Vacutainer Tubes Research Articles

Stability of Tumor Markers CA 19.9, CA 125, and CA 15.3 in Serum Obtained from Plain Tubes and Tubes Containing Thixotropic Gel Separator

The group of tumor-associated antigens with superficial carbohydrate structure influencing cell–cell interaction processes and cell growth regulation is commonly named “mucins,” characterized by large and heterogeneic molecular mass and the presence of O -linked carbohydrates. Mucins are released in extracellular space and can be found and measured in serum and other biological fluids. Among mucins, CA 19.9 is widely used for diagnosing gastrointestinal cancers (1), CA 125 for gynecological cancers (2), and CA 15.3 for breast cancer (3). Despite the wide use of these tumor markers in clinical laboratories, few data about their preanalytical phase exist. We studied the stability of CA19.9, CA 125, and CA 15.3 for 72 h and the effect of serum collection differences between plain tubes and tubes with thixotropic gel. We used our findings to define practical and empirical guidelines for blood drawing, storage, transportation, and delay from venipuncture to analysis. We collected blood by routine sampling, namely, in plain tubes (pink cap, 7-mL Vacutainer Tube; Becton Dickinson) and in gel-containing tubes (gold cap, 5-mL Vacutainer Tube), completely filling the tubes and centrifuging them at 4 °C for 10 min …

Rapid Detection of the Fibrinogen Aα16Arg→His Mutation

We have now identified mutations in 17 families with dysfibrinogenemias. Over half of these families have the Aα16Arg→His mutation. This mutation is the most commonly reported cause of dysfibrinogenemia and, like other dysfibrinogenemias, is readily detected because of the associated prolonged thrombin and reptilase times (1)(2)(3). The mutation alters the thrombin cleavage site such that release of fibrinopeptide A is delayed. However, fibrinopeptide release assays are difficult and do not directly confirm the molecular basis of the impaired fibrinopeptide release. We have therefore designed a rapid and technically simple PCR-based method for detection of the Aα16Arg→His mutation. This allows reliable identification of a common dysfibrinogenemia that, in its heterozygous form, is usually asymptomatic and does not pose any substantial threat to the health of the patient. Application of this method will allow clinical laboratories to determine the molecular defect in many of the cases that they detect during coagulation studies. We examined nine families with the Aα16Arg→His mutation. These had been referred for further investigation when routine coagulation studies were consistent with dysfibrinogenemia. All procedures were carried out in accordance with the guidelines of our local ethics committee. Blood samples were collected into Na+ citrate Vacutainer Tubes (Becton Dickinson), and coagulation studies were performed by routine clinical tests for thrombin and reptilase times. …

Rapid Determination of Total Homocysteine in Human Plasma by Using N(O,S)-Ethoxycarbonyl Ethyl Ester Derivatives and Gas Chromatography–Mass Spectrometry,

The measurement of total homocysteine (tHcy), i.e., the sum of free and protein-bound homocysteine, and the homocysteinyl moieties of the disulfides homocystine and cysteinylhomocysteine in human serum or plasma is of significant value for the diagnosis and follow-up of folate and cobalamin (vitamin B12) deficiencies (1)(2). These deficiency states are the most abundant causes of marked increases of plasma homocysteine. In addition, a moderately increased concentration of homocysteine is of growing interest for its claimed link with the development of thromboembolism and vascular disease, including coronary atherosclerosis (3)(4)(5)(6). Previous studies have dealt with several of different protocols to measure tHcy concentrations in human serum or plasma by using HPLC and gas chromatography–mass spectrometry (GC-MS) techniques (7)(8). The derivatization protocols most widely used are laborious, time consuming, and require expensive reagents. Here we present a more rapid methodology suitable for sensitive tHcy determination in human plasma by using a simple aqueous, room-temperature, one-step derivatization protocol with ethyl chloroformate (ECF) that provides volatile N ( O , S )-ethoxycarbonyl amino acid ethyl esters (9)(10) and GC-MS analysis. Blood was collected by venipuncture into Vacutainer Tubes (Sarstedt) containing EDTA at a final concentration of 2.7 mmol/L. The study was in accordance with ethical standards of the local committee. Plasma was recovered without delay after centrifugation at 5000 g for 3 min at 0–2 °C. Plasma can be stored at −20 °C until analysis. Plasma aliquots (100 μL) were supplemented with 20 μL of reducing agent (tri- n -butylphosphine, 360 mmol/L in dimethylformamide) and dl-[3,3,3′,3′,4,4,4′,4′-2H8] homocystine (isotopic purity 98%; CIL; final concentration 40 μmol/L) as an internal standard (IS). The samples were incubated for 30 min at 4 °C to reduce and release (endogeneous) homocysteine from …

