An engineered solution to the maladministration of spinal injections

BACKGROUND

An overview is provided of the progress made in a Department of Health (DH) initiative to implement an engineered solution to the maladministration of spinal injections. In an effort to eliminate the possibility of misconnection errors at the spinal route, the DH is investigating the potential for dedicated spinal equipment that will be incompatible with standard Luer syringes, needles and associated devices.

METHOD

Background information on the problem of misconnection errors is provided and a systematic approach to their eradication is detailed. Research to date has entailed extensive bench-testing of prototype non-Luer connectors, a prospective hazard analysis of spinal procedures in haematology and anaesthesia and usability evaluation of prototype non-Luer devices in simulated environments.

RESULTS

The prospective hazard analysis identified two potential risks which will need to be managed as part of a successful implementation programme.

CONCLUSION

Usability testing of two prototype connection systems concluded that one design was inadequate, as the non-Luer element was provided as a separable adapter. The second connection system was modified following the first round of testing, and achieved improved satisfaction ratings from clinicians in round two. This system was selected to proceed to a pre-implementation evaluation and the research team are currently evaluating its acceptability in clinical use.

Evidence for an integrated oral sensory module in the human anterior ventral insula

Taste, which is almost always accompanied by other oral sensations, serves to identify potential nutrients and toxins. The present study was designed to determine the influence of sensory modality (chemesthetic vs. gustatory) and physiological significance (potentially nutritive vs. potentially harmful) on insular response to oral stimulation. Sixteen subjects underwent functional magnetic resonance imaging scanning while receiving 2 potentially nutritive solutions (sucrose and NaCl), 2 potentially harmful solutions (quinine and capsaicin, a chemesthetic stimulus), and a tasteless control solution. We identified a region of anterior ventral insula that responded to oral stimulation irrespective of modality or physiological significance. However, when subjects tasted a potentially nutritive stimulus, the connectivity between the insula and a feeding network including the hypothalamus, ventral pallidum, and striatum was greater than when tasting a potentially harmful stimulus. No differential connectivity was observed as a function of modality (gustatory vs. chemesthetic). These results support the existence of an integrated supramodal flavor system in the anterior ventral insula that preferentially communicates with the circuits guiding feeding when the flavor is potentially nutritive.

Assessing sources of inconsistencies in genotypes and their effects on genome-wide association studies with HapMap samples

The discordance in results of independent genome-wide association studies (GWAS) indicates the potential for Type I and Type II errors. We assessed the repeatibility of current Affymetrix technologies that support GWAS. Reasonable reproducibility was observed for both raw intensity and the genotypes/copy number variants. We also assessed consistencies between different SNP arrays and between genotype calling algorithms. We observed that the inconsistency in genotypes was generally small at the specimen level. To further examine whether the differences from genotyping and genotype calling are possible sources of variation in GWAS results, an association analysis was applied to compare the associated SNPs. We observed that the inconsistency in genotypes not only propagated to the association analysis, but was amplified in the associated SNPs. Our studies show that inconsistencies between SNP arrays and between genotype calling algorithms are potential sources for the lack of reproducibility in GWAS results.

Screening colonoscopy for the detection of neoplastic lesions in asymptomatic HIV-infected subjects

BACKGROUND

Although non-AIDS defining malignancies are rapidly increasing as HIV-infected subjects live longer, little is know about the results of screening for colonic neoplasms (adenomatous polyps and adenocarcinomas) in this population.

METHODS

We conducted a screening colonoscopy study to determine the prevalence of colonic neoplasms in 136 asymptomatic HIV-infected subjects >or=50 years of age and 272 asymptomatic uninfected control subjects matched for age, sex, and family history of colorectal cancer. Advanced neoplasms were defined as adenomas >or=10 mm or any adenoma, regardless of size, with villous histology, high-grade dysplasia, or adenocarcinoma.

RESULTS

The prevalence of neoplastic lesions was significantly higher in HIV-infected subjects than in control subjects (62.5% vs 41.2%, p<0.001), and remained highly significant after adjustment for potential confounding variables (odds ratio = 3.00; 95% confidence interval, 1.83 to 4.93). Among patients with colorectal adenocarcinoma, HIV-infected subjects were significantly younger (52.4 (SD 1.3) vs 60.3 (SD 4.0) years, p = 0.002) and were more likely to have advanced cancers (stage III or IV) than control subjects (60.0% vs 16.7%, p = 0.24). Of HIV-infected subjects with advanced neoplasms proximal to the splenic flexure, distal neoplastic lesions were absent in 88.9% of individuals and these would have been missed by flexible sigmoidoscopy.

