasis of these substances is complex and also involves the gastrointestinal tract and the bone. This article reviews the functions, homeostasis, and renal handling and regulation of phosphorus and magnesium. The major sites of tubular reabsorption and the presumed cellular mechanisms involved are described.