Trending peripheral venous PCO2 in patients with respiratory failure using mathematically arterialised venous blood gas samples.

BACKGROUND: Trending venous blood gases (VBGs) has been suggested as an alternative to arterial blood gases (ABGs) in patients with respiratory failure, but there are limits to its utility. The aim of this study was to compare the trending of venous carbon dioxide partial pressure (pCO2) (pCO2v) with mathematically arterialised pCO2 (pCO2ca) and to further evaluate whether pCO2ca follows change in arterial pCO2 (pCO2a) more accurately. METHODS: We analysed two data sets. The first was a retrospective study of patients with respiratory failure admitted to the intensive care unit. Venous samples were mathematically arterialised using the vTAC method. The change in pCO2 between two consecutive samples (ΔpCO2) for pCO2v was compared with the change in calculated pCO2ca values. In the second data set taken from previously published work, we analysed 82 trend points (difference between consecutive samples) for change in pCO2. There were pCO2v, pCO2a and pCO2ca values for each trend point. The primary outcome measures were the 95% limits of agreement (LOAs) between different sampling methods for ΔpCO2. RESULTS: In the first data set, 46 patients had 203 VBG results giving 157 trend points for ΔpCO2 analysis. The 95% LOAs for ΔpCO2ca and ΔpCO2v were -9.28 to 11.12 mm Hg.In the second data set, 95% LOAs for ΔpCO2 were -9.46 to 9.48 mm Hg for ΔpCO2a and ΔpCO2v, -8.94 to 8.58 mm Hg for ΔpCO2ca and ΔpCO2v, and -4.54 to 4.91 mm Hg for ΔpCO2a and ΔpCO2ca. CONCLUSION: This study suggests that trending pCO2v is not an accurate way to trend pCO2a in patients with respiratory failure. ΔpCO2ca via vTAC trended differently to ΔpCO2v. Our data suggest pCO2ca more accurately trends pCO2a.

Introducing a Clinical Practice Guideline Using Early CT in the Diagnosis of Scaphoid and Other Fractures.

OBJECTIVE: We developed and implemented clinical practice guideline (CPG) using computerized tomography (CT) as the initial imaging method in the emergency department management of scaphoid fractures. We hypothesized that this CPG would decrease unnecessary immobilization and lead to earlier return to work. METHODS: This observational study evaluated implementation of our CPG, which incorporated early wrist CT in patients with "clinical scaphoid fracture": a mechanism of injury consistent with scaphoid fracture, anatomical snuff box tenderness, and normal initial plain x-rays. Outcome measures were the final diagnosis as determined by orthopaedic review of the clinical and imaging data. Patient outcomes included time to return to work and patient satisfaction as determined by telephone interview at ten days. RESULTS: Eighty patients completed the study protocol in a regional emergency department. In this patient population CT detected 28 fractures in 25 patients, including six scaphoid fractures, five triquetral fractures, four radius fractures, and 13 other related fractures. Fifty-three patients had normal CT. Eight of these patients had significant ongoing pain at follow up and had an MRI, with only two bone bruises identified. The patients with normal CTs avoided prolonged immobilization (mean time in plaster 2.7 days) and had no or minimal time off work (mean 1.6 days). Patient satisfaction was an average 4.2/5. CONCLUSION: This CPG resulted in rapid and accurate management of patients with suspected occult scaphoid injury, minimized unnecessary immobilization and was acceptable to patients.