Point-of-care immunotesting: Approaching the analytical performance of central laboratory methods

The use of point-of-care (POC) immunoassays has increased significantly and the menu of analytes continues to expand. Most of the rapid immunoassays are currently based on simple manual assay devices such as the immunochromatographic, agglutination, and immunofiltration assays. Although automated readers have recently been introduced at an increasing pace, the major benefit of these genuinely hand-portable assay devices is that they do not usually necessitate instrumentation but can be performed anywhere. Significant advances in assay and detection technologies have, however, recently facilitated the introduction of truly quantitative, sophisticated immunoassay methods to POC settings as well, with the analytical performance characteristics approaching those of conventional laboratory assays. Furthermore, innovative assay technologies such as those based on immunosensors have been introduced to POC testing (POCT) without ever being employed in clinical laboratories. However, further simplification of the assay procedures and analyzers is still feasible, and strong efforts are directed towards the development of miniaturized and simple, yet sensitive and quantitative, novel assay technologies to keep up with the increasing expectations set on future POC immunotesting.

Adrenal Vein Sampling: How to Make It Quick, Easy, and Successful

Adrenal vein sampling has a reputation as a difficult procedure. However, it is being performed more frequently at some institutions due to the realization that primary aldosteronism is more common than previously believed. At the author's institution, adrenal vein sampling with computed tomographic (CT) and laboratory correlation has been performed more than 800 times in the past 10 years. Adrenal vein sampling is used to determine whether autonomous hormone production is unilateral or bilateral; unilateral secretion can be treated with surgery. The venous drainage of each adrenal gland is predominantly via a central vein. Recognition of the right adrenal vein is the crux of adrenal vein sampling. CT is useful in planning adrenal vein sampling by demonstrating the anatomy and positions of the adrenal veins. A small amount of contrast material is injected gently and slowly into the adrenal vein; it is not necessary to perform formal venography to outline the entire gland. To confirm that the vein is draining the majority of adrenal cortical blood, the adrenal vein sample should have a significantly higher level of cortisol than a peripheral sample. Adrenal glands that are producing aldosterone demonstrate an aldosterone-cortisol ratio that is higher than the peripheral value.

Effect of low central venous pressure and phlebotomy on blood product transfusion requirements during liver transplantations

Correction of coagulation defects with plasma transfusion did not decrease the need for intraoperative red blood cells (RBC) transfusions during liver transplantations. On the contrary, it led to a hypervolemic state that resulted in an increase of shed blood. As well, plasma transfusion has been associated with a decreased one-year survival rate. The aim of the present prospective survey was to evaluate whether anesthesiologists could reduce intraoperative RBC transfusions during liver transplantations by changing their anesthesia practice, more specifically by maintaining a low central venous pressure (CVP), through restriction of volume replacement, elimination of all plasma transfusion and by using intraoperative phlebotomy during the transplantation. One hundred consecutive liver transplantations were prospectively studied during a two-year period and were compared to a retrospective series (1998-2002). A low CVP was maintained in all patients prior the anhepatic phase. Coagulation disorders were not corrected preoperatively, intraoperatively, or post-operatively unless uncontrollable bleeding. Phlebotomy and Cell Saver (CS) were used following pre-established criteria. Independent variables were analyzed in a univariate and multivariate fashion. The mean number of intraoperative RBC units transfused was 0.4 +/- 0.8. No plasma, platelets, albumin, or cryoprecipitate were transfused. Seventy-nine percent of the patients received no blood products during their liver transplantation. The average final hemoglobin value was 85.9 +/- 17.8 g/L. In 57 patients (58.2%), intraoperative phlebotomy and CS were used either together or separately. The one-year year survival rate was 89.1%. Logistic regression showed that avoidance of plasma transfusion, starting hemoglobin value and phlebotomy were significantly linked to liver transplantation without RBC transfusion. In conclusion, the avoidance of plasma transfusion and maintenance of a low CVP prior to the anhepatic phase were associated with a decrease in RBC transfusions during liver transplantations. Previous reports indicating that it is neither useful nor necessary to correct coagulation defects with plasma transfusion prior to liver transplantation are further corroborated by this prospective survey. We believe that this work also supports the practice of lowering CVP with phlebotomy in order to reduce blood loss, during liver dissection, without any deleterious effect.

