Umbilical Artery Cord Gas Abnormalities in the Presence of a Nuchal Cord in Term Singleton Pregnancies: A Cohort Study

OBJECTIVE

 The clinical significance of nuchal cord (NC) at the time of delivery is unclear. Studies have found that NC is associated with lower umbilical artery (UA) pH. Since fetal hypercarbia precedes respiratory acidosis, we hypothesize UA pCO2 is elevated in neonates with NC at the time of delivery.

STUDY DESIGN

 This is a secondary analysis of a prospective cohort study of women with full-term singleton pregnancies admitted in labor or for induction of labor at an institution with a universal umbilical cord gas policy. We compared patients with NC at the time of delivery to those without NC. Women were excluded if they did not have validated UA gases, had a major fetal anomaly, or had an intrauterine fetal demise. The primary outcome of the study was UA pCO2. Secondary outcomes were other components of UA gas and neonatal morbidity composite. Baseline characteristics were compared utilizing chi-square or Fisher's exact test or the Student's t-test. UA gas parameters were compared using the Kruskal-Wallis test. Multivariable logistic regression was utilized to adjust for confounders.

RESULTS

 Of the 8,580 study participants, 7,608 had validated umbilical cord gases. The incidence of NC in the population was 24.15% (n = 1,837). UA pCO2 was higher in those with NC than without (58 mm Hg [53-64] vs. 55 mm Hg [50-60], p < 0.01). There was a greater odds of hypercarbia in the NC group (pCO2 > 65 mmHg; adjusted odds ratio [aOR]: 1.97, 95% confidence interval [CI]: 1.72-2.25, p < 0.01). Additionally, the NC group was more likely to be mildly acidemic (pH < 7.2, aOR: 1.74, 95% CI: 1.51-2.01, p < 0.01). There was no difference in composite neonatal morbidity between the groups.

CONCLUSION

 NC is associated with an increased risk of hypercarbia and acidemia. However, this is not associated with increased risk of neonatal morbidity.

KEY POINTS

· Nuchal cord is associated with an increased risk of hypercarbia and mild acidemia.. · Nuchal cord is not likely associated with neonatal morbidity.. · Neonatal management should not be altered due to the presence of a nuchal cord at delivery..

Apnea Testing Practice to Increase Baseline PaCO2 and Frequency of Blood Gas Analyses

OBJECTIVE

To study the influence of the initial partial pressure of carbon dioxide (PaCO2) and frequency of blood gas analyses on the positivity rate and safety of apnea testing (AT).

DESIGN

A prospective multicenter cohort study.

SETTING

Seven teaching hospitals.

PARTICIPANTS

A total of 55 patients who underwent AT.

INTERVENTIONS

Patients were divided into 2 groups according to their initial PaCO2-the experimental group (≥40 mmHg, 27 patients) and the control group (<40 mmHg, 28 patients). Blood gas analysis was performed at 3, 5, and 8 minutes, and vital signs were taken. AT results and complications were compared between the groups.

RESULTS

The initial PaCO2 of the experimental group was 42.8 ± 2.2 mmHg v 36.4 ± 2.9 mmHg in the controls. The AT positivity rate was 100%. The experimental group needed less time to reach the target PaCO2 than the control group (4.07 ± 1.27 minutes v 5.68 ± 2.06 minutes; p = 0.001). Twenty-six patients (96.3%) in the experimental group reached the target PaCO2 in 5 minutes v 17 in the control group (60.7%) (p = 0.001). Seven patients (12.7%) were unable to complete 8-minute disconnection due to hypotension. The experimental group had a slightly lower incidence of hypotension than the control group, but there was no statistical difference (7.4% v 17.9%, p = 0.245).

CONCLUSION

Increasing the baseline PaCO2 and doing more blood gas analyses can significantly shorten the time needed for AT and improve the AT positivity rate.

Racial effects on masimo pulse oximetry: impact of low perfusion index

PURPOSE

 Evaluate the SpO2-SaO2 difference between Black and White volunteer subjects having a low perfusion index (Pi) compared to those having a normal Pi.

METHODS

 The Pi data were abstracted from electronic files collected on 7183 paired SpO2-SaO2 samples (3201 Black and 3982 White) from a recently reported desaturation study of 75 subjects (39 Black and 36 White) where SaO2 values were sequentially decreased from 100 to 70%. The Pi values from that dataset were divided into two groups (Pi ≤ 1 or Pi > 1) for analysis. A Pi value ≤ 1 was considered "low perfusion" and a Pi value > 1 was considered "normal perfusion". Statistical calculations included values of bias (mean difference of SpO2-SaO2), precision (standard deviation of the difference), and accuracy (root-mean-square error [ARMS]). During conditions of low perfusion (Pi ≤ 1, range [0.1 to 1]), overall bias and precision were + 0.48% ± 1.59%, while bias and precision were + 0.19 ± 1.53%, and + 0.91 ± 1.57%, for Black and White subjects, respectively.

RESULTS

 During normal perfusion (Pi > 1, range [1 to 12]), overall bias and precision were + 0.18% ± 1.34%, while bias and precision were -0.26 ± 1.37%, and - 0.12 ± 1.31%, for Black and White subjects, respectively. ARMS was 1.37% in all subjects with normal perfusion and 1.64% in all subjects with low perfusion.

CONCLUSION

 Masimo SET® pulse oximeters with RD SET® sensors are accurate for individuals of both Black and White races when Pi is normal, as well as during conditions when Pi is low. The ARMS for all conditions studied is well within FDA standards. This study was conducted in healthy volunteers during well-controlled laboratory desaturations, and results could vary under certain challenging clinical conditions.

[Design of Pulse and Respiratory Signals Detection System]

A pulse and respiration synchronous detection system is designed to explore the changes of physiological signals in different situations. The system obtains the corresponding signal through STM32 control pulse and respiratory acquisition circuit, calculates and displays real-time parameters such as heart rate and respiratory rate, and transmits the data to the upper computer for storage in the database. The experimental test results show that the system can monitor pulse and respiratory waveform in different situations, and the waveform is in good condition. Compared with medical pulse oximeter, the error of measured heart rate and blood oxygen concentration is less than 3%, and the error of respiratory rate is less than 5% compared with the actual value, which verifies the accuracy of system signal acquisition. The system is small in size, low in cost, and comfortable to wear, and can be applied in experimental research related to pulse and respiratory signals.

Venous blood gases and electrolyte values of captive red foot tortoise (Chelonoidis carbonarius)

Blood gas analysis reflects the exchange of oxygen and carbon dioxide in the lungs. This test provides important information, since the relationship between these gases has a direct impact on the acid-basic balance in the body. Given the significance of blood gas analysis in Brazilian reptiles, this study set out to establish temperature-corrected and uncorrected reference intervals for venous blood gas measurements in Chelonoidis carbonarius, and to compare values between females and males. In this study, 19 animals were used, 8 males and 11 females. Blood samples were collected from the dorsal coccygeal vein, and the analyses were performed immediately after blood sample collection. The following parameters were measured: pH, PO2, HCO3-, TCO2, BEecf, Na, K, ICa, and Glu, and were compared between females and males. Additionally, pH, pCO2, and pO2 values were compared with and without temperature correction. Oxygen saturation and Na levels were significantly higher (p<0.05) in males. Furthermore, it was possible to infer that the lower the body temperature relative to the environmental temperature, the larger the difference in pH following temperature correction.

Characteristics of pulse oximetry and arterial blood gas in patients with fibrotic interstitial lung disease

BACKGROUND

Fibrotic interstitial lung disease (ILD) is frequently associated with abnormal oxygenation; however, little is known about the accuracy of oxygen saturation by pulse oximetry (SpO2) compared with arterial blood gas (ABG) saturation (SaO2), the factors that influence the partial pressure of carbon dioxide (PaCO2) and the impact of PaCO2 on outcomes in patients with fibrotic ILD.

STUDY DESIGN AND METHODS

Patients with fibrotic ILD enrolled in a large prospective registry with a room air ABG were included. Prespecified analyses included testing the correlation between SaO2 and SpO2, the difference between SaO2 and SpO2, the association of baseline characteristics with both the difference between SaO2 and SpO2 and the PaCO2, the association of baseline characteristics with acid-base category, and the association of PaCO2 and acid-base category with time to death or transplant.

RESULTS

A total of 532 patients with fibrotic ILD were included. Mean resting SaO2 was 92±4% and SpO2 was 95±3%. Mean PaCO2 was 38±6 mmHg, with 135 patients having PaCO2 <35 mmHg and 62 having PaCO2 >45 mmHg. Correlation between SaO2 and SpO2 was mild to moderate (r=0.39), with SpO2 on average 3.0% higher than SaO2. No baseline characteristics were associated with the difference in SaO2 and SpO2. Variables associated with either elevated or abnormal (elevated or low) PaCO2 included higher smoking pack-years and lower baseline forced vital capacity (FVC). Lower baseline lung function was associated with an increased risk of chronic respiratory acidosis. PaCO2 and acid-base status were not associated with time to death or transplant.

