Abstract

NM-275

Determining the Ideal Method for Detecting Rapid Intravenous Cannulation

Ku A, Muffly M, Caruso T, Rodriguez S, Ku A, Tsui B
Lucile Packard Children's Hospital, Stanford University Medical Center, Stanford, California, United states of america

Background
Anesthesiologists sometimes prime the inner bore of an angiocatheter needle with saline prior to intravenous (IV) cannulation because the visual detection of blood is subjectively faster than for an un primed angiocatheter needle. The ability to rapidly detect intravascular placement of the angiocatheter needle increases the chances of successful IV catheter placement.

General Aim
We hypothesized that a saline-primed angiocatheter needle will produce earlier visual detection of blood in the flash chamber than for an unprimed angiocatheter needle. The primary outcome was time from puncture of a silicone membrane (meant to simulate venous cannulation) to visual detection of blood in the angiocatheter flash chamber.

Materials and Methods
Freshly donated, heparinized human blood was used as the test substance. Needle insertion into the silicone membrane of an intravenous tubing “t-piece” was videotaped to determine the time from needle contact with blood to visual detection of blood in the angiocatheter flash chamber. When the angiocatheter needle punctured the test membrane and contacted the blood, an electrical circuit was completed and illuminated a LED. The blood was suspended at such a height as to maintain the desired pressure (50 mmHg) and was continuously measured using arterial pressure line monitoring system. This pressure was chosen based on experimentally derived pressures of the occluded vein.

Based on a pilot study of 20 primed and unprimed angiocatheters, we calculated that 86 angiocatheters in each group would be required to detect a difference between groups at 90% power with a type -1 error rate of 0.5%. One-hundred unprimed and 100 saline-primed catheters were tested. This laboratory study was deemed exempt from full review by the Stanford Institutional Review Board.

Results
Ninety-eight catheters in the unprimed angiocatheter group and 97 catheters in the saline primed group were included in the analysis due to LED malfunction or visual blockage in the video.

The median (IQR) time for the unprimed 24 gauge angiocatheters at 50 mmHg was 1.14 (0.63-1.49) seconds; whereas for the saline-primed angiocatheters the median (IQR) time was 0.80 (0.44-1.30) seconds (P=0.018; Mann-Whitney).

The distribution of flash times were not normally distributed in either group (Shapiro-Wilk Test, P<0.0001)). We therefore compared the medians using the two-tailed Mann-Whitney U Test which demonstrated a statistically significant difference in the median flash time for unprimed versus saline-primed angiocatheters (P=0.018)

Discussion
The visible detection of blood in the flash chamber of saline-primed IV catheters was faster than for unprimed IV catheters. This difference is likely clinically significant given that the ability to rapidly detect intravascular placement of the angiocatheter needle increases the chances of successful IV catheter placement.