Deepening the quality of clinical reasoning and decision-making in rural hospital nursing practice.

INTRODUCTION: Rural acute care nursing requires an extensive breadth and depth of knowledge as well as the ability to quickly reason through problems in order to make sound clinical decisions. This reasoning often occurs within an environment that has minimal medical or ancillary support. Registered nurses (RN) new to rural nursing, and employers, have raised concerns about patient safety while new nurses make the transition into rural practice. In addition, feeling unprepared for the rigors of rural hospital nursing practice is a central issue influencing RN recruitment and retention. Understanding how rural RNs reason is a key element for identifying professional development needs and may support recruitment and retention of skilled rural nurses. The purpose of this study was to explore how rural RNs reason through clinical problems as well as to assess the quality of such reasoning. METHODS: This study used a non-traditional approach for data collection. Fifteen rural acute care nurses with varying years of experience working in southern Alberta, Canada, were observed while they provided care to patients of varying acuity within a simulated rural setting. Following the simulation, semi-structured interviews were conducted using a substantive approach to critical thinking. RESULTS: Findings revealed that the ability to engage in deep clinical reasoning varied considerably among participants despite being given the same information under the same circumstances. Furthermore, the number of years of experience did not seem to be directly linked to the ability to engage in sound clinical reasoning. Novice nurses, however, did rely heavily on others in their decision making in order to ensure they were making the right decision. Hence, their relationships with other staff members influenced their ability to engage in clinical reasoning and decision making. In situations where the patient's condition was deteriorating quickly, regardless of years of experience, all of the participants depended on their colleagues when making decisions and reasoning throughout the simulation. CONCLUSIONS: Deep clinical reasoning and decision making is a function of reflection and self-correction that requires a critical self-awareness and is more about how nurses think than what they think. The degree of sophistication in reasoning of experts and novices is at times equivalent in that the reasoning of experts and novices can be somewhat limited and focused primarily on human physicality and less on conceptual knowledge. To become proficient in clinical reasoning, practice is necessary. The study supports the accumulating evidence that using clinical simulation and reflective interviewing that emphasize how clinical decisions are made enhances reasoning skills and confidence.

The accumulation of exercise and postprandial endothelial function in boys.

The purpose of this study was to investigate the effect of accumulating 60 min of exercise on endothelial function and triacylglycerol concentrations following the ingestion of a high-fat breakfast and lunch in 14 adolescent boys (aged 12 to 14 years). Two, 2-day main trials (control and exercise) were completed in a counter-balanced, cross-over design. Participants were inactive on day 1 of the control trial but on day 1 of the exercise trial completed 6 × 10 min runs at 70% of peak oxygen uptake, spread over the day. On day 2, triacylglycerol concentrations and flow-mediated dilation (FMD) were measured prior to, and following, ingestion of the high-fat meals. In the control trial, FMD was reduced by 30% and 33% (P < 0.001) following the high-fat breakfast and lunch; following exercise these reductions were negated (main effect trial, P = 0.002, interaction effect trial × time, P < 0.001). The total and incremental areas under the triacylglycerol concentration vs time curve were reduced by 11% and 16% in the exercise trial; however, these differences were not significant (P > 0.05). These results support the concept of accumulating physical activity for health in adolescents as the accumulated exercise attenuated the decline in FMD seen following the consumption of high-fat meals.

What is inside a nonionic reverse micelle? Probing the interior of Igepal reverse micelles using decavanadate.

The interiors of reverse micelles formed using nonionic surfactants to sequester water droplets in a nonpolar environment have been investigated using the decavanadate molecule as a probe. Chemical shifts and line widths of the three characteristic signals in the 51V NMR spectrum of decavanadate, corresponding to vanadium atoms in equatorial peripheral, equatorial interior, and axial locations, measure the local proton concentration and characteristics of the reverse micellar interior near the decavandate probe. All samples investigated indicate deprotonation of the vanadate probe in the reverse micelle environment. However, the relative mobility of the decavanadate molecule depends on the reverse micellar components. Specifically, the 51V NMR signals of the decavandate in reverse micelles formed using only the Igepal CO-520 surfactant display sharp signals indicating that the decavandate molecule tumbles relatively freely while reverse micelles formed from a mixture of Igepal CO-610 and -430 present a more viscous environment for the decavanadate molecule; the nature of the interior of the nonionic reverse water pool varies significantly depending on the specific Igepal. The 51V NMR spectra also indicate that the interior core water pool of the reverse micelles is less acidic than the bulk aqueous solution from which the samples were created. Together, these data provide a description that allows for a comparison of the water pools in these different nonionic reverse micelles.

Effects of the new class III antiarrhythmic drug dofetilide on the atrial and ventricular intracardiac monophasic action potential in patients with angina pectoris.

