Blood Gas Measurements Research Articles

Effect of Hemolysis on Routine Blood Gas and Whole Blood Analytes.

Hemolysis is a major pre-analytical concern for many laboratory analytes; however, instruments utilized for whole blood chemistries and blood gas measurements lack the ability to detect and measure the degree of hemolysis. This study evaluated the effect of hemolysis on 13 routine whole blood and blood gas analytes and compared visual assessments of hemolysis to measured hemolysis (H-index). Remnant whole blood samples (n = 85) were split into 2 portions and aspirated through a syringe one or more times. To induce hemolysis, a needle was affixed to the end of the syringe to provide shear stress, and a mock procedure without syringe was used as a control. Samples were analyzed on a Radiometer ABL800 series instrument, centrifuged, and the H-index of the plasma portion was measured. Two medical technologists recorded a visual categorization of the specimens as slightly, moderately, or severely hemolyzed. Hemolysis had a modest effect on metabolites and most cooximetry components, with percent bias within ±5% at all levels of hemolysis. Methemoglobin exhibited a larger overall negative bias, up to 13.3%. The absolute pH bias was fairly consistent (within 0.1 pH units) across all levels of hemolysis. As expected, potassium displayed a significant positive bias with increasing hemolysis. Sodium and ionized calcium displayed overall linear trends with a significant negative bias. Hemolysis can falsely increase or decrease certain blood gas analytes and lead to misinterpretation of results. Therefore, hemolysis detection capabilities are crucial for mitigating this effect and ensuring accurate results for patient care.

Correlation Between EtCO2 and PCO2 in Patients Undergoing Critical Care Transport

Objectives End-tidal carbon dioxide (EtCO2) monitoring is widely used as a surrogate for the partial pressure of carbon dioxide (PCO2) in critically ill patients receiving manual or mechanical ventilation in prehospital, emergency, and critical care settings. Specific targets for ETCO2 are a key component of Emergency Medical Services (EMS) protocols, especially for specific patient groups such as those with traumatic brain injury. However, the correlation between EtCO2 and venous or arterial PCO2 is uncertain. We aimed to assess the correlation between EtCO2 and PCO2 in intubated patients undergoing critical care transport (CCT), and in specific subgroups of patients. Methods We performed a retrospective review of patients undergoing emergency transport by a multi-state CCT agency. Patients were included if they had an advanced airway and both an EtCO2 and PCO2 reading within 5 min of each other. We obtained data on patient demographics, transport characteristics, medical categories, vital signs, lab values, and specific interventions. We performed univariable and multivariable binary logistic regression to assess the association between delta PCO2 and these characteristics. Results We included 6,459 patients (mean age 58.4 years [SD 18.5], 57.1% male), of which a subset of 551 patients had multiple EtCO2-PCO2 measurements within 5 min. The median (IQR) initial delta PCO2 was 12.9 mmHg (7.1, 21.9). 3,967 (61.4%) patients had a delta PCO2 >10 mmHg and 1,843 (28.5%) had a delta PCO2 >20 mmHg. We identified an independent association between delta PCO2 >10 mmHg and age, male sex, interfacility transport, venous sampling site, respiratory rate, hypotension, hypoxia, and thoracostomy. In patients with multiple blood gas measurements, 76% had delta PCO2 >10 mmHg over the duration of the transport. Conclusions We identified substantial differences between EtCO2 and PCO2 across patients with medical and traumatic conditions undergoing critical care transport. The PCO2 assessment should be strongly considered as part of ventilatory management in patients encountered in emergency and critical care settings.

Abstract 4136700: Sodium-Potassium Pump: Newly O-GlcNAc Protein Offering Potential Benefits in Hemorrhagic Shock situation

