Point of Care Measurement of Lactate

Tear-Based Ocular Wearable Biosensors for Human Health Monitoring

Wearable tear-based biosensors have garnered substantial interest for real time monitoring with an emphasis on personalized health care. These biosensors utilize major tear biomarkers such as proteins, lipids, metabolites, and electrolytes for the detection and recording of stable biological signals in a non-invasive manner. The present comprehensive review delves deep into the tear composition along with potential biomarkers that can identify, monitor, and predict certain ocular diseases such as dry eye disease, conjunctivitis, eye-related infections, as well as diabetes mellitus. Recent technologies in tear-based wearable point-of-care medical devices, specifically the state-of-the-art and prospects of glucose, pH, lactate, protein, lipid, and electrolyte sensing from tear are discussed. Finally, the review addresses the existing challenges associated with the widespread application of tear-based sensors, which will pave the way for advanced scientific research and development of such non-invasive health monitoring devices.

Determining lactate concentrations in Korean indigenous calves and evaluating its role as a predictor for acidemia in calf diarrhea

BACKGROUND

Calf diarrhea leads to high mortality rates and decreases in growth and productivity, causing negative effects on the livestock industry. Lactate is closely associated with metabolic acidosis in diarrheic calves. However, there have been no reports on lactate concentrations in Korean indigenous (Hanwoo) calves, especially those with diarrhea. This study aimed to determine the reference range of L-lactate and D-lactate concentrations in Hanwoo calves and to better understand the utility of lactate as predictive factors for acidemia in diarrheic calves.

RESULTS

L-lactate and D-lactate concentrations were measured in healthy (n = 44) and diarrheic (n = 93) calves, and blood gas analysis was performed on diarrheic calves. The reference range in healthy calves was 0.2-2.25 mmol/L for L-lactate and 0.42-1.38 mmol/L for D-lactate. Diarrheic calves had higher concentrations of L-lactate and D-lactate than healthy calves. In diarrheic calves, L-lactate and D-lactate each had weak negative correlation with pH (r = - 0.31 and r = - 0.35). In diarrheic calves with hyper-L-lactatemia, the combined concentrations of L-lactate and D-lactate had moderate correlation with pH (r = - 0.51) and anion gap (r = 0.55). Receiver operating characteristic analysis showed D-lactate had fair predictive performance (AUC = 0.74) for severe acidemia, with an optimal cut-off value of > 1.43 mmol/L. The combined concentrations of L-lactate and D-lactate showed fair predictive performance for predicting acidemia (AUC = 0.74) and severe acidemia (AUC = 0.72), with cut-off values of > 6.05 mmol/L and > 5.95 mmol/L.

CONCLUSIONS

The determined reference ranges for L-lactate and D-lactate in Hanwoo calves enable the identification of hyper-L-lactatemia and hyper-D-lactatemia. Diarrheic calves exhibited increased lactate concentrations correlated with acid-base parameters. While the concentrations of L-lactate and D-lactate have limitations as single diagnostic biomarkers for predicting acidemia or severe acidemia, their measurement remains important, and L-lactate has the advantage of being measurable at the point-of-care. Assessing lactate concentrations should be considered by clinicians, especially when used alongside other clinical indicators and diagnostic tests. This approach can improve calf diarrhea management, contributing positively to animal welfare and providing economic benefits to farms.

Ultrasonographic measurement of caudal vena cava to aorta ratio during fluid resuscitation of dogs with spontaneous circulatory shock

OBJECTIVES

To describe the change in the caudal vena cava to aorta ratio (CVC:Ao) ratio during fluid resuscitation of circulatory shock in dogs and compare these results with those of the physical examination and blood lactate.

MATERIALS AND METHODS

Perfusion parameters and blood lactate were recorded at admission. An abdominal point-of-care ultrasound protocol was performed, during which the caudal vena cava to aorta ratio was measured on the spleno-renal view. Measurements were performed within 5 minutes before and after a 10 mL/kg crystalloid fluid bolus. Investigators were not blinded to therapeutic interventions.

