Blood Gas Samples Research Articles

Comparison of terbutaline and atosiban as tocolytic agents in intrauterine repair of myelomeningocele: a retrospective cohort study

BackgroundMyelomeningocele (MMC) is a neural tube defect disease. Antenatal repair of fetal MMC is an alternative to postnatal repair. Many agents can be used as tocolytics during the in utero fetal repair such as β2-agonists and oxytocin receptor antagonists, with possible maternal and fetal repercussions. This study aims to compare maternal arterial blood gas analysis between terbutaline or atosiban, as tocolytic agents, during intrauterine MMC repair. MethodsRetrospective cohort study. Patients were divided into two groups depending on the main tocolytic agent used during intrauterine MMC repair: atosiban (16) or terbutaline (9). Maternal arterial blood gas samples were analyzed on three moments: post induction (baseline, before the start of tocolysis), before extubation, and two hours after the end of the surgery. ResultsTwenty-five patients were included and assessed. Before extubation, the terbutaline group showed lower arterial pH (7.347 ± 0.05 vs. 7.396 ± 0.02 for atosiban, p = 0.006) and higher arterial lactate (28.33 ± 12.76 mg.dL−1 vs. 13.06 ± 6.35 mg.dL−1, for atosiban, p = 0.001) levels. ConclusionsPatients who received terbutaline had more acidosis and higher levels of lactate, compared to those who received atosiban, during intrauterine fetal MMC repair.

Evaluating the efficacy of a standardized 4 mL/kg fluid bolus technique in critically ill patients with elevated PvaCO2: secondary analysis of two prospective studies.

Limiting the fluid bolus (FB) volume may attenuate side effects, including hemodilution and increased filling pressures, but it may also reduce hemodynamic responsiveness. The minimum volume to create hemodynamic effects is considered to be 4 mL/kg. In critically ill patients, the hemodynamic effects of FB with this volume have not been adequately investigated and compared to higher quantities. We hypothesized that a standardized FB approach using 4 mL/kg has comparable hemodynamic and metabolic effects to the common practice of physician-determined FB in critically ill patients. We conducted post hoc analysis of two trials in non-selected critically ill patients with central venous-to-arterial CO2 tension (PvaCO2) >6 mmHg and no acute bleeding. All patients received crystalloids either at a physician-determined volume and rate or at 4 mL/kg pump-administered at 1.2 L/h. Cardiac index (CI) was calculated with transthoracic echocardiogram, and arterial and venous blood gas samples were assessed before and after FB. Endpoints were changes in CI and oxygen delivery (DO2) >15%. A total of 47 patients were eligible for the study, 15 of whom received physician-determined FB and 32 of whom received standardized FB. Patients in the physician-determined FB group received 16 (12-19) mL/kg at a fluid rate of 1.5 (1.5-1.9) L/h, compared to 4.1 (3.7-4.4) mL/kg at a fluid rate of 1.2 (1.2-1.2) L/h (p < 0.01) in the standardized FB group. The difference in CI elevations between the two groups was not statistically significant (8.8% [-0.1-19.9%] vs. 8.4% [0.3-23.2%], p = 0.76). Compared to physician-determined FB, the standardized FB technique had similar probabilities of increasing CI or DO2 by >15% (odds ratios: 1.3 [95% CI: 0.37-5.18], p = 0.66 and 1.83 [95% CI: 0.49-7.85], p = 0.38). A standardized FB protocol (4 mL/kg at 1.2 L/h) effectively reduced the volume of fluid administered to critically ill patients without compromising hemodynamic or metabolic effects.

Intradermal and Subcutaneous Lignocaine for Arterial Blood Gas Sampling: A Randomized Controlled Trial