Hemorrhagic shock(HS) results from significant blood loss, leading to insufficient oxygen delivery, which causes metabolic changes and multi-organ dysfunction.The HS-related acute kidney injury developed by the patient are mainly due to alteration in Na/K ATPase.In previous O-GlcNAcylomic studies, we identified the Na/K ATPase as potentially O-GlcNAcylated.O-GlcNAcylation, a post-translational modification, plays a role in various cellular processes, such as cell survival and stress response.O-GlcNAcylation may have beneficial effect in shock situations. The objective of this study is to ascertain whether Na/K ATPase is O-GlcNAcylated and to elucidate its potential role during HS. Hemorrhagic shock was induced by an exsanguination of rats.They were then randomly treated or not with an O-GlcNAcase inhibitor, the NButGT(10mg/kg), to increase O-GlcNAc level.Blood pressure and heart rate were monitored throughout the experiment.Blood samples were collected for complete blood analysis, including biochemistry and gas measurements. kidneys were immediately frozen for histological and biochemical studies.To study the O-GlcNAcylation of Na/K ATPase an immunoprecipitation and Wheat Germ Agglutinin(WGA) based lectin affinity gel electrophoresis were used. HEK cells were treated with or without NButGT(100µM,6 hours) and/or ouabain(Na/K ATPase inhibitor) and a colorimetric kit was assessed to study O-GlcNAcylation impact on Na/K ATPase activity. O-GlcNAc levels increased by 2 folds in heart and kidney due to the NButGT treatment(p<0.05).Mean arterial pressure(MAP,p<0.01) and bicarbonate(p<0.01) are restored in treated group as kalemia(Sham:4.2 ± 0.1;HS:4.7±0.1;NButGT:4.3 ±0.1;mmol/L;p<0.05) and natremia(Sham:141.5±0.4;HS:139.8±0.5;NButGT:141.9 ±0.4; mmol/L;p<0.01).The study of the O-GlcNAcylation of the Na/K ATPase validated its O-GlcNAcylation.Histological analysis of the kidney showed that HS decreased Na/K ATPase expression, but treatment restored it(Sham:15.1±1.1;HS:10.3±0.6;NButGT:13.78±1.1;%area;p<0.05). An acute increase in O-GlcNAc levels through NButGT enhances Na/K ATPase activity. Increased O-GlcNAcylation during hemorrhagic shock restored MAP and reduced indicators of metabolic acidosis.Treatment with NButGT restored natremia and kalemia.This effect is linked to an increase in the expression and activity of Na/K ATPase.Our study is the first to confirm that Na/K ATPase is regulated by O-GlcNAcylation, particularly in terms of its localization and stability.

Glenn circulation causes early and progressive shunting in a surgical model of pulmonary arteriovenous malformations.

Pulmonary arteriovenous malformations (PAVMs) universally develop in patients with single ventricle congenital heart disease. Single ventricle PAVMs have been recognized for over 50 years but remain poorly understood. To improve our understanding, we developed a surgical rat model of Glenn circulation and characterized PAVM physiology over multiple time points. We performed a left thoracotomy and end-to-end anastomosis of the left superior vena cava to the left pulmonary artery (unilateral Glenn), or sham surgical control. To assess PAVM physiology, we quantified intrapulmonary shunting using two independent methods (bubble echocardiography and fluorescent microsphere injection). Additionally, we performed arterial blood gas measurements to assess oxygenation and plethysmography to assess ventilation. We identified pathologic intrapulmonary shunting by bubble echocardiography as early as 2 weeks post-Glenn, and shunting continued at 2- and 6-months post-Glenn. Shunting also progressed over time, demonstrated by increased shunting of 10 μm microspheres at 6 months. Shunting was accompanied by mildly decreased oxygenation but no differences in ventilation. Our surgical animal model of unilateral Glenn circulation recreates the clinical condition of single ventricle PAVMs with early and progressive intrapulmonary shunting. This model is poised to characterize single ventricle PAVM pathophysiology and lead to mechanistic and therapeutic discovery.

Low oxygen saturation and discordant arterial blood gas measures have diagnosed a case of hemoglobinopathy

Pulse oximeter is a simple non-invasive equipment used to determine patient’s arterial blood oxygen saturation (SpO2). However, in some people, arterial blood gas measures (SaO2) are normal and low SpO2 values are related to hemoglobin variant rather than cardiac or pulmonary illnesses. Aim. We present a case of thalassemia that manifested with low SpO2 and discordant SaO2. Conclusion. When examining a patient with an unusually low SpO2, the differential diagnosis of a suspected hemoglobin variant should be investigated. Establishing an accurate diagnosis as soon as possible may help avoid unnecessary tests.

