Clinical evaluation of a portable lactate meter in type I glycogen storage disease

Repeat lactate level predicts mortality better than rate of clearance

BACKGROUND

Lactate clearance has been developed into a marker of resuscitation in trauma, but no study has compared the predictive power of the various clearance calculations. Our objective was to determine which method of calculating lactate clearance best predicted 24-hour and in-hospital mortality after injury.

STUDY DESIGN

Retrospective chart review of patients admitted to a Level-1 trauma center directly from the scene of injury from 2010 to 2013 who survived >15min, had an elevated lactate at admission (≥3mmol/L), followed by another measurement within 24h of admission. Lactate clearance was calculated using five models: actual value of the repeat level, absolute clearance, relative clearance, absolute rate, and relative rate. Models were compared using the areas under the respective receiver operating curves (AUCs), with an endpoint of death at 24h and in-hospital mortality.

RESULTS

3910 patients had an elevated admission lactate concentration on admission (mean=5.6±3.0mmol/L) followed by a second measurement (2.7±1.8mmol/L). Repeat absolute measurement best predicted 24-hour (AUC=0.85, 95% CI: 0.84-0.86) and in-hospital death (AUC=0.77; 95% CI, 0.76-0.78). Relative clearance was the best model of lactate clearance (AUC=0.77, 95% CI: 0.75-0.78 and AUC=0.705, 95% CI: 0.69-72, respectively) (p<0.0001 for each). A sensitivity analysis using a range of initial lactate measures yielded similar results.

CONCLUSIONS

The absolute value of the repeat lactate measurement had the greatest ability to predict mortality in injured patients undergoing resuscitation.

Bendable Electro-chemical Lactate Sensor Printed with Silver Nano-particles

Here we report a flexible amperometric lactate biosensor using silver nanoparticle based conductive electrode. Mechanically bendable cross-serpentine-shaped silver electrode is generated on flexible substrate for the mechanical durability such as bending. The biosensor is designed and fabricated by modifying silver electrode with lactate oxidase immobilized by bovine serum albumin. The in-sensor pseudo Ag/AgCl reference electrode is fabricated by chloridization of silver electrode, which evinced its long-term potential stability against a standard commercial Ag/AgCl reference electrode. The amperometric response of the sensor shows linear dependence with lactate concentration of 1~25 mM/L. Anionic selectivity is achieved by using drop-casted Nafion coated on silver electrode against anionic interferences such as ascorbate. This non-invasive electrochemical lactate sensor also demonstrates excellent resiliency against mechanical deformation and temperature fluctuation which leads the possibility of using it on human epidermis for continuous measurement of lactate from sweat. Near field communication based wireless data transmission is demonstrated to reflect a practical approach of the sensor to measure lactate concentration portably using human perspiration.

Valores de lactato sérico e sua correlação com parâmetros clínicos de cães saudáveis, mensurados durante atendimento ambulatorial veterinário

Resumo: A mensuração do lactato sérico é utilizada na rotina médica como marcador prognóstico de pacientes em estado de emergência. Sua interpretação não deve ser feita de forma isolada, mas conjunta aos demais parâmetros clínicos, pois seus valores podem sofrer interferência do estresse metabólico ou ambiental, contenção física e/ ou manipulação dos pacientes. Assim, buscou-se mensurar os valores do lactato sérico e parâmetros clínicos de cães saudáveis, bem como as suas correlações, durante o atendimento clínico ambulatorial veterinário. Para isso, foram avaliados 80 cães, machos ou fêmeas, com idade de um a oito anos, atendidos para revacinação anual polivalente. Foram considerados cães saudáveis os que não apresentaram intercorrências clínicas nos últimos 60 dias e alterações nos exames físicos e nos valores de hemograma e glicemia sérica. Foram mensurados inicialmente o peso corporal, a frequência cardíaca (FC) e respiratória (FR), tempo de preenchimento capilar (TPC), coloração de mucosas, temperatura retal (TR), periférica (TP) e a diferença entre TR e a TP, o Delta T°C. Por último, realizaram-se os exames de hemograma e glicemia sérica, juntamente com a mensuração do lactato sérico, utilizando para isso um lactímetro portátil, por meio da amostra sanguínea obtida da veia cefálica. Além disso, havendo a correlação dos valores do lactato séricos com o peso corporal os cães foram divididos conforme o cálculo do 33° e 66° percentil. Os cães avaliados evidenciaram valores médios de 18,3±12,1 kg de peso corporal e 3,0±1,9 anos de idade; FC de 126,6±29,1bpm, FR de 66±24mpm, TR de 38,9±0,4°C, TP de 31,5±1,0°C, Delta TºC de 7,3±1,0°C e lactato sérico de 3,2±0,4mmol/L; com este último, evidenciando intervalo de confiança a 95% de 3,1-3,3mmol/L e correlação significativa (p<0,05) dos seus valores com o peso corporal (r=0,6) e a frequência cardíaca (r=0,4). Os valores do lactato sérico obtidos foram comparados entre os grupos de cães conforme o peso corporal, evidenciando diferenças significativas (p<0,05) entre eles. Dessa forma, pode se concluir que os valores do lactato sérico em cães hígidos sob atendimento ambulatorial é de 3,2mmol/L, com o intervalo de confiança de 3,1-3,3mmol/L, ressaltando a influência que a FC e o peso corporal podem exercer nos seus valores.