Introduction: The use of local anesthesia (LA) prior to arterial blood gas sampling is recommended but is not widely used. We tested the hypothesis that intradermal administration of local anesthesia would be as effective as subcutaneous administration in reducing pain from arterial blood gas sampling. Aims: The primary aim of this study was to evaluate the effect of intradermal and subcutaneous lignocaine on patient-perceived pain during arterial blood gas sampling. The secondary aims were to evaluate if different routes of LA administration had an impact on the difficulty and complications of ABG sampling. Methods: We undertook a randomized, single-blind, placebo-controlled trial in New Zealand. We enrolled patients attending a nurse-led outpatient oxygen clinic who were 18 to 90 years of age and who had an oxygen saturation of 93% or less at rest. Patients were randomly assigned to receive intradermal 1% lignocaine, subcutaneous 1% lignocaine, or subcutaneous normal saline. Patients and nurse assessors were blinded to the treatment allocation. The primary endpoint was a patient-assessed pain score using a graphic rating scale (0-10). Results: 135 patients were randomized (54 patients in the intradermal lignocaine group, 54 patients in the subcutaneous lignocaine group, and 27 in the subcutaneous saline group). The mean patient-assessed pain score for the intradermal lignocaine group was 1.8 (+/- 1.1), which was a relative reduction of 47% (95% C.I. 31%-59%, p &lt; 0.0001) from the mean patient-assessed pain score of 3.4 (+/- 1.1) for the subcutaneous saline group. The mean patient-assessed pain score for the subcutaneous lignocaine group was 2.1 (+/- 1.1), which was also a significant relative reduction of 36% (95% C.I. 17%-51%, p = 0.0001) compared to the subcutaneous saline group. Intradermal lignocaine reduced pain more than subcutaneous lignocaine, with a relative pain reduction difference of 20% (95% CI -4%-49%, p = 0.05). Bruising was more frequent in the subcutaneous lignocaine group (9.3%) than in the intradermal (0%) and saline groups (0%). Conclusion: Intradermal lignocaine is at least as effective as subcutaneous lignocaine for reducing patient-perceived pain from arterial blood gas sampling and results in less bruising.

The Predictive Role of Lactate in the Emergency Department in Patients with Severe Dyspnea.

An accurate identification of patients at the need for prioritized diagnostics and care are crucial in the emergency department (ED). Blood gas (BG) analysis is a widely available laboratory test, which allows to measure vital parameters, including markers of ventilation and perfusion. The aim of our analysis was to assess whether blood gas parameters in patients with dyspnea at an increased risk of respiratory failure admitted to the ED can predict short-term outcomes. The study group eventually consisted of 108 patients, with available BG analysis. The clinical and laboratory parameters were retrospectively evaluated, and three groups were distinguished-arterial blood gas (ABG), venous blood gas (VBG), and mixed blood gas. The primary endpoint was short-term, all-cause mortality during the follow-up of median (quartile 1-quartile 3) 2 (1-4) months. The independent risk factors for mortality that could be obtained from blood gas sampling were evaluated. The short-term mortality was 35.2% (38/108). Patients who died were more frequently initially assigned to the red triage risk group, more burdened with comorbidities, and the median SpO2 on admission was significantly lower than in patients who survived the follow-up period. In the multivariable analysis, lactate was the strongest independent predictor of death, with 1 mmol/L increasing all-cause mortality by 58% in ABG (95% CI: 1.01-2.47), by 80% in VBG (95% CI: 1.13-2.88), and by 68% in the mixed blood gas analysis (95% CI: 1.22-2.31), what remained significant in VBG and mixed group after correction for base excess. In each group, pH, pO2, and pCO2 did not predict short-term mortality. In patients admitted to the ED due to dyspnea, at risk of respiratory failure, lactate levels in arterial, venous, and mixed blood samples are independent predictors of short-term mortality.

A Split-Lung Ex Vivo Perfusion Model for Time- and Cost-Effective Evaluation of Therapeutic Interventions to the Human Donor Lung.

With the ongoing shortage of donor lungs, ex vivo lung perfusion (EVLP) offers the opportunity for objective assessment and potential therapeutic repair of marginal organs. There is a need for robust research on EVLP interventions to increase the number of transplantable organs. The use of human lungs, which have been declined for transplant, for these studies is preferable to animal organs and is indeed essential if clinical translation is to be achieved. However, experimental human EVLP is time-consuming and expensive, limiting the rate at which promising interventions can be assessed. A split-lung EVLP model, which allows stable perfusion and ventilation of two single lungs from the same donor, offers advantages scientifically, financially and in time to yield results. Identical parallel circuits allow one to receive an intervention and the other to act as a control, removing inter-donor variation between study groups. Continuous hemodynamic and airway parameters are recorded and blood gas, perfusate, and tissue sampling are facilitated. Pulmonary edema is assessed directly using ultrasound, and indirectly using the lung tissue wet:dry ratio. Evans blue dye leaks into the tissue and can quantify vascular endothelial permeability. The split-lung ex vivo perfusion model offers a cost-effective, reliable platform for testing therapeutic interventions with relatively small sample sizes.

High-flow nasal cannula oxygen versus noninvasive ventilation for the management of acute cardiogenic pulmonary edema: a randomized controlled pilot study.