A-345 Effect of Hemolysis on Routine Blood Gas Analytes

Abstract Background Hemolysis is a major pre-analytical concern for most laboratory analytes. Detection of hemolysis and mitigation efforts are especially important for analytes, such as potassium, with high intracellular concentrations. Routine serum and plasma chemistry tests are performed on analyzers with the capacity to detect and measure the degree of hemolysis. However, for whole blood chemistries and blood gas measurements, the instruments utilized lack this capacity. The aim of this study was to evaluate the effect of hemolysis on whole blood and blood gas analytes and to compare visual assessments of hemolysis to measured hemolysis indices (H-index). Methods Remnant whole blood samples were split into two portions and each portion was aspirated and dispensed through a syringe one or more times. For the mock portion, only the syringe was used, while the hemolyzed portion had a needle affixed to the end of the syringe. The needle provided shear stress on the red blood cells to induce hemolysis, while the mock procedure was used to assess the impact of aspirating/dispensing on the sample in the absence of hemolysis. Each portion was then analyzed on a Radiometer ABL800 series instrument, spun down, and the H-index of the plasma portion was measured on a Roche cobas 8000 instrument. Medical technologists recorded their visual assessment of the specimens, with two technologists agreeing to the categorization of the specimen as either slightly, moderately, or severely hemolyzed. Degree of hemolysis was categorized by the delta (hemolyzed - mock) of the measured H-index: slight hemolysis was defined as an H-index delta of <100, moderate as 100-500 and severe as >500. Results The effect of hemolysis, with H-indices ranging from 2 to 3861, on 13 routine blood gas analytes was studied for 85 whole blood specimens. Hemolysis had little effect on metabolites, as percent bias was within ±3% at all levels of hemolysis for glucose, creatinine, and lactate. Similarly, most cooximetry components were minimally affected, with total hemoglobin, oxyhemoglobin, carboxyhemoglobin, and oxygen saturation within ±5% bias at all levels of hemolysis. Methemoglobin had a larger overall negative bias, with slight, moderate, and severe hemolysis levels yielding percent biases of -6.6, -12.3, and -13.3%, respectively. As expected, potassium displayed a significant positive bias with increasing hemolysis, with a generally linear trend. At moderate levels of hemolysis, the average potassium bias was 24.0% and at severe levels, over 100%. Sodium and ionized calcium also displayed overall linear trends but with a negative bias. At slight, moderate, and severe levels of hemolysis, sodium had a -0.56, -1.10, and -3.96% bias, and ionized calcium had a -2.99, -5.65, and -15.5% bias respectively. Conclusions Hemolysis can falsely increase or decrease a range of blood gas analytes and lead to misinterpretation of results and adversely affect clinical decision-making. Therefore, equipping current blood gas analyzers with hemolysis detection capabilities is crucial to enable laboratories to mitigate this effect and ensure accurate results for patient care.

A-342 Precision Evaluation of the pH, PO2 and PCO2 tests in the i-STAT® G3+ Cartridge using the i-STAT 1 System for Venous, Arterial and Capillary Whole Blood Specimens in Clinical Settings

Abstract Background Precise and accurate measurements of blood gases are important for the diagnosis, monitoring and treatment of respiratory, metabolic, and acid-base disturbances. This study demonstrates the precision of the pH, partial pressure of oxygen (PO2), and partial pressure of carbon dioxide (PCO2) tests in the i-STAT G3+ cartridge with the i-STAT 1 System in arterial, venous, and capillary whole blood specimens in point-of-care or clinical laboratory settings. Methods The precision of the i-STAT pH, PO2, and PCO2 tests in the i-STAT G3+ cartridge was assessed at external clinical sites by end-users using whole blood specimens across the measurement range for each test: pH (6.500 - 7.800 pH units), PO2 (5 - 700 mmHg), PCO2 (5.0 - 130.0 mmHg). The study included venous whole blood samples from ∼140 adult subjects (≥ 18 years) and arterial whole blood samples from ∼140 adult subjects at 3 clinical sites. Each whole blood sample was run in duplicate on the i-STAT G3+ cartridge. In addition, ∼140 specimens were collected in capillary tubes using two fingerstick draws from adult subjects and ∼20 capillary heel-stick specimens were collected into two capillary tubes from neonate subjects (birth - 28 days) at two clinical sites. Specimens used in this study were prospectively collected venous, arterial, or capillary specimens under an Institutional Review Board approved informed consent or were de-identified leftover venous or arterial specimens. For each specimen type, duplicates from each subject were grouped into subintervals based on their mean values. The subintervals included the medical decision levels of 7.300, 7.350 and 7.450 pH units for pH, 30, 45 and 60 mmHg for PO2 and 35, 45, 50 and 70 mmHg for PCO2. The estimates of the pooled standard deviation (SD) and pooled coefficient of variation (%CV), as well as their respective 95% confidence intervals were calculated for each subinterval. Results Across all specimen types (excluding outliers), the pooled SD for pH ranged from 0.00591 - 0.01747 pH units for subintervals 6.500 - 7.300, >7.300 - 7.450, >7.450 - 7.800 pH units. For PO2, the pooled SD ranged from 0.71 - 3.76 mmHg for subintervals 10 - 40 mmHg and >40 - 50 mmHg and the pooled %CV ranged from 1.63 - 8.76 %CV for subintervals >50 - 100 mmHg, >100 - 250 mmHg and >250 - 700 mmHg. For PCO2, the pooled SD ranged from 0.000 - 1.709 mmHg for subintervals 5.0 - 35.0 mmHg, >35.0 - 50.0 mmHg and >50.0 - 62.5 mmHg and the pooled %CV ranged from 1.10 - 3.62 %CV for subinterval >62.5 - 130.0 mmHg. Conclusions The precision study demonstrated that the pH, PO2 and PCO2 tests in the i-STAT G3+ cartridge when tested using the i-STAT 1 System deliver precise results within ∼2 minutes for venous, arterial, and capillary whole blood patient specimens when tested by end users in a point-of-care or clinical laboratory setting. These studies were funded by Abbott Laboratories.