The Effect of an Acute Bout of Moderate-Intensity Aerobic Exercise on Motor Learning of a Continuous Tracking Task

INTRODUCTION

There is evidence for beneficial effects of acute and long-term exercise interventions on several forms of memory, including procedural motor learning. In the present study we examined how performing a single bout of continuous moderate intensity aerobic exercise would impact motor skill acquisition and retention in young healthy adults, compared to a period of rest. We hypothesized that exercise would improve motor skill acquisition and retention, compared to motor practice alone.

MATERIALS AND METHODS

Sixteen healthy adults completed sessions of aerobic exercise or seated rest that were immediately followed by practice of a novel motor task (practice). Exercise consisted of 30 minutes of continuous cycling at 60% peak O2 uptake. Twenty-four hours after practice, we assessed motor learning with a no-exercise retention test (retention). We also quantified changes in offline motor memory consolidation, which occurred between practice and retention (offline). Tracking error was separated into indices of temporal precision and spatial accuracy.

RESULTS

There were no differences between conditions in the timing of movements during practice (p = 0.066), at retention (p = 0.761), or offline (p = 0.966). However, the exercise condition enabled participants to maintain spatial accuracy during practice (p = 0.477); whereas, following rest performance diminished (p = 0.050). There were no significant differences between conditions at retention (p = 0.532) or offline (p = 0.246).

DISCUSSION

An acute bout of moderate-intensity aerobic exercise facilitated the maintenance of motor performance during skill acquisition, but did not influence motor learning. Given past work showing that pairing high intensity exercise with skilled motor practice benefits learning, it seems plausible that intensity is a key modulator of the effects of acute aerobic exercise on changes in complex motor behavior. Further work is necessary to establish a dose-response relationship between aerobic exercise and motor learning.

Failure to clear elevated lactate predicts 24-hour mortality in trauma patients

BACKGROUND

Lactate clearance is a standard resuscitation goal in patients in nontraumatic shock but has not been investigated adequately as a tool to identify trauma patients at risk of dying. Our objective was to determine if trauma patients with impaired lactate clearance have a higher 24-hour mortality rate than patients whose lactate concentration normalizes.

METHODS

A retrospective chart review identified patients who were admitted directly from the scene of injury to an urban trauma center between 2010 and 2013 and who had at least one lactate concentration measurement within 24 hours. Transfers, patients without lactate measurement, and those who were dead on arrival were excluded. Of the 26,545 screened patients, 18,304 constituted the initial lactate measurement population, and 3,887 were the lactate clearance cohorts.

RESULTS

Initial lactate had an area under the receiver operating characteristic curve of 0.86 and 0.73 for mortality at 24 hours and in the hospital, respectively. An initial concentration of 3 mmol/L or greater had a sensitivity of 0.86 and a specificity of 0.73 for mortality at 24 hours. The mortality rate among patients with elevated lactate concentrations (n = 2,381; 5.6 [2.8] mmol/L) that did not decline to less than 2.0 mmol/L in response to resuscitative efforts (mean [SD] second measurement, 3.7 [1.9] mmol/L) was nearly seven times higher (4.1% vs. 0.6%, p < 0.001) than among those with an elevated concentration (n = 1,506, 5.3 [2.7] mmol/L) that normalized (1.4 [0.4] mmol/L). Logistic regression analysis showed that failure to clear lactate was associated with death more than any other feature (odds ratio, 7.4; 95% confidence interval, 1.5-35.5), except having an Injury Severity Score (ISS) greater than 25 (odds ratio, 8.2; 95% confidence interval, 2.7-25.2).