Whether high-flow nasal oxygen can improve clinical signs of acute respiratory failure in acute heart failure (AHF) is uncertain. To compare the effect of high-flow oxygen with noninvasive ventilation (NIV) on respiratory rate in patients admitted to an emergency department (ED) for AHF-related acute respiratory failure. Multicenter, randomized pilot study in three French EDs. Adult patients with acute respiratory failure due to suspected AHF were included. Key exclusion criteria were urgent need for intubation, Glasgow Coma Scale <13 points or hemodynamic instability. Patients were randomly assigned to receive high-flow oxygen (minimum 50 l/min) or noninvasive bilevel positive pressure ventilation. The primary outcome was change in respiratory rate within the first hour of treatment and was analyzed with a linear mixed model. Secondary outcomes included changes in pulse oximetry, heart rate, blood pressure, blood gas samples, comfort, treatment failure and mortality. Among the 145 eligible patients in the three participating centers, 60 patients were included in the analysis [median age 86 (interquartile range (IQR), 90; 92) years]. There was a median respiratory rate of 30.5 (IQR, 28; 33) and 29.5 (IQR, 27; 35) breaths/min in the high-flow oxygen and NIV groups respectively, with a median change of -10 (IQR, -12; -8) with high-flow nasal oxygen and -7 (IQR, -11; -5) breaths/min with NIV [estimated difference -2.6 breaths/min (95% confidence interval (CI), -0.5-5.7), P = 0.052] at 60 min. There was a median SpO 2 of 95 (IQR, 92; 97) and 96 (IQR, 93; 97) in the high-flow oxygen and NIV groups respectively, with a median change at 60 min of 2 (IQR, 0; 5) with high-flow nasal oxygen and 2 (IQR, -1; 5) % with NIV [estimated difference 0.8% (95% CI, -1.1-2.8), P = 0.60]. PaO 2 , PaCO 2 and pH did not differ at 1 h between groups, nor did treatment failure, intubation and mortality rates. In this pilot study, we did not observe a statistically significant difference in changes in respiratory rate among patients with acute respiratory failure due to AHF and managed with high-flow oxygen or NIV. However, the point estimate and its large confidence interval may suggest a benefit of high-flow oxygen. NCT04971213 ( https://clinicaltrials.gov ).

Changes in arterial pH do not explain the reductions in ionised calcium observed during COVID-19 infection

BackgroundHypocalcaemia predicts coronavirus disease 2019 (COVID-19) severity and mortality. We hypothesized an association between respiratory alkalosis secondary to hypoxia and low ionised calcium (iCa) concentration in patients with COVID-19. MethodsArterial blood gas samples taken from January 2019 to March 2021 were retrospectively matched with infection status. Principal components regression was undertaken to determine the correlation between pH, partial pressure arterial oxygen (PaO2), partial pressure arterial carbon dioxide (PaCO2), and iCa. ResultsWe included 4056 patients (300 COVID-19 detected, 19 influenza detected), corresponding to 5960 arterial blood samples. The COVID-19 detected group had a statistically significantly lower iCa, PaO2 and PaCO2, and more alkalotic pH than infection-free groups. The influenza group had a lower iCa and PaCO2, higher PaO2, and a more alkalotic pH than infection-free groups, but these differences were non-significant. Principal components regression revealed that pH, PaCO2, and PaO2 explain just 2.72 % of the variance in iCa. An increase in pH by 1 unit was associated with an iCa reduction of 0.141 ​mmol/L (p ​< ​0.0001). ConclusionReduction in iCa concentration in patients with COVID-19 is not associated with pH derangement. Influenza infection was associated with a minor reduction in iCa in our small sample, a hitherto unreported finding, although statistical significance was not demonstrated.