INTERPRETATION

SaO2 and SpO2 are weakly-to-moderately correlated in fibrotic ILD, with limited ability to accurately predict this difference. Abnormal PaCO2 was associated with baseline FVC but was not associated with outcomes.

Oxygen saturation index: an adjunct for oxygenation index in congenital diaphragmatic hernia

OBJECTIVE

Our objective was to investigate the correlation of Oxygen Saturation Index (OSI) with Oxygenation Index (OI) and determine OSImax values that could predict need for ECMO and death in Congenital Diaphragmatic Hernia (CDH).

STUDY DESIGN

This is a retrospective cohort study of infants with CDH admitted to a tertiary level VI NICU. Pearson's correlation coefficient and simple linear regression analysis were used to investigate the OSI: OI correlation, and logistic regression analysis to investigate OSImax values that predicted need for ECMO and death.

RESULTS

Among the 180 infants, OSImax value of >13 at 6 h of life (HOL) best predicted need for ECMO and death. There was a strong correlation between OSI: OI paired values (r = 0.876, p < 0.001). The linear regression equation was OI = -2.4 + 2.4(OSI).

CONCLUSION

OSI could be used as a valuable adjunct to OI in the clinical management of newborn infants with CDH.

First Family Case of Hemoglobinopathy Titusville in China with Falsely Low SpO2 and Unmeasurable SaO2

BACKGROUND

Normal hemoglobin is a tetrameric structure, consisting of two alpha-globin chains and two nonalpha (beta, gamma, delta) chains. Hemoglobinopathies occur when the presence of gene mutations affect the molecular structure or expression of the globin chains.

METHODS

We reported the case of a 9-year-old Chinese girl who presented with abnormal low oxygen saturation values on pulse oximetry and no oximetry results were obtained during blood gas analysis (BGA).

RESULTS

High-performance liquid chromatography (HPLC) and capillary electrophoresis demonstrated that the presence of a low oxygen affinity hemoglobin variant, characterized as hemoglobin Titusville, was proven by gene sequencing. The patient's mother and aunt also carry the hemoglobin variant, representing the first Chinese family case reported.

CONCLUSIONS

Hemoglobin Titusville is a rare genetic hemoglobin structural defect. early diagnosis can help patients and clinicians avoid unnecessary anxiety and costly or excessive clinical investigations.

Effect of high flow nasal oxygen on inspiratory effort of patients with acute hypoxic respiratory failure and do not intubate orders

High flow nasal oxygen (HFNO) is recommended as a first-line respiratory support during acute hypoxic respiratory failure (AHRF) and represents a proportionate treatment option for patients with do not intubate (DNI) orders. The aim of the study is to assess the effect of HFNO on inspiratory effort as assessed by esophageal manometry in a population of DNI patients suffering from AHRF. Patients with AHRF and DNI orders admitted to Respiratory intermediate Care Unit between January 1st, 2018 and May 31st, 2023 to receive HFNO and subjected to esophageal manometry were enrolled. Esophageal pressure swing (ΔPes), clinical variables before and after 2 h of HFNO and clinical outcome (including HFNO failure) were collected and compared as appropriate. The change in physiological and clinical parameters according to the intensity of baseline breathing effort was assessed and the correlation between baseline ΔPes values and the relative change in breathing effort and clinical variables after 2 h of HFNO was explored. Eighty-two consecutive patients were enrolled according to sample size calculation. Two hours after HFNO start, patients presented significant improvement in ΔPes (12 VS 16 cmH2O, p < 0.0001), respiratory rate (RR) (22 VS 28 bpm, p < 0.0001), PaO2/FiO2 (133 VS 126 mmHg, p < 0.0001), Heart rate, Acidosis, Consciousness, Oxygenation and respiratory rate (HACOR) score, (4 VS 6, p < 0.0001), Respiratory rate Oxygenation (ROX) index (8.5 VS 6.1, p < 0.0001) and BORG (1 VS 4, p < 000.1). Patients with baseline ΔPes below 20 cmH2O where those who improved all the explored variables, while patients with baseline ΔPes above 30 cmH2O did not report significant changes in physiological or clinical features. A significant correlation was found between baseline ΔPes values and after 2 h of HFNO (R2 = 0.9, p < 0.0001). ΔPes change 2 h after HFNO significantly correlated with change in BORG (p < 0.0001), ROX index (p < 0.0001), HACOR score (p < 0.001) and RR (p < 0.001). In DNI patients with AHRF, HFNO was effective in reducing breathing effort and improving respiratory and clinical variables only for those patients with not excessive inspiratory effort.

Feasibility and accuracy of noninvasive continuous hemoglobin monitoring using transesophageal photoplethysmography in porcine model

BACKGROUND

Continuous and noninvasive hemoglobin (Hb) monitoring during surgery is essential for anesthesiologists to make transfusions decisions. The aim of this study was to investigate the feasibility and accuracy of noninvasive and continuous Hb monitoring using transesophageal descending aortic photoplethysmography (dPPG) in porcine model.

METHODS

Nineteen landrace pigs, aged 3 to 5 months and weighing 30 to 50 kg, were enrolled in this study. A homemade oximetry sensor, including red (660 nm) and infrared (940 nm) lights, was placed in the esophagus for dPPG signal detection to pair with the corresponding reference Hb values (Hbi-STAT) measured by blood gas analysis. The decrease and increase changes in Hb concentration were achieved by hemodilution and transfusion. Metrics, including alternating current (AC), direct current (DC), and AC/DC for both red and infrared light were extracted from the dPPG signal. A receiver operating characteristic (ROC) curve was built to evaluate the performance of dPPG metrics in predicting the Hb "trigger threshold" of transfusion (Hb < 60 g/L and Hb > 100 g/L). Agreement and trending ability between Hb measured by dPPG (HbdPPG) and by blood gas analysis were analyzed by Bland-Altman method and polar plot graph. Error grid analysis was also performed to evaluate clinical significance of HbdPPG measurement.

RESULTS

The dPPG signal was successfully detected in all of the enrolled experimental pigs, without the occurrence of a continuous loss of dPPG signal for 2 min during the entire measurement. A total of 376 pairs of dPPG signal and Hbi-STAT were acquired. ACred/DCred and ACinf/DCinf had moderate correlations with Hbi-STAT, and the correlation coefficients were 0.790 and 0.782, respectively. The areas under the ROC curve for ACred/DCred and ACinf/DCinf in predicting Hbi-STAT < 60 g/L were 0.85 and 0.75, in predicting Hbi-STAT > 100 g/L were 0.90 and 0.83, respectively. Bland-Altman analysis and polar plot showed a small bias (1.69 g/L) but a wide limit of agreement (-26.02-29.40 g/L) and a poor trend ability between HbdPPG and Hbi-STAT. Clinical significance analysis showed that 82% of the data lay within the Zone A, 18% within the Zone B, and 0% within the Zone C.

CONCLUSION

It is feasible to establish a noninvasive and continuous Hb monitoring by transesophageal dPPG signal. The ACred/DCred extracted from the dPPG signal could provide a sensitive prediction of the Hb threshold for transfusion. The Hb concentration measured by dPPG signal has a moderate correlation with that measured by blood gas analysis. This animal study may provide an experimental basis for the development of bedside HbdPPG monitoring in the future.

L-cysteine ethylester reverses the adverse effects of morphine on breathing and arterial blood-gas chemistry while minimally affecting antinociception in unanesthetized rats

L-cysteine ethylester (L-CYSee) is a membrane-permeable analogue of L-cysteine with a variety of pharmacological effects. The purpose of this study was to determine the effects of L-CYSee on morphine-induced changes in ventilation, arterial-blood gas (ABG) chemistry, Alveolar-arterial (A-a) gradient (i.e., a measure of the index of alveolar gas-exchange), antinociception and sedation in male Sprague Dawley rats. An injection of morphine (10 mg/kg, IV) produced adverse effects on breathing, including sustained decreases in minute ventilation. L-CYSee (500 μmol/kg, IV) given 15 min later immediately reversed the actions of morphine. Another injection of L-CYSee (500 μmol/kg, IV) after 15 min elicited more pronounced excitatory ventilatory responses. L-CYSee (250 or 500 μmol/kg, IV) elicited a rapid and prolonged reversal of the actions of morphine (10 mg/kg, IV) on ABG chemistry (pH, pCO2, pO2, sO2) and A-a gradient. L-serine ethylester (an oxygen atom replaces the sulfur; 500 μmol/kg, IV), was ineffective in all studies. L-CYSee (500 μmol/kg, IV) did not alter morphine (10 mg/kg, IV)-induced sedation, but slightly reduced the overall duration of morphine (5 or 10 mg/kg, IV)-induced analgesia. In summary, L-CYSee rapidly overcame the effects of morphine on breathing and alveolar gas-exchange, while not affecting morphine sedation or early-stage analgesia. The mechanisms by which L-CYSee modulates morphine depression of breathing are unknown, but appear to require thiol-dependent processes.

