Reflective testing: how useful is the practice of adding on tests by laboratory clinicians?

AIMS: To investigate the clinical value and practice of reflective testing, a new term to describe the practice of adding on tests when reporting or clinically authorising results. METHODS: A consultant medical biochemist collected over a calendar year (2001) copies of clinical biochemistry reports on samples to which he had added on either iron studies (iron, total iron binding capacity (TIBC), and percentage saturation), or vitamin D. Iron studies and vitamin D were added on when biochemical results, available clinical information, demographic data, and clinical experience-or combinations thereof-suggested the possibility of haemochromatosis or vitamin D deficiency, respectively. The number of reports that the consultant authorised was estimated for the same calendar year. The number and percentage of raised TIBC percentage saturation and low vitamin D results from the tests that were added on were collated. RESULTS: Raised TIBC saturation values were found in 28 patients (18.7% of the iron studies added on), of whom 16 were subsequently genotyped, eight having a genotype consistent with haemochromatosis. Thirty one patients with vitamin D deficiency (23.1% of the vitamin D tests added on) were identified. CONCLUSIONS: The addition of iron studies and vitamin D tests by a laboratory clinician, when reporting, resulted in the identification of patients with haemochromatosis and vitamin D deficiency. The practice of adding on tests should be called reflective testing, because it is discretionary and is based on the clinical judgement of a laboratory clinician in the interpretation of results.     

Living with diabetes as a transformational experience

The construct of transformation has been presented in many research studies as the epitome of living with a chronic illness. Because it has been inadequately defined, however, many other concepts (e.g., hope, meaning, control) are used in ways that suggest considerable overlap and correspondence with transformation. This article represents an attempt to explicate the structures and processes of transformation as they were revealed in a qualitative inquiry into the experience of individuals with Type I diabetes. In the accounts constructed with participants in this study, the process of personal transformation was significant in the attainment of healthy outcomes. The authors describe this transformation and examine its relationship to control and to the valued outcomes of intensified sense of self, meaning, and mastery.     

Mini-thoracotomy for diaphragmatic plication with thoracoscopic assistance

We describe a technique of mini-thoracotomy to plicate the paralyzed hemidiaphragm with thoracoscopic assistance. Most of the hemidiaphragm can be plicated expeditiously under direct vision with light derived from a posterior thoracoscope placed in the auscultatory triangle. Videoscopic vision is employed only occasionally when the view of the posteromedial hemidiaphragm is obscured. Continuous suture traction can be easily applied through the mini-thoracotomy, thus maintaining suture tension and enabling maximal inversion of the elevated hemidiaphragm.     

Vagal control of heart rate is modulated by extracellular potassium

Heart rate (HR) recovery from heavy exercise is associated with a shift in cardiac sympatho-vagal balance and a transient hypokalaemia. Since changes in extracellular potassium ([K+]0) affect membrane currents in the sino-atrial node, in particular the acetylcholine-activated potassium current (I(K,ACh)), the hyperpolarization-activated current (I(f)) and the L-type calcium current (I(Ca,L)), we investigated whether mimicking [K+]0 concentrations seen during and immediately after exercise could directly modulate the HR response to vagal nerve stimulation (VNS) in the isolated guinea-pig atria preparation pre-stimulated with noradrenaline (NA, 1 microM). Lowering [K+]0 from 4 to 3 mM significantly enhanced the HR response to VNS (5 Hz, 5 V, 30 s, deltaHR 84.5 +/- 14.1 bpm and 119.3 +/- 18.2 bpm, respectively). Increasing [K+]0 to 8 or 10 mM significantly decreased the drop in HR with VNS in comparison to the response to 3 mM K+ Tyrode (deltaHR 56.4 +/- 9.1 bpm and 52.1 +/- 8.7 bpm, respectively). These results could be simulated using the OXSOFT heart sino-atrial node computer model by activating I(K,ACh) during changes in [K+]0. However, changing [K+]0 in the model had no significant effect on the decrease in beating frequency brought about by decreasing I(f) or I(Ca,L). We conclude that the magnitude of the decrease in HR with VNS is enhanced in low [K +]0 and reduced in high [K+]0. The increased efficacy of cardiac vagal activation in low [K+]0 might therefore facilitate the drop in HR after heavy exercise where there is a transient hypokalaemia. Modelling suggests this result may be explained by the effects of changes in [K+]0 on the current-voltage relationship for I(K,ACh).     

Application of probabilistic neural network analysis to a disease with complex inheritance: the GAW11 simulated data

A probabilistic neural network analysis was applied to the simulated GAW11 data. Six replicates drawn at random from one of the simulated populations were used to generate training and test vectors for pairs of siblings. The vectors incorporated two environmental indicators as well as identical-by-descent allele sharing scores from each of 300 genetic markers. The performance of a 'na?ve' probabilistic neural network (PNN) was fair. However, by combining a traditional linkage analysis with a PNN which incorporated gene x environment interaction, the performance was considerably enhanced.