A-329 Accuracy of the pH, PO2, and PCO2 Tests in the i-STAT® G3+ Cartridge Using the i-STAT 1 System for Venous, Arterial and Capillary Whole Blood Specimens in Clinical Settings

Abstract Background Precise and accurate measurements of blood gases are important for the diagnosis, monitoring and treatment of respiratory, metabolic, and acid-base disturbances. This study demonstrates the accuracy of the pH, partial pressure of oxygen (PO2), and partial pressure of carbon dioxide (PCO2) tests in the i-STAT G3+ cartridge with the i-STAT 1 System in arterial, venous, and capillary whole blood specimens in point of care or clinical laboratory settings. Methods The accuracy of the PO2, and PCO2 tests in the i-STAT G3+ cartridge was assessed at external clinical sites in a method comparison study using whole blood specimens across the measurement range for each test: pH 6.5-7.8, PO2 5-700 mmHg, PCO2 5.0-130.0 mmHg. Specimens used in this study were venous, arterial, and capillary specimens prospectively collected under Institutional Review Board-approved informed consent or were leftover de-identified venous or arterial specimens. The study included venous and arterial whole blood samples from ∼140 adult subjects (≥ 18 years) at 3 clinical sites, and capillary whole blood samples from ∼180 adult subject at 3 clinicals sites and ∼25 neonate subjects (birth to 28 days) at 2 clinical sites. The RapidPoint System was used as comparator. For venous and arterial whole blood, samples were collected and tested in duplicate on the i-STAT G3+ cartridge and in singlicate on the RapidPoint System. For capillary whole blood samples, adult fingerstick samples and neonate heel-stick samples were collected in capillary tubes and tested in singlicate on the i-STAT G3+ cartridge and on the RapidPoint System. Passing-Bablok regression was performed for venous and arterial whole blood samples combined, using the first replicate from the i-STAT G3+ cartridge versus the singlicate result from the comparator, and for capillary whole blood samples (adult and neonate combined) using the singlicate result from the i-STAT G3+ cartridge versus the singlicate result from the comparator. Results Passing-Bablok regression of i-STAT G3+ cartridge results versus the comparator was used to calculate slope and correlation coefficient (r). For adult venous and arterial whole blood results, pH had slope = 0.96 and r = 0.99, PO2 had slope = 1.05 and r = 1.00, and PCO2 had slope = 1.04 and r = 0.98. For adult and neonate capillary whole blood results, pH had slope = 1.02 and r = 0.98, PO2 had slope = 1.09 and r = 0.99, and PCO2 had slope = 1.07 and r = 0.96. Conclusions These results demonstrate that the i-STAT 1 System delivers accurate pH, PO2, and PCO2 test results with ∼2 minutes using the i-STAT G3+ cartridge for venous, arterial and capillary whole blood samples for adult and neonate subjects when tested by end-users in a point of care or clinical laboratory setting. This study was funded by Abbott Laboratories.

The Effect of Lactic Acidosis on Neonatal Outcomes in Premature Infants

The aim of the study was to evaluate neonatal outcomes in preterm infants.Materials and methods. The study included 58 premature neonates divided into 2 groups: «A» (N=34) with an adverse neonatal period ending in death and «B» (N=24) who survived. Clinical assessment of the infant, measurement of blood gases, acid-base balance (ABB) and lactate, recording of lung ventilation parameters, calculation of mean airway pressure, oxygenation index (OI) and ventilation efficiency index (VEI), neurosonography and, in case of death, pathological and histological examination of the brain were performed.Results. Elevated lactate was found in 24 patients (70.5%) in group A and in 12 patients (50%) in group B. The mean lactate levels in groups A and B were 8.1±3.3 and 6.3±2.8 mmol/L, respectively. In group A, 19 (55.9%) infants had severe acidosis, corresponding to a pH of 7.19 to 6.80. In group B, only 8 (33.3%) infants had a pH between 7.0 and 7.19. At birth, neonates in both groups were found to have a base deficit (BD), which was significantly lower in group A than in group B (P=0.004). There were no trends toward reduction of acidosis or normalization of ABB in infants in group A. Plasma BE levels in group B had returned to normal by 96 hours postpartum. The frequency of grade II, III peri/intraventricular hemorrhage (PIVH) and hemorrhage of other localization in group A were 8 (23.5%), 9 (26.5%), and 3 (8.8%), respectively. In group B, grade I PIVH and hemorrhage of other localization occurred in 5 (20.8%) and 1 (4.2%) cases, respectively. In neonates with grade II PIVH, severe lactic acidosis was diagnosed at birth: venous blood pH was 6.97 [6.8; 7.22], BE was (–21.6) [–30; –7.2] mmol/L, lactate level was 8.5 [6.3; 12.9] mmol/L, and pO₂ was 50.5 [20.5; 64] mm Hg. In infants with grade III PIVH, pH was –7.26 [7.12; 7.28], BE was (–8.1) [–8.9; –7] mmol/L, lactate was 7.6 [4.8; 8.9] mmol/L, and pO₂ was 33 [30; 50] mm Hg. Cell damage of varying severity affected all brain structures, as evidenced by absence or deformation of nuclei and nucleoli, and peripheral chromatin condensation. Morphological immaturity of brain structures was another negative factor.Conclusion. Lactic acidosis diagnosed at birth in premature infants is one of the indicators of perinatal hypoxia severity. Critical pH, BE, and lactate levels, as well as lack of response to treatment, contribute to structural brain damage and worsen prognosis. Severe changes in oxygen and lactate levels that persist for two days after birth lead to severe PIVH and irreversible brain changes.