Challenges Encountered during Anaesthetic Management of a Patient with Congenital Methaemoglobinemia Posted for Laproscopic Inguinal Hernia Repair: A Case Report

Methaemoglobinemia is a rarely encountered haematological condition that can be congenital or acquired. Methaemoglobin is an abnormal type of haemoglobin that is oxidised and incapable of delivering oxygen to tissues. This can lead to cyanosis, hypoxia, acidosis, arrhythmias, and more, depending on the methaemoglobin concentration, and can be fatal. A thorough understanding of the disease process is essential to develop a suitable anaesthesia plan and prevent complications. Ensuring adequate tissue oxygenation, assessing oxygenation using appropriate monitoring tools, and avoiding trigger agents are the cornerstones of anaesthetic management. A co-oximeter is the gold standard for monitoring, as it detects and quantifies methaemoglobin levels. Methylene blue acts as an antidote, functioning as an oxidising agent that converts itself to leukomethylene blue, which reduces methaemoglobin back to haemoglobin. In the present case of a 60-year-old male, the authors present the anaesthetic management and challenges in a diagnosed case of congenital methaemoglobinemia undergoing laparoscopic inguinal hernia repair surgery. Methylene blue was administered prophylactically preoperatively. An arterial line was established before anaesthesia induction for close haemodynamic monitoring and quick blood gas and oxyhaemoglobin sampling, as a co-oximeter was not available. Adequate oxygenation during induction and emergence was ensured to prevent hypoxia, given the lower amount of normal haemoglobin in these patients. All potential trigger agents, such as nitrous oxide, local anaesthetics, nitrates, and metoclopramide, were avoided. The patient had an uneventful intraoperative and postoperative course and was discharged after one day.

Comparison of PCO2gap, SvO2 and plasmatic lactate in patients on venoarterial extracorporeal circulation support.

Clinical assessment and laboratory markers provide valuable information on tissue perfusion and enhance the optimalisation of management in the treatment of patients on extracorporeal membrane oxygenation (ECMO). The PCO2 gap is areliable marker of cardiac output (CO) and perfusion. The aim of this study was to evaluate the PCO2 gap as amarker of tissue hypoperfusion and to compare it to lactate and SvO2. Asingle-center retrospective study on 131 adult cardiac patients who underwent ECMO implantation in the period between 2010 and 2021. Baseline characteristics, laboratory markers and mortality were analyzed. There was astatistically significant difference in the plasmatic levels of lactate, SvO2 and PCO2 gap between patients that survived and those who died post ECMO implantation (3.6±3.29 vs 7.15±7.38 mmol/l, p<0.001; 69.13±9 vs 67.38±10%, p<0.001; 7.65±2.93 vs 8.34±3.71, p<0.001 respectively). There was astatistically significant difference in PCO2 gap in the first 5 arterial blood gas (ABG) samples post ECMO implantation between patients that survived and those who died (9.08±4.79 vs 10.37±5.35, p<0.003). For SvO2, this difference was not statistically significant (69.82±11.91 vs 68.51±11.72, p<0.104). There was astatistically significant but low negative correlation between SvO2 and PCO2 gap post ECMO implantation (r = ‒0.354, p<0.001). The PCO2 gap is avaluable biomarker for monitoring tissue perfusion in patients on ECMO. It is associated with increased mortality and should be an integral part of clinical evaluation. (Tab. 1, Fig. 5, Ref. 26). Text in PDF www.elis.sk Keywords: PCO2 gap, VA-ECMO, lactate.

Assessment of the variation of the pulmonary gas exchange model in the critical care setting

Background and Aims: In intensive care units (ICUs), clinicians use various mathematical models to assess and monitor respiratory illness. However, evidence suggests that some pulmonary internal and external physiolog¬ical factors are not integrated in the calculation of these models. This research aimed to demonstrate the variation in these models within a short period in critical care settings. Methods: A retrospective cohort study was conducted from 2017 to 2019 with adults admitted to an ICU and mechanically ventilated for more than 24 hours. Two different arterial blood gas samples were selected within a mean of 120 minutes. The coefficient of variation percent [(CV%)=SD/Mean] was calculated. Results: In total, 211 intubated ICU patients were included. The mean age was 57 (SD +/- 19.62) years, and 33% were female. The degree of variation of the average CV% for all the mathematical models was 14%-30%. The mean CV% for the arterial oxygen tension to inspired oxygen fraction (PaO2/FiO2) and arterial/alveolar oxygen tension ratio (PaO2/ PAO2) was 14%, which is a low variation compared to the respiratory index (RI) for which the mean CV% was 30%. Conclusions: The findings of this study indicate that most of the existing oxygen mathematical models used in clinical settings lack physiological realism, necessitating a new mathematical model that integrate both assess illness severity and enhance other models’ accuracy.

Evaluation of the classifications of severity in acute respiratory distress syndrome in childhood by the Berlin Consensus and the Pediatric Acute Lung Injury Consensus Conference.