Reply: H2-Breath Tests-Importance of Adequate Storage of Breath Samples

To the Editor: Thank you for the opportunity to respond to the letter from Bodamer and Leonard. We stated in the Methods section that “The detailed methodology for breath sampling has been described elsewhere (1).” In the reference paper (Am J Clin Nutr 1990;52:342-70), it has been clearly stated that “Immediately after each breath collection, samples were transferred for storage into silicongreased 30-ml syringes (Terumo, Sydney) fitted with plastic three-way stopcocks and transported to the Clinical Research Division laboratory in Rangoon (Yangon).” We never use plastic bags, breath sampling bags, or Vacutainer tubes as storage for breath samples. Regarding hydrogen concentrations of stored samples in silicon-greased 30-ml syringes (Terumo, Sydney) fitted with a plastic three-way stopcock, we have shown that at room temperature, initial hydrogen concentrations of 55 ppm declined by 5-10% in 24 h, but with low initial hydrogen concentrations very little hydrogen loss occurred (Am J Clin Nutr 1990;52:342-70). We have also noted the contamination of sterilized, silicone coated Vacutainer Tubes with methane (Genge JR. Contamination of breath samples in sterilized Vacutainer tubes [letter]. Clin Chem 1991;37:2019), and we have shown that plastic syringes fitted with two-way plastic stopcocks are practical vessels for storing breath samples for several days before analysis for methane (Myo-Khin, Genge JR, Bolin TD, Htain-Win. Storage of methane breath-test samples in plastic syringes [letter]. Clin Chem 1991;37:2161). Terry D. Bolin; Myo-Khin Gastrointestinal Unit; Department of Medicine; Prince of Wales Hospital; Randwick, Australia

In vitro assessment of platelet function.

With the realization that the skin bleeding time is often an unreliable measure of platelet function, efforts have been made to identify ways to assess qualitative platelet dysfunction. Currently available techniques measure platelet adhesion, platelet aggregation, the ability of platelets to retard or stop flow through fibers, and the contribution of platelets to in vitro clot formation. Glass bead adhesion, which continues to be performed in some laboratories, is gradually being replaced by measures of platelet adhesion to filters composed of glass fibers, Dacron fibers, or collagen. In each instance, anticoagulated platelet-rich plasma or whole blood flows through the filter under a regulated pressure gradient. The amount of blood flowing through the filter versus time and/or the time to filter occlusion are measured. Recent developments in platelet aggregation have focused on whole blood and stagnation point flow aggregation techniques. Whole blood aggregation does not require blood sample processing and accommodates blood obtained from citrated vacutainer tubes. Stagnation point flow measures both platelet adhesion and aggregation and may be able to detect pathologically-enhanced platelet function. Global measures of hemostasis attempt to simultaneously evaluate the adequacy of fluid phase coagulation and platelet function. Currently available techniques include Thromboelastography, SonoClot Analyzer, Hemodyne Hemostasis Analyzer, PITT, and Hemostatometry. Although each of these technologies have been shown to provide interesting data in the research setting, the ability of any of these techniques to detect abnormal or clinical inadequate platelet function remains to be established.