CONCLUSION

Failure to clear lactate is a strong negative prognostic marker after injury. An initial lactate measurement combined with a second measurement for high-risk individuals might constitute a useful method of risk stratifying injured patients.

LEVEL OF EVIDENCE

Prognostic study, level III.

Diagnosis and management of glycogen storage disease type I: a practice guideline of the American College of Medical Genetics and Genomics

PURPOSE

Glycogen storage disease type I (GSD I) is a rare disease of variable clinical severity that primarily affects the liver and kidney. It is caused by deficient activity of the glucose 6-phosphatase enzyme (GSD Ia) or a deficiency in the microsomal transport proteins for glucose 6-phosphate (GSD Ib), resulting in excessive accumulation of glycogen and fat in the liver, kidney, and intestinal mucosa. Patients with GSD I have a wide spectrum of clinical manifestations, including hepatomegaly, hypoglycemia, lactic acidemia, hyperlipidemia, hyperuricemia, and growth retardation. Individuals with GSD type Ia typically have symptoms related to hypoglycemia in infancy when the interval between feedings is extended to 3–4 hours. Other manifestations of the disease vary in age of onset, rate of disease progression, and severity. In addition, patients with type Ib have neutropenia, impaired neutrophil function, and inflammatory bowel disease. This guideline for the management of GSD I was developed as an educational resource for health-care providers to facilitate prompt, accurate diagnosis and appropriate management of patients.

METHODS

A national group of experts in various aspects of GSD I met to review the evidence base from the scientific literature and provided their expert opinions. Consensus was developed in each area of diagnosis, treatment, and management.

RESULTS

This management guideline specifically addresses evaluation and diagnosis across multiple organ systems (hepatic, kidney, gastrointestinal/nutrition, hematologic, cardiovascular, reproductive) involved in GSD I. Conditions to consider in the differential diagnosis stemming from presenting features and diagnostic algorithms are discussed. Aspects of diagnostic evaluation and nutritional and medical management, including care coordination, genetic counseling, hepatic and renal transplantation, and prenatal diagnosis, are also addressed.

CONCLUSION

A guideline that facilitates accurate diagnosis and optimal management of patients with GSD I was developed. This guideline helps health-care providers recognize patients with all forms of GSD I, expedite diagnosis, and minimize adverse sequelae from delayed diagnosis and inappropriate management. It also helps to identify gaps in scientific knowledge that exist today and suggests future studies.

Pre-resuscitation lactate and hospital mortality in prehospital patients

OBJECTIVE

Serum lactate elevations are associated with morbidity and mortality in trauma patients, but their value in prehospital medical patients prior to resuscitation is unknown. We sought to assess the distribution of blood lactate concentrations prior to intravenous (i.v.) resuscitation and examine the association of elevation on in-hospital death.

METHODS

A convenience sample of adult patients over 14 months who received an i.v. line by eight EMS agencies in Western Pennsylvania had lactate measurement prior to any i.v. treatment. We assessed the lactate values and any relationship between these and hospital mortality (our primary outcome) and admission to the intensive care unit (ICU). We also compared the ability of lactate to discriminate outcomes with a prehospital critical illness score using age, Glasgow Coma Score, and initial vital signs.

RESULTS

We included 673 patients, among whom 71 (11%) were admitted to the ICU and 21 (3.1%) died in-hospital. Elevated lactate (≥2 mmol/L) occurred in 307 (46%) patients and was strongly associated with hospital death after adjustment for known covariates (odds ratio = 3.57, 95% confidence interval [CI]: 1.10, 11.6). Lactate ≥2 mmol/L had a modest sensitivity (76%) and specificity (55%), and discrimination for hospital death (area under the curve [AUC] = 0.66, 95%CI: 0.56, 0.75). Compared to the prehospital critical illness score alone (AUC = 0.69, 95% CI: 0.59, 0.80), adding lactate to the score offered modest improvement (net reclassification improvement = 0.63, 95%CI: 0.23, 1.01, p < 0.05).

CONCLUSIONS

Initial lactate concentration in our prehospital medical patient population was associated with hospital mortality. However, it is a modest predictor of outcome, offering similar discrimination to a prehospital critical illness score.

