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  1. RG Edwards1,
  2. A Kehoe1,2,
  3. B Graham1,
  4. J Smith2
  1. 1Plymouth Hospitals NHS Trust, Plymouth, Devon, UK
  2. 2Centre for Clinical Trials & Population Studies, Plymouth University Peninsula Schools of Medicine & Dentistry, Plymouth, UK


    Objectives & Background Inadvertent intra-arterial cannulation (IIAC) occurs in some Emergency Department (ED) patients. Interpretation of point of care blood gas analysis (BGA) by a senior emergency physician (EP) may be used to screen for this. We conducted a prospective observational pilot study to investigate the rate of IIAC in the ED setting and to explore feasibility questions to inform a future larger study.


    • ▸ To assess the performance of medical students and foundation year one doctors in ultrasound (US) assessment of cannula location.

    • ▸ To determine the time taken to complete US assessment of one cannula.

    • ▸ To assess EP confidence in BGA interpretation.

    • ▸ To explore whether or not venous BGA values varied by site of cannula.

    Methods Five medical students and FY1 doctors received a two-hour training session from an EP in US assessment of peripheral cannula location. Competence was confirmed by five observed US assessments. Data collectors performed US assessment of cannulas inserted in a convenience sample of ED patients over a two week period (83 patients). Their confidence and time taken to complete US assessment were recorded. Routine BGA obtained during cannula insertion were shown to an EP whose confidence in interpretation was recorded. Data collectors completed a survey to record their experience of various aspects of the study.

    Results 100% of data collectors found using ultrasound to determine the location of a cannula to be 'very easy' or 'quite easy'. Adequate US views were obtained in 94% of examinations. Mean duration of US assessment was 11 minutes 25 seconds. 87% of cannulae had a routine BGA taken and EPs were 'quite confident' or 'very confident' in their interpretation in 97% of BGAs. There was no difference in blood gas values between different insertion sites.

    Conclusion Junior doctors and medical students can be trained in US assessment of cannula placement. BGA is frequently performed during cannula insertion. EPs interpret BGA confidently. Insertion site does not complicate interpretation. It is feasible to use this methodology for larger studies.

    • emergency departments

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