CONCLUSIONS

HIV-infected subjects have a higher prevalence of colonic neoplasms, and adenocarcinomas develop at a younger age and are more advanced than in uninfected subjects. Our findings suggest that screening colonoscopy should be offered to HIV-infected subjects, but the age of initiation and the optimal frequency of screening require further study.

Spindle cell tumour with glandular elements: an unusual ileal neoplasm

This report describes a tumour in the ileum with clinical features initially suggestive of a gastrointestinal stromal tumour (GIST). Histopathological examination revealed a biphasic tumour in which the spindle cell component showed immunohistochemical evidence of smooth muscle differentiation but without the characteristic profile of a GIST. A well-differentiated epithelial component was also present, comprising glandular structures with immunohistochemical features suggestive of Mullerian differentiation. Similar glandular differentiation has been described in uterine leiomyomas but not, to our knowledge, in tumours associated with the small bowel. None of the characteristic mutations of GISTs were identified in this case. There were no overt features of malignancy but, because of the unusual nature of the case, we assessed the biological behaviour as uncertain.

Factors predictive of intravenous fluid administration errors in Australian surgical care wards

BACKGROUND

Intravenous (IV) fluid administration is an integral component of clinical care. Errors in administration can cause detrimental patient outcomes and increase healthcare costs, although little is known about medication administration errors associated with continuous IV infusions.

OBJECTIVES

(1) To ascertain the prevalence of medication administration errors for continuous IV infusions and identify the variables that caused them. (2) To quantify the probability of errors by fitting a logistic regression model to the data.

METHODS

A prospective study was conducted on three surgical wards at a teaching hospital in Australia. All study participants received continuous infusions of IV fluids. Parenteral nutrition and non-electrolyte containing intermittent drug infusions (such as antibiotics) were excluded. Medication administration errors and contributing variables were documented using a direct observational approach.

RESULTS

Six hundred and eighty seven observations were made, with 124 (18.0%) having at least one medication administration error. The most common error observed was wrong administration rate. The median deviation from the prescribed rate was -47 ml/h (interquartile range -75 to +33.8 ml/h). Errors were more likely to occur if an IV infusion control device was not used and as the duration of the infusion increased.

CONCLUSIONS

Administration errors involving continuous IV infusions occur frequently. They could be reduced by more common use of IV infusion control devices and regular checking of administration rates.

Indirect impacts of invasive cane toads (Bufo marinus) on nest predation in pig-nosed turtles (Carettochelys insculpta)

The cane toad (Bufo marinus) was introduced into Australia in 1935. Because this toxic frog is novel to the Australian fauna, its introduction has impacted native fauna in a variety of ways. We anticipated a severe decline in the yellow-spotted monitor lizard (Varanus panoptes) associated with the arrival of cane toads along the Daly River, Northern Territory, and predicted a simultaneous impact on nest predation in the pig-nosed turtle (Carettochelys insculpta) because the lizard is the chief predator of C. insculpta eggs at the site. We surveyed for monitors and cane toads for five years at two sites before and after the arrival of cane toads, and surveyed for turtle nest predation for three years before, and one year after, the arrival of the toads. Collectively, our data and observations, combined with unpublished reports, indicate that: (1) cane toads arrived at our study sites during the wet seasons of 2003–04 and 2004–05; (2) the lizard V. panoptes readily succumbs to cane toad toxins; (3) . panoptes has experienced a marked decline in relative population numbers coincident with the arrival of the toads at the site; and (4) V. panoptes has been reduced to such low numbers that it is currently no longer a significant predator of pig-nosed turtle eggs.

A pharmacokinetic-pharmacodynamic model for the mobilization of CD34 hematopoietic progenitor cells by AMD3100

BACKGROUND

AMD3100 is a small-molecule CXCR4 antagonist that has been shown to induce the mobilization of CD34 + hematopoietic progenitor cells from bone marrow to peripheral blood. AMD3100 has also been shown to augment the mobilization of CD34 + cells in cancer patients when administered in combination with granulocyte colony-stimulating factor (G-CSF) (filgrastim). The purpose of this study was to characterize the exposure-response relationship of AMD3100 in mobilizing CD34 + cells when administered as a single agent in healthy volunteers.