Pregnancy in women with glycogen storage disease Ia and Ib

Over the past 9 decades since glycogen storage disease (GSD) was described, an almost universally fatal disease has become one where women are living well into adulthood and choosing to bear children. This inborn error of metabolism associated with the creation and utilization of glycogen, when untreated, manifests with unrelenting hypoglycemia. The initiation of continuous feeds has improved outcomes, and later in 1982, the administration of intermittent doses of cornstarch in water provided a continuous supply of exogenous glucose. As metabolic control has improved, morbidity has decreased. Glycogen storage disease Ib has the same severity of hypoglycemia as GSD Ia, with associated immune disturbance. Prior to the introduction of granulocyte colony-stimulating factor (G-CSF), infections caused significant mortality in GSD Ib. Pregnancy in patients with GSD Ia and Ib poses unique challenges during gestation and delivery. Good metabolic control before conception and throughout pregnancy is directly related to successful outcomes. There is no nursing literature to date addressing perinatal and neonatal care in this population.

Capillary measurement of lactate and glucose for free flap monitoring

BACKGROUND

It is reported that the salvage rate of free flaps is inversely related to the time interval between the onset of pedicle impairments and their clinical recognition. Monitoring of free flaps is therefore of major importance and clinical monitoring remains the most used technique because of lack of low-cost and non-invasive techniques. The authors suggested an efficient, simple and cheap technique to detect early thrombotic events in monitoring free flaps with skin paddle.

METHODS

In this multicentre prospective study, measurements of capillary glucose and lactate in the flaps were done. These parameters were compared to standardized clinical monitoring during the first five days. Two sets of data (eventful versus uneventful postoperative period) were analyzed to define the thresholds of lactate and glucose values for diagnosis of pedicle complications, and to establish parameters for this screening test.

RESULTS

Over a period of 19 months, 37 patients were included. With 5 pedicle impairments, complication thresholds were defined as lactate ≥ 6.4 mmol L(-1) and glucose ≤ 3.85 mmol L(-1), in order to obtain a sensitivity of 98.5% and a specificity of 99.5% for the test. Modifications of capillary glucose and lactate measurements appeared in average 5.7 hours earlier than clinical symptoms in pedicle impairments. The mean cost of a five-day monitoring was about 90 USD.

CONCLUSION

This simple and cheap technique could be used as a routine technique in monitoring free flaps to improve safety of this reconstructive technique.

Lactate biosensors: current status and outlook

Many research efforts over the last few decades have been devoted to sensing lactate as an important analytical target in clinical care, sport medicine, and food processing. Therefore, research in designing lactate sensors is no longer in its infancy and now is more directed toward viable sensors for direct applications. In this review, we provide an overview of the most immediate and relevant developments toward this end, and we discuss and assess common transduction approaches. Further, we critically describe the pros and cons of current commercial lactate sensors and envision how future sensing design may benefit from emerging new technologies.

Diagnostic accuracy of a single point-of-care prehospital serum lactate for predicting outcomes in pediatric trauma patients

BACKGROUND

Preliminary evidence suggests that a single prehospital lactate level (pLA) improves prediction of morbidity and mortality in adult trauma patients independent of vital signs. However, the value of pLA for pediatric trauma patients is unknown. Our objective was to determine whether pLA is associated with the need for critical care in pediatric trauma patients.

METHODS

We conducted a cohort study of 217 patients transported by helicopter to a level I pediatric trauma center over 24 months. The primary outcome was the need for predefined critical care measures. Covariates included vital signs and Glasgow Coma Scale (GCS) scores documented by prehospital providers.

RESULTS

Forty-one subjects required critical care. Abnormal prehospital vital signs were not associated with need for critical care. Overall, median pLA level for patients who required critical care was 2.1 mmol/L (interquartile range [IQR], 1.6-2.7 mmol/L) versus 1.7 mmol/L (IQR, 1.2-2.2 mmol/L) for those who did not (P = 0.01). In addition, there were 85 subjects who had normal vital signs and a normal GCS during transport. Of these, 11 (13%) required critical care. In the subset of patients with normal prehospital vital signs and GCS, median pLA level for patients who required critical care was 2.6 mmol/L (IQR, 1.8-2.6 mmol/L) versus 1.7 mmol/L (IQR, 1-2.1 mmol/L) for those who did not (P = 0.01).