The Study of Effects on Metabolism of Dietary Aluminum in Broilers

The aim of this study was to investigate the effects on metabolism and body weight of aluminum added to ration of broilers. Day-old thirty broiler chicks were divided into two equal groups and fed for 40 days. The broilers in experimental group were fed with dietary supplementation fo 2g/kg aluminum sulfate and broilers in control group were fed with supplementary dietary sodium sulfate containing sulfate equal to those supplied by aluminum sulfate in diet of experimental group. In days 20 to 40 of experimental period, the broilers were weighed, and blood samples were taken with vacutainer tubes. In obtained sera, ALP, CK, \gamma-GT levels increased with time in experimental group was always found higher than control group. It was determined that other parameters were not affected more by dietary aluminum. The rising in serum ALP levels and the fallign in Pi levels in experimental group could show a disorder in bone mineralisation or phosphorus metabolism. The increase of \gamma-GT levels and higher glucose levels in experimental group may be an indicator of liver degeneration.

Unusual interference from primary collection tube in a high-performance liquid chromatography assay of amiodarone

We describe an unusual interference in our routine high-performance liquid chromatography (HPLC) assay of amiodarone and its active metabolite, desethylamiodarone, used to quantify the parent drug and the active metabolite in serum from the primary sample collection tube. The interfering peak had a retention time very similar to that of the authentic desethylamiodarone. Substitution of Corvac tubes with Vacutainer tubes for the collection and transportation of serum samples eliminated the source of interference. We routinely suggest the use of Vacutainer collection tubes for obtaining blood samples of cardiac patients undergoing amiodarone therapy.

A comparison of hemolysis rates using intravenous catheters versus venipuncture tubes for obtaining blood samples

The primary purpose of this study was to compare the rate of hemolysis in blood samples obtained by an i.v. catheter versus the rate in samples obtained by venipuncture (Vacutainer tubes and needles; Becton Dickinson Vacutainer Systems, Franklin Lakes, N.J.). Subsequently, variance in i.v. catheter diameter was reviewed to determine its influence on hemolysis rate of i.v. catheter aspirate. A randomized, prospective study was used to evaluate hemolysis differences between the two blood sampling methods. A descriptive, retrospective review of study data was used to evaluate the importance of the variable i.v. catheter diameter. The study group consisted of patients who came to the emergency department and required both an i.v. infusion and blood sampling for determination of electrolyte levels and complete blood cell count. Pediatric patients (younger than 16 years) were excluded. The ED patients who qualified for the study were randomly assigned to either group A or B. The blood samples for patients in the A group were obtained through the i.v. catheter at the time of insertion. The i.v. catheters ranged in size from 24 gauge to 14 gauge. Patients in the B group also had insertion of an i.v. line, but their blood samples were obtained by Vacutainer venipuncture at a separate site. The Vacutainer needle was standardized at 21 gauge. All blood samples were collected by one of seven experienced ED nurses. The nurse who collected the blood sample for an study patient was responsible for result follow-up. A total of 165 patients participated in the study; 87 patients were assigned to the A (i.v.) group, and 78 patients participated in the B (venipuncture) group. In group A a total of 12 of 87 (13.7%) blood samples hemolyzed. Hemolysis occurred in 3 of 78 (3.8%) of group B samples. These findings were statistically significant (p < 0.05). When we examined the variable i.v. catheter diameter, we noted a lower incidence of hemolysis with larger catheter diameters: 24 gauge (100%), 22 gauge (25%), 20 gauge (15%), 18 gauge (10%), 16 gauge (0%), 14 gauge (0%). This findings was statistically significant (p < 0.05). Hemolysis of blood samples obtained by an i.v. catheter was significantly higher than when blood was obtained through Vacutainer venipuncture. There is an inverse correlation between i.v. catheter diameter and the rate of hemolysis.