METHODS

AMD3100 concentrations and CD34 + cell counts obtained from 29 healthy subjects in a single-dose, intensively sampled pharmacokinetic/pharmacodynamic (PK-PD) study were analyzed by use of nonlinear mixed effects regression with the software NONMEM. FOCE (first order conditional estimation) with interaction was the estimation method, and simultaneous PK-PD fitting was adopted.

RESULTS

The pharmacokinetics of AMD3100 was described by a 2-compartment model with first-order absorption. The population estimates (+/-SE) for clearance and central volume of distribution were 5.17 +/- 0.49 L/h and 16.9 +/- 3.79 L, respectively. CD34 + cell mobilization was best described by an indirect effect model that stimulates the entry process of CD34 + from bone marrow to peripheral blood in the form of a sigmoid maximum effect model. The population estimates (+/-SE) of maximum effect, concentration causing 50% of maximum response, and equilibration time were 12.6 +/- 4.89, 53.6 +/- 11.9 mug/L, and 5.37 +/- 1.31 hours, respectively.

CONCLUSIONS

This study characterizes the exposure-response relationship of AMD3100 in mobilizing CD34 + cells after subcutaneous administration. This PK-PD model will be useful in assessing relevant covariates and for optimizing the use of AMD3100 in various patient populations.

Dosing strategy for enoxaparin in patients with renal impairment presenting with acute coronary syndromes

BACKGROUND

Phase III clinical studies have confirmed that enoxaparin is superior to standard heparin in reducing the rate of recurrent ischaemic events in patients with non-ST elevation acute coronary syndromes. Patients with moderate to severe renal impairment were, however, excluded from these studies. Due to the hydrophilic disposition of enoxaparin, accumulation is likely in patients with renal dysfunction, thereby increasing the risk of haemorrhagic complications if standard weight adjusted treatment doses are used. Arbitrary dose reduction has been reported to increase the risk of ischaemic events, presumably due to inadequate enoxaparin concentrations.

AIM

The aims of this study were to investigate the influence of glomerular filtration rate (GFR) on the pharmacokinetics of subcutaneously administered enoxaparin, and to develop a practical dosing algorithm in renal impairment that can easily be used at the bedside.

METHODS

Thirty-eight patients, median age 78 years (range 44-87), mean GFR 32 ml min(-1) (range 16-117) and mean weight 69 kg (range 32-95), presenting with acute coronary syndrome were recruited into the study. Approximately 10 anti-Xa concentrations were taken per patient over their period of therapy. A population pharmacokinetic model was developed using non linear mixed effects modelling techniques, utilizing the software NONMEM. Stochastic simulations were performed to identify the most suitable dosing regimen.

RESULTS

Three hundred and thirteen anti-Xa concentrations were collected. A two compartment, first order input model was identified as the best baseline model. Covariates found to improve model fitting were GFR as a linear function on clearance (CL) and weight as a linear function on the central volume compartment (Vc). The fraction of drug excreted unchanged (Fu) was estimated at 71%. CL and Vc from the final covariate model were estimated as; CL (l h(-1)) = 0.681 per 4.8 l hr(-1) (GFR) + 0.229 Vc (l) = 5.22 per 80 kg (total body weight)

CONCLUSIONS

Clearance of enoxaparin was predictably related to GFR estimated using the Cockroft and Gault equation, with ideal body weight used as the size descriptor. According to our model no dosage adjustment from the standard 1.0 mg kg(-1) 12 hourly is required for the first 48 h of treatment. Maintenance doses thereafter can be calculated using standard proportional adjustments based on Fu equal to 0.71.

Do risk factors for lactic acidosis influence dosing of metformin?

BACKGROUND

Metformin is commonly prescribed to treat type 2 diabetes mellitus, however it is associated with the potentially lethal condition of lactic acidosis. Prescribing guidelines have been developed to minimize the risk of lactic acidosis development, although some suggest they are inappropriate and have created confusion amongst prescribers. The aim of this study was to investigate whether metformin dose was influenced by the presence of risk factors for lactic acidosis.

