Smartphone Application Monitoring of Acceleration Forces During Pneumatic Tube System Transport of Emergency Department Patient Samples.

BACKGROUND: The use of pneumatic tube system (PTS) transport has gained considerable popularity in modern hospitals but is also associated with sample hemolysis. The potential contribution of PTS-associated acceleration forces to high hemolysis rates observed in the emergency department (ED) has not been investigated before and can be easily examined nowadays using smartphone applications. The first aim of our study was to investigate whether our PTS induces hemolysis of patient samples obtained from our ED. We also explored a potential correlation between hemolysis index (HI) on the one hand and acceleration forces during PTS transport or other potential causes of hemolysis related to patient characteristics on the other for two different blood sampling techniques. METHODS: Blood samples from 100 ED patients were collected in one Sarstedt S-Monovette® serum tube (PTStransported to laboratory) and two BD Vacutainer® serum tubes (one PTS-transported and one hand-carried). For all serum samples HI was measured. A smartphone was sent along with the samples in order to register accelerations during transport. Patient's erythrocyte sedimentation rate (ESR), mean corpuscular volume (MCV), hematocrit, total cholesterol, low density lipoprotein (LDL), and high-density lipoprotein (HDL) concentration were determined as well. RESULTS: Hemolysis rate was only 1 - 4% and 5% for PTS and hand-carried transport, respectively. Calculated acceleration vector sums for PTS transport from the ED to laboratory reached up to 131.49 m/second2 (13.40 g). No correlation could be demonstrated between HI on the one hand and acceleration forces acting on the samples during PTS transport or ESR, MCV, hematocrit, and HDL concentration on the other. However, an inverse correlation was noted between HI and cholesterol (total and LDL) concentration in serum tubes transported via PTS, though not in those carried by hand. CONCLUSIONS: We demonstrated that our PTS does not induce or contribute to hemolysis of ED patient samples, even at high acceleration vector sums up to 13 g. Technological advancements such as the development of smartphone applications offer the ability to regularly monitor acceleration forces during PTS transport of patient samples. Low total cholesterol and LDL concentrations may affect the erythrocyte membrane fluidity, making erythrocytes more prone to hemolysis.

High anion gap metabolic acidosis induced by cumulation of ketones, L- and D-lactate, 5-oxoproline and acute renal failure.

INTRODUCTION: Frequent causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis and impaired renal function. In this case report, a HAGMA caused by ketones, L- and D-lactate, acute renal failure as well as 5-oxoproline is discussed. CASE PRESENTATION: A 69-year-old woman was admitted to the emergency department with lowered consciousness, hyperventilation, diarrhoea and vomiting. The patient had suffered uncontrolled type 2 diabetes mellitus, underwent gastric bypass surgery in the past and was chronically treated with high doses of paracetamol and fosfomycin. Urosepsis was diagnosed, whilst laboratory analysis of serum bicarbonate concentration and calculation of the anion gap indicated a  HAGMA. L-lactate, D-lactate, ß-hydroxybutyric acid, acetone and 5-oxoproline serum levels were markedly elevated and renal function was impaired. DISCUSSION: We concluded that this case of HAGMA was induced by a variety of underlying conditions: sepsis, hyperglycaemia, prior gastric bypass surgery, decreased renal perfusion and paracetamol intake. Risk factors for 5-oxoproline intoxication present in this case are female gender, sepsis, impaired renal function and uncontrolled type 2 diabetes mellitus. Furthermore, chronic antibiotic treatment with fosfomycin might have played a role in the increased production of 5-oxoproline. CONCLUSION: Paracetamol-induced 5-oxoproline intoxication should be considered as a cause of HAGMA in patients with female gender, sepsis, impaired renal function or uncontrolled type 2 diabetes mellitus, even when other more obvious causes of HAGMA such as lactate, ketones or renal failure can be identified.

Causes, consequences and management of sample hemolysis in the clinical laboratory.

Preanalytical hemolysis of blood samples is a common problem in medical practice, especially in emergency departments. Several potential influences on sample hemolysis have been investigated, including sampling techniques, centrifugation and sample transport. In particular, the use of intravenous catheters and the vacuum sampling technique have often been demonstrated to provoke hemolysis. Other factors playing a role include the use of inappropriate puncture sites, complicated blood sampling, prolonged tourniquet application, underfilling of tubes and excessive shaking of specimens. Training of phlebotomists can play a pivotal role in overcoming these issues. A sample may also undergo hemolysis at the point of centrifugation, more specifically when centrifugation lasts too long or is done repeatedly. Pneumatic tube system (PTS)-transported samples tend to be more strongly affected by hemolysis compared to hand-carried ones, though whether this difference is clinically relevant remains questionable. The velocity at which the sample moves, the distance it covers and the shock forces it sustains all determine to what extent hemolysis occurs during PTS transport. The use of cushion inserts in the carrier to stabilize the samples and the presence of a gel separator in the transported serum tubes may prevent PTS-induced hemolysis. Finally, there is considerable variation between patients in the extent to which samples are prone to hemolysis. Sample hemolysis leads to unreliable laboratory results, delayed diagnosis and patients suffering avoidable discomfort. Specifically, hemolysis may interfere with laboratory results due to release of intracellular components, dilution effects, proteolysis and interference with analytical techniques. There is ongoing debate about how laboratories should deal with results altered by hemolysis. Laboratory specialists should clearly communicate with the ordering clinicians in order to make an informed decision about how to interpret hemolysis-affected analytical results. This review looks into current evidence concerning the causes and consequences of in vitro hemolysis, and aims to explain how to deal with it.