Evaluation of the Du Pont Axial Separation system

We evaluated the Du Pont Axial Separation Technology (AST) system, which permanently separates a blood specimen into serum or plasma and cells in 1 min. Blood was collected in axial processing containers by standard venipuncture techniques and processed in an Axial Separation Module. Paired patient samples (n = 48 serum pairs, n = 50 plasma pairs) revealed no clinically significant differences in results for common chemistry analytes from samples collected in Becton Dickinson Vacutainer Tubes and centrifuged conventionally vs those from samples collected and processed in the AST system, except for a bias in serum (but not plasma) lactate dehydrogenase activity. This bias was dependent on the extent of stretching of the clot during processing and could be minimized by clotting the blood sample horizontally (axially). We believe the rapid separation of blood by the AST system has the potential to substantially reduce preanalytical specimen handling time.

Clinical trials of a novel centrifugation method: axial separation

Specimen centrifugation is one of the most time-consuming tasks associated with preanalytical specimen processing. We report the first clinical use and impact study of the novel centrifugation method, axial separation, using the Axial Separation Module (ASM). The ASM centrifuges medical specimens one at a time (in 1 min 9 s) in proprietary Axial Process Containers (APC). Here we report tests of the ASM in an outpatient clinical laboratory. Use of the ASM in the outpatient clinic laboratory led to an average total improvement (decrease in total bench time) of 8 min 9 s per specimen compared with conventional centrifugation. Laboratory analysis revealed no statistical difference between plasma obtained from the APC vs that from a Becton Dickinson Vacutainer Tube. We conclude the ASM offers a cost-effective alternative to conventional centrifugation. Further, the use of axial separation may allow specimen separation to become an integral part of the phlebotomy process.

Flow cytometric evaluation of platelet activation in blood collected into EDTA vs. Diatube‐H, a sodium citrate solution supplemented with theophylline, adenosine, and dipyridamole

With platelet activation, there is modulation of platelet surface molecule expression. In flow cytometric analyses of in vivo platelet activation, results are often confounded by activation induced in vitro by the preparative procedures. It is particularly important therefore to prevent or retard platelet activation as soon as possible after withdrawal of the blood sample. Taking blood into paraformaldehyde, or fixing the cells with paraformaldehyde as soon as possible after withdrawal, has been employed to prevent platelet activation in vitro, but paraformaldehyde-fixed platelets cannot be further used in functional studies. We investigated the efficacy of Diatube-H, a commercially available combination of platelet antagonists (theophylline, adenosine, and dipyridamole), in preventing or retarding platelet activation in vitro, along with its effects on modulation of platelet membrane glycoproteins (GP) and adhesion molecules. In contrast to blood taken into EDTA, blood taken into Diatube-H vacutainer tubes could be stored at room temperature for up to 4 hr prior to paraformaldehyde fixation without significant in vitro platelet activation, as measured by CD62P, CD63 and modulation of GPIb and GPIIbIIIa surface expression. Hence, paraformaldehyde fixation could be deferred for several hours, permitting transport of samples from distant sites. Studies of thrombin-induced platelet activation indicated that platelets taken into Diatube-H remained functional i.e. were able to be activated. Expression of the CD29, CD49b and CD31 adhesion molecules on the platelet surface was unaffected by storage in Diatube-H. The results suggest that Diatube-H may be a useful reagent for flow cytometric studies of platelets when the samples cannot be processed immediately.

Comparative stabilities of quantitative human immunodeficiency virus RNA in plasma from samples collected in VACUTAINER CPT, VACUTAINER PPT, and standard VACUTAINER tubes

