National Comparative Audit of Blood Use in Elective Primary Unilateral Total Hip Replacement Surgery in the UK

INTRODUCTION

Blood is a scarce and expensive product. Although it may be life-saving, in recent years there has been an increased emphasis on the potential hazards of transfusion as well as evidence supporting the use of lower transfusion thresholds. Orthopaedic surgery accounts for some 10% of transfused red blood cells and evidence suggests that there is considerable variation in transfusion practice.

PATIENTS AND METHODS

NHS Blood and Transplant, in collaboration with the Royal College of Physicians, undertook a national audit on transfusion practice. Each hospital was asked to provide information relating to 40 consecutive patients undergoing elective, primary unilateral total hip replacement surgery. The results were compared to indicators and standards.

RESULTS

Information was analysed relating to 7465 operations performed in 223 hospitals. Almost all hospitals had a system for referring abnormal pre-operative blood results to a doctor and 73% performed a group-and-save rather than a cross-match before surgery. Of hospitals, 47% had a transfusion policy. In 73%, the policy recommended a transfusion threshold at a haemoglobin concentration of 8 g/dl or less. There was a wide variation in transfusion rate among hospitals. Of patients, 15% had a haemoglobin concentration less than 12 g/dl recorded in the 28 days before surgery and 57% of these patients were transfused compared to 20% with higher pre-operative values. Of those who were transfused, 7% were given a single unit and 67% two units. Of patients transfused two or more units during days 1–14 after surgery, 65% had a post transfusion haemoglobin concentration of 10 g/dl or more.

CONCLUSIONS

Pre-operative anaemia, lack of availability of transfusion protocols and use of different thresholds for transfusion may have contributed to the wide variation in transfusion rate. Effective measures to identify and correct pre-operative anaemia may decrease the need for transfusion. A consistent, evidence-based, transfusion threshold should be used and transfusion of more than one unit should only be given if essential to maintain haemoglobin concentrations above this threshold.     

Prediction of the effect of erythromycin, diltiazem, and their metabolites, alone and in combination, on CYP3A4 inhibition

Predictive models of complex drug-drug interactions between multiple inhibitors and their metabolites have not been evaluated. The purpose of this study was to evaluate an interaction model for cytochrome P450 3A4 (CYP3A4) that incorporated the simultaneous reversible and irreversible inhibition by multiple inhibitors. Erythromycin (ERY) and diltiazem (DTZ), and their major metabolites, N-desmethylerythromycin (nd-ERY) and N-desmethyldiltiazem (nd-DTZ), were chosen to evaluate the model. k(inact) (rate constant for maximal inactivation), K(I) (inhibitor concentration at 50% maximal inactivation), and K(i) (reversible inhibition constant) were estimated for ERY, DTZ, nd-ERY, and nd-DTZ, respectively, using cDNA-expressed CYP3A4 and human liver microsomes under optimal experimental conditions. To evaluate the interaction model, combinations of inhibitors and metabolites were incubated at concentrations equal to K(I), (1/2)K(I), and 2K(I) of each inhibitor for specified durations in both enzyme systems. The models were further evaluated by the incubation of combinations of inhibitors with the substrate testosterone for 10 min. CYP3A4 inhibition in the presence of drug mixtures was predicted from the inhibition parameters determined for each drug or metabolite alone. The CYP3A4 activity in the presence of multiple inhibitors was well predicted by the model incorporating additive irreversible inhibition as modified by mutual competitive inhibition (percent mean error and percent mean absolute error ranged from -0.06 to 0.04 and from 0.03 to 0.09, respectively). In conclusion, the additive model predicted the combined effect of multiple inhibitors on CYP3A inhibition in vitro. However, simultaneous reversible and irreversible inhibition effects should be taken into account in a reaction mixture of substrate and multiple inhibitors of CYP3A4.     

