The insertion of peripheral vascular catheters (PVCs) is the most often invasive procedure performed in hospital settings. During hospitalization, the majority of patients need to have a PVC inserted. These devices are not risk-free, affecting patients' safety and well-being. In clinical settings, health professionals must deal with difficult venous accesses due to the patient's age, physical characteristics, clinical status, and medication, which hinder the PVC insertion. When veins are not visible or palpable, this may lead to successive puncture attempts, causing pain to the patient and discomfort to the nurse, which results in increased costs.

Guidelines state that puncture should be attempted only twice per professional, to a maximum of four attempts; against this recommendation and due to the patient's therapeutic needs and clinical situation, health professionals attempt to puncture multiple times in a single scenario. In this regard, health professionals should consider using specific technologies that help to select the vein and reduce the number of puncture attempts and catheter-related mechanical complications. Taking into account the multiplicity of existing technologies in the international market that assist health professionals in peripheral venous catheterization, ultrasound and infrared devices emerge in the literature as two of the most commonly used during this procedure.

These technologies were developed with the purpose of improving peripheral intravenous catheterization success rate and thus reducing the number and extent of the negative effects of multiple or unsuccessful attempts, with the additional purpose of avoiding the frustrations of health professionals in these scenarios. However, such technologies are still underused in clinical practice, since health professionals are not familiar with the use of these devices. Moreover, the costs associated with their purchase and maintenance may be considered as excessive in relation to the traditional method.

The project investigators aim to determine whether the use of either ultrasound or near-infrared vascular imaging will significantly improve the success rate of peripheral intravenous catheterization in adults on first attempt by nurses compared with the standard approach, reduce immediate related complications and improve patient and provider satisfaction.

Inclusion Criteria:

• Participants who require peripheral intravenous catheterization as part of routine care;
• Participants whose primary nurse agrees to participate in the study;
• Participants who are able to give written assent or oral assent.

Exclusion Criteria:

• Confused and/or disoriented participants;
• Participants who are unable to communicate orally and/or in writing.

No individual participant data will be shared with other researchers.

Because of the physical nature of the interventions, it will not be possible to conceal the group allocation from the nurses or trial participants.