Suckling- and sucrose-induced analgesia in human newborns

This experiment had three goals: 1. To identify the basis of sucking-induced analgesia in healthy, term, newborn humans undergoing the painful, routine, procedure of heel lance and blood collection. 2. To evaluate how taste-induced and sucking-induced analgesias combine to combat pain. 3. To determine whether facial grimacing was an accurate index of diminished pain, or whether it was linked to tissue trauma. We report that: 1. Sucking an unflavored pacifier was analgesic when and only when suck rate exceeded 30 sucks/min. 2. The combination of sucrose and nonnutritive sucking was remarkably analgesic; we saw no behavioral indication in nine of the ten infants that the heel lance had even occurred. 3. Grimacing was reduced to almost naught by procedures that essentially eliminated crying and markedly reduced heart rate during the blood harvesting procedure.

Trends in blood culture contamination: a College of American Pathologists Q-Tracks study of 356 institutions

CONTEXT

Blood culture contamination extends hospital stays and increases the cost of care.

OBJECTIVES

To measure blood culture contamination rates in a large number of institutions over time and to elucidate practice patterns and demographic factors associated with sustained reduction in contamination rates.

DESIGN

Longitudinal cohort study of 356 clinical laboratories that provided quarterly data about blood culture results, using a uniform definition of contamination. Mixed linear model analysis of the 1999 through 2003 data set.

RESULTS

Blood culture contamination was significantly higher in institutions that used nonlaboratory personnel to collect blood (P = .03) and significantly lower in facilities that used a dedicated phlebotomy team (P < .001). Higher volume of blood collection was significantly associated with lower contamination rates (P < .001). Continued participation in the Q-Tracks monitoring program was associated with significant and progressive reduction in contamination rates. By the fifth year of participation, the median institution had reduced its blood culture contamination rate by 0.67% (P < .001).

CONCLUSIONS

Institutions that use decentralized patient-centered personnel rather than dedicated phlebotomy teams to collect blood cultures experience significantly higher contamination rates. Long-term monitoring of contamination is associated with sustained improvement in performance.

A clinical study to evaluate the efficacy of ELA-Max (4% liposomal lidocaine) as compared with eutectic mixture of local anesthetics cream for pain reduction of venipuncture in children

OBJECTIVE

A double-randomized, blinded crossover trial was performed to assess the efficacy of ELA-Max (4% liposomal lidocaine) as compared with eutectic mixture of local anesthetics (EMLA) for pain relief during pediatric venipuncture procedures. Safety was assessed by evaluation for topical or systemic effects and measurement of serum lidocaine concentrations.

METHODS

A total of 120 children who were scheduled for repeat venipuncture for non-study-related reasons at 2 sites participated in the study. Patients were doubly randomized to treatment regimen (study medication application time of either 30 or 60 minutes) and to the order of application of the topical anesthetics for each venipuncture. The primary outcome measures were the child's rating of pain immediately after the venipuncture procedures using a 100-mm visual analog scale (VAS) tool and the parent's and blinded research observer's Observed Behavioral Distress scores.

RESULTS

Both ELA-Max and EMLA seemed to alleviate venipuncture pain. There was no clinically or statistically significant difference in the patient VAS scores within the 30-minute or 60-minute treatment groups, and there was no clinical or statistical difference in VAS scores between the 30-minute ELA-Max treatment without occlusion and the 60-minute EMLA treatment with occlusion. There were no clinically or statistically significant differences between treatment with ELA-Max and EMLA in parental or blinded researcher Observed Behavioral Distress scores, the most frequent response at any observation time being "no distress."