This study compared the levels of human immunodeficiency virus (HIV) virion RNA in plasma from whole blood collected in VACUTAINER CPT (cell preparation tube), VACUTAINER PPT (plasma preparation tube), VACUTAINER SST (serum separation tube), and standard VACUTAINER tubes with sodium heparin, acid citrate dextrose, sodium citrate, and potassium EDTA used as anticoagulants. Quantitative plasma HIV RNA levels were measured by branched-DNA signal amplification. Blood from all tubes was either processed within 1 to 3 h after collection or stored at room temperature or at 4 degrees C for analysis at 6 to 8 and 30 h postdraw. Immediately separated plasma from sodium citrate CPT tubes held at 4 degrees C maintained better stability of HIV RNA equivalents than whole blood held at room temperature or 4 degrees C. The highest number of HIV RNA equivalents was seen with EDTA VACUTAINER tubes. HIV RNA equivalents in all types of plasma were significantly higher than in SST tubes. Although a decline in HIV RNA equivalents was seen in all collection devices after 30 h, a significantly greater decline in plasma HIV RNA equivalents occurred in acid citrate dextrose VACUTAINER tubes than in citrate CPT, PPT, and standard EDTA VACUTAINER tubes. In order to minimize the variability of quantitative HIV RNA test results, our data suggest that samples collected for a particular assay should be processed at the same time postdraw using a particular tube type throughout a given study.

Determination of Serum Ionized Calcium Concentration in Dairy Cattle After Frozen Anaerobic Storage

The stability of serum ionized calcium concentration (ICa) from dairy cows was studied after anaerobic collection and frozen storage. Paired blood samples were obtained from five groups of cows: nonlactating, first third of lactation, midlactation, last third of lactation, and 2-year-old nonlactating heifers. Vacutainer multiple sample needles and serum separator tubes (SST) were used for venipuncture. Aspiration of serum was within 1.5 hours after collection: one sample for immediate determination (within 2 hours of collection); the other sample stored at -4 degrees C in evacuated plastic vacutainer tubes filled with serum to provide dead space of less than 75% of volume, and analyzed after 14 to 30 days in storage (half, 15, of the samples from each lactation group were analyzed after frozen anaerobic storage at 14 or 30 days, respectively). Processing samples in this manner significantly altered the values obtained for ICa, normalized calcium concentration (NCa), and pH. Analysis after frozen storage in evacuated tubes caused ICa and NCa concentrations to decrease and pH to increase (P< 0.05); total calcium levels were not significantly different from initial values. There were no significant differences among lactation groups. The difference between values obtained from these paired samples was either due to loss of CO(2) during transfer from the SST to the evacuated tube or during frozen storage. Changes in samples assayed after freezing and storage could be adjusted to original values by using the mean difference between the fresh and frozen levels as correction factors: ICa (+0.4379), NCa (+0.2797), and pH (-0.0926). It was concluded that immediate determination of serum ICa in dairy cattle is the ideal but using this methodology and performing analyses later may be acceptable if correction factors are determined.

Is heparinized plasma suitable for use in routine biochemistry?

Using lithium heparin plasma and serum, we compared the values of 27 biochemical analyses performed with a Kodak Ektachem 500 analyzer. For 16 of the 27 tests, we observed statistical differences between the mean results obtained from the analysis of heparinized plasma and those obtained from the analysis of serum (Student t-test; P < .001). However, none of these differences were medically significant. When the concentration of lithium heparin was increased to three and five times normal (reflecting incomplete Vacutainer tube filling), alanine aminotransferase, amylase, aspartate aminotransferase, lipase, and potassium all exhibited some changes compared with serum. Therefore, heparin may be used to shorten the turnaround time in the routine biochemistry laboratory, but the anticoagulant tubes should be completely filled to prevent spurious intraindividual variations in serial specimen analysis.

Development and evaluation of a robotics-based system for glycosylated hemoglobin analysis