Arterial blood gas analysis predicts futile recanalization in mechanical thrombectomy-treated acute ischemic stroke patients: a multicenter study

OBJECTIVE: It is known that providing recanalization alone in large vessel occlusions is not sufficient to provide a good 90-day clinical outcome. It is advocated that neuroprotection should be increased before endovascular treatment and that the penumbra should be protected from reperfusion damage after recanalization. However, the effects of blood gas parameters before and after mechanical thrombectomy on clinical outcomes are not clear. The objective of this study is to assess the effectiveness of serial blood gas measures in accurately predicting futile recanalization at an early stage. PATIENTS AND METHODS: This study is a multicenter inquiry that collected data in a prospective manner and analyzed it retrospectively. Patients with a 2b-3 thrombolysis in cerebral infarction (TICI) score after mechanical thrombectomy for recanalization were consecutively analyzed from July 2022 to March 2023. Arterial blood gas parameters, including pH, oxygen saturation (SaO2), partial carbon dioxide pressure (PaCO2), partial oxygen pressure (PaO2), lactate, and bicarbonate (HCO3), were measured at four time points: before mechanical thrombectomy treatment (preoperative), immediately after recanalization (postoperative 1st), during the 3rd hour (postoperative 3rd), and at the 5th hour (postoperative 5th). The patients were categorized into groups based on their modified Rankin Scale (mRS) scores. RESULTS: The study included 136 patients with an average age of 69.71±11.22. The postoperative 1st-hour SaO2 values were lower in the mRS 3-6 group (p=0.038). The postoperative pH and lactate mean were greater in the mRS 3-6 group than in the 0-2 group (p=0.038 and 0.018, respectively). In logistic regression, a unit rise in lactate increased poor functional outcomes 1,632 times (p=0.024). Early neurological recovery was associated with decreased postoperative 3rd-hour lactate (p=0.014). The mean postoperative PaO2 (average of 1, 2, 3 PaO2) was higher in those with symptomatic cerebral bleeding (p=0.044). CONCLUSIONS: Monitoring lactate and pH levels in AIS patients who have had mechanical recanalization can be utilized to predict mortality and morbidity, especially in the first five hours after the procedure.

Graphical Abstract

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Reliability of a point of care testing blood gas analyzer for measurement of lactate levels in cerebrospinal fluid

Analysis of cerebrospinal fluid (CSF), including lactate, is key for diagnosis of acute meningitis. Since blood gas analyzers (BGA) enable rapid and safe blood-lactate measurements, we evaluated the reliability of RAPIDPoint 500 BGA to provide a fast and accurate measure of CSF lactate. In this study, CSF lactate levels were measured by a reference assay and on RAPIDPoint 500 BGA. Comparability was evaluated through difference analysis, using Bland Altman test, and linear regression analysis, using the Passing Bablok test. Agreement rate according to CSF lactate (≥3.5 and <3.5 mmol/L) was calculated using kappa (κ) statistic. Population study included 98 CSF samples. Concerning difference analysis, according to Bland-Altman test, bias was 0.13 mmol/L (CI 95%: -0.26 to 0.52 mmol/L. In regression analysis, according to Passing-Bablok equation a systematic difference between both assays was found. In concordance analysis, the interrate realibility was very high (κ: 0.964). According to our resuls, although a systematic difference was detected when lactate levels were measured on RAPIDPoint 500 BGA, the results from Bland-Altman test and the high agreement rate support that this POCT analyzer could be useful for a early and safe detection of patients with high probability of increased CSF lactate level.

Impact of mechanical power and positive end expiratory pressure on central vs. mixed oxygen and carbon dioxide related variables in a population of female piglets

INTRODUCTION

The use of the pulmonary artery catheter has decreased overtime; central venous blood gases are generally used in place of mixed venous samples. We want to evaluate the accuracy of oxygen and carbon dioxide related parameters from a central versus a mixed venous sample, and whether this difference is influenced by mechanical ventilation.

MATERIALS AND METHODS

We analyzed 78 healthy female piglets ventilated with different mechanical power.

RESULTS

There was a significant difference in oxygen-derived parameters between samples taken from the central venous and mixed venous blood (Sv ¯ $$ \overline{v} $$ O2 = 74.6%, ScvO2 = 83%, p < 0.0001). Conversely, CO2-related parameters were similar, with strong correlation. Ventilation with higher mechanical power and PEEP increased the difference between oxygen saturations, (Δ[ScvO2-Sv ¯ $$ \overline{v} $$ O2 ] = 7.22% vs. 10.0% respectively in the low and high MP groups, p = 0.020); carbon dioxide-related parameters remained unchanged (p = 0.344).

CONCLUSIONS

The venous oxygen saturation (central or mixed) may be influenced by the effects of mechanical ventilation. Therefore, central venous data should be interpreted with more caution when using higher mechanical power. On the contrary, carbon dioxide-derived parameters are more stable and similar between the two sampling sites, independently of mechanical power or positive end expiratory pressures.

Multiple blood gas variables predict AKI survival in an independent manner

BACKGROUND AND AIM

Acute kidney injury (AKI) is becoming increasingly prevalent among hospitalized patients and carries a poor prognosis. While new biomarkers show promise in identifying early stages of AKI, accurately predicting severe outcomes such as the need for kidney replacement therapy (KRT) or death remains a challenge. However, blood gas analyses (BGA) can be used to diagnose life-threatening complications associated with AKI. The objective of this study was to assess the role of BGA as a biomarker panel in both emerging and established cases of AKI.

METHODS

Retrospective observational study examining subjects with newly developed acute kidney injury (AKI). The study will document venous and arterial pH, pCO2, and actual bicarbonate levels upon hospital admission and at the onset of AKI. The primary endpoints include in-hospital mortality, the need for kidney replacement therapy (KRT), and the recovery of kidney function (ROKF).

RESULTS

A total of 202 individuals were included in the study. Three variables were found to be independent predictors of in-hospital survival: admission arterial pH, arterial pH at acute kidney injury (AKI) onset, and arterial pCO2 at AKI onset. Additionally, venous pCO2 at AKI onset was identified as an independent predictor for the need of kidney replacement therapy (KRT).

CONCLUSIONS

Our study suggests that blood gas analysis may have a potential role in predicting severe outcome variables in acute kidney injury (AKI). The associated costs are minimal.

Clinical characteristics and mortality predictors among very old patients with pulmonary thromboembolism: a multicenter study report

BACKGROUND

Clinical characteristics of patients with pulmonary thromboembolism have been described in previous studies. Although very old patients with pulmonary thromboembolism are a special group based on comorbidities and age, they do not receive special attention.

OBJECTIVE

This study aims to explore the clinical characteristics and mortality predictors among very old patients with pulmonary thromboembolism in a relatively large population.

DESIGN AND PARTICIPANTS

The study included a total of 7438 patients from a national, multicenter, registry study, the China pUlmonary thromboembolism REgistry Study (CURES). Consecutive patients with acute pulmonary thromboembolism were enrolled and were divided into three groups. Comparisons were performed between these three groups in terms of clinical characteristics, comorbidities and in-hospital prognosis. Mortality predictors were analyzed in very old patients with pulmonary embolism.

KEY RESULTS

In 7,438 patients with acute pulmonary thromboembolism, 609 patients aged equal to or greater than 80 years (male 354 (58.1%)). There were 2743 patients aged between 65 and 79 years (male 1313 (48%)) and 4095 patients aged younger than 65 years (male 2272 (55.5%)). Patients with advanced age had significantly more comorbidities and worse condition, however, some predisposing factors were more obvious in younger patients with pulmonary thromboembolism. PaO2 < 60 mmHg, eGFR < 60 mL/min/1.73m2, malignancy, anticoagulation as first therapy were mortality predictors for all-cause death in very old patients with pulmonary thromboembolism. The analysis found that younger patients were more likely to have chest pain, hemoptysis (the difference was statistically significant) and dyspnea triad.

CONCLUSION

In very old population diagnosed with pulmonary thromboembolism, worse laboratory results, atypical symptoms and physical signs were common. Mortality was very high and comorbid conditions were their features compared to younger patients. PaO2 < 60 mmHg, eGFR < 60 mL/min/1.73m2 and malignancy were positive mortality predictors for all-cause death in very old patients with pulmonary thromboembolism while anticoagulation as first therapy was negative mortality predictors.

Abhd2, a Candidate Gene Regulating Airway Remodeling in COPD via TGF-β

Purpose

The typical characteristic of COPD is airway remodeling, affected by environmental and genetic factors. However, genetic studies on COPD have been limited. Currently, the Abhd2 gene is found to play a critical role in maintaining alveolar architecture and stability. The research aims to investigate the predictive value of Abhd2 for airway remodeling in COPD and its effect on TGF-β regulation.