Comparison of Blood-Gas Hemoglobin and Electrolyte Measurements and Automated Laboratory Values in Pediatric Kidney Transplant Patients.

The reliability of blood-gas measurements compared with automated laboratory tests in providing rapid results for pediatric patients is currently under investigation. The compatibility between fast-response blood-gas tests and standard automatic laboratory tests remains a subject of debate. In this retrospective single-center study, our objective was to compare the measurements of hemoglobin and electrolytes obtained through blood-gas analysis with the corresponding values obtained from standard laboratory tests in pediatric renal transplantation, specifically focusing on the immediate pretransplant period. We retrospectively investigated 26 pediatric kidney transplant patients in the pretransplant period. We reviewed their medical records and compared and simultaneous measurements of hemoglobin, sodium, and potassium from a blood-gas analyzer versus a laboratory automatic analyzer. We assessed the agreement between the 2 analyses with BlandAltman analysis and Cohen kappa statistic. Among the 26 pediatric kidney transplant recipients, mean age was 10.1 ± 4.9 years and 60.0% were male patients. The mean differences between blood-gas and the venous laboratory analyzer (95% CI) were as follows: 0.11 g/dL for hemoglobin (-0.27 to 0.05 g/dL; P > .05), 0.39 mEq/L for sodium (-0.58 to 1.35 mEq/L; P > .05), and 0.00 mEq/L for potassium (-0.25 to 0.25 mEq/L; P > .05). Cohen kappa test showed the highest agreement for sodium, with no significant difference in mean values. Our study demonstrated strong agreement between hemoglobin, sodium, and potassium values obtained through blood-gas measurements and venous blood samples in pediatric kidney transplant recipients. Demonstrating the concordance between rapid blood-gas analysis and automated laboratory tests can offer valuable guidance to clinicians.

Association of dynamic changes in arterial partial pressure of carbon dioxide with neurological outcomes in aneurysmal subarachnoid hemorrhage

BackgroundCerebral blood flow (CBF) is closely regulated by carbon dioxide (CO2). In patients with aneurysmal subarachnoid hemorrhage (aSAH), abnormal arterial partial pressure of CO2 (PaCO2) might deteriorate brain injuries. Nevertheless, the impact of dynamic PaCO2 fluctuations on neurological outcomes in aSAH patients has not been extensively studied. Our study aimed to investigate the association between dynamic PaCO2 levels and unfavorable neurological outcomes in aSAH patients. MethodsIn this retrospective observational study, we consecutively enrolled 159 aSAH patients from December 2019 to July 2021. Arterial blood gas measurements within 10 days after intensive care unit (ICU) admission for each patient were recorded to calculate the time-weighted average (TWA)-PaCO2, an indicator representing the dynamic changes in PaCO2 levels. For the association between TWA-PaCO2 levels and unfavorable neurological outcomes in aSAH patients, multivariable logistic analysis was used to explore TWA-PaCO2 levels as categorical variables, and restricted cubic spline (RCS) was used to explore TWA-PaCO2 levels as continuous variables. ResultsIn multivariable logistic analysis, after adjusting confounders, when TWA-PaCO2 35–45 mmHg was as a reference, TWA-PaCO2 < 35 mmHg (odds ratio [OR] 2.15, 95 % confidence interval [CI] 0.83–5.55, P = 0.113) and TWA-PaCO2 > 45 mmHg (OR 8.31, 95 % CI 0.72–96.14, P = 0.090) were not independently associated with unfavorable neurological outcomes (modified Rankin score of 3–6). The RCS shows a “U” shape curve between TWA-PaCO2 levels and unfavorable neurological outcomes, with a nonlinear P-value of 0.023. The lowest ORs of unfavorable neurological outcomes were within PaCO2 32.8–38.1 mmHg. ConclusionsBoth lower and higher PaCO2 levels are harmful to aSAH patients. PaCO2 in the range of 32.8–38.1 mmHg is associated with lowest unfavorable neurological outcomes.