The class III antiarrhythmic drug dofetilide is known to prolong action potential duration by specific blockade of the delayed rectifier potassium channel Ik. As dofetilide is likely to be used in the treatment of atrial arrhythmias it is important to determine the relative sensitivity of the atrium and ventricle in man. Twelve male patients underwent monophasic action potential and refractory period recordings from the high right atrium and right ventricular septum. The patients received either 8 micrograms.kg-1 dofetilide or placebo intravenously. The mean QTc was prolonged by 11% (SD 5%, P < 0.00001) in the active group; the mean monophasic action potential increased by 31% (SD 15%, P < 0.0005) in the atrium and 27% (SD 9%, P < 0.00005) in the ventricle; the mean effective refractory period increased by 30% (SD 16%, P < 0.0005) in the atrium and 20% (SD 6%, P < 0.0001) in the ventricle. No significant change occurred in the placebo group. There was no significant difference in effect between the two chambers. The change in QTc did not accurately reflect acute changes in refractory period or monophasic action potential duration. This has important implications for the use of QT prolongation to assess the acute effect of class III drugs.

Somatosensory evoked potentials in acute neurological decompression illness.

Somatosensory evoked potentials (SSEPs) were recorded on posterior tibial nerve stimulation during compression in 21 episodes of acute neurological decompression illness (DCI) involving 20 patients. A further two cases were monitored immediately after treatment only. The results were compared with previously published normal data from this laboratory and with recordings obtained during the compression of four normal volunteers. Compression had no effect on SSEPs in normal subjects: SSEP latency abnormalities were found in 17 of the episodes of DCI. An SSEP improvement at final recording was noted in 7 of the 11 episodes which were monitored during treatment and classified initially as neurophysiologically abnormal. SSEPs may assist in the diagnosis of DCI.

Chemical cardioversion of atrial fibrillation with intravenous dofetilide.

We studied the effects of two active dose levels of dofetilide (8 and 12 micrograms/kg) and placebo in 16 patients with recent onset atrial fibrillation. The study was of a crossover design such that all patients received a therapeutic agent, 15 patients completed the study. Cardioversion was achieved in 2/6 patients receiving 8 micrograms/kg dofetilide and in 2/9 patients receiving 12 micrograms/kg. No patients cardioverted as a result of the placebo infusion. Two patients who cardioverted suffered episodes of torsades de pointes following the active drug. Electrical cardioversion was attempted in eight patients who remained in atrial fibrillation and was successful in six. The average duration of atrial fibrillation was 35 days in those who cardioverted and 83 days in those who did not. The compound appears to have only limited effect in cardioversion of atrial fibrillation of moderate duration.

Effect of manipulation and fractionated finger movements on subcortical sensory activity in man.

Previous studies have shown that the somatosensory evoked potentials (SEPs) recorded from the scalp are modified or gated during motor activity in man. Animal studies show corticospinal tract terminals in afferent relays, viz. dorsal horn of spinal cord, dorsal column nuclei and thalamus. Is the attenuation of the SEP during movement the result of gating in subcortical nuclei? This study has investigated the effect of manipulation and fractionated finger movements of the hand on the subcortically generated short latency SEPs in 9 healthy subjects. Left median nerve SEPs were recorded with electrodes optimally placed to record subcortical activity with the least degree of contamination. There was no statistically significant change in amplitude or latency of the P9, N11, N13, P14, N18 and N20 potentials during rest or voluntary movement of the fingers of the left hand or manipulation of objects placed in the hand. The shape of the N13 wave form was not modified during these 3 conditions. It is concluded that in man attenuation of cortical waves during manipulation is not due to an effect of gating in the subcortical sensory relay nuclei.

Transient memory loss for people.

A patient had transient memory loss for close family members. She could not even recognise their names as familiar. Her everyday memory was relatively preserved and she retained a clear recollection of the episode. Standard and sleep deprived EEG showed a mild abnormality of the left temporal lobe. Neuropsychological testing found evidence for a mild verbal memory impairment. The findings provide further evidence for the fractionation of transient forms of amnesia, support the dissociation of semantic/retrograde amnesia from episodic/anterograde amnesia, and offer evidence in favour of a left temporal lobe site for retrieval of past memories relating to the identification of people.

The causative rhythm in out-of-hospital cardiac arrests witnessed by the emergency medical services in the Heartstart Scotland Project.