Methods

In humans, Abhd2 protein was obtained from peripheral blood monocytes. Peripheral blood TGF-β, pulmonary surfactant proteins (SPs), metalloproteinases, inflammatory indicators (WBC, NEU, NLR, EOS, CRP, PCT, D-Dimer), chest CT (airway diameter and airway wall thickness), pulmonary function, and blood gas analysis were used to assess airway remodeling. In animals, Abhd2 deficient mice (Abhd2Gt/Gt) using gene trapping and C57BL6 mice were injected intraperitoneally with CSE to construct COPD models. HE staining, Masson staining and immunohistochemistry were used to observe the pathological changes of airway in mice, and RT-PCR, WB, ELISA and immunofluorescence were used to detect the expression of secreted proteins and EMT markers.

Results

COPD patients with worse pulmonary function and higher airway remodeling-related inflammatory factors had lower Abhd2 protein expression. Moreover, indicators followed the same trend for COPD patients grouped by prognosis (Group A vs Group B). Serum TGF-β was negatively correlated with Abhd2 protein expression, FEV1/FVC, FEV1, and FEV1% PRED. In mice, Abhd2 depletion promoted deposition of TGF-β, leading to more pronounced emphysema, airway thickening, increased alveolar macrophage infiltration, decreased AECII number and SPs, and EMT phenomenon.

Conclusion

Downregulation of Abhd2 can promote airway remodeling in COPD by modulating repair after injury and EMT via TGF-β. This study suggests that Abhd2 may serve as a biomarker for assessing airway remodeling and guiding prognosis in COPD.

Measuring Pericellular Oxygen Tension for In Vitro Cell Culture

Cell culture, the process of growing cells in conditions that mimic those in the body, is a key technique in biomedical research. Oxygen is not controlled in conventional cell culture, although chambers that control oxygen in the surrounding gas phase are commercially available. In both cases, it is valuable to understand the pericellular oxygen tension (i.e., the oxygen concentration that cells experience) in cultures. Herein we describe a procedure for using commercial optical sensor spots to measure pericellular oxygen for adherent and suspension cultures. Spots are placed on surfaces on which cells are grown, and optical cables are attached to the outside of the cell culture vessels and connected to a computer. Associated software allows for the real-time monitoring of pericellular oxygen during cell culture experiments. This procedure enhances the reproducibility and control of cell culture.

Oxygenation saturation index in neonatal hypoxemic respiratory failure

BACKGROUND

This study aimed to assess the validity of the oxygenation saturation index (OSI) and the ratio of oxygen saturation to the fraction of inspired oxygen (FIO2) (S/F ratio) with percutaneous oxygen saturation (OSISpO2 and the Sp/F ratio) and to evaluate the correlation between these values and the oxygen index (OI). It also determined their cut-off values for predicting OI in accordance with neonatal hypoxic respiratory failure severity.

METHODS

We reviewed the data of 77 neonates (gestational age 31.7 ± 6.1 weeks; birthweight, 1768 ± 983 g) requiring invasive mechanical ventilation between 2013 and 2020, 1233 arterial blood gas samples in total. We calculated the OI, OSISpO2, OSI with arterial oxygen saturation (SaO2) (OSISaO2), Sp/F ratio, and the ratio of SaO2 to FIO2 (Sa/F ratio).

RESULTS

The regression and Bland-Altman analysis showed good agreement between OSISpO2 or the Sp/F ratio and OSISaO2 or the Sa/F ratio. Although a significant positive correlation was found between OSISpO2 and OI, OSISpO2 was overestimated in SpO2 > 98% with a higher slope of the fitted regression line than that below 98% of SpO2. Furthermore, receiver-operating characteristic curve analysis using only SpO2 ≤ 98% samples showed that the optimal cut-off points of OSISpO2 and the Sp/F ratio for predicting OI were: OI 5, 3.0 and 332; OI 10, 5.3 and 231; OI 15, 7.7 and 108; OI 20, 11.0 and 149; and OI 25, 17.1 and 103, respectively.

CONCLUSION

The cut-off OSISpO2 and Sp/F ratio values could allow continuous monitoring for oxygenation changes in neonates with the potential for wider clinical applications.

Effectiveness of the oxygen reserve index in detecting and preventing hyperoxia in critically ill patients on mechanical ventilation: a randomized controlled trial

AIM

To assess the effectiveness of fraction of inspired oxygen (FiO2) titration guided by oxygen reserve index (ORi) in preventing hyperoxia in intensive care unit (ICU) patients receiving mechanical ventilator support.

METHODS

Patients aged 18 years and older who were admitted to a tertiary ICU and required mechanical ventilator support were randomly divided into two groups: the control group (n=30) and the oxygen saturation (SpO2) +ORi group (n=30). In the SpO2+ORi group, the goal was to maintain SpO2 between 95% and 98% and ORi at 0.00. In both groups, SpO2, ORi, partial pressure of oxygen (PaO2), partial pressure of carbon dioxide, positive end-expiratory pressure, FiO2, and hemodynamic parameters were recorded every six hours for two consecutive days.

RESULTS

A very strong positive linear correlation was found between PaO2 and ORi (r=0.937; P<0.001). In the ORi+SpO2 group, PaO2 values were significantly lower and decreased with FiO2 titration over time. Severe hyperoxia was observed in 24.8% of the control group and in only 3.3% of the ORi+SpO2 group. When PaO2>120 mm Hg, FiO2>0.40 was found in 83.5% of the control group, and in 40% of the ORi+SpO2 group.

CONCLUSION

FiO2 titration guided by ORi+SpO2 effectively prevents hyperoxia and reduces the exposure time to hyperoxia in critically ill patients.

A scoring model based on clinical factors to predict postoperative moderate to severe acute respiratory distress syndrome in Stanford type A aortic dissection

BACKGROUND

Postoperative acute respiratory distress syndrome (ARDS) after type A aortic dissection is common and has high mortality. However, it is not clear which patients are at high risk of ARDS and an early prediction model is deficient.

METHODS

From May 2015 to December 2017, 594 acute Stanford type A aortic dissection (ATAAD) patients who underwent aortic surgery in Anzhen Hospital were enrolled in our study. We compared the early survival of MS-ARDS within 24 h by Kaplan-Meier curves and log-rank tests. The data were divided into a training set and a test set at a ratio of 7:3. We established two prediction models and tested their efficiency.

RESULTS

The oxygenation index decreased significantly immediately and 24 h after TAAD surgery. A total of 363 patients (61.1%) suffered from moderate and severe hypoxemia within 4 h, and 243 patients (40.9%) suffered from MS-ARDS within 24 h after surgery. Patients with MS-ARDS had higher 30-day mortality than others (log-rank test: p-value <0.001). There were 30 variables associated with MS-ARDS after surgery. The XGboost model consisted of 30 variables. The logistic regression model (LRM) consisted of 11 variables. The mean accuracy of the XGBoost model was 70.7%, and that of the LRM was 80.0%. The AUCs of XGBoost and LRM were 0.764 and 0.797, respectively.

CONCLUSION

Postoperative MS-ARDS significantly increased early mortality after TAAD surgery. The LRM model has higher accuracy, and the XGBoost model has higher specificity.

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

Introduction

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.

Methods

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.

Results

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.

Conclusions

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.

Prehospital blood gas analyses in acute patients treated by a ground-based physician-manned emergency unit: a cohort study

BACKGROUND

The prehospital patients treated by ambulances and mobile emergency care units (MECU) are potentially critically ill or injured. Knowing the risks of serious outcomes in these patients is important for guiding their treatment. Some settings allow for prehospital arterial blood gas analyses. This study aimed to assess the outcomes of prehospital patients in relation to their prehospitally measured lactate, pH, and CO2 levels. The primary outcome was 7-day mortality.

METHODS

This register-based cohort study included patients with one or more prehospital blood gas analyses during their prehospital treatment by a physician-manned MECU, from January 2015 to December 2018. The blood samples were analyzed on an ABL90 Flex analyzer. Absolute values with percentages and odds ratios (OR) with 95% confidence intervals (CI) were calculated for the primary and secondary outcomes within prespecified subgroups.

RESULTS

The study included 745 patients, with an overall 7-day mortality rate of 20.0%.

LACTATE LEVEL

The 7-day mortality rates were 11.5% in patients with normal lactate levels (< 2.0 mmol/L), 14.4% with intermediate lactate levels (2.0-3.9 mmol/L), and 33.0% with high lactate levels (≥ 4.0 mmol/L). This corresponded to an OR of 1.30 (95% CI: 0.75-2.24) in the intermediate lactate group (2.0-3.9 mmol/L) and an OR of 3.77 (95% CI: 2.44-5.85) in the high lactate group (≥ 4.0 mmol/L), compared to the reference group with normal lactate.

PH LEVEL

The ORs of 7-day mortality rates were 4.82 (95% CI: 3.00-7.75) in patients with blood pH of < 7.35 and 1.33 (95% CI: 0.65-2.72) in patients with blood pH > 7.45, compared to the reference group with normal pH (7.35-7.45). CO2 LEVEL : The ORs of 7-day mortality rates were 2.54 (95% CI: 1.45-4.46) in patients with blood CO2 of < 4.3 kPa and 2.62 (95% CI: 1.70-4.03) in patients with blood CO2 > 6.0 kPa, compared to the reference group with normal CO2 (4.3-6.0 kPa).