Accuracy and Interpretation of Transcutaneous Carbon Dioxide Monitoring in Critically Ill Children.

Transcutaneous carbon dioxide (Tc co2 ) monitoring can noninvasively assess ventilation by estimating carbon dioxide ( CO2 ) levels in the blood. We aimed to evaluate the accuracy of Tc co2 monitoring in critically ill children by comparing it to the partial pressure of arterial carbon dioxide (Pa co2 ). In addition, we sought to determine the variation between Tc co2 and Pa co2 acceptable to clinicians to modify patient care and to determine which patient-level factors may affect the accuracy of Tc co2 measurements. Retrospective observational cohort study. Single, quaternary care PICU from July 1, 2012, to August 1, 2020. Included participants were admitted to the PICU and received noninvasive ventilation support (i.e., continuous or bilevel positive airway pressure), conventional mechanical ventilation, or high-frequency oscillatory or percussive ventilation with Tc co2 measurements obtained within 15 minutes of Pa co2 measurement. None. Three thousand four hundred seven paired arterial blood gas and Tc co2 measurements were obtained from 264 patients. Bland-Altman analysis revealed a bias of -4.4 mm Hg (95% CI, -27 to 18.3 mm Hg) for Tc co2 levels against Pa co2 levels on the first measurement pair for each patient, which fell within the acceptable range of ±5 mm Hg stated by surveyed clinicians, albeit with wide limits of agreement. The sensitivity and specificity of Tc co2 to diagnose hypercarbia were 93% and 71%, respectively. Vasoactive-Infusion Score (VIS), age, and self-identified Black/African American race confounded the relationship between Tc co2 with Pa co2 but percent fluid overload, weight-for-age, probe location, and severity of illness were not significantly associated with Tc co2 accuracy. Tc co2 monitoring may be a useful adjunct to monitor ventilation in children with respiratory failure, but providers must be aware of the limitations to its accuracy.

Utility of Skin Tone on Pulse Oximetry in Critically Ill Patients: A Prospective Cohort Study.

Pulse oximetry, a ubiquitous vital sign in modern medicine, has inequitable accuracy that disproportionately affects minority Black and Hispanic patients, with associated increases in mortality, organ dysfunction, and oxygen therapy. Previous retrospective studies used self-reported race or ethnicity as a surrogate for skin tone which is believed to be the root cause of the disparity. Our objective was to determine the utility of skin tone in explaining pulse oximetry discrepancies. Prospective cohort study. Patients were eligible if they had pulse oximetry recorded up to 5 minutes before arterial blood gas (ABG) measurements. Skin tone was measured using administered visual scales, reflectance colorimetry, and reflectance spectrophotometry. Admitted hospital patients at Duke University Hospital. None. Sao2-Spo2 bias, variation of bias, and accuracy root mean square, comparing pulse oximetry, and ABG measurements. Linear mixed-effects models were fitted to estimate Sao2-Spo2 bias while accounting for clinical confounders.One hundred twenty-eight patients (57 Black, 56 White) with 521 ABG-pulse oximetry pairs were recruited. Skin tone data were prospectively collected using six measurement methods, generating eight measurements. The collected skin tone measurements were shown to yield differences among each other and overlap with self-reported racial groups, suggesting that skin tone could potentially provide information beyond self-reported race. Among the eight skin tone measurements in this study, and compared with self-reported race, the Monk Scale had the best relationship with differences in pulse oximetry bias (point estimate: -2.40%; 95% CI, -4.32% to -0.48%; p = 0.01) when comparing patients with lighter and dark skin tones. We found clinical performance differences in pulse oximetry, especially in darker skin tones. Additional studies are needed to determine the relative contributions of skin tone measures and other potential factors on pulse oximetry discrepancies.

Biomarker screening for pulmonary hypertension in VLBW infants at risk for bronchopulmonary dysplasia.