CONCLUSIONS

Prehospital lactate level was higher in pediatric trauma patients who required critical care, including those who had normal prehospital vital signs and GCS. In this cohort, lactate was an early identifier of children with severe traumatic injuries.

A method-comparison study regarding the validity and reliability of the Lactate Plus analyzer

OBJECTIVES

The aims of this study were to: (1) determine the validity and reliability of the Nova Biomedical Lactate Plus portable analyzer, and quantify any fixed or proportional bias; (2) determine the effect of any bias on the determination of the lactate threshold and (3) determine the effect that blood sampling methods have on validity and reliability.

DESIGN

In this method comparison study we compared blood lactate concentration measured using the Lactate Plus portable analyzer to lactate concentration measured by a reference analyzer, the YSI 2300.

SETTING

University campus in the USA.

PARTICIPANTS

Fifteen active men and women performed a discontinuous graded exercise test to volitional exhaustion on a motorised treadmill. Blood samples were taken via finger prick and collected in microcapillary tubes for analysis by the reference instrument at the end of each stage. Duplicate samples for the portable analyzer were either taken directly from the finger or from the micro capillary tubes. PRIMARY OUTCOME MEASUREMENTS: Ordinary least products regressions were used to assess validity, reliability and bias in the portable analyzer. Lactate threshold was determined by visual inspection.

RESULTS

Though measurements from both instruments were correlated (r=0.91), the differences between instruments had large variability (SD=1.45 mM/l) when blood was sampled directly from finger. This variability was reduced by ∼95% when both instruments measured blood collected in the capillary tubes. As the proportional and fixed bias between instruments was small, there was no difference in estimates of the lactate threshold between instruments. Reliability for the portable instrument was strong (r=0.99, p<0.05) with no proportional bias (slope=1.02) and small fixed bias (-0.19 mM/l).

CONCLUSIONS

The Lactate Plus analyzer provides accurate and reproducible measurements of blood lactate concentration that can be used to estimate workloads corresponding to blood lactate transitions or any absolute lactate concentrations.

The utility of early lactate testing in undifferentiated pediatric systemic inflammatory response syndrome

OBJECTIVES

Failure to recognize shock contributes to inadequate early resuscitation in many children with sepsis. Serum lactate levels are used to identify adult patients with septic shock, but physical examination diagnosis alone is recommended in pediatric sepsis. The authors sought to test the utility of lactate testing in pediatric emergency department (ED) patients with systemic inflammatory response syndrome (SIRS). The hypothesis was that early hyperlactatemia (serum lactate ≥ 4.0 mmol/L) would be associated with increased risk of organ dysfunction.

METHODS

This was a prospective cohort study of children younger than 19 years with SIRS presenting to a pediatric ED. The primary outcome was organ dysfunction within 24 hours of triage; secondary outcomes included disposition, serious bacterial infection (SBI), treatments, and mortality. Study personnel measured venous lactate level on a point-of-care meter, with clinicians blinded to results, and patients received usual care.

RESULTS

A total of 239 subjects were enrolled; 18 had hyperlactatemia. The hyperlactatemia group had a relative risk of 5.5 (95% confidence interval [CI] = 1.9 to 16.0) of developing 24-hour organ dysfunction. As a test for organ dysfunction, hyperlactatemia had a positive likelihood ratio of 5.0, a sensitivity of 31% (95% CI = 13% to 58%), and specificity of 94% (95% CI = 90% to 96%). Subjects with hyperlactatemia were significantly more likely to receive intravenous (IV) antibiotics and fluid boluses; despite increased therapy, they were at significantly increased risk for intensive care unit (ICU) admission and bacterial infection.

CONCLUSIONS

Among undifferentiated children with SIRS, early hyperlactatemia is significantly associated with increased risk of organ dysfunction, resuscitative therapies, and critical illness. The addition of serum lactate testing to the currently recommended clinical assessment may improve early identification of pediatric sepsis requiring resuscitation.

Point-of-care capillary blood lactate measurements in human immunodeficiency virus-uninfected children with in utero exposure to human immunodeficiency virus and antiretroviral medications

OBJECTIVES

To estimate the prevalence of elevated point-of-care (POC) capillary blood lactate concentrations in human immunodeficiency virus (HIV)-exposed, uninfected children (HEU) and to determine if POC lactate varies with in utero antiretroviral (ARV) exposure.