CONCLUSIONS

This study found a strong correlation between increasing 7-day mortality rates and high blood lactate levels, low levels of pH, and abnormal CO2 blood levels, in prehospital patients undergoing prehospital blood analysis.

Effects of dexmedetomidine on pulmonary function in patients receiving one-lung ventilation: a meta-analysis of randomized controlled trial

BACKGROUND

Mechanical ventilation, particularly one-lung ventilation (OLV), can cause pulmonary dysfunction. This meta-analysis assessed the effects of dexmedetomidine on the pulmonary function of patients receiving OLV.

METHODS

The Embase, PubMed, MEDLINE, Cochrane Library, ClinicalTrials.gov, and Chinese Clinical Trial Registry databases were systematically searched. The primary outcome was oxygenation index (OI). Other outcomes including the incidence of postoperative complications were assessed.

RESULTS

Fourteen randomized controlled trials involving 845 patients were included in this meta-analysis. Dexmedetomidine improved the OI at 30 (mean difference [MD]: 40.49, 95% CI [10.21, 70.78]), 60 (MD: 60.86, 95% CI [35.81, 85.92]), and 90 min (MD: 55, 95% CI [34.89, 75.11]) after OLV and after surgery (MD: 28.98, 95% CI [17.94, 40.0]) and improved lung compliance 90 min after OLV (MD: 3.62, 95% CI [1.7, 5.53]). Additionally, dexmedetomidine reduced the incidence of postoperative pulmonary complications (odds ratio: 0.44, 95% CI [0.24, 0.82]) and length of hospital stay (MD: -0.99, 95% CI [-1.25, -0.73]); decreased tumor necrosis factor-α, interleukin (IL)-6, IL-8, and malondialdehyde levels; and increased superoxide dismutase levels. However, only the results for the OI and IL-6 levels were confirmed by the sensitivity and trial sequential analyses.

CONCLUSIONS

Dexmedetomidine improves oxygenation in patients receiving OLV and may additionally decrease the incidence of postoperative pulmonary complications and shorten the length of hospital stay, which may be related to associated improvements in lung compliance, anti-inflammatory effects, and regulation of oxidative stress reactions. However, robust evidence is required to confirm these conclusions.

Accuracy of the Nova StatStrip® glucometer in patients undergoing major abdominal surgery: an observational study

PURPOSE

While the Nova StatStrip® Glucose Hospital Meter System (Nova Biomedical, Waltham, MA, USA) is approved for point-of-care testing (POCT) in critically ill patients, its use during major abdominal surgery has not been evaluated. The purpose of this study was to assess the accuracy of the Nova StatStrip glucometer in patients undergoing major hepatobiliary procedures using the Parkes error grid (ISO15197:2013) and criteria defined by the Clinical and Laboratory Standards Institute (CLSI) POCT12-A3 guideline.

METHODS

This study was a post hoc exploratory study of patients participating in a prospective randomized controlled trial on the effects of hyperinsulinemic normoglycemia (HNC) on infectious outcomes after hepatobiliary surgery. Arterial blood samples were collected before surgery and one hour, two hours, and three hours after baseline. Blood glucose levels were analyzed by the Nova StatStrip glucometer and the GEM® PremierTM 5000 blood gas analyzer. Accuracy of the StatStrip glucometer was assessed using the Parkes error grid for type 1 diabetes mellitus (when 99% of samples were within zones A and B on the Parkes error grid and clinical accuracy was acceptable) and the CLSI POCT12-A3 criteria.

RESULTS

Blood glucose levels were analyzed in 135 patients, 70 of whom received the HNC. In the Parkes error grid plotted, all samples at all time-points were within zones A and B. The Nova StatStrip glucometer also satisfied CLSI POCT12-A3 criteria at all time-points.

CONCLUSION

The Nova StatStrip glucometer was accurate in patients undergoing major upper abdominal surgery, independent of the administration of high-dose insulin therapy.

STUDY REGISTRATION

ClinicalTrials.gov (NCT01528189); registered 7 February 2012.

Association between Oxygen Reserve index and arterial partial pressure of oxygen during one-lung ventilation: a retrospective cohort study

PURPOSE

We aimed to investigate the association between the Oxygen Reserve index (ORi) and arterial partial pressure of oxygen (PaO2) during one-lung ventilation in patients who underwent non-cardiac thoracic surgery requiring one-lung ventilation.

METHODS

This retrospective study assessed the eligibility of 578 adult patients who underwent elective non-cardiac thoracic surgery requiring one-lung ventilation at a tertiary hospital, and their electronic medical records were reviewed. The ORi monitor was used in all patients during anesthesia, and arterial blood gas analysis was routinely performed 15 min after the initiation of one-lung ventilation. The primary endpoint was the association between ORi and PaO2 which were measured simultaneously during one-lung ventilation. We also investigated the risk factors for PaO2 less than 150 mmHg during one-lung ventilation.

RESULTS

Total of 554 patient were included in the analysis. The ORi value measured 15 min after the start of one-lung ventilation was significantly associated with PaO2 in the linear regression model (r2 = 0.5752, P < 0.001), and 0.27 of the ORi value could distinguish PaO2 ≥ 150 mmHg (sensitivity 0.909, specificity 0.932). Risk factors for PaO2 < 150 mmHg during one-lung ventilation included a lower ORi, older age, higher body mass index, left-sided one-lung ventilation, and lower hemoglobin concentrations.

CONCLUSION

This study suggested that ORi could provide useful information on arterial oxygenation even during one-lung ventilation for non-cardiac thoracic surgery.

Perioperative monitoring of the oxygen reserve: where do we stand?

The Oxygen Reserve Index (ORi) is an advanced plethysmography-derived variable that may help to quantify the degree of hyperoxia in patients receiving supplemental oxygen administration. ORi is a (relative) indicator of the actual partial pressure of oxygen dissolved in arterial blood (PaO2). As such, it may help in the titration of oxygen administration or it may help to warn the clinician of a deterioration of oxygen status of the patient.In this issue of the journal, Fadel et al. provide a 'classical' clinical validation study by assessing the correlation between ORi and PaO2 in patients about to undergo open-heart surgery. Within the moderate hyperoxic range (100-200 mmHg PaO2), there is a sound correlation between ORi and PaO2. This editorial discusses the clinical implications of this validation study and elaborates on the possible role of ORi monitoring in addition to SpO2 (peripheral arterial oxygen saturation) monitoring alone.

Oxygen Reserve Index and Arterial Partial Pressure of Oxygen: Relationship in Open Heart Surgery

BACKGROUND

Mild to moderate hyperoxia is potentially beneficial to patients undergoing open heart surgery. Oxygen Reserve Index (ORI) is a novel parameter that correlates to arterial oxygen tension (PaO2) in the hyperoxic range. This prospective study aimed to assess whether the relationship between ORI and PaO2 remains intact in the setting of open-heart surgery.

METHODS

This study included patients undergoing valve, aortic arch and coronary artery bypass grafting (CABG) surgeries, on and off pump, between September 1st 2019 and August 31st 2021. Enrolled patients had arterial blood gas samples collected and analyzed after induction of anesthesia and increases in FiO2 in steps of 0.08 with ORI being recorded at the time of sample collection for cross reference and analysis.

RESULTS

ORI values showed a statistically significant correlation with PaO2 values in the 100-200 mmHg range (r = 0.8193, p < 0.001). Additionally, there was a significant correlation between ORI and SpO2 values in the range of 95% and 100% (r = 0.529, p < 0.05).

CONCLUSIONS

The preserved relationship between ORI and PaO2 in the mild and moderate hyperoxic range can allow more precise titration of oxygen therapy to guide therapy targeting normoxia, mildly and moderately hyperoxia. Additionally, it could have a potential use as an early warning system for impeding hypoxia.

The importance of arterial blood gas analysis as a systemic diagnosis approach in assessing and preventing chronic diseases, from emergency medicine to the daily practice

Blood gas analysis is a diagnostic tool to evaluate the partial pressures of gas in blood and acid-base content. The use of blood gas analysis enables a clear understanding of respiratory, circulatory, and metabolic disorders. The arterial blood gas (ABG) explicitly analyzes blood taken from an artery, assessing the patient's partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) pH (acid/base). PaO2 indicates the oxygenation status, and PaCO2 indicates the ventilation status (chronic or acute respiratory failure). PaO2 is affected by hyperventilation, characterized by rapid or deep breathing, and hypoventilation, characterized by slow or shallow breathing. The acid-base balance tested by the ABG procedure measures the pH and PaCO2 directly, while the use of the Hasselbach equation gives the serum bicarbonate (HCO3) and base deficit or excess. The measured HCO3 is based on a strong alkali that frees all CO2 in serum, including dissolved CO2, carbamino compounds, and carbonic acid. The calculation uses a standard chemistry analysis, giving the amount of "total CO2"; the difference will amount to around 1.2 mmol/L. Though ABG is frequently ordered in emergency medicine contests for acute conditions, it may also be needed in other clinical settings. The ABG analysis shows to be an exceptional diagnostic tool, including the group of diseases known as acid-base diseases (ABDs), which include a great variety of conditions such as severe sepsis, septic shock, hypovolemic shock, diabetic ketoacidosis, renal tubular acidosis, chronic respiratory failure, chronic heart failure, and diverse metabolic diseases.

