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.

Composite outcome measures in high-impact critical care randomised controlled trials: a systematic review.

BACKGROUND: The use of composite outcome measures (COM) in clinical trials is increasing. Whilst their use is associated with benefits, several limitations have been highlighted and there is limited literature exploring their use within critical care. The primary aim of this study was to evaluate the use of COM in high-impact critical care trials, and compare study parameters (including sample size, statistical significance, and consistency of effect estimates) in trials using composite versus non-composite outcomes. METHODS: A systematic review of 16 high-impact journals was conducted. Randomised controlled trials published between 2012 and 2022 reporting a patient important outcome and involving critical care patients, were included. RESULTS: 8271 trials were screened, and 194 included. 39.1% of all trials used a COM and this increased over time. Of those using a COM, only 52.6% explicitly described the outcome as composite. The median number of components was 2 (IQR 2-3). Trials using a COM recruited fewer participants (409 (198.8-851.5) vs 584 (300-1566, p = 0.004), and their use was not associated with increased rates of statistical significance (19.7% vs 17.8%, p = 0.380). Predicted effect sizes were overestimated in all but 6 trials. For studies using a COM the effect estimates were consistent across all components in 43.4% of trials. 93% of COM included components that were not patient important. CONCLUSIONS: COM are increasingly used in critical care trials; however effect estimates are frequently inconsistent across COM components confounding outcome interpretations. The use of COM was associated with smaller sample sizes, and no increased likelihood of statistically significant results. Many of the limitations inherent to the use of COM are relevant to critical care research.

The burden and prognostic significance of suspected sepsis in the prehospital setting: A state-wide population-based cohort study.

OBJECTIVE: Despite high in-hospital mortality, the epidemiology of prehospital suspected sepsis presentations is not well described. This retrospective cohort study aimed to quantify the burden of such presentations, and to determine whether such a diagnosis was independently associated with longer-term mortality. METHODS: Retrospective, observational population-based cohort study examining all adult prehospital presentations in Victoria, between January 2015 and June 2019, who required subsequent in-hospital assessment. Linked data were extracted from clinical and administrative datasets. Demographics, illness severity, prehospital treatment and mortality were compared between prehospital suspected sepsis and non-sepsis patients. Multivariable logistic regression was used to determine the adjusted association between prehospital assessment (suspected sepsis vs non-sepsis) and 6-month mortality. RESULTS: A total of 1 218 047 patients were included. The age-adjusted incidence rate of prehospital suspected sepsis was 65 cases per 100 000 person-years. Those with prehospital suspected sepsis were older (74 vs 62 years), more frequently male (55% vs 47%), with greater physiological derangement. Intravenous cannulas were more often inserted prehospital (60% vs 29%). Crude in-hospital mortality was 6.5-fold higher in the prehospital suspected sepsis group (11.8% vs 1.8%), and by 6 months, 22.6% had died. After adjustment for demographics, illness severity, comorbidity, treatment and hospital location, a diagnosis of prehospital suspected sepsis was associated with a 35% higher likelihood of 6-month mortality (OR 1.35, 95% CI 1.29-1.41). CONCLUSIONS: The burden of prehospital suspected sepsis in the Australian setting is significant, with paramedics identifying patients at high-risk of poor longer-term outcomes. This implies the need to consider improved care pathways for this highly vulnerable group.