RESULTS

Twenty-nine dogs with physical signs of circulatory shock were enrolled. Caudal vena cava to aorta ratios were below reference interval in 28 of 29 dogs. After bolus administration, median caudal vena cava diameter increased by 0.14 cm (0.69 to 0.83 cm) and median aorta diameter increased by 0.03 cm (0.87 to 0.90 cm) and caudal vena cava to aorta ratio returned to within reference range in 65% of dogs (13/29). Bolus administration was associated with an increase in median caudal vena cava to aorta ratio of 0.10 (95% CI:0.05 to 0.16, P=0.0005). Blood lactate did not change significantly. Heart rate and capillary refill time decreased significantly after fluid bolus (heart rate: estimate=-19 bpm, 95% CI:-30 to -8, P=0.002; capillary refill time: estimate=-1.0 s, 95% CI:-1.3 to -0.7, P < 0.0001).

CLINICAL SIGNIFICANCE

In this population of dogs with circulatory shock, the caudal vena cava to aorta ratio significantly increased after a fluid bolus. Future studies that implement blinding of the outcome assessors are warranted to confirm these findings.

Comparison of two point of care lactate instruments in guinea pigs (Cavia porcellus)

Background

Lactate measurements have been utilized as diagnostic and prognostic tools for a variety of veterinary species. Reference intervals for lactate have not been published or validated in guinea pigs.

Methods

Whole blood from 48 anesthetized laboratory guinea pigs (46 Dunkin Hartley [38 males, eight females]; two Strain 13 [two males]) was analyzed using two point of care instruments (iSTAT and Lactate Plus). There were two consecutive timepoints on the iSTAT (iSTAT time 1 and time 2) and three consecutive timepoints on the Lactate Plus (Lactate Plus time 1, time 2, and time 3).

Results

There was agreement with no constant or proportional bias between the two instruments compared at equivalent timepoints (iSTAT time 1 and Lactate Plus time 3) as determined by Bland-Altman (bias: -0.19; 95% LoA: -0.55 to 0.16) and Deming linear regression analyses (slope: 1.092, 95% confidence intervals (CI): -0.9 to 1.29; y-intercept: 0.09, 95% CI: -0.12 to 0.30). Reference intervals for iSTAT time 1 were 0.49 to 1.83 mmol/L and Lactate Plus time 1 were 0.60 to. 2.2 mmol/L. There was a significant increase in lactate values from iSTAT time 1 to iSTAT time 2 and from Lactate Plus time 1 to Lactate Plus time 3.

Conclusions and Clinical Relevance

This study found strong agreement between the point of care instruments. Reference intervals for lactate for both the iSTAT and Lactate Plus instruments were similar to canine and feline intervals. Analysis should occur within 5 minutes of sample collection. Future work should assess lactate as a prognostic indicator in guinea pigs.

Comparison of the predictive ability of lactate and central venous blood gas in pediatric venoarterial mode extracorporeal membrane oxygenation outcome

BACKGROUND

This study aims to compare lactate and central venous blood gas in the prediction of outcome in pediatric venoarterial mode extracorporeal membrane oxygenation (V-A ECMO).

METHOD

This was a retrospective observational study conducted on patients undergoing V-A ECMO care in the pediatric intensive care unit of a tertiary medical center in Taiwan. Patients under 18 years of age undergoing V-A ECMO from January 2009 to April 2019 were included in this study.

RESULTS

This study consisted of 47 children who received V-A ECMO with an overall weaning rate of 66.0%. The mean age was 5.5 years and mean ECMO duration was 11.6 days. Successful weaning group had significantly lower lactate levels at initial (58.7 ± 47.0 mg/dL vs. 108.0 ± 55.3 mg/dL, p = 0.003), 0-12 h (37.8 ± 29.0 mg/dL vs. 83.5 ± 60.0 mg/dL, p Z 0.001), and 12-24 h (29.4 ± 26.9 mg/dL vs. 69.1 ± 59.1 mg/dL, p = 0.003) after ECMO initiation; however, the central venous blood gas including pH, HCO₃, CO₂, base excess (BE), and O₂ saturation showed no significant difference. The favorable outcome group had significantly lower lactate levels at 0-12 h (32.8 ± 26.3 mg/dL vs. 71.3 ± 53.3 mg/dL, p = 0.005), and 12-24 h (20.7 ± 10.2 mg/dL vs. 61.9 ± 53.5 mg/dL, p = 0.002); however, the HCO₃ levels (26.2 ± 4.5 mmol/L vs. 22.9 ± 6.8 mmol/L, p = 0.042) and BE (2.2 ± 5.4 vs. 2.2 ± 8.5, p = 0.047) were significantly higher at 12-24 h. In multivariate logistic regression, 12-24 h lactate value was an independent factor for unfavorable outcomes (p = 0.015, odds ratio [OR] = 1.1) with the best cut-off value of 48.6 mg/dL (sensitivity 48%, specificity 100%).