Cardiovascular changes induced by targeted mild hypercapnia after out of hospital cardiac arrest. A sub-study of the TAME cardiac arrest trial

AIM

Hypercapnia may elicit detrimental haemodynamic effects in critically ill patients. We aimed to investigate the consequences of targeted mild hypercapnia versus targeted normocapnia on pulmonary vascular resistance and right ventricular function in patients resuscitated from out-of-hospital cardiac arrest (OHCA).

METHODS

Pre-planned, single-centre, prospective, sub-study of the Targeted Therapeutic Mild Hypercapnia After Resuscitated Cardiac Arrest (TAME) trial. Patients were randomised to mild hypercapnia (PaCO2 = 6.7-7.3 kPa) or normocapnia (PaCO2 = 4.7-6.0 kPa) for 24 hours. Haemodynamic assessment was performed with right heart catheterisation and serial blood-gas analyses every4th hour for 48 hours.

RESULTS

We studied 84 patients. Mean pH was 7.24 (95% CI 7.22-7.30) and 7.32 (95% CI 7.31-7.34) with hypercapnia and normocapnia, respectively (P-group < 0.001). Pulmonary vascular resistance index (PVRI), pulmonary artery pulsatility index, and right atrial pressure did not differ between groups (P-group > 0.05). Mean cardiac index was higher with mild hypercapnia (P-group < 0.001): 2.0 (95% CI 1.85-2.1) vs 1.6 (95% CI 1.52-1.76) L/min/m2. Systemic vascular resistance index was 2579 dyne-sec/cm-5/ m2 (95% CI 2356-2830) with hypercapnia, and 3249 dyne-sec/cm-5/ m2 (95% CI 2930-3368) with normocapnia (P-group < 0.001). Stroke volumes (P-group = 0.013) and mixed venous oxygen saturation (P-group < 0.001) were higher in the hypercapnic group.

CONCLUSION

In resuscitated OHCA patients, targeting mild hypercapnia did not increase PVRI or worsen right ventricular function compared to normocapnia. Mild hypercapnia comparatively improved cardiac performance and mixed venous oxygen saturation.

Effect of cord blood double collection method on cord blood hematopoietic stem cell transplantation-related indices and blood gas analysis

BACKGROUND

Umbilical cord blood has been widely used in clinical transplantation. Blood gas analysis of umbilical cord blood is routinely used to evaluate neonatal asphyxia. This study aimed to evaluate an improved umbilical cord blood collection method that does not affect the results of umbilical cord blood gas analysis and hematopoietic stem cell transplantation-related indices.

METHODS

Three hundred pregnant women were recruited between December 2019 and August 2022. In total, 270 umbilical cord blood samples were included and randomly divided into 3 groups. Group A was defined as the group in which both umbilical cord blood samples for hematopoietic stem cell transplantation and blood gas analysis were collected. Group B was defined as the group from which umbilical cord blood was collected for hematopoietic stem cell transplantation. Group C was defined as that wherein umbilical cord blood was collected only for blood gas analysis. Hematopoietic stem cell transplantation-related indices were detected in groups A and B, and blood gas analysis was performed in groups A and C.

RESULTS

Hematopoietic stem cell transplantation-related indices were not significantly different between groups A and B. The pH, base excess, and lactic acid values were not significantly different between groups A and C.

CONCLUSION

The cord blood double collection method would not affect the results of umbilical cord blood gas analysis and hematopoietic stem cell transplantation-related indices. It is suitable for cord blood collection when preparing for hematopoietic stem cell transplantation and blood gas analysis.

Early warning for SpO2 decrease by the oxygen reserve index in neonates and small infants

INTRODUCTION

Continuously assessing the oxygenation levels of patients to detect and prevent hypoxemia can be advantageous for safe anesthesia, especially in neonates and small infants. The oxygen reserve index (ORI) is a new parameter that can assess oxygenation through a relationship with arterial oxygen partial pressure (PaO2 ). The aim of this study was to examine whether the ORI provides a clinically relevant warning time for an impending SpO2 (pulse oximetry hemoglobin saturation) reduction in neonates and small infants.

METHODS

ORI and SpO2 were measured continuously in infants aged <2 years during general anesthesia. The warning time and sensitivity of different ORI alarms for detecting impending SpO2 decrease were calculated. Subsequently, the agreement of the ORI and PaO2 with blood gas analyses was assessed.

RESULTS

The ORI of 100 small infants and neonates with a median age of 9 months (min-max, 0-21 months) and weight of 8.35 kg (min-max, 2-13 kg) were measured. For the ORI/PaO2 correlation, 54 blood gas analyses were performed. The warning time and sensitivity of the preset ORI alarm during the entire duration of anesthesia were 84 s (25th-75th percentile, 56-102 s) and 55% (95% CI 52%-58%), and those during anesthesia induction were 63 s (40-82 s) and 56% (44%-68%), respectively. The positive predictive value of the preset ORI alarm were 18% (95% CI 17%-20%; entire duration of anesthesia) and 27% (95% CI 21%-35%; during anesthesia induction). The agreement of PaO2 intervals with the ORI intervals was poor, with a kappa of 0.00 (95% CI = [-0.18; 0.18]). The weight (p = .0129) and height (p = .0376) of the infants and neonates were correlated to the correct classification of the PaO2 interval with the ORI interval.

CONCLUSIONS

The ORI provided an early warning time for detecting an impending SpO2 decrease in small infants and neonates in the defined interval in this study. However, the sensitivity of ORI to forewarn a SpO2 decrease and the agreement of the ORI with PaO2 intervals in this real-life scenario were too poor to recommend the ORI as a useful early warning indicator for this age group.

High, Low, and Minimal Flow Anaesthesia Management: Effects on Oxygen Reserve Index and Arterial Partial Oxygen Pressure

OBJECTIVE

To determine the oxygen reserve index (ORI) as a supporting parameter to the arterial partial oxygen pressure (PaO2) in blood gases in hypoxia and hyperoxia monitoring with different fresh gas flows (FGF) in patients undergoing abdominal surgery.

STUDY DESIGN

Randomised controlled trial. Place and Duration of the Study: Department of Anaesthesiology and Reanimation, Samsun Education and Research Hospital, Turkey, from January to September 2020.

METHODOLOGY

The study population of ninety patients was divided into three groups. After the high-flow period, the inspired oxygen fraction (FiO2) and flow-guided ventilation (FGF) were set to be 4 L/m and 40% in Group H (high-flow), 1 L/m and 50% in Group L (low-flow), and 0.5 L/m and 68% in Group M (minimal-flow), respectively.

RESULTS

There was a very high statistically positive correlation between PaO2 and ORI in H, L, and M groups. When using a cut-off value of 0.005 for ORI for the detection of PaO2 >100 mmHg, the area under the curve (AUC) was 0.97 (p<0.001) with a sensitivity of 94.4% and specificity of 95.3%. The AUC was detected to be 0.95 in receiver operating characteristic (ROC) analysis when the hyperoxia cut-off value of ORI was used to determine PaO2 >150 mmHg in the estimation of hyperoxia.

CONCLUSION

ORI can be used to complement SpO2 in low-flow anaesthesia in patients undergoing abdominal surgeries, provide guidance for PaO2, give information about tissue oxygen delivery, and contribute to the individualisation of oxygen therapy, and will therefore be included in the standard monitoring in the future.

KEY WORDS

Anaesthesia, Index, Inhalation, Oxygen, Pressure, Surgery.

Implications of differences between point-of-care blood gas analyser and laboratory analyser potassium results on hyperkalaemia diagnosis & treatment

BACKGROUND

Hyperkalaemia is managed in the emergency department (ED) following measurement of potassium results by blood gas analysers (BGA) or laboratory analysers (LAB).

AIMS

To determine the prevalence of clinically significant differences between BGA and LAB potassium results and the impact on ED hyperkalaemia management.

METHODS

Retrospective analysis of time-matched ED BGA and LAB potassium samples from 2019 to 2020 (taken within 15 min, one or both results ≥6.0 mmol/L). Mean differences and 95% limits of agreement (LoA) were determined for pairs with one or both results ≥6.0 mmol/L and a separate 500 consecutive sample pairs.

RESULTS

Four hundred eighty-eight matched BGA and LAB samples met the inclusion criteria. Of these, 201 (41.2%) differed by ≤0.5 mmol/L, 169 (34.6%) included a haemolysed LAB sample, and 12 (2.5%) had an unreportable BGA sample. One hundred six (21.7%) pairs differed by >0.5 mmol/L, and 60/106 (57%) had normal LAB potassium results, but BGA indicated moderate/severe hyperkalaemia (two of these pairs received hyperkalaemia treatment). Of patients with a haemolysed LAB sample, or where pairs differed by >0.5 mmol, 48 were treated with insulin and five (10.4%) experienced hypoglycaemia. Mean differences and LoA for pairs with LAB results <6.0 mmol/L but BGA ≥6.0 mmol/L demonstrated unacceptable agreement, with 18 (25.7%) BGA results exceeding 8.0 mmol/L.

