Arterial Blood Gas Analysis: as safe as we think? A multicentre historical cohort study

Efficacy and Safety of the Distal Radial Artery as an Arterial Blood Sampling Site

Background: Arterial blood sampling is a common clinical procedure, but traditional sampling sites have some limitations. In recent years, distal radial artery (DRA) puncture has been widely used in interventional treatment of cardiovascular diseases and demonstrating certain advantages. This study aims to evaluate the feasibility and safety of blood sampling via the DRA compared with conventional radial artery (CRA) sampling. Methods: This study is a single-center, prospective, randomized controlled trial. Adult subjects requiring blood gas analysis in the intensive care unit of Rushan People's Hospital from February 2024 to July 2024 were enrolled. The primary end point was to test the noninferiority of first-attempt success rate between the two groups. Secondary end points included blood collection time, hemostasis time, and complications within 24 h. Results: The first-attempt success rates for the DRA (n = 90) and CRA (n = 90) groups were 77.8% and 80.0%, respectively, with no statistically significant difference (P = .72) (mean difference -2.22%; 95% CI: -14.1% to 9.7%). The DRA group had a slightly longer blood collection time than the CRA group (P < .001) but significantly shorter hemostasis time (86 s vs 215 s, P < .001). There was no significant difference in complication rates within 24 h between the two groups. Conclusion: DRA blood sampling was noninferior to CRA sampling in terms of first-attempt success rate and had the advantage of significantly shorter hemostasis time. This new method was comparable with the traditional method in terms of safety and may provide a valuable alternative for clinical practice.

A Wearable Prototype Measuring PtcCO2 and SpO2

The proper functioning of the respiratory system is evaluated by monitoring the exchange of blood oxygen and carbon dioxide. While wearable devices for monitoring both blood oxygen and carbon dioxide are emerging, wearable carbon dioxide monitors remain relatively rare. This paper introduces a novel wearable prototype that integrates the measurement of transcutaneous carbon dioxide and peripheral blood oxygen saturation on a miniaturized custom-designed printed circuit board. The device employs a fluorescent sensing film consisting of two distinct luminophore types and utilizes the time-domain dual lifetime referencing technique to enhance measurement accuracy by mitigating the effects of confounding factors. Thorough testing on human subjects validated the prototype's functionality, comparing its performance against commercial clinical devices. The prototype effectively tracked changes in transcutaneous carbon dioxide induced by hyperventilation, with a resolution as low as 1 mmHg. Additionally, blood oxygen saturation measurements were tested on human subjects to compare our prototypes' performance to that of clinical devices. The results confirm the potential of the proposed novel wearable for prolonged use with minimal maintenance and underscore its significance in advancing wearable health monitoring technologies.

Oxygen therapy in acute hypoxemic respiratory failure: guidelines from the SRLF-SFMU consensus conference

INTRODUCTION

Although largely used, the place of oxygen therapy and its devices in patients with acute hypoxemic respiratory failure (ARF) deserves to be clarified. The French Intensive Care Society (Société de Réanimation de Langue Française, SRLF) and the French Emergency Medicine Society (Société Française de Médecine d'Urgence, SFMU) organized a consensus conference on oxygen therapy in ARF (excluding acute cardiogenic pulmonary oedema and hypercapnic exacerbation of chronic obstructive diseases) in December 2023.

METHODS

A committee without any conflict of interest (CoI) with the subject defined 7 generic questions and drew up a list of sub questions according to the population, intervention, comparison and outcomes (PICO) model. An independent work group reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Fifteen experts in the field from both societies proposed their own answers in a public session and answered questions from the jury (a panel of 16 critical-care and emergency medicine physicians, nurses and physiotherapists without any CoI) and the public. The jury then met alone for 48 h to write its recommendations.

RESULTS

The jury provided 22 statements answering 11 questions: in patients with ARF (1) What are the criteria for initiating oxygen therapy? (2) What are the targets of oxygen saturation? (3) What is the role of blood gas analysis? (4) When should an arterial catheter be inserted? (5) Should standard oxygen therapy, high-flow nasal cannula oxygen therapy (HFNC) or continuous positive airway pressure (CPAP) be preferred? (6) What are the indications for non-invasive ventilation (NIV)? (7) What are the indications for invasive mechanical ventilation? (8) Should awake prone position be used? (9) What is the role of physiotherapy? (10) Which criteria necessarily lead to ICU admission? (11) Which oxygenation device should be preferred for patients for whom a do-not-intubate decision has been made?

CONCLUSION

These recommendations should optimize the use of oxygen during ARF.