CONCLUSION

Lactate has better outcome prediction than central venous blood gas in pediatric V-A ECMO. The lactate value 12-24 h after ECMO initiation was an independent factor for unfavorable outcomes.

The Effect of Two Acute Bouts of Exercise on Oxidative Stress, Hematological, and Biochemical Parameters, and Rectal Temperature in Trained Canicross Dogs

Canicross is a sport discipline that connects human and canine athletes in running. Changes in physiological, hematological, and biochemical parameters, and exercise-induced oxidative stress have not been thoroughly characterized in canicross dogs. The aim of our study was the assessment of the health status of trained canicross dogs that were subjected to two acute bouts of exercise with their owners during the training season. Health status was assessed by measuring the rectal temperature, hematological and biochemical parameters, as well as blood oxidative stress parameters (plasma malondialdehyde, lipid peroxidation marker; whole blood glutathione peroxidase and erythrocyte superoxide dismutase1, antioxidant enzymes) before and during a two-day canicross training session and after a 24-h rest period. Seven trained canicross dogs (three females/four males) aged 12–120 months were included in the study. Blood samples were collected before and immediately after the first acute bout of exercise (day 1), after the second acute bout of exercise (day 2), and after 24 h of rest (day 3). Rectal temperature was measured at the same time as blood sample collection. The majority of hematological and biochemical parameters remained within reference ranges at all sampling times. Rectal temperature was significantly higher after training on days 1 and 2 compared to resting temperature on day 3. Hematological parameters did not change significantly; however, there were significant differences in urea, creatinine, creatine kinase, and triglycerides between specific sampling times. Despite significant changes, these biochemical parameters remained within reference ranges. Significant changes in biochemical parameters seem to reflect the dogs' physiological response to each acute bout of exercise, considering all biochemical parameters and rectal temperature returned to pre-exercise values after a 24-h rest period (day 3). No significant differences in oxidative stress parameters were found between any sampling times. Relatively high erythrocyte superoxide dismutase1 activity at all sampling times may indicate that the canicross dogs are adapted to training by an increased expression of antioxidant enzymes. Based on our results, we can conclude that the trained canicross dogs included in our study were healthy, in good physical condition, and fit for the two acute bouts of field exercise.

Efficacy of high-intensity interval training compared with moderate-intensity continuous training on maximal aerobic potency in dogs: Trial protocol for a randomised controlled clinical study

BACKGROUND

High-intensity interval training (HIIT) is a more efficient method to improve exercise capacity than moderate-intensity continuous training (MICT) because of its greater physiological stimulus.

OBJECTIVE

The aim of this protocol is to evaluate the efficacy of HIIT on maximal aerobic potency in dogs as compared to MICT.

METHODS

This protocol is for a randomised, blinded controlled clinical trial, with three parallel groups for the purpose of demonstrating superiority. Thirty dogs aged between 12 and 84 months of both sexes and different breeds will be included. Dogs, before initiating and after finalising the training will perform an incremental exercise test on a treadmill to obtain maximal speed and lactate threshold; resting parameters of heart and respiratory rate, left ventricle chamber and systolic function will be measured. Dogs assigned to each intervention will endure a 42-min session of HIIT or MICT during 12 weeks. HIIT comprises four intervals of 4 min each at a load of 85%, alternating with a 4-min resting period. MICT group will have a continuous load of 60%. The control group will remain in a cage. An intention-to-treat statistical analysis will be implemented. Analysis of covariance will be used to estimate the effect of HIIT compared with MICT training on maximal aerobic potency, aerobic resistance, systolic function at rest, left ventricle chamber measurements and indexes, respiratory rate and HR at rest.

CONCLUSION

Significant time and effort are invested into training sports/working dogs, which could benefit from improving physical capacity by means of the HIIT methodology.

Soluble urokinase plasminogen activator receptor and lactate as prognostic biomarkers in patients presenting with non-specific chief complaints in the pre-hospital setting - the PRIUS-study

BACKGROUND

Emergency Medical Services (EMS) are faced daily with patients presenting with non-specific chief complaints (NSC). Patients presenting with NSCs often have normal vital signs. It has previously been established that NSCs may have a serious underlying condition that has yet to be identified. The aim of the current study was to determine if soluble urokinase plasminogen activator receptor (suPAR) and lactate could be used to identify serious conditions among patients presenting with NSCs to the EMS. The secondary aim was to describe the prognostic value for mortality in the group.

