*4.1.1 Techniques to increase vein visibility in difficult venous access*

The literature recommends the use of ultrasound and vein imaging devices for the detection of veins with low visibility and palpability. Information regarding the diameter and the depth of the veins may be obtained using the ultrasound technique. Previous studies have demonstrated that the use of an ultrasound device increased the rate of successful catheter placement at the first attempt, particularly in difficult venous access [16, 37]. Moreover, it is reported that the use of vascular imaging devices, which enables the visualization of the veins using infrared rays, prior to the procedure is particularly effective in pediatric patients and the individuals with impaired vascular structure receiving intravenous chemotherapy treatment (**Figure 1**) [1, 18, 30]. Eren (2018) reported that the use of a vein imaging device in patients with difficult venous access significantly shortened the time to determine the appropriate vein compared to the use of a tourniquet and fist-clenching techniques [30]. In a study carried out by Caglar et al. (2019) with preterm infants, it is found that success of the first attempt was significantly higher in the infrared and transilluminator groups than in the control group (*p* ≤ .05). It is also found that time to successful cannulation was significantly lower for the infrared group (8.70 ± 2.56 seconds) than for the transilluminator group (45.27 ± 30.83 seconds) and the control group [38]. Considering the patient outcomes of studies conducted using the ultrasound device, ultrasound guidance increases the likelihood of successful peripheral cannulation in difficult access patients. Ultrasound guided peripheral IV catheter placement has a greater success rate with fewer skin punctures, decreased time for IV catheter placement, and fewer complications [39, 40]. Chiriloco et al. (2015) reported that first attempt success was 85% with using ultrasound at 200 patients with DIVA. They also said that patient satisfaction was higher in ultrasound guided vascular access group than traditional peripheral venous catheter insertion group [41]. In summary, ultrasound guided insertion significantly improved first attempt success rates and demonstrated higher patient satisfaction scores when compared to conventional venous catheter use.

Besides these techniques, tourniquet application, hot application, topical vasodilator application, fist-clenching, holding the arm below the chest level, hitting the vein, and massaging may be used to make the veins fuller for easier vein determination [30, 32, 34, 38, 42–44]. Tourniquet application is one of the most commonly used techniques for vein determination. The literature recommends the use of a sphygmomanometer rather than a tourniquet for the individuals with sensitive/ fragile veins and those with a risk of difficult venous access. It is suggested to inflate

**Figure 1.** *PIVC used with vein imaging device.*

the manometer to the level of the individual's diastolic blood pressure [38, 43]. Nitroglycerin, a topical vasodilator, increases the visibility of the vein, although it may not be suitable for every patient as it is absorbed into the skin [45]. Another technique, named hot application, assists in expanding the veins to make them fuller. Studies have demonstrated that hot application facilitates vein detection and catheter insertion in patients with DIVA [43, 46].