METHODS

The Surveillance Monitoring for Antiretroviral Therapy Toxicities protocol of the Pediatric HIV/AIDS Cohort Study enrolled 1934 children between 2007 and 2009, 0 to 12 years of age, born to HIV-infected mothers. POC lactate was measured annually on capillary blood using the Lactate Pro device. Associations of POC lactate with in utero ARV exposure and other characteristics were evaluated using logistic regression models, adjusting for maternal characteristics and other confounders.

RESULTS

Of 1641 children with POC measurements (median age, 3.0 years), 3.4% had POC lactate >3 mmol/L. Median POC lactate level decreased with age (1.9 mmol/L, 1.7 mmol/L, and 1.6 mmol/L for children 0-<6 months [99% ≤6 weeks of life], 6-<24 months, and ≥24 months of age, respectively; P < 0.001). Prevalence of elevated POC lactate did not differ by in utero ARV exposure drug class, but was significantly higher in children exposed in utero to emtricitabine or efavirenz, cocaine or opiates, and those of white race.

CONCLUSIONS

POC lactate testing is a useful rapid laboratory screening assay for HEU children with ARV exposure. ARV use during pregnancy has resulted in a dramatic decrease in mother-to-child transmission of HIV, and the risk of elevated lactate in HEU children is low. However, as new ARVs and more complex regimens are used during pregnancy by HIV-infected women, continued monitoring for infant toxicities is essential.

The use of continuous glucose monitoring in the practical management of glycogen storage disorders

Continuous glucose monitoring systems (CGMS) are now in widespread use in diabetes management with an increasing evidence base. There are few reports of their use in GSD. Liver glycogen storage disorders (GSDs) are most often managed by intensive dietary regimens. Risks of over and under-treatment remain. We describe our use of CGMS in a cohort of GSD patients, the results obtained and the frequency of complications. Our experience is that CGM is a reliable, well accepted and valid tool in the monitoring of GSD patients and allows for assessment of blood sugar control in the 'real-life' setting, unlike hospital admissions. Combining CGM with urine ketone and / or blood lactate measurements, again at home, improves the investigation yet further. It is possible to perform CGM for periods including both schooldays and weekends, and also to change the dietary regimen during the period of monitoring to reduce the frequency of assessments. Risks of decreased reliability in the low range of blood sugars may be outweighed by the increased validity of the patient being in the home environment, with a normal diet and activity schedule.

Glucose-6-phosphatase deficiency

Glucose-6-phosphatase deficiency (G6P deficiency), or glycogen storage disease type I (GSDI), is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea). Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty), generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma) and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency). GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia) which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib). Mutations in the genes G6PC (17q21) and SLC37A4 (11q23) respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most commonly confirmed by G6PC (GSDIa) or SLC37A4 (GSDIb) gene analysis, and the indications of liver biopsy to measure G6P activity are getting rarer and rarer. Differential diagnoses include the other GSDs, in particular type III (see this term). However, in GSDIII, glycemia and lactacidemia are high after a meal and low after a fast period (often with a later occurrence than that of type I). Primary liver tumors and Pepper syndrome (hepatic metastases of neuroblastoma) may be evoked but are easily ruled out through clinical and ultrasound data. Antenatal diagnosis is possible through molecular analysis of amniocytes or chorionic villous cells. Pre-implantatory genetic diagnosis may also be discussed. Genetic counseling should be offered to patients and their families. The dietary treatment aims at avoiding hypoglycemia (frequent meals, nocturnal enteral feeding through a nasogastric tube, and later oral addition of uncooked starch) and acidosis (restricted fructose and galactose intake). Liver transplantation, performed on the basis of poor metabolic control and/or hepatocarcinoma, corrects hypoglycemia, but renal involvement may continue to progress and neutropenia is not always corrected in type Ib. Kidney transplantation can be performed in case of severe renal insufficiency. Combined liver-kidney grafts have been performed in a few cases. Prognosis is usually good: late hepatic and renal complications may occur, however, with adapted management, patients have almost normal life span. DISEASE NAME AND SYNONYMS: Glucose-6-phosphatase deficiency or G6P deficiency or glycogen storage disease type I or GSDI or type I glycogenosis or Von Gierke disease or Hepatorenal glycogenosis.

