Does Radial Artery Cannulation Affect the Perfusion Index(PI) of the Hand in Liver Transplant Operations?

\## DLiver transplantation is associated with major hemodynamic changes, and continuous invasive arterial pressure monitoring is an essential part of perioperative management. The radial artery is the most commonly used site. Repeated punctures and mechanical trauma during catheterization may cause local complications and affect peripheral perfusion. Ultrasound guidance may facilitate catheter placement with fewer punctures.

The perfusion index (Pi), derived from pulse oximetry, is the ratio of the pulsatile to the non-pulsatile optical signal and is used to monitor peripheral perfusion. Because Pi is also influenced by systemic hemodynamics, sympathetic activity, temperature, nociception and drugs, changes in Pi were not interpreted as direct evidence of radial artery vasospasm.

In this prospective, randomized, controlled, two-arm parallel-group trial, adult liver transplant recipients were randomized 1:1 to palpation-guided or ultrasound-guided radial artery catheterization. Randomization used a computer-generated sequence and sequentially numbered, opaque, sealed envelopes prepared by an independent person. The envelope was opened after induction of general anesthesia, once hemodynamic stability was achieved and immediately before catheterization. All procedures were performed by a single anesthesiologist experienced in both techniques, using the same 20-gauge non-guidewire arterial cannula in both groups, preferably on the non-dominant hand after a normal modified Allen test.

In the ultrasound group, a high-frequency linear probe was used with a short-axis out-of-plane approach and dynamic needle tip positioning. Pi was measured continuously with a pulse oximetry sensor placed on the index finger the hand. Pi, heart rate, SpO2, pleth variability index (PVI), SpHb and SpOC were recorded immediately before catheterization (baseline) and immediately after catheterization; Pi was additionally recorded 5 and 10 minutes after catheterization.

The primary outcome was the change in Pi from baseline over time. The primary analysis used a linear mixed-effects model including group, time and the group-by-time interaction to account for repeated measurements. Secondary outcomes were compared with appropriate tests (t test or Mann-Whitney U test; chi-square or Fisher's exact test). Results were reported with effect estimates and 95% confidence intervals; a two-sided p\<0.05 was considered statistically significant.

Conventional Palpation

Procedure: Conventional Palpation

-Radial artery catheterization was performed after induction of general anesthesia using the conventional palpation technique. The radial pulse was identified by palpation and the artery was cannulated using anatomical landmarks with a 20-gauge non-guidewire arterial cannula, limited to a maximum of three skin punctures.

Procedure: Ultrasound-Guided Catheterization

Radial artery catheterization was performed after induction of general anesthesia, preferably on the non-dominant hand after a normal modified Allen test. The radial pulse was identified by palpation and the artery was cannulated using anatomical landmarks with a 20-gauge non-guidewire arterial cannula, the same cannula used in the ultrasound group. The procedure was limited to a maximum of three skin punctures.

Radial artery catheterization performed under real-time ultrasound guidance using an integrated guidewire arterial cannula system.

Time frame: Perfusion index (Pi) will be measured at baseline, immediately after radial artery catheterization, and at 5 and 10 minutes after the procedure to evaluate changes in peripheral perfusion.

Perfusion index (Pi) will be measured at baseline, immediately after radial artery catheterization, and at 5 and 10 minutes after the procedure to assess changes in peripheral perfusion between the palpation-guided and ultrasound-guided catheterization groups.

Time frame: During the catheterization procedure

The proportion of participants in whom radial artery catheterization is successfully completed on the first skin puncture.

Does Radial Artery Cannulation Affect the Perfusion Index of the Hand in Liver Transplant?