METHOD

A blinded prospective observational cohort study was conducted of patients brought to the ED by ambulance after calling the national emergency number 112 and who were assessed as having NSC by the EMS. Biomarkers were measured during index EMS assessment before transportation to the ED. Patients were followed via EMS and hospital electronic health records. Descriptive and logistic regression analyses were used.

RESULTS

A total of 414 patients were included, with a median age of 82 years. A serious condition was present in 15.2% of the patients. Elevated suPAR above 3 ng/ml had a positive likelihood ratio (LR+) of 1.17 and a positive predictive value (PPV) of 17.3% as being predictive of a prevalent serious condition. Elevated suPAR above 9 ng/ml had LR+ 4.67 and a PPV of 16.7% as being predictive of 30-day mortality. Lactate was not significantly predictive.

CONCLUSION

Pre-hospital suPAR and lactate cannot differentiate serious conditions in need of urgent treatment and assessment in the ED among patients presenting with non-specific chief complaints. suPAR has shown to be predictive of 30-day mortality, which could add some value to the clinical assessment.

TRIAL REGISTRATION

NCT03089359. Registered 20 March 2017, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03089359 .

Salbutamol-induced lactic acidosis in status asthmaticus survivor

Background

Salbutamol-induced lactic acidosis is a rare presentation that could manifest in specific clinical context as acute asthmatic attack treatment. An increase of glycolysis pathway leading to pyruvate escalation is the mechanism of hyperlactatemia in β2-adrenergic agonist drug.

Case presentation

A 40-year-old man who had poor-controlled asthma, presented with progressive dyspnea with coryza symptom for 6 days. He was intubated and admitted into medical intensive care unit due to deteriorated respiratory symptom. Severe asthmatic attack was diagnosed and approximate 1.5 canisters of salbutamol inhaler was administrated within 24 h of admission. Initial severe acidosis consisted of acute respiratory acidosis from ventilation-perfusion mismatch and acute metabolic acidosis resulting from bronchospasm and hypoxia-related lactic acidosis, respectively. The lactate level was normalized in 6 h after hypoxemia and ventilation correction. Given the lactate level re-elevated into a peak of 4.6 mmol/L without signs of tissue hypoxia nor other possible etiologies, the salbutamol toxicity was suspected and the inhaler was discontinued that contributed to rapid lactate clearance. The patient was safely discharged on the 6th day of admission.

Conclusion

The re-elevation of serum lactate in status asthmaticus patient who had been administrated with the vast amount of β2-adrenergic agonist should be considered for salbutamol-induced lactic acidosis and promptly discontinued especially when there were no common potentials.

Shock index is associated with mortality in canine vehicular trauma patients

OBJECTIVE

To calculate and compare shock index (SI) in healthy dogs and vehicular trauma dogs (VT), determine the prognostic value of SI in VT dogs, and to assess the correlation between SI and the animal trauma triage score, modified Glasgow Coma Scale score, and lactate in VT dogs.

DESIGN

Retrospective study from April 2016 to February 2018.

SETTING

Twenty-four-hour tertiary referral level II trauma center.

ANIMALS

One hundred twenty-one dogs presented to the emergency service for VT and 60 healthy control dogs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Heart rate and systolic blood pressure were measured on each patient and used to calculate SI. SI was significantly higher in VT dogs compared to healthy control dogs (median SI, 1.0 vs 0.75; P < 0.0001). SI was significantly higher in those that died versus those that survived to discharge (median, 1.27 vs 0.96; P = 0.017). SI positively correlated with animal trauma triage score (95% confidence interval, 0.039-0.49; P = 0.019; r = 0.26) but did not with plasma lactate level at presentation (P = 0.068; r = 0.22) or modified Glasgow Coma Scale (P = 0.85; r = -0.021, 95% confidence interval, -0.24 to 0.20).

CONCLUSIONS

SI is easy to calculate during triage of a trauma patient. Given its significant relationship with mortality, higher SIs should prompt the clinician to pursue additional monitoring, diagnostics, and intervention.

Retrospective evaluation of the influence of azotemia on plasma lactate concentrations in hypotensive dogs and cats (2008-2018): 337 cases

OBJECTIVE

To evaluate the relationship between azotemia and plasma lactate concentration in hypotensive dogs and cats presented to an emergency department.

DESIGN

Retrospective case-control study.

SETTING

University veterinary teaching hospital.