Influence of separator gel in Sarstedt S-Monovette® serum tubes on various therapeutic drugs, hormones, and proteins.

BACKGROUND: A separator or barrier gel is a common component of serum and plasma collection tubes. Despite their advantages, the use of these tubes is not universally accepted, especially for therapeutic drug monitoring (TDM). The aim of this study was to evaluate whether the polyacrylester separator gel in Sarstedt S-Monovette\® tubes influences the concentration of 10 selected parameters (amikacin, vancomycin, valproic acid, acetaminophen, cortisol, free thyroxine, thyroid-stimulating hormone, transferrin, prealbumin and carcinoembryonic antigen) in a clinically significant way. METHODS: Results from patient samples collected in plastic Sarstedt S-Monovette® tubes with separator gel were compared with those from plain serum sample tubes. Analytes were measured in both tubes on 4 consecutive days to study the influence of prolonged contact with the separator gel. Between analyses tubes were stored at 4°C. Stability was also evaluated over 72 h for each collection tube. When statistical differences were detected, the clinical significance was evaluated based on the total allowable error (TEa). RESULTS: On day 1 no statistically significant differences were observed between samples collected in Sarstedt S-Monovette® tubes with and without separator gel. Statistical differences were present from day 2 on, but were not clinically significant. All evaluated parameters were clinically stable over 72 h at 4°C based on TEa, except for transferrin en fT4. CONCLUSION: The separator gel in Sarstedt S-Monovette® tubes did not show statistically significant differences on the day of phlebotomy. Later on statistically significant differences appeared but except for the stability of fT4 and transferrin they all remained clinically insignificant.

Sample evaporation from pierceable cups: still an important source of analytical error.

BACKGROUND: We illustrate the impact of sample evaporation on analytical results in laboratory practice and highlight preventive measures. METHODS: Plasma (n=10) was analysed for glucose, Na(+), HCO(3)(-) and calcium on six different sample configurations at 5 time points within 2h. RESULTS: With time glucose, Na(+) and calcium values increased and HCO(3)(-) values decreased in a clinically significant way. CONCLUSIONS: Analytical error due to evaporation may be significant, but can be reduced with optimal sample handling. A pierceable cover does not prevent loss of HCO(3)(-).

Analysis of gamma-hydroxybutyric acid, DL-lactic acid, glycolic acid, ethylene glycol and other glycols in body fluids by a direct injection gas chromatography-mass spectrometry assay for wide use.

Analysis of blood of severely intoxicated patients always requires prompt investigation. Diagnosis of intoxication with ethylene glycol, gamma-hydroxybutyric acid or D-lactic acid takes hours, since several different procedures are required. Rapid derivatization of the common hydroxyl function may resolve this analytical problem. Here we describe a fast method for the simultaneous measurement of ethylene glycol, glycolic acid, gamma-hydroxybutyric acid and racemic lactic acid. Only 20 microl of serum, plasma or urine are required for immediate derivatization at 70 degrees C with 750 microl of bis-N,O-trimethylsilyl trifluoroacetamide after adding 20 microl of internal standard solution (1,3-propylene glycol) and 20 microl of the catalyst dimethylformamide. After centrifugation an aliquot is transferred to a gas chromatographic system and analyzed with electron-impact mass spectrometry in selective ion monitoring mode. The derivatized acids and ethylene glycol are well separated and detected with a limit of detection ranging from 0.12 mg/l for ethylene glycol to 0.95 mg/l for gamma-hydroxybutyric acid, while the limit of quantification ranged from 0.4 mg/l for ethylene glycol to 3.15 mg/l for gamma-hydroxybutyric acid. The method is linear from 0.5 to 1800 mg/l blood for ethylene glycol, from 0.7 to 1200 mg/l for lactic acid, from 1.2 to 1800 mg/l for glycolic acid, and from 3.2 to 200 mg/l for gamma-hydroxybutyric acid, with analytical recoveries, accuracy, day-to-day and within-day precision well within the required limits. Total analysis time with one calibrator was 30 min, derivatization time included. This method is very suitable for emergency toxicology, since several toxic substances can be quantified simultaneously in a fast and sensitive manner.