CONCLUSION

This study demonstrates that a 30-minute application of ELA-Max without occlusion is as safe and as effective for ameliorating pain associated with venipuncture as a 60-minute application of the prescription product EMLA requiring occlusion.

Adrenal vein sampling in primary aldosteronism: towards a standardised protocol

Primary aldosteronism comprises subtypes that need different therapeutic strategies. Adrenal vein sampling is recognised by Endocrine Society guidelines as the only reliable way to correctly diagnose the subtype of primary aldosteronism. Unfortunately, despite being the gold-standard procedure, no standardised procedure exists either in terms of performance or interpretation criteria. In this Personal View, we address several questions that clinicians are presented with when considering adrenal vein sampling. For each of these questions we provide responses based on the available evidence, and opinions based on our experience. In particular, we discuss the most appropriate way to prepare the patient, whether adrenal vein sampling can be avoided for some subgroups of patients, the use of ACTH (1-24) during the procedure, the most appropriate criteria for interpretation of adrenal vein cannulation and lateralisation, the use of contralateral suppression, and strategies to improve success rates of adrenal vein sampling in centres with little experience.

Donors who react may not come back: Analysis of repeat donation as a function of phlebotomist ratings of vasovagal reactions

Previous studies using small or restricted samples suggest that vasovagal reactions to blood donation are associated with a decreased likelihood of repeat donation. In the present study, we examined data for all allogeneic whole blood donors (n=89,587) in the American Red Cross Blood Services, Central Ohio Region during an entire year. Results of a one-year follow-up revealed that moderate and severe vasovagal reactions reduced the likelihood of repeat donation by 50% or more. Light vasovagal reactions, which represented 97% of all reactions recorded, significantly reduced return rates by 20% for first-time donors and 33% for experienced donors.

Doing it right the first time: quality improvement and the contaminant blood culture

The aim of the project was to determine whether the rate of contaminant blood cultures could be reduced by using a team of dedicated phlebotomists. Comparisons were made between adult patients requiring blood cultures for suspected bacteremia on medical and surgical units before and after the introduction and withdrawal of a dedicated blood culture team. The results showed that a significant reduction in the contaminant blood culture rate was achieved by the blood culture team (P < 0.001; chi(2) test). Therefore, in our experience, the rate of contaminant blood cultures can be reduced in a teaching hospital by using a team of dedicated phlebotomists. Calculations made with our data and those published by others suggest that cost savings from reducing false-positive blood cultures are greater than the cost of the blood culture team.

Hemoglobin level in older persons and incident Alzheimer disease: prospective cohort analysis

OBJECTIVE

To test the hypothesis that level of hemoglobin is associated with incident Alzheimer disease (AD).

METHODS

A total of 881 community-dwelling older persons participating in the Rush Memory and Aging Project without dementia and a measure of hemoglobin level underwent annual cognitive assessments and clinical evaluations for AD.

RESULTS

During an average of 3.3 years of follow-up, 113 persons developed AD. In a Cox proportional hazards model adjusted for age, sex, and education, there was a nonlinear relationship between baseline level of hemoglobin such that higher and lower levels of hemoglobin were associated with AD risk (hazard ratio [HR] for the quadratic of hemoglobin 1.06, 95% confidence interval [CI] 1.01-1.11). Findings were unchanged after controlling for multiple covariates. When compared to participants with clinically normal hemoglobin (n = 717), participants with anemia (n = 154) had a 60% increased hazard for developing AD (95% CI 1.02-2.52), as did participants with clinically high hemoglobin (n = 10, HR 3.39, 95% CI 1.25-9.20). Linear mixed-effects models showed that lower and higher hemoglobin levels were associated with a greater rate of global cognitive decline (parameter estimate for quadratic of hemoglobin = -0.008, SE -0.002, p < 0.001). Compared to participants with clinically normal hemoglobin, participants with anemia had a -0.061 z score unit annual decline in global cognitive function (SE 0.012, p < 0.001), as did participants with clinically high hemoglobin (-0.090 unit/year, SE 0.038, p = 0.018).