To compare two methods for defining and classifying the severity of pediatric acute respiratory distress syndrome: the Berlin classification, which uses the relationship between the partial pressure of oxygen and the fraction of inspired oxygen, and the classification of the Pediatric Acute Lung Injury Consensus Conference, which uses the oxygenation index. This was a prospective study of patients aged 0 - 18 years with a diagnosis of acute respiratory distress syndrome who were invasively mechanically ventilated and provided one to three arterial blood gas samples, totaling 140 valid measurements. These measures were evaluated for correlation using the Spearman test and agreement using the kappa coefficient between the two classifications, initially using the general population of the study and then subdividing it into patients with and without bronchospasm and those with and without the use of neuromuscular blockers. The effect of these two factors (bronchospasm and neuromuscular blocking agent) separately and together on both classifications was also assessed using two-way analysis of variance. In the general population, who were 54 patients aged 0 - 18 years a strong negative correlation was found by Spearman's test (ρ -0.91; p < 0.001), and strong agreement was found by the kappa coefficient (0.62; p < 0.001) in the comparison between Berlin and Pediatric Acute Lung Injury Consensus Conference. In the populations with and without bronchospasm and who did and did not use neuromuscular blockers, the correlation coefficients were similar to those of the general population, though among patients not using neuromuscular blockers, there was greater agreement between the classifications than for patients using neuromuscular blockers (kappa 0.67 versus 0.56, p < 0.001 for both). Neuromuscular blockers had a significant effect on the relationship between the partial pressure of oxygen and the fraction of inspired oxygen (analysis of variance; F: 12.9; p < 0.001) and the oxygenation index (analysis of variance; F: 8.3; p = 0.004). There was a strong correlation and agreement between the two classifications in the general population and in the subgroups studied. Use of neuromuscular blockers had a significant effect on the severity of acute respiratory distress syndrome.

Comparison of early term results of umbilical cord blood gas sampling among uncomplicated primiparous and multiparous vaginal deliveries and elective cesarean section

Objective: This study aims to investigate the early effects of the mode of delivery on the newborn in cases of non-complicated primiparous and multiparous vaginal deliveries who were admitted to the clinic in active labor, and elective cesarean section by analyzing fetal umbilical cord blood gas. Materials and methods: In this retrospective study, 120 cases were enrolled in the study, including 40 primiparous cases, 40 multiparous cases, and 40 elective cesarean section cases. Age, pregnancy history, medical history, age of gestation at birth, delivery type, fetal Weight, APGAR score, baby gender and fetal blood gas values were statistically analyzed. Results: Statistically significant differences were found between the primiparous vaginal delivery group and the cesarean section and multiparous vaginal delivery groups in the parameters of age, gravidity, parity, and fetal Weight, with primiparous vaginal delivery showing significantly lower parameters. When compared with multiparous and primiparous vaginal delivery, a statistically significant difference was observed in APGAR 1 score, with C/S births having lower scores. In primiparous vaginal delivery, it was found that pH, pH(T), Base(Ecf)c, cHCO3(P)c, cHCO3(p,st)c, cBase(B,ox)c, and cBase(Ecf,ox)c were significantly lower compared to other groups, while only higher levels of pCO2 and mOsmc were observed. In the cesarean section group, lower levels of ctHb, Hctc, cCa, cGlu, and cLac parameters were observed compared to other groups, while the cNa level was significantly higher. Significant differences were found only between primiparous vaginal delivery and cesarean section groups in the parameter cK, with a significantly lower cK value in the C/S group. Conclusion: Primiparous pregnant women exhibited lower birth weight, lower pH in umbilical cord blood, and higher levels of pCO2, while in the cesarean group, lower APGAR score at 1 minute, lower levels of hemoglobin, calcium, glucose, lactate, and potassium were observed.

Comparison of Liquid Sodium Heparin Syringe and Preheparinised Syringe for Sample Rejection in Arterial Blood Gas Analysis: A Cross-sectional Study