Very low birth weight (VLBW) infants demonstrate altered alveolar and pulmonary vascular development and carry an increased risk of developing bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH). Risk stratification for BPD-associated PH (BPD-PH) in at-risk infants may help tailor management, improve outcomes, and optimize resource utilization. VLBW infants were screened for PH with blood gas measurements, serum NT-proBNP and bicarbonate (HCO3) levels, and echocardiograms if they remained on respiratory support at 34 weeks corrected gestational age. We then tested 11 models using different cutoffs for NT-proBNP and HCO3 to predict infants at low risk of BPD-PH. We identified PH in 34 of 192 (17.6%) VLBW infants. The median NT-proBNP in VLBWs with PH was 2769 pg/mL versus 917 pg/mL in those without PH (p < 0.0001). A model with NT-proBNP < 950 pg/mL and HCO3 < 32 mmol/L had a sensitivity of 100%, specificity of 34.2%, and negative predictive value of 100%. Using this model, 54 of 192 (28%) of the patients in this study would have been categorized as low risk for PH and could have avoided a screening echocardiogram. NT-proBNP and HCO3 together may serve as sensitive and cost-effective screening tools for BPD-PH in VLBW infants. NT-proBNP and HCO3 concentrations obtained together may help identify very low birth weight infants at risk for bronchopulmonary dysplasia who should undergo screening for pulmonary hypertension with echocardiography. This large dataset demonstrates that NT-proBNP and HCO3 levels together are more sensitive than NT-proBNP alone in identifying VLBW infants to undergo echocardiography. The combination of NT-proBNP and HCO3 levels may identify VLBW infants at low risk for pulmonary hypertension and thus those who may be able to avoid screening echocardiography.

Blood Gas Measurements Using Point-of-Care Testing Devices in Pediatric Patients

Blood Gas Measurements Using Point-of-Care Testing Devices in Pediatric Patients

Association of extreme hyperoxemic events and mortality in pediatric critical care: an observational cohort study.

Our aim was to confirm whether extreme hyperoxemic events had been associated with excess mortality in our diverse critical care population. Retrospective analysis of 9 years of data collected in the pediatric and cardiothoracic ICUs in Children's Hospital Los Angeles was performed. The analysis was limited to those mechanically ventilated for at least 24 h, with at least 1 arterial blood gas measurement. An extreme hyperoxemic event was defined as a PaO2 of ≥300 torr. Multivariable logistic regression was used to assess the association of extreme hyperoxemia events and mortality, adjusting for confounding variables. Selected a-priori, these were Pediatric Risk of Mortality III predicted mortality, general or cardiothoracic ICU, number of blood gas measurements, as well as an abnormal blood gas measurements (pH < 7.25, pH > 7.45, and PaO2 < 50 torr). There were 4,003 admissions included with a predicted mortality of 7.1% and an actual mortality of 9.7%. Their care was associated with 75,129 blood gas measurements, in which abnormal measurements were common. With adjustments for these covariates, any hyperoxemic event was associated with excess mortality (p < 0.001). Excess mortality increased with multiple hyperoxemic events (p < 0.046). Additionally, treatment resulting in SpO2 > 98% markedly increased the risk of a hyperoxemic event. Retrospective analysis of critical care admissions showed that extreme hyperoxemic events were associated with higher mortality. Supplemental oxygen levels resulting in SpO2 > 98% should be avoided.

Carboxyhemoglobin as Potential Biomarker for Cardiac Surgery Associated Acute Kidney Injury

Carboxyhemoglobin (CO-Hb) is a marker of hemolysis and inflammation, both risk factors for cardiac surgery-associated AKI (CSA-AKI). However, the association between CO-Hb and CSA-AKI remains unknown. A retrospective cohort study. Tertiary university-affiliated metropolitan hospital: single center. Adult on-pump cardiac surgery patients from July 2014 to June 2022 (N = 1,698). None. Patients were stratified into quartiles based on CO-Hb levels at intensive care unit (ICU) admission. A progressive increased risk of CSA-AKI was observed with higher CO-Hb levels at ICU admission. On multivariable logistic regression analysis, the highest quartile (CO-Hb ≥ 1.4%) showed an independent association with the occurrence of CSA-AKI (odds ratio 1.45 compared to the lowest quartile [CO-Hb < 1.0%], 95% CI 1.023-2.071; p = 0.038). Compared to patients with CO-Hb <1.4%, patients with CO-Hb ≥ 1.4% at ICU admission had significantly higher postoperative creatinine (135 vs 116 μmol/L, p < 0.001), higher rates of postoperative RRT (6.7% vs 2.3%, p < 0.001) and AKI (p < 0.001) on univariable analysis and shorter time to event for AKI or death (p < 0.001). CO-Hb ≥ 1.4% at ICU admission is an independent risk factor for CSA-AKI, which is easily obtainable and available on routine arterial blood gas measurements. Thus, CO-Hb may serve as a practical and biologically logical biomarker for risk stratification and population enrichment in trials of CSA-AKI prevention.

Comparison of Blood Gas Analysis and Auto-Analyzer Results for Sodium and Potassium Levels in Elderly and Non-elderly Adult Emergency Department Patients.