Ultrastrukturelle Veränderungen am Nierenparenchym durch ESWL unter Acetylsalicylsäure (ASS)

BACKGROUND: The risk of hemorrhagic complications after extracorporeal shock-wave lithotripsy (ESWL) increases in patients with aspirin intake, but the hematoma-inducing mechanism has not been understood completely at the ultrastructural level. METHODS: The effect off shock-waves on the kidneys of male Wistar-rats (n=24) was investigated in an experimental setting using a special ESWL device. Ultrastructural examination was performed by light-, transmission electron- and scanning electron microscopy. RESULTS: Shock-wave induced tissue damage appeared in all kidneys independently of aspirin intake. Endothelial detachment, lethal cell injury, gaps and mechanical disruption of the glomerular basement membrane were regularly found. After 1 week, repair processes were completed with evidence of permanent fibrosis in some cases. CONCLUSIONS: ESWL can induce modest as well as fatal damage to renal tissue cells. Therefore, after an ESWL-induced hematoma a second ESWL should not be performed within 1 week of the first treatment.     

Six new cases of CRB2-related syndrome and a review of clinical findings in 28 reported patients

The Crumbs homolog-2 (CRB2)-related syndrome (CRBS-RS) is a rarely encountered condition initially described as a triad comprising ventriculomegaly, Finnish nephrosis, and elevated alpha-fetoprotein levels in maternal serum and amniotic fluid. CRB2-related syndrome is caused by biallelic, pathogenic variants in the CRB2 gene. Recent reports of CRB2-RS have highlighted renal disease with persistent proteinuria and steroid-resistant nephrotic syndrome (SRNS). We report six new and review 28 reported patients with pathogenic variants in CRB2. We compare clinical features and variant information in CRB2 in patients with CRB2-RS and in those with isolated renal disease. The kidneys were the most frequently involved body system and 11 patients had only renal manifestations with SRNS or nephrotic syndrome. Central nervous system involvement was the next most common manifestation, followed by cardiac findings that included Scimitar syndrome. There was a significant clustering of pathogenic variants for CRB2-RS in exons 8 and 10, whereas pathogenic variants in exons 12 and 13 were associated with isolated renal disease. Further information is needed to determine optimal management but monitoring for renal and ocular complications should be considered.     

Transfusion Transmitted Infections in Armed Forces: Prevalence and Trends

Background

This study presents data on the prevalence rate of infectious markers among voluntary and replacement donors in the blood transfusion service in Armed Forces from 2000 to 2004.

Methods

39,646 units of blood were collected from donors during the period from 2000 to 2004. All the samples were screened for hepatitis B surface antigen (HBsAg), human immunodeficiency virus (HIV) 1&2, hepatitis C virus (HCV), and by venereal disease research laboratory test (VDRL).

Results

24,527 (61.9%) were voluntary donations and 15,119 (38.1%) replacement donations. Prevalence of HBsAg had decreased, amongst voluntary donors from 1.67% to 0.77% but the positivity rate has not showed significant change. Seropositivity of HIV had decreased both in voluntary and replacement donors to 0.22% and 0.86% respectively. The seropositivity for anti-HCV showed steady decrease amongst voluntary donors from 0.46% to 0.20% in 2004, but in replacement donors, there was an increase in reactivity rate from 0.43% to 0.65%.

Conclusion

The increased seropositivity for HCV, HIV and HBsAg could be decreased by introduction of nucleic acid amplification testing (NAT) in minipools for HCV and HIV and introduction of anti-HBcAg (IgM) for hepatitis B virus (HBV) infection. But this may not be possible in near future in developing countries due to financial constraints. At present implementation of strict donor criteria and with use of sensitive laboratory screening tests it is possible to reduce the incidence of transfusion transmitted infections (TTI) in Indian scenario.Key Words: Transfusion transmitted infections, Human immunodeficiency virus, Hepatitis C virus, Hepatitis B virus     

Lung function in children: a simple guide to performing and interpreting spirometry

Spirometry is the measurement of the volume and flow of air during expiration and inspiration. It is non-invasive and inexpensive and probably under-used in children. Whilst remaining a relatively simple test, it gives valuable information that can be used in the diagnosis and monitoring of respiratory conditions. Adequate spirometry requires good patient engagement, effort and technique. With practice, robust spirometry data can be collected in preschool children as young as 4 years of age. Increasing availability of portable spirometry equipment means that good quality data can be collected in a variety of clinical locations outside the lung function laboratory - even in the patient's own home. There are, however, a number of important considerations in both the performance and interpretation of spirometry. This review considers the equipment required, the basic techniques required and the essentials of interpretation of spirometry data.