Predicting Peripheral Venous Access Difficulty in the Emergency Department Using Body Mass Index and a Clinical Evaluation of Venous Accessibility

Background

Peripheral venous (PV) cannulation, one of the most common technical procedures in Emergency Medicine, may prove challenging, even to experienced Emergency Department (ED) staff. Morbid obesity (body mass index [BMI] ≥ 40) has been reported as a risk factor for PV access failure in the operating room.

Objectives

We investigated PV access difficulty in the ED, across BMI categories, focusing on patient-related predicting factors.

Methods

Prospective, observational study including adult patients requiring PV lines. Operators were skilled nurses and physicians. PV accessibility was clinically evaluated before all cannulation attempts, using vein visibility and palpability. Patient and PV placement characteristics were recorded. Primary outcome was failure at first attempt. Outcome frequency and comparisons between groups were examined. Predictors of difficult cannulation were explored using logistic regression. A p-value <0.05 was considered significant.

Results

PV lines were placed in 563 consecutive patients (53 ± 23 years, BMI: 26 ± 7 kg/m²), with a success rate of 98.6%, and a mean attempt of 1.3 ± 0.7 (range 1–7). Failure at the first attempt was recorded in 21% of patients (95% confidence interval [CI] 17.6–24.4). Independent risk factors were: a BMI ≥ 30 (odds ratio [OR] 1.98, 95% CI 1.09–3.60), a BMI < 18.5 (OR 2.24; 95% CI 1.07–4.66), an unfavorable (OR 1.66, 95% CI 1.02–2.69), and very unfavorable clinical assessment of PV accessibility (OR 2.38, 95% CI 1.15–4.93).

Conclusion

Obesity, underweight, an unfavorable, and a very unfavorable clinical evaluation of PV accessibility are independent risk factors for difficult PV access. Early recognition of patients at risk could help in planning alternative approaches for achieving rapid PV access.