Arterial blood gas analysis or venous blood gas analysis for adult hospitalised patients with respiratory presentations: a systematic review

BACKGROUND

Identification of hypoxaemia and hypercapnia is essential for the diagnosis and treatment of acute respiratory failure. While arterial blood gas (ABG) analysis is standard for PO2 and PCO2 measurement, venous blood gas (VBG) analysis is increasingly used as an alternative. Previous systematic reviews established that VBG reporting of PO2 and PCO2 is less accurate, but the impacts on clinical management and patient outcomes are unknown.

AIMS

This study aimed to systematically review available evidence of the clinical impacts of using ABGs or VBGs and examine the arteriovenous difference in blood gas parameters.

METHODS

A comprehensive search of the MEDLINE, Embase and Cochrane Library databases since inception was conducted. Included studies were prospective or cross-sectional studies comparing peripheral ABG to peripheral VBG in adult non-critical care inpatients presenting with respiratory symptoms.

RESULTS

Of 15 119 articles screened, 15 were included. No studies were found that examined clinical impacts resulting from using VBG compared to ABG. Included studies focused on the agreement between ABG and VBG measurements of pH, PO2, PCO2 and HCO3 -. Due to the heterogeneity of the included studies, qualitative evidence synthesis was performed. While the arteriovenous difference in pH and HCO3 - was generally predictable, the difference in PO2 and PCO2 was more significant and less predictable.

CONCLUSIONS

Our study reinforces the notion that VBG is not comparable to ABG for physiological measurements. However, a key revelation from our research is the significant lack of data regarding the clinical implications of using VBG instead of ABG, a common scenario in clinical practice. This highlights a critical knowledge gap.

Evaluating the Accuracy of Off-Label Placement of Pulse Oximetry Sensors in Comparison to On-Label Placement in the Adult Cardiac Intensive Care Unit Patient Population

BACKGROUND

Continuous pulse oximetry (Spo2) is a commonly utilized tool to obtain an indirect, noninvasive measurement of hemoglobin oxygen saturation. Difficulty obtaining measurement with Spo2 sensors can lead nurses to try off-label sites until they find placement that provides a signal. Currently, there is limited evidence to support this application.

PURPOSE

The purpose of this study was to evaluate the accuracy of off-label placement of pulse oximetry sensors in comparison to on-label placement in adult cardiac intensive care patients.

METHODS

Data were collected on 24 participants. At the time of a medically necessary arterial blood gas laboratory draws, 4 Spo2 measurements were gathered from an on-label finger sensor, an off-label finger sensor, an on-label ear sensor, and an off-label ear sensor. Results were analyzed using 4 Pearson correlation coefficients, Bland-Altman plots, and 2 linear mixed-effect models.

RESULTS

Our study found that while both our on-label finger and off-label finger pulse oximetry sensor overestimated when compared to the arterial hemoglobin saturation (gold standard), there was greater overestimation found with the off-label placement. Though there was not a significant difference observed between the ear probe on the nose and the gold standard, figures examining off-label ear probe and gold standard measures show that, in lower ranges of oxygen saturation, the off-site probe substantially overestimates true oxygen saturation, while in higher ranges of oxygen saturation, the off-site ear probe underestimates true oxygen saturation.

CONCLUSIONS

No changes should be made to the current practice of using pulse oximetry sensor placement.

P. aeruginosa infection of the ulna, a rare complication after arterial puncture

Pseudomonas aeruginosa, a Gram-negative bacterium known to induce severe infections, is seldomly reported in scientific literature as a contributor of osteomyelitis. In this case report, a 71-year-old woman exhibited recurring infections and enduring forearm pain. A subsequent MRI revealed osteomyelitis in the distal ulna, linked to an arterial blood gas sample taken months earlier. Despite undergoing multiple extended courses of antibiotic treatment, the patient eventually underwent surgery on her left forearm. Biopsy cultures conclusively confirmed the presence of P. aeruginosa.

Diagnosis and Management of Acute Respiratory Failure

Acute hypoxemic respiratory failure is defined by Pao2 less than 60 mm Hg or SaO2 less than 88% and may result from V/Q mismatch, shunt, hypoventilation, diffusion limitation, or low inspired oxygen tension. Acute hypercapnic respiratory failure is defined by Paco2 ≥ 45 mm Hg and pH less than 7.35 and may result from alveolar hypoventilation, increased fraction of dead space, or increased production of carbon dioxide. Early diagnostic maneuvers, such as measurement of SpO2 and arterial blood gas, can differentiate the type of respiratory failure and guide next steps in evaluation and management.