CONCLUSIONS

In older persons without dementia, both lower and higher hemoglobin levels are associated with an increased hazard for developing AD and more rapid cognitive decline.

A randomized trial of povidone-iodine compared with iodine tincture for venipuncture site disinfection: effects on rates of blood culture contamination

BACKGROUND

Contamination of blood cultures creates problems in their interpretation and unneeded resource utilization. Because skin flora comprise the major group of contaminant species, more effective skin disinfection at the venipuncture site could reduce contamination.

SUBJECTS AND METHODS

We performed a randomized trial in adult inpatients at a tertiary care teaching hospital. Antecubital venipuncture sites were randomly disinfected with povidone-iodine or iodine tincture, and blood cultures (two bottles, 10 mL of blood) were drawn by professional phlebotomists. Scoring of contaminant species was restricted to skin flora. Hospital resource utilization was compared among patients with contaminated blood cultures and those with sterile blood cultures.

RESULTS

Of the 3,851 blood cultures collected during the study, 120 (3.1%) were contaminated with skin flora. The contamination rate for blood cultures collected after povidone-iodine was 3.8% (74 of 1,947), compared with a rate of 2.4% (46 of 1,904, P = 0.01) after iodine tincture. The difference in mean total hospital costs for patients with contaminated blood cultures and those with sterile blood cultures was $4,100 (95% confidence interval: $740 to $7,400, P = 0.02).

CONCLUSIONS

Iodine tincture is superior to povidone-iodine for venipuncture site antisepsis before blood culture sampling. Because of the high costs associated with contaminated blood cultures, hospitals should consider switching from povidone-iodine to iodine tincture. Reduction of the contamination rate may improve the quality of patient care and reduce hospital costs.

Preanalytical phase--a continuous challenge for laboratory professionals

Preanalytical phase is the most vulnerable part of the total testing process and is considered to be among the greatest challenges to the laboratory professionals. However, preanalytical activities, management of unsuitable specimens and reporting policies are not fully standardized, nor harmonized worldwide. Several standards related to blood sampling and sample transportation and handling are available, but compliance to those guidelines is low, especially outside the laboratory and if blood sampling is done without the direct supervision of the laboratory staff. Furthermore, for some most critical procedures within the preanalytical phase, internationally accepted guidelines and recommendations as well as related quality measures are unfortunately unavailable. There is large heterogeneity in the criteria for sample rejection, the different strategies by which unacceptable samples are managed, processed and test results reported worldwide. Management of unacceptable specimens warrants therefore immediate harmonization. Alongside the challenging and long road of patient safety, preanalytical phase offers room for improvement, and Editors at Biochemia Medica Journal definitely hope to continue providing a respective mean for reporting studies on different preanalytical phase topics. With pleasure and delight we invite potential future authors to submit their articles examining the quality of various preanalytical activities to Biochemia Medica. We will keep nurturing this topic as our prominent feature and by this we hope to be able to deliver valid evidence for some future guidelines and recommendations.

Incorporating psychological approaches into routine paediatric venepuncture

Studies of paediatric procedural distress have flourished over the past two decades, with psychological intervention strategies showing consistently high efficacy in reducing pain and fear. This review concentrates briefly on the acquisition and treatment of fear, arguing that what is witnessed clinically is not needle fear or phobia, but anticipatory or procedural distress. The main focus is on how such procedures could be amended to incorporate psychological techniques routinely, outlining specific guidelines for clinical practice.

The effect of blood drawing techniques and equipment on the hemolysis of ED laboratory blood samples

OBJECTIVE

The objective of this study was to identify venipuncture and blood draw factors associated with hemolysis (red blood cell damage) of ED blood samples.

METHODS

A convenience sample of ED blood samples was studied for degree of hemolysis and phlebotomy technique using data obtained from surveys completed by ED nurses and/or ED clinical technicians. The questionnaires were submitted with each blood sample sent to the laboratory for diagnostic testing. The level of hemolysis per sample was designated by laboratory technicians. Completed questionnaires were gathered and analyzed. Chi-square analysis was used to determine significant relationships.