METHODS

The study was prospective, and retrieved information from patients admitted to hospital who were prescribed metformin at their time of admission.

RESULTS

Eighty-three patients were included in the study, 60 of whom had a least one risk factor for lactic acidosis. Of those 60 patients, 78.3% had a dose adjustment, with renal impairment, hepatic impairment, surgery and use of radiological contrast media--the risk factors most likely to result in a dose adjustment. When dose adjustments did occur, metformin was withheld on 88.7% of occasions.

CONCLUSION

Metformin dose was influenced by the presence of risk factors for lactic acidosis, although it was dependent upon the number and particular risk factor/s present.

Disordered eating behaviours in women with Type 2 diabetes mellitus

The aim of the article is to investigate the relationship between disordered eating, particularly binge eating, and Type 2 diabetes in women. Subjects included 215 women with Type 2 diabetes (mean age: 58.9 years, mean body mass index (BMI)=33.5 kg/m(2)). Measurements included a structured clinical interview for disordered eating (Eating Disorder Examination, EDE), self-report measures of psychological functioning, glycosylated haemoglobin A1c, BMI. A total of 20.9% of women was binge eating regularly. Binge eating was associated with poorer well being, earlier age of diagnosis, poorer self-efficacy for diet and exercise self-management, and higher BMI. Binge eating frequency predicted blood glucose control after controlling for BMI and exercise level. A history of binge eating independently predicted age of diagnosis of diabetes. Binge eating is relatively common in women with Type 2 diabetes. The relationship between binge eating severity and diabetic control is not explained by overweight. Binge eating may be an independent risk factor for Type 2 diabetes.

Myocardial infarction and type II diabetes--preferential treatment for high risk patients?

OBJECTIVES

To compare variability of blood glucose concentration in patients with type II diabetes with (cases) and without (controls) myocardial infarction. A secondary objective was identification of predictive factors for higher blood glucose on discharge from hospital.

DESIGN

A retrospective matched case-control study.

PARTICIPANTS

Medical notes of 101 type II diabetic patients admitted with a myocardial infarction (MI) and 101 type II diabetic patients (controls) matched on gender and age with no MI were reviewed. Blood glucose concentrations over two consecutive 48-h periods were collected. Demographic data and therapy on admission/discharge were also collected.

RESULTS

Patient characteristics were comparable on recruitment excluding family history of cardiovascular disease (P=0.003), dyslipidaemia (P=0.004) and previous history of MI (P=0.007). Variability of blood glucose in cases was greater over the first 48 h compared with the second 48 h (P=0.03), and greater when compared with controls over the first 48 h (P=0.01). Cases with blood glucose on discharge >8.2 mmol / L (n=45) were less likely to have a history of previous MI (P=0.04), ischaemic heart disease (P=0.03) or hypertension (P=0.02).

CONCLUSIONS

Type II diabetics with an MI have higher and more variable blood glucose concentrations during the first 48 h of admission. Only cardiovascular 'high risk' patients had target blood glucose set on discharge. The desirability of all MI patients with diabetes, having standardized-glucose infusions to reduce variability of blood glucose, should be evaluated in a randomized controlled trial.

Osteoporosis prophylaxis during corticosteroid treatment: failure to prescribe

AIMS

To investigate prescribing patterns to prevent steroid induced osteoporosis. To compare prophylactic prescribing with National Osteoporosis Society (NOS) guidelines.

METHOD

All patients (n=92) taking oral corticosteroids admitted to general medical wards at a district general hospital were prospectively investigated over a nine month period.

RESULTS

Variations from recommended management were revealed. Altogether 64.7% of all inpatients who qualified for prophylaxis for steroid induced osteoporosis were not provided with any suitable agent. It was also found that 21.6% of those who qualified for treatment received a bisphosphonate, the only treatment currently licensed for preventing steroid induced osteoporosis. Of those prescribed prophylactic treatment, a bisphosphonate was selected for 39.3%, hormone replacement therapy was given to 25.0%, and 35.7% received treatment that is not recommended in NOS guidelines.

CONCLUSION

This study revealed substantial variations from NOS guidelines. It is suggested that osteoporosis prophylaxis during steroid treatment is promoted by local hospital guidelines, hospital and community pharmacists, audit, and general practitioners.