ANIMALS

The electronic medical record database was searched for dogs and cats presented to the emergency department that had severe azotemia (creatinine ≥ 443.1 μmol/L [5 mg/dL]), hypotension (systolic blood pressure ≤ 90 mm Hg), and a plasma lactate measurement within 2 h of each another. Non-azotemic, normotensive dogs and cats; non-azotemic, hypotensive dogs and cats; and azotemic, normotensive dogs and cats that presented to the emergency department were used as control populations.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Severely azotemic, hypotensive dogs (n = 10) and cats (n = 63) had a lower plasma lactate than non-azotemic, hypotensive dogs and cats (P = 0.031 and P < 0.001, respectively). Median plasma lactate concentrations in hypotensive dogs (1.75 mmol/L) and cats (1.90 mmol/L) with severe azotemia were within reference intervals.

CONCLUSIONS

Hypotensive dogs and cats with severe azotemia have decreased plasma lactate concentrations as compared to hypotensive, non-azotemic dogs and cats. The median plasma lactate in azotemic, hypotensive dogs and cats was within reference intervals. This may be due to either decreased cellular production of lactate or increased excretion of lactate. Further research is needed to determine which of these mechanisms is responsible and the clinical significance of plasma lactate concentrations in azotemic, hypotensive dogs and cats.

Response to fatigue observed through magnetic resonance imaging on the quadriceps muscle in postmenopausal women

OBJECTIVES

Menopause marks the end of women's reproductive period and can lead to sarcopenia and osteoporosis (OP), increasing the risk of falls and fractures. The aim of this study is to evaluate the influence of normal and low bone mineral density (BMD) on muscular activity, observed through inflammatory edema when mapping using magnetic resonance imaging (MRI) on the quadriceps muscle of postmenopausal women.

METHODS

This was a cross-sectional study involving 16 older women, who were divided into two groups: osteoporosis group (OG), older women with OP, and control group (CG), older women without OP. The groups were evaluated in terms of nuclear MRI exam before and after carrying out fatigue protocol exercises using an isokinetic dynamometer and squatting exercises.

RESULTS

The results of the present study showed that in intragroup comparisons, for both groups, there was a significant increase (p<0.05) in the T2 signal of the nuclear MRI in the quadriceps muscle after carrying out exercises using both thighs. In the intergroup comparison, no statistically significant difference was observed between the OG and CG, pre- (p=0.343) and postexercise (p=0.874).

CONCLUSION

The acute muscular activation of the quadriceps evaluated by T2 mapping on nuclear MRI equipment is equal in women with and without OP in the postmenopausal phase. BMD did not interfere with muscle response to exercise when muscle fatigue was reached.

A pilot study comparing bone marrow aspirates and venous blood for emergency point-of-care blood parameters in healthy dogs

OBJECTIVE

To compare intravenous and intraosseous blood aspirates using point-of-care diagnostic equipment available in veterinary hospitals.

DESIGN

Prospective study.

SETTING

Private referral hospital.

ANIMALS

Dogs undergoing a tibial plateau leveling osteotomy or extracapsular anterior cruciate ligament stabilization procedure were enrolled.

METHODS

Under general anesthesia, simultaneous 0.5 mL intravenous and intraosseous blood samples were collected from the jugular vein and proximal tibia, respectively. Samples were evaluated in duplicate within 10 minutes of collection and averaged for each of the following parameters: blood urea nitrogen (BUN), glucose, packed cell volume, total plasma protein (TPP), plasma lactate, sodium, potassium, chloride, urea, glucose, pH, anion gap, pO_2, and pCO₂ . Normalcy was tested with Kolmogorov-Smirnov test. A Student's t-test and Bland-Altman plot were used to compare intravenous and intraosseous samples.

RESULTS

Twelve dogs were recruited into the study. There were statistically significant differences between intravenous and intraosseous samples for sodium (P = 0.0216), chloride (P = 0.0225), BUN (P = 0.014), and potassium (P < 0.0001), respectively. No significant differences were detected for the other parameters evaluated.

DISCUSSION

The intraosseous space provides an easily accessible, noncollapsible alternative for assessing blood parameters. Omitting potassium, the statistically significant differences noted between sites was not felt to be clinically significant. Although statistically insignificant, the large difference in hematocrit values indicates that the samples should not be used interchangeably.

CONCLUSION

Intraosseous aspirates, excluding potassium and hematocrit, appear to be a reliable alternative for assessing most point-of-care analytes in healthy dogs, although a larger sample size should be investigated. The application of these data in shock patients is unknown.