Pipetting robots are ideal for automating manually intensive areas of the clinical chemistry laboratory. Glycosylated hemoglobin (GHb), which is helpful in monitoring long term glucose control in diabetics, requires extensive technologist time for analysis. Since separation of GHb is achieved on individual disposable columns, we were able to minimize technologist ‘hands on’ time required by programming a Hamilton Microlab 2200 automated pipetting Cartesian robot to complete the procedure from aspiration of blood specimen from the vacutainer tube to transfer of the separated GHb and non-GHb fractions to a microtiter plate for absorbance reading. After demonstrating that we could use unwashed red blood cells without interferences, we evaluated the system for throughput, precision, linearity, recovery and lyse method. The robotic system can analyze, in parallel, 96 specimens including patient specimens and control material in approximately 3 h. The Hamilton robotic method decreased the required technologist time relative to the manual method by 80% in ‘hands on” time and decreased the analysis time by 40%. The precision at different levels of GHb ranged from 1.6 to 3.5% within-run and from 2.7 to 3.5% day-to-day. The method correlated with the Accuflex semi-automated robot which used the identical disposable column. Automation of the GHb procedure improved throughput, precision and laboratory safety with the added benefit of reduced labor cost.

Determination of carbidopa and levodopa in human plasma by high-performance liquid chromatography with electrochemical detection

A validated reversed-phase high-performance liquid chromatographic procedure employing electrochemical detection (LCEC) for the analysis of carbidopa and levodopa in human plasma is reported. The method is sensitive and specific with amperometric detection at a glassy carbon working electrode with Eapp=0.75 V vs. Ag/AgCl. The retention times of levodopa, internal standard, and carbidopa are 3.3, 4.5, and 9.7 minutes, respectively, with an overall chromatographic run time of 12.0 minutes. The peak height ratio versus plasma concentration is linear over the range of 5.0 to 500 ng/mL for each analyte and exhibits correlation coefficients of 0.9957 or better (n=9). The mean absolute recovery of carbidopa and levodopa using the described assay is 36.6 and 66.0%, respectively. The inter- and intra-day accuracy and precision are within 11.8% of the actual values for all concentrations. Also, due to the demonstrated instability of carbidopa and levodopa in plasma a procedure is provided to circumvent this. Blood collected in pre-treated Vacutainer tubes can be stored in an ice bath for up to 4 hours without any significant degradation, thereby providing a practical means for processing several clinical samples simultaneously.

Factor VII activation and oral contraceptives

The relation between oral contraceptive (OC) use and changes in factor VII activation using standard factor VII clotting test and enzyme-linked immunosorbent assay (ELISA) for the quantification of antigen factor VII (factor YIIag) in view of the increased risk of thromboembolism in OC users was studied. 30 healthy women using OC and 30 women matched for age and smoking status were recruited from a health check-up center in Paris. The combined OC contained 50 mcg of ethinyl estradiol with any progestogen. Controls had not taken any hormonal therapy for the 2 previous months. The mean duration of OC use was 50 months with a range of 6-204 months. Fasting venous blood (9 volumes) was collected during the menstrual cycle into siliconized vacutainer tubes containing 3.2% trisodium citrate (1 volume). Factor VIIc was assayed using a human factor VII-deficient plasma. Factor VIIag was measured by ELISA using a commercial kit (Diagnostic Stago, France). The activity of factor VII was assessed by calculating the ratio of factor VIIc to factor VIIag. Serum cholesterol and triglyceride concentrations were determined by enzymatic methods using automated procedure and reagents from Boehringer Mannheim. There was a significant difference between the 2 groups only in serum triglyceride concentrations. There was a positive correlation between factor VIIc and factor VIIag in both controls and OC users (r = 0.71 and 0.87, respectively; p 0.0001). Both factor VIIc and factor VIIag levels were positively associated with serum triglyceride concentrations (correlation coefficients ranged from 0.26 (p 0.10) to 0.46 (p 0.05) with the 2 groups). Mean levels of factor VIIc and factor VIIag were significantly higher in OC users than in controls (about 17% and 21%, respectively). The ratio of factor VIIc and factor VIIag was not significantly higher in OC users than in controls. The raised factor VII coagulant activity in OC users failed to provide evidence of an enhanced activation of factor VII relative to OCs.

Keep the lid on it: artefactual hypernatraemia in samples from paediatric patients.