CONCLUSIONS

Potentially significant discordance may occur between BGA and LAB potassium results. Clinicians need to be aware of factors impacting both analytical methods' accuracy (such as poor venepuncture or sample handling, (K) EDTA interference) and undetectable haemolysis with BGA measurements. We recommend BGA hyperkalaemia be confirmed with LAB results using a non-haemolysed sample where time permits.

Poisoning by abnormally high blood phenobarbital concentration treated with extracorporeal therapy

Phenobarbital poisoning, which may cause circulatory collapse as well as respiratory arrest in severe cases, has one of the highest mortality rates among acute drug poisonings. A 58-year-old man arrived at the emergency room in a deep coma (Glasgow Coma Scale E1V1M1) after taking an unknown dose of phenobarbital which had been prescribed for his cat's seizures. Venous blood gas analysis revealed hypercapnia (PvCO2: 113.0 mmHg) and a blood phenobarbital concentration of 197.3 μg/mL. Shortly after his arrival, respiratory arrest and circulatory collapse occurred. Mechanical ventilation after intubation, intravenous noradrenaline infusion, and multiple-dose activated charcoal through a nasogastric tube was started. Six hours after arrival, blood phenobarbital concentration was abnormally elevated to 356.8 μg/mL with circulatory collapse requiring an increased dose of intravenous noradrenaline infusion (up to 0.13 μg/kg/min). Continuous renal replacement therapy including high flow continuous hemodialysis was performed until hospital day 5, during which blood phenobarbital concentration decreased to 96.2 μg/mL on hospital day 4, resulting in a sufficient resumption of spontaneous breathing and full improvement of circulatory collapse. A search of the literature revealed that the peak phenobarbital concentration in the present case exceeded those of fatal cases, as well as those of survivors of acute phenobarbital poisoning. However, the patient was successfully treated with continuous renal replacement therapy. Among modalities of extracorporeal treatment, continuous renal replacement therapy could be considered if a patient's circulation is unstable.

Choosing Wisely audit: Blood gas ordering in the emergency department

OBJECTIVE

Our aim was to reduce unnecessary blood gases to improve patient flow, reduce false positives and reduce unnecessary treatments.

METHODS

This was a retrospective, single-centre audit of 100 patients in June 2022.

RESULTS

There were approximately 45 blood gases per 100 ED presentations. Following education and poster reminders, a re-audit was undertaken in October 2022, resulting in a reduction of 33% of blood gases ordered.

CONCLUSION

We have found that many blood gases are ordered for patients who are not critically unwell, and whose disposition was not affected by their result.

Relative hypoxemia at depth during breath-hold diving investigated through arterial blood gas analysis and lung ultrasound

Pulmonary gas exchange in breath-hold diving (BHD) consists of a progressive increase in arterial partial pressures of oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]) during descent. However, recent findings have demonstrated that [Formula: see text] does not consistently rise in all subjects. This study aimed at verifying and explaining [Formula: see text] derangements during BHD analyzing arterial blood gases and searching for pulmonary alterations with lung ultrasound. After ethical approval, 14 fit breath-hold divers were included. Experiments were performed in warm water (temperature: 31°C). We analyzed arterial blood gases immediately before, at depth, and immediately after a breath-hold dive to -15 m of fresh water (mfw) and -42 mfw. Signs of lung interstitial edema and atelectasis were searched simultaneously with a marinized lung ultrasound. In five subjects (-15 mfw) and four subjects (-42 mfw), the [Formula: see text] at depth seems to decrease instead of increasing. [Formula: see text] and lactate showed slight variations. At depth, no lung ultrasound alterations were seen except in one subject (hypoxemia and B-lines at -15 mfw; B-lines at the surface). Lung interstitial edema was detected in 3 and 12 subjects after resurfacing from -15 to -42 mfw, respectively. Two subjects developed hypoxemia at depth and a small lung atelectasis (a focal pleural irregularity of triangular shape, surrounded by thickened B-lines) after resurfacing from -42 mfw. Current experiments confirmed that some BH divers can experience hypoxemia at depth. The hypothesized explanation for such a discrepancy is lung atelectasis, which could not be detected in all subjects probably due to limited time available at depth.NEW & NOTEWORTHY During breath-hold diving, arterial partial pressure of oxygen ([Formula: see text]) and arterial partial pressure of carbon dioxide ([Formula: see text]) are believed to increase progressively during descent, as explained by theory, previous end-tidal alveolar gas measurements, and arterial blood gas analysis in hyperbaric chambers. Recent experiments in real underwater environment found a paradoxical [Formula: see text] drop at depth in some divers. This work confirms that some breath-hold divers can experience hypoxemia at depth. The hypothesized explanation for such a discrepancy is lung atelectasis, as suggested by lung ultrasound findings.

Validation of non-invasive point of care blood content analysis using the TensorTip™ MTX device: a method comparison study

OBJECTIVES

The TensorTip™ MTX is a non-invasive device designed to determine several physiological parameters with additional analysis of haemoglobin, haematocrit and blood gas analysis by interpreting blood diffusion colour of the finger skin based on spectral analysis. The aim of our study was to investigate the accuracy and precision of the TensorTip MTX in a clinical setting in comparison with routine analysis of blood samples.

METHODS

Forty-six patients, scheduled for elective surgery, were enrolled in this study. Placement of an arterial catheter had to be part of the standard of care. Measurements were performed during the perioperative period. The measurements obtained with the TensorTip MTX were compared with the results of routine analysis of the blood samples as a reference using correlation, Bland-Altman analysis and mountain plots.

RESULTS

No significant correlation was present in the measurements. Measurement of haemoglobin with the TensorTip MTX had a mean bias of 0.4 mmol/L, haematocrit's bias was 3.0 %. Bias of partial pressure of carbon dioxide and oxygen was 3.6 and 66.6 mmHg, respectively. Calculated percentage errors were 48.2 , 48.9, 39.9 and 109.0 %. Proportional bias was present in all Bland-Altman analyses. Less than 95 % of the differences fell within the pre-set limits of allowable error.

CONCLUSIONS

Non-invasive blood content analysis with the TensorTip MTX device is not equivalent to and did not correlate sufficiently with conventional laboratory analysis. None of the parameters measured showed results within the limits of allowable error. Therefore, the use of the TensorTip MTX is not recommended for perioperative care.

Evaluating of neonatal early onset sepsis through lactate and base excess monitoring

Early-onset sepsis (EOS) is one of the leading causes of neonatal death and morbidity worldwide and timely initiation of antibiotic therapy is, therefore, of paramount importance. This study aimed to evaluate the predictive effect of lactate and base excess (BE) values in the cord arterial blood gas and the 6th hour of life venous blood gas analysis on clinical sepsis in newborns. This is a cohort case-control study. In this study, 104 cases were divided into clinical and suspected sepsis groups according to the evaluation at the 24th hour after delivery. Lactate and BE values were evaluated in the cord arterial blood gas analysis (ABGA) and at the postnatal 6th-hour venous blood gas. The cord ABGA and postnatal 6th-hour results were compared in the clinical and suspected sepsis groups. Clinical sepsis was found to be associated with a lactate value above 2 mMol/L at postnatal 6th-hour venous blood gas (p = 0.041). This association was the highest when the clinical sepsis group's postnatal 6th-hour lactate cut-off value was determined as 3.38 mMol/L (sensitivity 57.9% and specificity 68.5%) (p = 0.032). However, no association was found between clinical sepsis diagnosis and venous BE's value in cord ABGA at the postnatal 6th hour. We found that a venous lactate value above 3.38 mMol/L at the postnatal 6th hour was the cut-off value that could indicate early-onset clinical sepsis. However, none of the biomarkers used in diagnosing EOS can accurately show all cases.

Development and in-vivo validation of a portable phosphorescence lifetime-based fiber-optic oxygen sensor

Oxygenation is a crucial indicator of tissue viability and function. Oxygen tension ([Formula: see text]), i.e. the amount of molecular oxygen present in the tissue is a direct result of supply (perfusion) and consumption. Thus, measurement of [Formula: see text] is an effective method to monitor tissue viability. However, tissue oximetry sensors commonly used in clinical practice instead rely on measuring oxygen saturation ([Formula: see text]), largely due to the lack of reliable, affordable [Formula: see text] sensing solutions. To address this issue we present a proof-of-concept design and validation of a low-cost, lifetime-based oxygen sensing fiber. The sensor consists of readily-available off-the shelf components such as a microcontroller, a light-emitting diode (LED), an avalanche photodiode (APD), a temperature sensor, as well as a bright in-house developed porphyrin molecule. The device was calibrated using a benchtop setup and evaluated in three in vivo animal models. Our findings show that the new device design in combination with the bright porphyrin has the potential to be a useful and accurate tool for measuring [Formula: see text] in tissue, while also highlighting some of the limitations and challenges of oxygen measurements in this context.