Individualized estimation of arterial carbon dioxide partial pressure using machine learning in children receiving mechanical ventilation

BACKGROUND

Measuring arterial partial pressure of carbon dioxide (PaCO2) is crucial for proper mechanical ventilation, but the current sampling method is invasive. End-tidal carbon dioxide (EtCO2) has been used as a surrogate, which can be measured non-invasively, but its limited accuracy is due to ventilation-perfusion mismatch. This study aimed to develop a non-invasive PaCO2 estimation model using machine learning.

METHODS

This retrospective observational study included pediatric patients (< 18 years) admitted to the pediatric intensive care unit of a tertiary children's hospital and received mechanical ventilation between January 2021 and June 2022. Clinical information, including mechanical ventilation parameters and laboratory test results, was used for machine learning. Linear regression, multilayer perceptron, and extreme gradient boosting were implemented. The dataset was divided into 7:3 ratios for training and testing. Model performance was assessed using the R2 value.

RESULTS

We analyzed total 2,427 measurements from 32 patients. The median (interquartile range) age was 16 (12-19.5) months, and 74.1% were female. The PaCO2 and EtCO2 were 63 (50-83) mmHg and 43 (35-54) mmHg, respectively. A significant discrepancy of 19 (12-31) mmHg existed between EtCO2 and the measured PaCO2. The R2 coefficient of determination for the developed models was 0.799 for the linear regression model, 0.851 for the multilayer perceptron model, and 0.877 for the extreme gradient boosting model. The correlations with PaCO2 were higher in all three models compared to EtCO2.

CONCLUSIONS

We developed machine learning models to non-invasively estimate PaCO2 in pediatric patients receiving mechanical ventilation, demonstrating acceptable performance. Further research is needed to improve reliability and external validation.

The High Price of Equity in Pulse Oximetry: A cost evaluation and need for interim solutions

Importance

Disparities in pulse oximetry accuracy, disproportionately affecting patients of color, have been associated with serious clinical outcomes. Although many have called for pulse oximetry hardware replacement, the cost associated with this replacement is not known.

Objective

To estimate the cost of replacing all pulse oximetry hardware throughout a hospital system.

Design

Single-center survey, 2023.

Setting

Single center.

Participants

One academic medical center with three hospitals.

Main Outcomes and Measures

Cost of fleet replacement as identified by current day prices for hardware.

Results

New and used prices for 5,079/5,678 (89.5%) across three hospitals for pulse oximetry devices were found. The average equipment cost to replace pulse oximetry hardware is $15,704.12 per bed. Replacement and integration costs are estimated at $28.5-31.8 million for the entire medical system. Extrapolating these costs to 5,564 hospitals in the United States results in an estimated cost of $14.1 billion.

Conclusions and Relevance

"Simply replacing" pulse oximetry hardware to address disparities may be neither simple, cheap, or timely. Solutions for addressing pulse oximetry accuracy disparities leveraging current technology may be necessary.

Trial Registration

Pro00113724, exempt.

Exploring the Feasibility of Calculating Expected pCO2 From Venous Blood Gas Samples Alone in Intensive Care Patients

Introduction This study highlights the significance of assessing acid-base balance and gas exchange in intensive care patients. The research investigates the applicability of using the "expected (pCO2 = HCO3 + 15)" formula, derived from venous blood gas samples, as an alternative to Winter's formula and practical formula. The study emphasizes the importance of identifying the primary acid-base abnormality accurately and efficiently for appropriate clinical intervention in critically ill patients. Methods  This study included 400 adult patients admitted to the Anesthesia Clinic in the Third Stage Anesthesia and Reanimation Intensive Care Unit at Hitit University Erol Olçok Training and Research Hospital between April 2020 and July 2023. Blood gas samples were collected simultaneously from both arterial lines and venous catheters. Patients under 18 years, pregnant women, hemodialysis patients, and those with missing data were excluded. The study aimed to calculate the expected partial pressure of carbon dioxide (pCO2) values using Winter's formula and simple formula for both arterial and venous blood gas samples and assess potential correlations between them. Results The results showed a narrow range for arterial pH values (7.12-7.72), a wider distribution for pCO2 values (17.90-81.30 mmHg), and a moderate dispersion for HCO3 values (12.80-44.33 mmol/L). Both Winter's and simple formulas were applied to estimate the expected pCO2 values, showing strong positive correlations between arterial and venous pH, pCO2, and HCO3 values. The scatterplot illustrated a very high level of association (Pearson's correlation coefficient, r = 1) between the expected pCO2 values derived from both formulas using arterial and venous blood gas samples. Conclusion The clinical study demonstrates that estimating expected pCO2 values in mixed acid-base disorders can be achieved using a simple and convenient formulation, eliminating the need for arterial blood gas sampling and its associated complications.