VO₂ requirements of boxing exercises

The purpose of this study was to quantify the physiological requirements of various boxing exercises such as sparring, pad work, and punching bag. Because it was not possible to measure the oxygen uptake (VO₂) of "true" sparring with a collecting gas valve in the face, we developed and validated a method to measure VO₂ of "true" sparring based on "postexercise" measurements. Nine experienced male amateur boxers (Mean ± SD: age = 22.0 ± 3.5 years, height = 176.0 ± 8.0 cm, weight = 71.4 ± 10.9 kg, number of fights = 13.0 ± 9.5) of regional and provincial level volunteered to participate in 3 testing sessions: (a) maximal treadmill test in the LAB, (b) standardized boxing training in the GYM, and (c) standardized boxing exercises in the LAB. Measures of VO₂, heart rate (HR), blood lactate concentration [LA], rated perceived exertion level, and punching frequencies were collected. VO₂ values of 43.4 ± 5.9, 41.1 ± 5.1, 24.7 ± 6.1, 30.4 ± 5.8, and 38.3 ± 6.5 ml·kg⁻¹·min⁻¹ were obtained, which represent 69.7 ± 8.0, 66.1 ± 8.0, 39.8 ± 10.4, 48.8 ± 8.5, and 61.7 ± 10.3%VO₂peak for sparring, pad work, and punching bag at 60, 120, and 180 b·min⁻¹, respectively. Except for lower VO₂ values for punching the bag at 60 and 120 b·min⁻¹ (p < 0.05), there was no VO₂ difference between exercises. Similar pattern was obtained for %HRmax with respective values of 85.5 ± 5.9, 83.6 ± 6.3, 67.5 ± 3.5, 74.8 ± 5.9, and 83.0 ± 6.0. Finally, sparring %HRmax and [LA] were slightly higher in the GYM (91.7 ± 4.3 and 9.4 ± 2.2 mmol·L⁻¹) vs. LAB (85.5 ± 5.9 and 6.1 ± 2.3 mmol·L⁻¹). Thus, in this study simulated LAB sparring and pad work required similar VO₂ (43-41 ml·kg⁻¹·min⁻¹, respectively), which corresponds to ~70%VO₂peak. These results underline the importance of a minimum of aerobic fitness for boxers and draw some guidelines for the intensity of training.

Integration of paper-based microfluidic devices with commercial electrochemical readers

The combination of simple Electrochemical Micro-Paper-based Analytical Devices (EµPADs) with commercially available glucometers allows rapid, quantitative electrochemical analysis of a number of compounds relevant to human health (e.g., glucose, cholesterol, lactate, and alcohol) in blood or urine.

Lactate is a better predictor than systolic blood pressure for determining blood requirement and mortality: could prehospital measures improve trauma triage?

BACKGROUND

Standard hemodynamic evaluation of patients in shock may underestimate severity of hemorrhage given physiologic compensation. Blood lactate (BL) is an important adjunct in characterizing shock, and point-of-care devices are currently available for use in the prehospital (PH) setting. The objective of this study was to determine if BL levels have better predictive value when compared with systolic blood pressure (SBP) for identifying patients with an elevated risk of significant transfusion and mortality in a hemodynamically indeterminant cohort.

STUDY DESIGN

We selected trauma patients admitted to a level I trauma center over a 9-year period with SBP between 90 and 110 mmHg. The predictive capability of initial emergency department (ED) BL for needing > or =6 units packed RBCs within 24 hours postinjury and mortality was compared with PH-SBP and ED-SBP by comparing estimated area under the receiver operator curve (AUC).

RESULTS

We identified 2,413 patients with ED-SBP and 787 patients with PH-SBP and ED-BL. ED-BL was statistically better than PH-SBP (p = 0.0025) and ED-SBP (p < 0.0001) in predicting patients who will need > or = 6 U packed RBCs within 24 hours postinjury (AUC: ED-BL, 0.72 vs PH-SBP, 0.61; ED-BL, 0.76 vs ED-SBP, 0.60). ED-BL was also a better predictor than both PH-SBP (p = 0.0235) and ED-SBP (p < 0.0001) for mortality (AUC: ED-BL, 0.74 vs PH-SBP, 0.60; ED-BL, 0.76 vs ED-SBP, 0.61).

CONCLUSIONS

ED-BL is a better predictor than SBP in identifying patients requiring significant transfusion and mortality in this cohort with indeterminant SBP. These findings suggest that point-of-care BL measurements could improve trauma triage and better identify patients for enrollment in interventional trials. Further studies using BL measurement in the PH environment are warranted.