Out-of-hospital defibrillation has been shown to improve survival in out-of-hospital cardiac arrests. The maximum performance of defibrillation-based systems is dependent on the proportion of cardiac arrests due to tachyarrhythmias. We reviewed 4248 reported arrests in the Heartstart Scotland database. We identified 3489 arrests due to cardiac or unknown cause. From this group we selected 258 cases known to be conscious on arrival of the crew. We were able to retrieve electrocardiographic data on the period within 2 min of the arrest in 106 cases. The first recorded rhythm at the arrest was ventricular fibrillation in 64%, ventricular tachycardia 4%, bradycardia in 28% and electromechanical dissociation in 4%. Defibrillatory shocks were delivered to 96% of patients in ventricular fibrillation and 60% of these patients survived. None of the patients with bradycardic arrests survived. Preceding chest pain was noted in 79% of patients subsequently developing ventricular fibrillation as the cause of arrest compared to only 37% of those suffering bradycardic arrests. It would appear that public awareness of the importance of early contact with the emergency services after the onset of chest pain could substantially improve the survival from out-of-hospital arrests.

Performance of an established system of first responder out-of-hospital defibrillation. The results of the second year of the Heartstart Scotland Project in the 'Utstein Style'.

The Heartstart Scotland project for out-of-hospital defibrillation covers the whole of Scotland, a population of approximately 5,102,400 (14.9% > 65 years, 48.3% male). All 395 ambulances in Scotland have been equipped with an automated external defibrillator and crews are trained in basic cardiopulmonary resuscitation and defibrillator use (EMT-D). Between 1 May 1990 and 30 April 1991 a total of 1700 cardiac arrests was reported by the ambulance service. Of the 1676 arrests which we could trace, 63% were witnessed. A total of 1383 (83%) of all patients were declared dead on arrival at hospital or in the emergency department, 119 (7%) died in hospital and 174 (10%) were discharged alive. Of the 174 survivors, 87% were conscious and normal at discharge, 9% had moderate residual disability and 2% severe disability. Survival of patients discharged alive from hospital was 85% at 1 year. Defibrillation was undertaken in 71% of the reported cardiac arrests. Survival of bystander witnessed arrests was increased from 7 to 15% with bystander CPR (P < 0.005). If the cardiac arrest was witnessed by the ambulance crew and required defibrillation, survival to discharge was 39%. Of bystander witnessed arrests reached while still in VF (n = 643), 11% were discharged alive. Patients who were defibrillated within 4 min of arrest had a 43% survival rate to hospital discharge.

Brain damage after profoundly hypothermic circulatory arrest: correlations between neurophysiologic and neuropathologic findings. An experimental study in vertebrates.

Five groups of neonatal pigs were subjected to cardiopulmonary bypass with circulatory arrest periods that varied from 70 to 120 minutes for the investigation of brain changes in induced deep-core hypothermia (15 degrees C) with circulatory arrest. The parameters that were analyzed were (1) microscopy of the brain in animals at 6 hours after bypass procedures and (2) intraoperative monitoring of somatosensory evoked potentials. Microscopic cellular damage appeared in all animals with a circulatory arrest period of more than 70 minutes. These changes involved mainly Purkinje's cells of the cerebellum, and they affected particularly the inferior half of the cerebellum. The prolongation of latency in the cortical responses, which reflects a slowing of the neural transmission with hypothermia, occurred in all animals. The late evoked potentials remained absent in all piglets with circulatory arrest periods of 90, 105, and 120 minutes, but they were fully recovered in all piglets of the control group and those with 70-minute arrest times. We concluded that the cerebellar region is the most sensitive site in which ischemic lesions attain their maximal severity and extent, and the maximum time of circulatory arrest without histopathologic and neurophysiologic sequelae should not exceed 70 minutes.

Effects of the class III antiarrhythmic drug dofetilide on ventricular monophasic action potential duration and QT interval dispersion in stable angina pectoris.

The effects of intravenous dofetilide on ventricular monophasic action potential duration and effective refractory period at the right ventricular apex and outflow tract were studied in 18 patients (aged 37 to 70 years) with ischemic heart disease. Six patients received low-dose dofetilide as a 3 micrograms/kg loading dose over 15 minutes and a 1.5 micrograms/kg maintenance dose over 45 minutes; 6 received high-dose dofetilide 6 + 3 micrograms/kg and 6 placebo. During atrial pacing at a cycle length of 800 ms high-dose dofetilide prolonged right ventricular apex monophasic action potential duration by 45 ms (16%) and the effective refractory period by 40 ms (16%). At the right ventricular outflow tract, monophasic action potential duration was prolonged by 45 ms (15%) and effective refractory period by 55 ms (21%). During atrial pacing at a cycle length of 500 ms high-dose dofetilide prolonged the right ventricular apex monophasic action potential duration by 40 ms (18%) and the effective refractory period by 43 ms (21%). The right ventricular outflow tract monophasic action potential duration was prolonged by 33 ms (14%) and effective refractory period by 45 ms (21%). Dofetilide produced no increase in the dispersion of repolarization between the 2 sites. During the maintenance infusion QTc prolongation by high-dose dofetilide averaged 43 ms (10%) with no increase of interlead QT dispersion. The effects of dofetilide on QT interval and effective refractory period are shown to be due to a direct effect on action potential duration with no effect on dispersion. No rate dependence of monophasic action potential prolongation was detected at these cycle lengths.

