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Achieving large‐bore venous access in a shocked patient is a frequent problem encountered by the emergency department physician. Alternatives1,2,3 to standard cannula‐over‐needle percutaneous cannulation are time/operator dependent, and confer increased potential morbidity. We aimed to prospectively validate the anecdotally described, but largely overlooked, technique of utilising an initial distending volume of saline to facilitate large‐bore peripheral venous cannulation.
With regional ethics committee approval and verbal consent, adult (16 years) patients presenting to our tertiary emergency department with a clinical diagnosis of hypovolaemia (pulse 100 bpm, systolic blood pressure 100 mm Hg, aetiology of presentation consistent with haemorrhage or dehydration) were studied. Patients were excluded if on application of standard tourniquet, a vein of suitable calibre was successfully cannulated.
The study technique involved siting a small‐calibre peripheral venous cannula (usual catheter‐over‐needle technique) distally in the upper limb, with the tourniquet remaining tightened, infusing 30–50 ml 0.9% NaCl to distend the venous compartment distal to the tourniquet. A presenting distended vein was then cannulated with a large‐bore catheter, again in a standard way. Achieving a cannnula bore of 18 G was the primary outcome measure.
Twenty patients (aged 19–78 years) with hypovolaemia of varying aetiology (7 with trauma, 6 with gastrointestinal tract haemorrhage, 5 with sepsis, 1 with abdominal aortic aneurysm rupture and 1 with fat emboli syndrome) were prospectively enrolled from a convenience sample of 52 presentations meeting the study criteria for hypovolaemia. Mean (SD) pulse rate was 119 (11.9) bpm and mean (SD) blood pressure was 86(10.9) mm Hg. Nineteen (95% CI 85 to 100) patients underwent successful incremental cannulation (median initial and subsequent cannula bore 20 (range 24–20) G and 16 (range 18–14) G, respectively). In six (30%) patients, the initial cannula was sited by a prehospital provider. One failure was observed in a 19‐year‐old patient with trauma treated with multiple prehospital venepuncture attempts (resultant extravasation) in the ipsilateral limb. All attempts were completed in <5 min.
The described technique for upgauging peripheral venous cannulae is simple, relies on the existing skill set of prehospital and emergency practitioners, and is reliable in achieving large‐bore peripheral venous cannulation. Although not universally successful, it should be considered as an adjunct to the emergency physicians' armamentarium of vascular access techniques. Of note, due to saline haemodilution, blood aspirated from the second cannula is unsuitable for laboratory analysis.
MH was involved in study synthesis, ethical approval, performance of the study technique, data analysis and manuscript generation. VT was involved in the study synthesis, performance of the study technique and manuscript generation. GC was involved in study synthesis and manuscript generation.
Competing interests: None declared.