Introduction: In hospital settings, Arterial Blood Gas (ABG) analysis is a routine investigation. Many errors can arise in the process, with 70% of errors in ABG analysis occurring during the preanalytical phase. Liquid heparin is commonly used as an anticoagulant in sample collection devices for Blood Gas (BG) analysis; however, inadequate heparin concentration and improper mixing of blood samples after collection often lead to incorrect results. This can be prevented by using syringes preloaded with lyophilised heparin. Aim: To monitor the prevalence of sample rejection collected by the device using liquid sodium heparin and calcium-balanced dried lithium heparin. Materials and Methods: This cross-sectional study was conducted at the ABG laboratory, Department of Biochemistry, Amrita Institute of Medical Sciences and Research Centre, Amrita Viswavidyapeetham University, Kochi, Kerala, India over a 4-month period from December 2022 to March 2023. ABG samples collected using either of the techniques were included, while venous BG samples were excluded. The sample size was 10,957 for each of the two groups- Group A and Group B. Group A included samples collected using liquid sodium heparin, and group B included spray-dried, calcium-balanced lithium heparin from different departments. The incidence of blood clots, air bubbles, and inadequate volume was studied. For all categorical variables, the results were expressed as the frequency and percentage of errors. An unpaired t-test (two-tailed) was used for data analysis. Results: In comparison with liquid sodium heparin collection, errors in the quality of the specimen such as blood clots (1.7% to 1.1%), air bubbles (0.04% to 0%), and inadequate volume (0.2% to 0.03%) were significantly reduced (p-value=0.002) with spray-dried, calcium-balanced lithium heparin (BD Preset™ Safety BG Syringe). Conclusion: The present study found that using calcium- balanced lithium heparin syringes over manually flushed liquid sodium heparin syringes reduces the risk of clots, thus preventing equipment malfunction and maintenance costs. With the introduction of preset syringes, the chance of air bubbles and insufficient volume can also be overcomed.

Comparing the EMMA capnograph with sidestream capnography and arterial carbon dioxide pressure at 284 kPa.

Capnography aids assessment of the adequacy of mechanical patient ventilation. Physical and physiological changes in hyperbaric environments create ventilation challenges which make end-tidal carbon dioxide (ETCO2) measurement particularly important. However, obtaining accurate capnography in hyperbaric environments is widely considered difficult. This study investigated the EMMA capnograph for hyperbaric use. We compared the EMMA capnograph to sidestream capnography and the gold standard arterial carbon dioxide blood gas analysis in a hyperbaric chamber. In 12 resting subjects breathing air at 284 kPa, we recorded ETCO2 readings simultaneously derived from the EMMA and sidestream capnographs during two series of five breaths (total 24 measurements). An arterial blood gas sample was also taken simultaneously in five participants. Across all measurements there was a difference of about 0.1 kPa between the EMMA and sidestream capnographs indicating a very slight over-estimation of ETCO2 by the EMMA capnograph, but fundamentally good agreement between the two end-tidal measurement methods. Compared to arterial blood gas pressure the non-significant difference was about 0.3 and 0.4 kPa for the EMMA and sidestream capnographs respectively. In this study, the EMMA capnograph performed equally to the sidestream capnograph when compared directly, and both capnography measures gave clinically acceptable estimates of arterial PCO2.

Agreement of pCO2 in venous to arterial blood gas conversion models in undifferentiated emergency patients

BackgroundVenous blood gas sampling has replaced arterial sampling in many critically ill patients, though interpretation of venous pCO2 still remains a challenge. Lemoël et al., Farkas and Zeserson et al. have proposed models to estimate arterial pCO2 based on venous pCO2. Our objective was to externally validate these models with a new dataset. This was a prospective cross-sectional study of consecutive adult patients with a clinical indication for blood gas analysis in an academic emergency department in Sweden. Agreement of pairs was reported as mean difference with limits of agreement (LoA). Vital signs and lead times were recorded.ResultsTwo hundred and fifty blood gas pairs were collected consecutively between October 2021 and April 2022, 243 valid pairs were used in the final analysis [mean age 72.8 years (SD 17.8), 47% females]. Respiratory distress was the most common clinical indication (84% of all cases). The model of Farkas showed the best metrics with a mean difference between estimated and arterial pCO2 of − 0.11 mmHg (95% LoA − 6.86, + 6.63). For Lemoël the difference was 2.57 mmHg (95% LoA − 5.65, + 10.8), Zeserson 2.55 mmHg (95% LoA − 7.43, + 12.53). All three models showed a decrease in precision in patients with ongoing supplemental oxygen therapy.ConclusionArterial pCO2 may be accurately estimated in most patients based on venous blood gas samples. Additional consideration is required in patients with hypo- or hypercapnia or oxygen therapy. Thus, conversion of venous pCO2 may be considered as an alternative to arterial blood gas sampling with the model of Farkas being the most accurate.