Heparin Concentration in Evacuated Tubes and Its Effect on pH, Ionized Calcium, Lactate, and Potassium in Venous Blood Gas Analysis

Arterial blood specimens collected in evacuated tubes are unacceptable for blood gas analysis. However, evacuated tubes are routinely used for venous blood-gas analysis. The impact of the blood to heparin ratio on venous blood in evacuated tubes is unclear. Venous blood was drawn into lithium and sodium heparin evacuated tubes that were 1/3 full, ½ full, 2/3 full, and fully filled. Specimens were analyzed for pH, ionized calcium (iCa), lactate, and potassium on a blood-gas analyzer. The results for specimens filled only 1/3 full for lithium and sodium heparin tubes revealed a significant increase in pH and a significant decrease in the iCa. Underfilling the lithium and sodium heparin evacuated tubes did not significantly impact the lactate or potassium results. Venous whole-blood specimens should be filled to at least 2/3 full for accurate pH and iCa results.

Role of respiratory characteristics in treatment adherence with noninvasive home mechanical ventilation in myotonic dystrophy type 1, a retrospective study

Chronic respiratory insufficiency is common in patients with myotonic dystrophy type 1 (DM1) and can be treated with noninvasive home mechanical ventilation (HMV). HMV is not always tolerated well resulting in low treatment adherence. We aimed to analyze if baseline respiratory characteristics such as pulmonary function, level of pCO2 and presence of sleep apnea are associated with HMV treatment adherence in DM1 patients. Pulmonary function testing, polysomnography and blood gas measurement data of DM1 patients were retrospectively collected. Initiation of HMV and treatment adherence after one year was documented. Patients with low treatment adherence (average daily use of HMV <5 h) were grouped with patients that discontinued HMV and compared with patients with high treatment adherence (average daily use of HMV >5 h). HMV was initiated in 101 patients. After one year, 58 patients had low treatment adherence. There were no differences between the low and high treatment adherence group regarding the respiratory characteristics. None of the included predictors (gender, age, body mass index, cytosine-thymine-guanine repeat length, FVC, daytime pCO2, bicarbonate, nighttime pCO2, nighttime base excess, apnea-hypopnea index and mean saturation during sleep) was able to significantly predict high treatment adherence. In conclusion, the respiratory characteristics are not associated with treatment adherence with HMV in DM1 patients and cannot be used to identify patients at risk for low HMV treatment adherence.

Performance of the ROX index in predicting high flow nasal cannula failure in COVID-19 patients: a systematic review and meta-analysis

COVID-19 patients with acute hypoxemic respiratory failure (AHRF) benefit from high flow nasal cannula (HFNC) oxygen therapy. However, delays in initiating invasive ventilation after HFNC failure are associated with poorer outcomes. The respiratory oxygenation (ROX) index, combining SpO2/FiO2 and respiratory rate, can predict HFNC failure. This meta-analysis evaluated the optimal ROX index cut-offs in predicting HFNC failure among COVID-19 patients at different measurement timings and clinical settings. Three databases were searched for eligible papers. From each study, we reconstructed the confusion matrices at different cut-offs, fitted linear mixed models to estimate the ROX index distribution function, and derived the area under the summary receiver operator characteristic curve (sAUC) and optimal cut-offs to predict HFNC failure. 24 studies containing 4790 patients were included. Overall sAUC was 0.771 (95% CI: 0.666-0.847) (optimal cut-off: 5.23, sensitivity: 0.732, specificity: 0.690). The cut-off values to achieve 80%, 90% sensitivity, 80%, 90% specificity were 5.70, 6.69, 4.45, 3.37, respectively. We stratified the analysis by ROX measurement time and estimated optimal cut-offs and cut-offs to achieve 80% sensitivity and specificity. For 2-6 h and 6-12 h post-HFNC initiation, we propose the use of 80% specific cut-offs to rule in HFNC failure of < 5.33 and < 3.69, respectively. For 12-24 h post-HFNC initiation, we propose the use of the 80% sensitive cut-off of > 6.07 to rule out HFNC failure. Our analysis confirms the overall utility of the ROX index in risk stratification of COVID-19 patients with AHRF receiving HFNC and provides potentially useful cut-offs for different times from HFNC initiation.

[Investigation of a carbon monoxide poisoning accident with a hidden source]

In June 2022, a carbon monoxide poisoning accident with hidden source occurred in a bonded gold/silver wire manufacturing enterprise in Guangzhou, causing 10 people to be poisoned, of which 1 was caused by carbon monoxide poisoning and 9 by carbon monoxide contact reaction. The symptoms were dizziness, fatigue and vomiting. After 5 to 7 h, the saturation of carboxyhemoglobin in finger pulse was 4% to 10%, and the saturation of carboxyhemoglobin in blood gas biochemical analysis was 1.9% to 5.8%. The concentration of carbon monoxide detected in the carbon borne purification plant of the enterprise was 34.46-37.26 mg/m(3). It was judged that the accident was carbon monoxide poisoning caused by carbon monoxide gas being transported to the work post along the gas transmission pipeline due to abnormal operation of the carbon borne purification plant. By investigating the source and cause of poison, this paper provides a warning for the similar process to prevent similar events, and provides a new idea for the identification of chemical poisoning risk. At the same time, it is warned that similar enterprises should fully consider the risk of poisoning under specific circumstances, strengthen equipment maintenance and repair, and prevent the occurrence of similar incidents.

Clinical Diagnostic Value of Serum GABA, NE, ET-1, and VEGF in Chronic Obstructive Pulmonary Disease with Pulmonary Hypertension

Background

Pulmonary hypertension (PH) is the one of the most common complications of chronic obstructive pulmonary disease (COPD). Whereas, the associated diagnostic factors are uncertain. The present study aims to investigate useful diagnostic factors in patients with COPD and PH (COPD-PH).

Patients and Methods

A total of 111 patients with COPD in Shanxi Bethune Hospital from December 2019 to December 2020 were divided into COPD (PASP≤50 mmHg) and COPD-PH groups (PASP>50 mmHg). Pulmonary function and chest CT results were collected. Routine blood, biochemical, and blood coagulation function indices were examined for all patients. Arterial blood gas analysis and serum cytokines were also measured. Differences in the distribution of the above indicators between the two groups were analyzed using binary logistic regression analysis to identify the risk factors of COPD-PH, and multiple linear regression analysis to determine the factors affecting PASP. The influencing factors and joint predictive factors of the above linear regression analysis were analyzed using the ROC curve. The area under the curve and the best cut-off value were calculated, and their predictive value and clinical significance in disease diagnosis were discussed.

Results

A total of 27 indexes with statistically significant differences between the two groups were identified (P < 0.05). Binary Logistic regression analysis showed that the factors influencing the diagnosis of pulmonary hypertension were serum GABA, NE, VEGF, BUN, and LYM% levels (P < 0.05). Multiple linear regression showed that the factors influencing PASP were serum NE, ET-1, GABA, and VEGF levels, and the goodness of fit of the model was 0.748 (P < 0.001). ROC curve showed that the AUC of the combined diagnosis of serum NE, ET-1, GABA, and VEGF levels was 0.966 (sensitivity, 87.5%; specificity, 93.65%).

Conclusion

Serum NE and ET-1 are risk factors for COPD-PH, whereas serum GABA and VEGF are protective factors against COPD-PH. The combined diagnostic value of serum NE, ET-1, GABA, and VEGF levels was the highest.

The risk factors of postoperative hypoxemia in patients with Stanford type A acute aortic dissection

Hypoxemia is one of the most common complications in patients after Stanford type A acute aortic dissection surgery. The aim of this study was to investigate the association of circulating ANG II level with postoperative hypoxemia and to identify the risk factors for postoperative hypoxemia in Stanford type A acute aortic dissection patients. In this study, 88 patients who underwent Stanford type A acute aortic dissection surgery were enrolled. Postoperative hypoxemia is defined by the oxygenation index (OI). Perioperative clinical data were collected and the serum ANG II and sACE2 levels were measured. The differences in the basic characteristics, intraoperative details, biochemical parameters, laboratory test data and clinical outcomes were compared between the hypoxemia group and the non-hypoxemia group by univariate analysis. Multivariate logistic regression analysis was performed on the variables with P < .1 in univariate analysis or that were considered clinically important to identify risk factors for postoperative hypoxemia. Twenty-five patients (28.4%) were considered to have postoperative hypoxemia (OI ≤ 200 mm Hg). The ANG II concentration remained a risk factor associated with postoperative hypoxemia [OR = 1.018, 95% CI (1.003-1.034), P = .022]. The other risk factors remaining in the logistic regression model were BMI [OR = 1.417, 95% CI (1.159-1.733), P = .001] and cTnI [OR = 1.003, 95% CI (1.000-1.005), P = .032]. Elevated levels of ANG II, BMI and cTnI are risk factors for postoperative hypoxemia in patients with Stanford type A acute aortic dissection.