Objectives This study aims to evaluate the concordance between blood gas and biochemical measurement methods for sodium and potassium levels in elderly and non-elderly patients within an emergency department (ED) setting. Methods A retrospective method comparison study was conducted at an ED from February 1, 2023, to March 1, 2023. The study included 414 patients, categorized into "elderly" (aged 65 and above; n = 138, 33.3%) and "non-elderly" (aged 18 to 64; n = 276, 66.7%) groups. Concordance was assessed using Bland-Altman, Passing-Bablok, and Lin's concordance correlation methods. Results In sodium measurements, the elderly group exhibited an average bias of -1.52 mEq/L (95% confidence interval [CI] -2.12 to -0.92), with lower and upper limits of agreement (LoA) at -8.46 and 5.42 mEq/L, respectively, indicating a broader variance than non-elderly patients, who showed an average bias of -0.82 mEq/L with limits of -4.97 to 3.32 mEq/L. For potassium, the elderly group's average bias was -0.46 mEq/L (95% CI -0.36 to -0.57), with limits of agreement from -1.68 to 0.75 mEq/L, compared to non-elderly patients with a bias of -0.29 mEq/L and limits of -0.71 to 0.13 mEq/L. Furthermore, concordance correlation coefficients revealed a reduced agreement in the elderly for both sodium (r ccc = 0.799) and potassium (r ccc = 0.529) compared to the non-elderly cohort (sodium r ccc = 0.821, potassium r ccc = 0.715). Conclusion The study identifies significant discrepancies in sodium and potassium levels between elderly and non-elderly patients, suggesting a need for diagnostic precision. It emphasizes the importance of customizing diagnostic approaches to better serve the elderly population in EDs.

BOLD: Blood-gas and Oximetry Linked Dataset

Pulse oximeters measure peripheral arterial oxygen saturation (SpO2) noninvasively, while the gold standard (SaO2) involves arterial blood gas measurement. There are known racial and ethnic disparities in their performance. BOLD is a dataset that aims to underscore the importance of addressing biases in pulse oximetry accuracy, which disproportionately affect darker-skinned patients. The dataset was created by harmonizing three Electronic Health Record databases (MIMIC-III, MIMIC-IV, eICU-CRD) comprising Intensive Care Unit stays of US patients. Paired SpO2 and SaO2 measurements were time-aligned and combined with various other sociodemographic and parameters to provide a detailed representation of each patient. BOLD includes 49,099 paired measurements, within a 5-minute window and with oxygen saturation levels between 70–100%. Minority racial and ethnic groups account for ~25% of the data – a proportion seldom achieved in previous studies. The codebase is publicly available. Given the prevalent use of pulse oximeters in the hospital and at home, we hope that BOLD will be leveraged to develop debiasing algorithms that can result in more equitable healthcare solutions.

Noninvasive Surrogate for Physiologic Dead Space Using the Carbon Dioxide Ventilatory Equivalent: Testing in a Single-Center Cohort, 2017-2023.

We sought to evaluate the association between the carbon dioxide ( co2 ) ventilatory equivalent (VEq co2 = minute ventilation/volume of co2 produced per min), a marker of dead space that does not require a blood gas measurement, and mortality risk. We compared the strength of this association to that of physiologic dead space fraction (V D /V t = [Pa co2 -mixed-expired P co2 ]/Pa co2 ) as well as to other commonly used markers of dead space (i.e., the end-tidal alveolar dead space fraction [AVDSf = (Pa co2 -end-tidal P co2 )/Pa co2 ], and ventilatory ratio [VR = (minute ventilation × Pa co2 )/(age-adjusted predicted minute ventilation × 37.5)]). Retrospective cohort data, 2017-2023. Quaternary PICU. One hundred thirty-one children with acute respiratory distress syndrome. None. All dead space markers were calculated at the same 1-minute timepoint for each patient within the first 72 hours of using invasive mechanical ventilation. The 131 children had a median (interquartile range, IQR) age of 5.8 (IQR 1.4, 12.6) years, oxygenation index (OI) of 7.5 (IQR 4.6, 14.3), V D /V t of 0.47 (IQR 0.38, 0.61), and mortality was 17.6% (23/131). Higher VEq co2 ( p = 0.003), V D /V t ( p = 0.002), and VR ( p = 0.013) were all associated with greater odds of mortality in multivariable models adjusting for OI, immunosuppressive comorbidity, and overall severity of illness. We failed to identify an association between AVDSf and mortality in the multivariable modeling. Similarly, we also failed to identify an association between OI and mortality after controlling for any dead space marker in the modeling. For the 28-day ventilator-free days outcome, we failed to identify an association between V D /V t and the dead space markers in multivariable modeling, although OI was significant. VEq co2 performs similarly to V D /V t and other surrogate dead space markers, is independently associated with mortality risk, and may be a reasonable noninvasive surrogate for V D /V t .