RESULTS

During the 19-day study, 598 surveys were collected, and 76% (n = 454) were complete enough to be included in the analysis. The predominant technique for drawing blood in new venipunctures (n = 372) was by intravenous catheters (69% [n = 255]), versus straight needles (31% [n = 117]). Thirty-two percent of the samples had some degree of hemolysis; 13% were so hemolyzed that tests were canceled by the laboratory. Blood drawn through intravenous catheters resulted in significantly more hemolysis and test cancellation than that drawn with a straight needle (20% versus <1%, significant at P <.001). Intravenous catheter hemolysis was higher when a vacutainer was used versus a syringe (22% canceled versus 9% canceled, significant at P =.02).

CONCLUSION

Drawing blood through intravenous catheters was associated with significantly more hemolysis than drawing blood with straight needles. Using a combination of intravenous catheter and vacutainer caused more hemolysis than using an intravenous catheter with a syringe.

Long term effects of phlebotomy on biochemical and histological parameters of chronic hepatitis C

OBJECTIVES

There is considerable evidence that iron is a risk factor for liver injury in chronic hepatitis C. Known as iron reduction therapy, phlebotomy reduces serum ALT activity. This effect might continue with maintenance phlebotomy and result in slower progression of liver fibrosis.

METHODS

We examined the biochemical parameters and liver histology of patients with chronic hepatitis C treated by maintenance phlebotomy. For biochemical evaluation, 25 patients were treated by initial phlebotomy to reduce serum ferritin levels to 10 ng/ml or less and then observed for 5 yr with maintenance phlebotomy to maintain the iron-deficient state. For histological evaluation, liver biopsies were performed before and after the study period in 13 of the patients. Thirteen patients who were virological nonresponders to interferon alone and had undergone second liver biopsies after more than 3 yr served as histological controls.

RESULTS

Serum aminotransferase levels were decreased significantly by initial phlebotomy and remained at the same levels during the study period (p < 0.05). The grading scores were improved significantly in the study group (p < 0.05) and unchanged in the controls. The staging scores remained unchanged in the study group but were increased in the controls (p < 0.005). Disease progression was significantly different between the two groups (p < 0.05).

CONCLUSIONS

These results suggest that phlebotomy with maintenance lowers serum aminotransferase levels, improves liver inflammation, and suppresses the progression of liver fibrosis in chronic hepatitis C.

Continuous wristband monitoring over 2 years decreases identification errors: a College of American Pathologists Q-Tracks Study

CONTEXT

Identification of patients is one of the first steps in ensuring the accuracy of laboratory results. In the United States, hospitalized patients wear wristbands to aid in their identification, but wristbands errors are frequently found.

OBJECTIVE

To investigate if continuous monitoring of wristband errors by participants of the College of American Pathologists (CAP) Q-Tracks program results in lower wristband error rates.

SETTING

A total of 217 institutions voluntarily participating in the CAP Q-Tracks interlaboratory quality improvement program in 1999 and 2000.

DESIGN

Participants completed a demographic form, answered a questionnaire, collected wristband data, and at the end of the year, best and most improved performers answered another questionnaire seeking suggestions for improvement. Each institution's phlebotomists inspected wristbands for errors before performing phlebotomy and recorded the number of patients with wristband errors. On a monthly basis, participants submitted data to the CAP for data processing, and at the end of each quarter, participants received summarized comparisons. At the end of each year, participants also received a critique of the results along with suggestions for improvement.

MAIN OUTCOME MEASURES

The percentage of wristband errors by quarter, types of wristband errors, and suggestions for improvement.

RESULTS

During 2 years, 1 757 730 wristbands were examined, and 45 197 wristband errors were found. The participants' mean wristband error rate for the first quarter in 1999 was 7.40%; by the eighth quarter, the mean wristband error rate had fallen to 3.05% (P <.001). Continuous improvement occurred in each quarter for participants in the 1999 and 2000 program and in 7 of 8 quarters for those who participated in both 1999 and 2000. Missing wristbands accounted for 71.6% of wristband errors, and best performers usually had wristband error rates under 1.0%. The suggestion for improvement provided by the largest number of best and most improved performers was that phlebotomists should refuse to perform phlebotomy on a patient when a wristband error is detected.