Elevated strong ion gap: A predictor of the initiation of continuous renal replacement therapy in acute kidney injury

BackgroundThere is no optimal timing for continuous renal replacement therapy (CRRT) in acute kidney injury (AKI). AKI is a reason for the increased unmeasured anions, which refers to the increased organic acids in the blood, and they can be detected by calculating strong ion gap (SIG). SIG level at the moment of the AKI diagnosis may be a predictor for the initiation of CRRT. MethodsPatients who were diagnosed with AKI in the first week of the intensive care unit (ICU) period were included in this prospective observational study. At the moment of the AKI diagnosis, blood gas samples were recorded, and SIG was calculated. ResultsThe median level of SIG at the moment of the AKI diagnosis of CRRT (+) patients was significantly higher than CRRT (-) patients (7.4 and 3.2 mmol L−1, respectively). In the multivariate Cox regression analysis, the likelihood of the initiation of CRRT was increased 1.16-fold (1.01-1.33) and 4.0-fold (1.9-8.7) by only 1 mmol L−1 increases in SIG and SIG ≥6 mmol L-1 at the moment of AKI diagnosis, respectively (p = 0.035 and p < 0.001). ConclusionsIncreased SIG at the moment of the AKI diagnosis in patients with AKI may be a predictive marker to initiate CRRT.

Abstract 12450: Mystifying Masquerade: Renal Cell Carcinoma Associated Arteriovenous Fistula Presenting as High-Output Heart Failure

Case Presentation: 59 year-old woman with CKD stage 3b and hypertension presented with 3 months of progressive dyspnea, abdominal distension, bilateral lower extremity edema, and a 60-pound weight gain. Physical exam noted diffuse anasarca, with stable hemodynamics on room air. EKG revealed low voltage leads and chest X-ray demonstrated an enlarged cardiac silhouette. CT abdomen was remarkable for significant ascites, body wall edema, and a suspicious large right renal mass. Diagnostic paracentesis indicated cardiac ascites. Echocardiogram showed preserved ejection fraction, moderate pericardial effusion and an enlarged right side of the heart. Right heart catheterization confirmed high-output heart failure (HOHF). A suspected renal mass-related arteriovenous fistula (AVF) was confirmed through inferior vena caval and renal venogram blood gas sampling, indicating arteriovenous shunting within the renal mass. Hepatic venogram excluded portal hypertension. MRI abdomen confirmed a large necrotic right renal mass consistent with renal cell carcinoma (RCC). Symptoms significantly improved after nephrectomy, with aggressive diuresis, and therapeutic paracenteses leading to an 80-pound weight loss. Postoperative echocardiography illustrated decrease in pericardial effusion and right ventricular size. Cardiac MRI and stress test were unremarkable prior to planned immunotherapy for stage III RCC. Discussion: AVF and HOHF associated with malignancy are unusual presentations. RCC is the most prevalent underlying malignancy linked with AVF and is hypothesized to be a result of hypervascularity caused by a VHL gene mutation. The most often utilized imaging modalities for detecting a tumor-related AVF are contrast enhanced CT or MRI. When imaging is inconclusive, a venogram with blood gas sample, as observed in our case, may be considered to establish an RCC-associated AVF.

Abstract 12042: Elevated Levels of Bicarbonate Predict Adverse Outcomes in Patients With Chronic Heart Failure

Background: The bicarbonate (HCO3 - ) buffer system plays a crucial role in maintaining acid-base homeostasis, and HCO3 - levels are affected by multiple factors in heart failure. Recently, a sub-analysis of the ADVOR trial for acute heart failure revealed that patients with elevated serum HCO3 - levels experienced beneficial effects of decongestion by acetazolamide. However, the significance of HCO3 - levels in chronic heart failure has not been fully understood. Aim: We sought to clarify whether HCO3 - levels have clinical relevance or prognostic impact in patients with chronic heart failure. Methods and Results: We conducted a prospective study involving hospitalized patients with stage C/D heart failure and measured HCO3 - levels in arterial blood gas samples prior to discharge. We enrolled a total of 718 patients (mean 68.3 years old and 62.1% male), with neutral pH ranging from 7.35 to 7.45, and found that 132 (18.4%) had HCO3 - levels exceeding 26 mmol/L. Patients with HCO3 - &gt; 26 mmol/L were more likely to be male and to use loop diuretics, and had higher serum sodium, as well as lower potassium levels, compared to those with HCO3 - &lt; 26 mmol/L, whereas there were no differences in B-type natriuretic peptide levels or left ventricular ejection fraction between the two groups. In a Kaplan-Meier analysis, patients with HCO3 - &gt; 26 mmol/L had lower event-free survival rates from cardiac deaths and decompensated heart failure as well as the composite of the cardiac events over a median follow-up period of 1540 days ( Figure ). In a multivariable Cox proportional hazard model after adjusting confounding variables, the presence of HCO3 - &gt; 26 mmol/L was independently associated with increased risks of the composite of cardiac events (hazard ratio, 1.64; P &lt; 0.01). Conclusion: Elevated HCO3 - levels may indicate enhanced proximal nephron activation and resistance to loop diuretics, which predicted adverse outcomes in patients with chronic heart failure, even within a normal pH range.