Efficacy of out of hospital defibrillation by ambulance technicians using automated external defibrillators. The Heartstart Scotland Project.

During the Heartstart Scotland project all 407 ambulances in Scotland were equipped with automated external defibrillators (AEDs). All cases of chest pain or collapse aged over 10 years were monitored and multiple 3-s rhythm strips recorded in a solid state memory module. A shockable rhythm was defined as an organised rhythm of > or = 180 beats/min or a disorganised rhythm of > or = 100 beats/min and amplitude > 0.1 mV. We analysed all the stored rhythm strips in two patient populations to determine the ability of the AED and ambulance crews to detect a shockable rhythm and to initiate appropriate defibrillation. The first population comprised 493 patients, all of whom had received shocks. A total of 4741 rhythm strips were analysed, of which 1461 were true positives, 33 false positives, 3161 true negatives and 86 false negatives. Overall sensitivity of the AED was 94.4% and specificity 99.0%. The second population comprised a random sample of 200 shocked and 200 non-shocked arrests. The combined group contained 4154 rhythm strips of which 562 were true positives, 12 false positives, 3460 true negatives and 120 false negatives. Overall sensitivity of the system (AED+crew) was 82.4% and specificity 99.7%. However, only 66 of the 120 false negatives were attributable to the AED giving a sensitivity of 90.3% for the AED. The sensitivity of the AED is dependent on the prevalence of shockable rhythms, but will be within the range 90.3-94.4% for most emergency medical services. We conclude that early management of potentially lethal arrhythmias by ambulance technicians using AEDs is practical with acceptable sensitivity and specificity.

Clinical and electrophysiologic effects of intravenous dofetilide (UK-68,798), a new class III antiarrhythmic drug, in patients with angina pectoris.

Dofetilide (UK-68,798) is a new class III antiarrhythmic agent. In animal experiments it selectively prolongs the refractory periods parallel to the action potential duration without any influence on upstroke velocity or conduction parameters. The present double-blind, placebo-controlled study was designed to show the effect of dofetilide on basic electrophysiologic parameters in patients with coronary artery disease. Eighteen patients (aged 31 to 64 years) with symptoms of stable angina pectoris admitted for routine coronary angiography were recruited. They were randomly allocated to receive either placebo or 1 of 2 dose levels of dofetilide intravenously with 6 patients in each group. Paired electrophysiologic variables were compared before and after administration of dofetilide. Both active dose levels produced significant prolongations (p less than 0.05) of 10 to 23% in atrial effective refractory period, 6 to 16% in ventricular effective refractory period and 11 to 15% in ventricular functional refractory period. Atrial functional refractory period was prolonged by 14 to 22% at the high-dose level (p less than 0.05). No effect was observed on conduction parameters (PA, AH, HV, PR or QRS intervals), sinus cycle length or sinus node recovery. The selective prolongation of the refractory periods in both atrium and ventricle, combined with a lack of effect on cardiac conduction parameters, indicates that this drug could be useful in the treatment of both atrial and ventricular reentrant tachyarrhythmias and fibrillation.

Pharmacokinetic and pharmacodynamic effects of UK-68,798, a new potential class III antiarrhythmic drug.

1. The pharmacokinetic and pharmacodynamic properties of UK-68,798, a novel selective potential class III antiarrhythmic agent, were studied in 18 patients with coronary artery disease. Three groups of four patients received intravenous doses of 1.5, 3.0 and 4.5 micrograms kg-1 respectively over 10 min. 2. UK-68,798 caused a mean increase in electrocardiographic QTc interval of 41, 40 and 81 ms, and in uncorrected QT interval of 36, 52 and 83 ms at the three dose levels. There were no significant effects on heart rate, blood pressure, PR interval and QRS duration. UK-68,798 was well tolerated with no significant adverse effects. 3. A dosing regimen using a loading infusion of two thirds of the total dose over 15 min with the remainder given over the following 45 min in six patients produced stable plasma concentrations and lengthening in QTc during the maintenance infusion. 4. There was a linear correlation between plasma concentration and change in QTc. The drug exhibited first-order kinetics with a mean clearance of 4.7 +/- 1.2 ml min-1 kg-1 and a mean terminal plasma half-life of 9.7 h. 5. UK-68,798 warrants further study as a selective potential Class III antiarrhythmic agent.