CONCLUSIONS

The wristband error rate decreased markedly when this rate was monitored continuously using the CAP Q-Tracks program. The Q-Tracks program provides a useful tool for improving the quality of services in anatomic pathology and laboratory medicine.

Fatal Clostridium perfringens sepsis from a pooled platelet transfusion

A male patient with acute myeloid leukaemia received a pooled platelet preparation prepared by Optipress system on the last day of its shelf life. The patient collapsed after two-thirds of the contents had been transfused. Clostridium perfringens was isolated from the platelet bag within 18 h of the acute event. Metronidazole, gentamicin and Clostridium antiserum were then administered in addition to the broad spectrum antibiotics started previously. However, the patient died 4 days after the platelets were transfused. The cause of death was given as cardiovascular shock, entirely compatible with an overwhelming bacteraemic and septic episode. A coroner's verdict of accidental death due to transfusion of a contaminated unit of platelets was recorded. On subsequent investigation Cl. perfringens type A serotype PS68,PS80 (identical to that found in the platelet bag) was cultured from the venepuncture site of the arm of one of the donors who contributed towards the platelet pool. The donor had two young children and frequently changed nappies. Faecal contamination of the venepuncture site was the suspected source for the transmission of Cl. perfringens, an organism commonly found in the soil and intestinal tract of humans. This case dramatically highlights the consequences of transfusing a bacterially contaminated unit. It is vital that such incidents are investigated and reported so that the extent of transfusion-associated bacterial transmission can be monitored and preventative measures taken if possible.

Epidemiology and neonatal pain management of heelsticks in intensive care units: EPIPPAIN 2, a prospective observational study

BACKGROUND

Heelstick is the most frequently performed skin-breaking procedure in the neonatal intensive care units (NICUs). There are no large multicenter studies describing the frequency and analgesic approaches used for heelsticks performed in NICUs.

OBJECTIVES

To describe the frequency of heelsticks and their analgesic management in newborns in the NICU. To determine the factors associated with the lack of specific preprocedural analgesia for this procedure.

DESIGN

EPIPPAIN 2 (Epidemiology of Procedural PAin In Neonates) is a descriptive prospective epidemiologic study.

SETTING

All 16 NICUs in the Paris region in France.

PARTICIPANTS

All newborns in the NICU with a maximum corrected age of 44 weeks +6 days of gestation on admission who had at least one heelstick during the study period were eligible for the study. The study included 562 newborns.

METHODS

Data on all heelsticks and their corresponding analgesic therapies were prospectively collected. The inclusion period lasted six weeks, from June 2, 2011 to July 12, 2011. Newborns were followed from their admission to the 14th day of their NICU stay or discharge, whichever occurred first.

RESULTS

The mean (SD) gestational age was 33.3 (4.4) weeks and duration of participation was 7.5 (4.4) days. The mean (SD; range) of heelsticks per neonate was 16.0 (14.4; 1-86) during the study period. Of the 8995 heelsticks studied, 2379 (26.4%) were performed with continuous analgesia, 5236 (58.2%) with specific preprocedural analgesia. Overall, 6764 (75.2%) heelsticks were performed with analgesia (continuous and/or specific). In a multivariate model, the increased lack of preprocedural analgesia was associated with female sex, term birth, high illness severity, tracheal or noninvasive ventilation, parental absence and use of continuous sedation/analgesia.

CONCLUSIONS

Heelstick was very frequently performed in NICUs. Although, most heelsticks were performed with analgesia, this was not systematic. The high frequency of this procedure and the known adverse effects of repetitive pain in neonates should encourage the search of safe and effective strategies to reduce their number.