1 2 TIme cenlrlfuQld (min) o + --------+--------+-----Centrifuging for 1, 2 or 3 min resulted in losses of 13 /-lL (2'2070 of initial volume), 24 /-lL (4'0%) and 31 /-lL (5' 5%), respectively. Leaving the tube uncapped either in the non-rotating centrifuge (temperature 33°C) or on the bench (-18°C) for 3 min resulted in volume losses of only 2 /-lL (0'34%) and l/-lL (0'17%), respectively. The results given are for single measurements only. Subsequently, blood was taken from a healthy adult volunteer and placed in a seriesof Mierotainer tubes. The mass of blood added to each was determined by differences in weight. Baseline measurements of sodium (144 mmol/L), urea (4'8 mmol/L) and creatinine (110 /-lmol/L) were obtained from a further sample collected in a standard 10 mL serum Vacutainer tube. After allowing time for clotting to occur, the Microtainer tubes were centrifuged, uncapped for I, 2 or 3 min. They were then re-capped and re-weighed to determine any loss of mass. The sera were then transferred into lidded cups for subsequent analysis. All chemistries were performed on Kodak Ektachem 700XR analysers which measure sodium by direct ISE technology. The resultsofmass loss and sodium measurement are shown in Fig. 1. The progressive volume loss associated with an artefactual increase in the measured sodium content is clearly demonstrated.

Performance of reticulocyte counts in stored blood specimens in a pediatric population utilizing new methylene blue.

Although reticulocyte counts can be reliably performed for up to 48 h after storage in EDTA, it is unclear whether this is applicable to the pediatric age group. In order to evaluate this, manual reticulocyte counts were performed on 20 specimens from pediatric patients stored at 4 degrees C for up to 24 h post collection. Samples were evaluated at 1-3, 6, 12, 18, and 24 h after storage in EDTA vacutainer tubes at 4 degrees C. The age of the subjects ranged from 1 day to 9 years with a median age of 3 years. Patients' reticulocyte counts ranged from 0 to 27% (5.89 +/- 7.21). No clinically significant changes were evident in the reticulocyte count over 24 h after specimen collection. The mean of the 20 specimens at 1-3 h was 5.50 and at 24 h was 5.40 (P > .05). The standard deviation of the mean values ranged from 7.03 to 7.26 (P > .05). The results indicate that reticulocyte counts may be performed on previously drawn blood held at 4 degrees C for up to 24 h post collection in a pediatric population without significant difference from baseline values.

Bedside visual colorimetry of peritoneal lavage fluid in abdominal trauma patients

Abdominal injuries account for an important fraction of deaths from trauma. Some patients with abdominal trauma who need emergency surgery are difficult to identify because bedside diagnosis based on physical findings alone is often misleading. ‘+2 When the need for laparotomy is initially unclear physicians currently rely on clinical laboratory determinations, particularly the automated red blood cell count (RBC) count of fluid obtained by peritoneal lavage.3 Unfortunately, the time required by the clinical laboratory to process and assay these specimens may sometimes delay essential surgical intervention. In a prior in vitro study we investigated the feasibility of using visual calorimetry as a rapid method for estimating the RBC count in simulated peritoneal lavage fluid.4 Here, we report the successful application of this method to the bedside evaluation of trauma patients at a level I trauma center. METHODS A simple visual colorimete?-8 was built in a home woodworking shop (Figures 1 through 4). This device permits direct comparison of light transmitted through pairs of glass test tubes containing colored fluids, while reducing ambient room light and reflections. To prepare stable color comparison standards, a stock solution of simulated peritoneal lavage fluid was made as follows: whole blood was obtained in 7-mL Vacutainer (Becton Dickinson, Rutherford, NJ) tubes containing ethylenediamine tetraacetic acid from a single healthy volunteer donor known to be human immunodeficiency virus-negative, at low risk for acquired immunodeticiency syndrome, and willing to donate blood periodically. The complete blood count was determined in triplicate using a Sysmex NE-8000 automated cell counter (TOA Medical Electronics Co, Ltd, Kobe, Japan). The mean RBC count for this donor was 5.71