Acute Carbohydrate Ingestion Affects Lactate Response in Highly Trained Swimmers

Purpose:

Effects of acute carbohydrate ingestion on blood lactate (BLa) response to graded exercise was examined in highly trained male and female swimmers.

Methods:

Twenty-three swimmers performed the United States Swimming Lactate Protocol, a graded interval test (5 × 200 on 5 min), following ingestion of carbohydrate sports drink (CHO) and placebo (PLA).

Results:

There was no difference in heart rate (P = .55), swim velocity (P = .95), or ratings of perceived exertion (P = .58) between beverages. There was a signifcant main effect for gender (P = .002) on BLa during all swim stages and recovery. In females, BLa was 27% to 50% higher for CHO during the first (P = .009) and second (P = .04) swim stages. Predicted BLa at selected swim velocity was higher (P = .048) for CHO versus PLA in females at 1.27 m·s−1 and higher (P < .02) for men at 1.4 m·s−1. Mean (±SD) BLa was significantly (P = .004) greater for CHO (2.7 ± 1.2) compared with PLA (2.0 ± 1.1 mmol·L−1) during the second test stage and when normalized relative to velocity (P = .004). Peak BLa after the final swim (9.6 ± 3.1 vs. 9.0 ± 3.2 mmol·L−1, P = .36) was not different between CHO and PLA.

Conclusions:

Acute CHO ingestion alters the BLa: swim velocity relationship during moderate intensity swims of an incremental swim test, particularly for females. Therefore, pretest beverage ingestion should be standardized during the administration of BLa testing to prevent potential erroneous interpretations regarding athlete’s training status.

Pregnancies in glycogen storage disease type Ia

OBJECTIVE

Reports on pregnancies in women with glycogen storage disease type Ia (GSD-Ia) are scarce. Because of improved life expectancy, pregnancy is becoming an important issue. We describe 15 pregnancies by focusing on dietary treatment, biochemical parameters, and GSD-Ia complications.

STUDY DESIGN

Carbohydrate requirements (milligrams per kilogram per minute), triglyceride and uric acid levels, liver ultrasonography, and creatinine clearance were investigated before, during, and after pregnancy. Data from the newborn infants were obtained from the records.

RESULTS

In the first trimester, a significant increase in carbohydrate requirements was observed (P = .007). Most patients had acceptable triglyceride and uric acid levels during pregnancy. No increase in size or number of adenomas was seen. In 3 of 4 patients, a decrease in glomerular filtration rate was observed after pregnancy. In 3 pregnancies, lactic acidosis developed during delivery with severe multiorgan failure in 1. All but 1 of the children are healthy and show good psychomotor development.

CONCLUSION

Successful pregnancies are possible in patients with GSD-Ia, although specific GSD-Ia-related risks are present.

Parasympathetic reactivation after repeated sprint exercise

The purpose of this study was to examine the effects of muscular power engagement, anaerobic participation, aerobic power level, and energy expenditure on postexercise parasympathetic reactivation. We compared the response of heart rate (HR) after repeated sprinting with that of exercise sessions of comparable net energy expenditure and anaerobic energy contribution. Fifteen moderately trained athletes performed 1) 18 maximal all-out 15-m sprints interspersed with 17 s of passive recovery (RS), 2) a moderate isocaloric continuous exercise session (MC) at a level of mean oxygen uptake similar to that of the RS trial, and 3) a high-intensity intermittent exercise session (HI) conducted at a level of anaerobic energy expenditure similar to that of the RS trial. Subjects were immediately seated after the exercise trials, and beat-to-beat HR was recorded for 10 min. Parasympathetic reactivation was evaluated through 1) immediate postexercise HR recovery, 2) the time course of the root mean square for the successive R-R interval difference between successive 30-s segments (RMSSD(30s)) and 3) HR variability vagal-related indexes calculated for the last 5-min stationary period of recovery. RMSSD(30s) increased during the 10-min period after the MC trial, whereas RMSSD(30s) remained depressed after both the RS and HI trials. Parasympathetic reactivation indexes were similar for the RS and HI trials but lower than for the MC trial (P < 0.001). When data of the three exercise trials were considered together, only anaerobic contribution was related to HR trial-derived indexes. Parasympathetic reactivation is highly impaired after RS exercise and appears to be mainly related to anaerobic process participation.