Rethinking Intravenous Catheter Size and Location for Computed Tomography Pulmonary Angiography

Abstract

Introduction Computed tomography pulmonary angiography (CTPA) is the test of choice for diagnosis of pulmonary embolism (PE) in the emergency department (ED), but this test may be indeterminate for technical reasons such as inadequate contrast filling of the pulmonary arteries. Many hospitals have requirements for intravenous (IV) catheter size or location for CTPA studies to reduce the chances of inadequate filling, but there is a lack of clinical data to support these requirements. The objective of this study was to determine if a certain size or location of IV catheter used for contrast for CTPA is associated with an increased chance of suboptimal CTPA. Methods This was a retrospective chart review of patients who underwent CTPA in the ED. A CTPA study was considered suboptimal if the radiology report indicated it was technically limited or inadequate to exclude a PE. The reason for the study being suboptimal, and the size and location of the IV catheter, were abstracted. We calculated the rate of inadequate contrast filling of the pulmonary vasculature and compared the rate for various IV catheter sizes and locations. In particular, we compared 20-gauge or larger IV catheters in the antecubital fossa or forearm to all other sizes and locations. Results A total of 19.3% of the 1500 CTPA reports reviewed met our criteria as suboptimal, and 51.6% of those were due to inadequate filling. Patients with a 20-gauge IV catheter or larger placed in the antecubital fossa or forearm had inadequate filling 9.2% of the time compared to 13.2% for patients who had smaller IVs or IVs in other locations (difference: 4.0% [95% confidence interval, −1.7%–9.7%]). There were also no statistically significant differences in the rates of inadequate filling when data were further stratified by IV catheter location and size. Conclusion We did not detect any statistically significant differences in the rate of inadequate contrast filling based on IV catheter locations or sizes. While small differences not detected in this study may exist, it seems prudent to proceed with CTPA in patients with difficult IV access who need emergent imaging even if they have a small or distally located IV.

An audit of the adequacy of contrast enhancement in CT pulmonary angiograms in a South African tertiary academic hospital setting

“…There were higher rates of inadequate contrast enhancement when IV cannulas were positioned in the hand (28.6%), compared to 21.6% in the antecubital fossa and 15.9% in the forearm; however, this small difference was not significant (p = 0.65). This is comparable to findings by Marshall et al 12 (with a larger sample size of 1500) and Roggenland et al 13 These two studies also found no significant difference between different IV cannula sizes, although, similar to our audit, they also had a limited frequency of 22 G IV cannulas. The RCR and American College of Radiology recommends a 20 G or a bigger IV cannula in the antecubital fossa or forearm, but there is no other literature supporting this practice for CTPAs.…”

“…The RCR and American College of Radiology recommends a 20 G or a bigger IV cannula in the antecubital fossa or forearm, but there is no other literature supporting this practice for CTPAs. 7,12,14 They also do not stipulate recommendations for contrast volume. Contrast opacification is related to iodine flow rate, which is a function of iodine concentration and flow rate.…”

Evaluation of pulmonary computed tomography angiography protocols: A multicenter audit in Togo

“…This study found that the rate of exams with insufficient enhancement was 7.87%. This result is lower than those of Basson et al 16 and Marshall et al 42 , which found 20.8% and 11.2%, respectively. This result is encouraging.…”

Hemolysis Control in the Emergency Department by Interventional Blood Sampling

“…A peripheral IV catheter, 20 gauge or larger, placed in the antecubital fossa or forearm is recommended for contrast computed tomography (CT), because a flow rate of 3 mL/s or higher is necessary for injecting contrast media [17]. Contrast CT scans are widely used during ED management [18][19][20]; thus, a 20-gauge or larger IV catheter is usually preferred in EDs.…”