A novel approach to measuring circulating blood volume: the use of a hemoglobin-based oxygen carrier in a rabbit model

Hemoglobin-based oxygen carriers (HBOC) may be ideal for monitoring circulating plasma volume (CV-P) and circulating blood volume (CV-B). We used an HBOC (Hemoglobin glutamer-200 [bovine], Oxyglobin; Biopure, Cambridge, MA) as an indicator for relative CV-B in the rabbit model. Accuracy of the technique was determined by comparison with the Evans blue dye (EBD) dilution technique in 19 anesthetized female New Zealand rabbits weighing 2.0 to 10.6 kg. The measurements were performed at baseline, after hemorrhage (1/3 of CV-B), normovolemic hemodilution (replacement of 1/3 CV-B by Hextend; Abbot Laboratories, North Chicago, IL), and hypervolemic hemodilution (additional infusion of Hextend(R) in a volume equal to 1/3 of CV-B). Hemoglobin concentration was measured by using a HemoCue photometer (HemoCue AB, Angelholm, Sweden). EBD concentration was analyzed by using linear regression to estimate Time 0 concentration; Time 0 was defined as EBD injection time. The difference between CV-P values determined by EBD and HBOC dilution was independent from the magnitude of the CV-P value. The relative bias was 1.29 mL, and the precision (one SD) was 2.82 mL. The difference did not reach statistical significance. IMPLICATIONS: Circulating plasma and blood volumes can be accurately estimated by plasma hemoglobin concentration measurements by using hemoglobin-based oxygen carrier infusion.     

Does determination of polyamines in body fluids require heating with hydrochloric acid?

In this study it is shown that hydrolysis of plasma and urine by heating with concentrated hydrochloric acid does not increase the recovery of spermidine from these body fluids.     

Conditions for successful reflective use of portfolios in undergraduate medical education

Aim Portfolios are often used as an instrument with which to stimulate students to reflect on their experiences. Research has shown that working with portfolios does not automatically stimulate reflection. In this study we addressed the question: What are the conditions for successful reflective use of portfolios in undergraduate medical education? Methodology/research design We designed a portfolio that was aimed at stimulating reflection in early undergraduate medical education, using experiences described in the medical education literature and elsewhere. Conditions for reflective portfolio use were identified through interviews with 13 teachers (mentors), who were experienced in mentoring students in the process of developing their portfolios. The interviews were analysed according to the principles of grounded theory. Results The conditions for successful reflective use of portfolios that emerged from the interviews fell into 4 categories: coaching; portfolio structure and guidelines; relevant experiences and materials, and summative assessment. According to the mentors, working with a portfolio designed to meet these conditions will stimulate students' reflective abilities. Conclusion This study shows that portfolios are a potentially valuable method of assessing and developing students' reflective skills in undergraduate medical training, provided certain conditions for effective portfolios are recognised and met. Portfolios have a strong potential for enhancing learning and assessment but they are very vulnerable and may easily lead to disappointment. Before implementing portfolios in education, one should first consider whether the necessary conditions can be fulfilled, including an appropriate portfolio structure, an appropriate assessment procedure, the provision of enough new experiences and materials, and sufficient teacher capacity for adequate coaching and assessment.     

Pharmacodynamics of rocuronium 0.3 mg kg(-1) in adult patients with and without renal failure

BACKGROUND AND AIM: The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg(-1) under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg(-1) rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients. METHODS: With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg(-1) was given intravenously after induction of anaesthesia with propofol 1-2 mg kg(-1) and fentanyl 2 microg kg(-1). Propofol 6-12 mg kg(-1) h(-1) was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant. RESULTS: No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block. CONCLUSIONS: Rocuronium 0.3 mg kg(-1) is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.     

Anesthetic management in a child with Arnold-Chiari malformation and bilateral vocal cord paralysis

We report a case of a child who was scheduled for an emergency ventriculoperitoneal shunt procedure. The patient had a type II Arnold-Chiari malformation (ACM) and associated hydrocephalus and presented with near complete respiratory obstruction from bilateral abductor vocal cord palsy. Early diagnosis and management of airway abnormalities associated with ACM may be lifesaving. Chiari malformations and anesthesia management are discussed.     

Dexamethasone suppression test in borderline personality disorder--effects of posttraumatic stress disorder

BACKGROUND: Divergent findings of hypothalamic-pituitary-adrenal (HPA) axis functioning in borderline personality disorder (BPD) may be caused by a different degree of comorbid posttraumatic stress disorder (PTSD), in which alterations of the HPA axis are well known. Here we investigate alterations of the HPA axis in BPD patients with and without comorbid PTSD compared to healthy controls. Considering previous findings current major depression (MDD) was taken into account as a confounding variable. METHODS: Apart from clinical assessment the 0.5 mg dexamethasone suppression test (DST) was performed in 21 female borderline patients and 23 healthy controls. RESULTS: Twelve BPD patients suffered from comorbid PTSD. Relative suppression (%) did not differ between healthy controls and the total BPD group, but BPD patients with comorbid PTSD showed increased suppression compared to those without. Comorbid MDD was not associated with suppression. CONCLUSIONS: Our results do not indicate a dysfunction of the HPA axis in BPD. However, comorbid PTSD seems to be associated with a relative hypersuppression in the 0.5 mg DST.     

Enterocin P causes potassium ion efflux from Enterococcus faecium T136 cells

Enterocin P is a bacteriocin produced by Enterococcus faecium P13. We studied the mechanism of its bactericidal action using enterocin-P-sensitive E. faecium T136 cells. The bacteriocin is incapable of dissipating the transmembrane pH gradient. On the other hand, depending on the buffer used, enterocin P dissipates the transmembrane potential. Enterocin P efficiently elicits efflux of potassium ions, but not of intracellularly accumulated anions like phosphate and glutamate. Taken together, these data demonstrate that enterocin P forms specific, potassium ion-conducting pores in the cytoplasmic membrane of target cells.     

The severity of alcohol withdrawal is not age dependent

Age has been considered to contribute to the severity of the alcohol withdrawal syndrome (AWS). To evaluate the relationship between age and the severity of the AWS, we examined 723 alcoholics [518 males, 205 females, mean age (+/- SD): 42.8 +/- 10.5 years, mean duration of alcohol dependence: 11.0 +/- 8.0 years] consecutively referred to a unit for detoxification of alcoholics in a general hospital. The severity of the AWS was assessed by the AWS scale of Wetterling et al. (1997; Alcohol and Alcoholism 32, 753-760). The history of alcohol abuse as well as drinking behaviour in the last 6 months was assessed by a semi-structured interview. There were 41 alcoholics aged > or =60 years; they were compared with younger patients. The average severity of AWS did not differ between age groups. Daily alcohol intake and frequency of drinking were higher in younger alcoholics, but even when adjustment was made for this, severity of AWS was equal in both age groups. A relationship between severity of AWS and age was not detected.