Prognostic Significance of the Strong Ion Gap in Patients in Medical and Surgical Intensive Care Units.

Background This study aimed to analyze acid-base imbalance by assessing the arterial blood gas (ABG) samples of the medical and surgical intensive care unit (ICU) patients by the Stewart approach and demonstrate the advantages of this method in delineating the acid-base status in cases where Henderson-Hasselbalch, anion gap, and base excess cannot optimally depict the imbalance and create recognition in the clinicians in this regard. Methodology Adult (i.e., age > 18 years) patients admitted to the ICU of our institution during a one-year study period were included in this study. The patients were divided into two groups based on the indication of admission to the ICU as medicalor surgical. The ABG, sodium, potassium, calcium, magnesium, phosphate, chloride, albumin, lactate, hemoglobin, hematocrit, leukocyte, blood urea nitrogen, and creatinine values determined during the first 24-hour period were used for calculating the Acute Physiologic Assessment and Chronic Health Evaluation (APACHE II), strong ion difference apparent (SIDa), and SID effective (SIDe) scores, which were subsequently compared between the groups. Results Overall, 220 (110 medical and 110 surgical) patients were included. The mean patient age was 63.56 ± 18.08 years. The mean APACHE II scores were 21.99 and 19.63 in the medical and surgical groups, respectively. Overall, 110 patients died, while 110 were referred to the regular patient floor. The mean APACHE II score of the patients who died was 28.3, and the latter group had a mean APACHE II score of 13.57. There was a significant difference between the surgical and medical patient groups regarding mean values of APACHE II, SIDa, and SIDe scores. Also, the differences were significant between the patients who died and were discharged. There was a significant difference between the patients who died and were discharged regarding the strong ion gap (SIG); however, the medical and surgical patient groups were not different concerning the SIG values. Conclusions We conclude that SIDa, SIDe, and SIG can be used in medical and surgical ICU patients to predict prognosis.

O009 Are there Differences in SpO2 Recordings from Two Oximeters on the same hand during an Overnight Sleep Study Significant?

Abstract Background Accurate non-invasive oxygen saturation (SpO2) measurement is crucial in healthcare, however is challenged by numerous devices using variable algorithms1. We compared two commonly used oximeter devices worn simultaneously in patients during an overnight polysomnogram. Aim To assess (1) differences between two SpO2 recording devices and (2) SpO2 accuracy against SaO2. Methods SpO2 data of two devices were recorded, downloaded and analysed with corresponding software: device 1 (Rad7 [Masimo, Irvine, CA, USA] set at 2-4sec averaging time) with software 1 (PSG 4 [Compumedics, Melbourne, Australia]) and device 2 (Wrist-Ox2® [Nonin Medical Inc, Plymouth, MN, USA] set at 3 sec averaging time) with software 2 (Noxturnal [Nox Medical Inc, Reykjavik, Iceland]). Responsiveness of each oximeter to changes in the patients’ desaturations associated with apnoeas and hypopnoeas overnight was assessed. In addition, both device SpO2 values were compared with SaO2 from simultaneous arterial blood gas sampling. Preliminary Results 7 patients (age 56.4±7.1 years, BMI 31.6±2.2 kg/m2, 100% male, 87% light skinned) were studied. The mean SpO2 with RAD7 was higher than the Nonin (95.9±1.6 vs 94.2±1.4%, mean difference 1.6±1.0%). Differences in the responsiveness of the oximeters during overnight desaturations were also observed. However, both device SpO2 values were found to be within ±2% of SaO2. Conclusions Discrepancies in SpO2 measurement do occur between devices and may have important clinical implications especially when it comes to the measurement of hypoxemic burden during sleep. 1.Blanchet MA et al. Accuracy of Multiple Pulse Oximeters in Stable Critically Ill Patients. Respir Care. 2023 May;68(5):565-574.