Factors Affecting Hemolysis Rates in Blood Samples Drawn From Newly Placed IV Sites in the Emergency Department

INTRODUCTION

To decrease the number of hemolyzed samples in the emergency department, performance improvement activities were implemented, including phlebotomy classes for staff, evaluation of blood draw equipment, and a study to evaluate factors attributed to hemolysis of blood samples when drawn at the time a new intravenous catheter is inserted.

METHODS

In a study with an observational design conducted in June and July 2004, researchers examined the cases of 100 randomly chosen patients who had blood drawn through newly placed peripheral intravenous access.

RESULTS

In this study, the blood draw collection factors with the highest hemolysis rates included blood samples drawn between 12:00 am to 5:59 am; samples drawn by patient care technicians; right-hand site; 22-gauge intravenous catheters; syringe draws; blue tubes; 6.0 mL tubes; difficulty drawing blood; 2 tries for intravenous placement; resistance when aspirating blood using a syringe; and respiratory discharge diagnoses. Statistically significant (P < .05) blood draw factors included intravenous placement sites of right hand/forearm and antecubital; intravenous catheter size 22 gauge; blood drawing categorized as difficult; number of tries for intravenous placement; blood tube size 1.8 mL; and discharge diagnoses of respiratory, gastrointestinal, reproductive, dermatologic, and endocrine.

DISCUSSION

Clinically meaningful factors associated with hemolysis rates included the use of a 22-gauge intravenous catheter size, which resulted in a hemolysis rate of 60%; in addition, intravenous placement sites on the right side had statistically significant higher hemolysis rates than the left side, a finding that merits further research. As a result of the study we modified our standard operating procedure to discontinue the use of a 22-gauge or smaller intravenous catheter in adults. If required for small vein sticks, the use of a straight needle stick to obtain blood samples should be considered. The results of this study underscore the importance of education and training and the consideration for regular competency testing for staff with phlebotomy responsibilities.

Analgesic effect of watching TV during venipuncture

AIMS

To assess the analgesic effect of passive or active distraction during venipuncture in children.

METHODS

We studied 69 children aged 7-12 years undergoing venipuncture. The children were randomly divided into three groups: a control group (C) without any distraction procedure, a group (M) in which mothers performed active distraction, and a TV group (TV) in which passive distraction (a TV cartoon) was used. Both mothers and children scored pain after the procedure.

RESULTS

Main pain levels rated by the children were 23.04 (standard deviation (SD) 24.57), 17.39 (SD 21.36), and 8.91 (SD 8.65) for the C, M, and TV groups, respectively. Main pain levels rated by mothers were 21.30 (SD 19.9), 23.04 (SD 18.39), and 12.17 (SD 12.14) for the C, M, and TV groups, respectively. Scores assigned by mothers and children indicated that procedures performed during TV watching were less painful (p<0.05) than control or procedures performed during active distraction.

CONCLUSION

TV watching was more effective than active distraction. This was due either to the emotional participation of the mothers in the active procedure or to the distracting power of television.

Evaluation of donor arm disinfection techniques

BACKGROUND AND OBJECTIVE

To validate a standardized optimal national procedure for donor arm disinfection.

MATERIALS AND METHODS

A direct swabbing and plating technique was used to enumerate bacteria present on the arm pre- and postdisinfection. Twelve donor arm disinfection techniques were evaluated.

RESULTS

The Medi-Flex Adapted method, consisting of a two-stage process with an initial application of isopropyl alcohol followed by tincture of iodine, produced the best arm disinfection. A percentage reduction in bacterial counts of 99.79% (logarithmic reduction of 2.67) was obtained. Postdisinfection, 70% of donors had bacterial counts of zero, and 98% had counts of 10 or less.

CONCLUSION

The Medi-Flex disinfection method offers the English National Blood Service a validated, optimal 'best practice' disinfection technique and should contribute significantly to the reduction in risk of transmission of bacteria by transfusion.

Time and Sample Site Dependency of the Optimized CO-Rebreathing Method

PURPOSE

A new method to estimate hemoglobin mass (Hbmass) requires capillary blood and rebreathing a carbon-monoxide (CO) bolus for 2 min. We hypothesized that incomplete circulatory mixing of CO could confound this method, so we compared capillary with venous blood to determine whether sampling site altered the percentage of carboxyhemoglobin (%HbCO) and the reliability and accuracy of the "2-min Hbmass." The conventional 20-min CO-rebreathing procedure was used as the Hbmass criterion.

METHODS

In the first experiment (N=12), both fingertip capillary and antecubital venous blood were sampled 4 and 6 min after commencing 2 min of CO-rebreathing. Within 8 d, these subjects completed two 2-min and one 20-min CO-rebreathing periods. For the latter, capillary and venous blood were collected simultaneously after two 10-min periods of rebreathing. In a second experiment (N=6), both capillary and venous blood were sampled 4, 6, 8, 10, and 12 min after commencing 2 min of CO-rebreathing. A third experiment (N=6) evaluated the reliability of a modified 2-min CO-rebreathing test with capillary blood sampled at minutes 8 and 10.

RESULTS

Typical error (TE) for the first two 2-min tests was 1.1% (90% confidence limits 0.9-1.8%), but the average Hbmass from 2-min capillary blood was 4.8% lower than from venous blood for the 20-min procedure. In the second experiment, peak venous %HbCO occurred at minute 6, and the difference between capillary and venous values was minimal (mean+/-SD; 0.08+/-0.07, 0.01+/-0.09) at minutes 8 and 10. TE for the third experiment was 1.2% (0.8-2.5%).

CONCLUSION

A modified 2-min CO-rebreathing procedure using capillary or venous blood sampled 8 and 10 min after starting CO-rebreathing allows complete circulatory mixing and provides an accurate and reliable estimate of Hbmass.

1999 Gary J. Becker Young Investigator Award. MR-guided transjugular portosystemic shunt placement in a swine model

PURPOSE

To evaluate the performance of portal venous puncture with use of magnetic resonance (MR) guidance, and to place a transjugular intrahepatic portosystemic shunt (TIPS) in a swine model.

MATERIALS AND METHODS

A study of 12 swine was performed to evaluate the ability of interventional MR imaging to guide portal vein puncture and TIPS placement. Six swine had catheters placed in the right hepatic vein under C-arm fluoroscopy. A nitinol guide wire was left in the vein and the animals were then moved into an open configuration MR imaging unit. A TIPS needle set was used to puncture the portal vein using MR fluoroscopy. The animals were transferred to the C-arm, and venography confirmed portal vein puncture. A follow-up study was performed in six additional swine to place a TIPS using only MR imaging guidance. MR tracking was used to advance a catheter from the right atrium into the inferior vena cava. Puncture of the portal vein was performed and a nitinol stent was placed, bridging the hepatic parenchyma. MR venogram confirmed placement.

RESULTS

Successful portal vein puncture was achieved in all animals. The number of punctures required decreased from 12 in the first animal to a single puncture in the last eight swine. A stent was successfully placed across the hepatic tract in all six swine.

CONCLUSIONS

Real-time MR imaging proved to be a feasible method to guide portal vein puncture and TIPS placement in pigs.

Capillary blood sampling from the ear of dogs and cats and use of portable meters to measure glucose concentration

Two new methods for collection of capillary blood from the ear of dogs and cats for the measurement of blood glucose concentration using portable blood glucose meters (PBGMs) are described. The first method uses a lancing device after pre-warming the ear, while the second employs a vacuum lancing device. Both methods generated blood drops of adequate size, although the latter method was faster and easier to perform. Accuracy of the two PBGMs was evaluated clinically and statistically. Although assessment of statistical accuracy revealed differences between the PBGMs and the reference method, all of the PBGM readings were within clinically acceptable ranges. Measurement of capillary blood glucose concentration is easy to perform, inexpensive and fast. It may be used by owners to determine blood glucose concentrations at home, and could serve as a new tool for monitoring diabetic dogs and cats.