What are the implications of introducing a stylet through a cannula (intravenous catheter)?

From the Guidelines

When introducing a stylet through a cannula, it is crucial to ensure compatibility in size and handle the stylet gently to avoid damaging the cannula or causing tissue trauma, as supported by general medical principles and guidelines for central venous catheters 1.

Key Considerations

• The stylet provides stiffness to the cannula, making it easier to navigate through tissues during procedures like central line placement, spinal taps, or airway management.
• After placement, the stylet is typically removed while the cannula remains in place to establish access.
• This technique helps prevent the cannula from kinking or deviating from the intended path during insertion.
• Maintaining sterile technique throughout the procedure is essential to prevent infection.

Specific Guidance for Airway Management

• In the context of airway management, particularly for patients with suspected or confirmed cervical spine injury, the use of a stylet or bougie as an adjunct during tracheal intubation should be considered to facilitate easier intubation and reduce the need for external maneuvers 1.
• The choice between a stylet and a bougie may depend on the specific clinical scenario and the availability of these tools.
• It is important to follow the most recent and highest quality guidelines for airway management in patients with cervical spine immobilization, such as those from the Difficult Airway Society and other relevant societies 1.

General Principles

• The principle of using a stylet through a cannula applies broadly across medical procedures that require the insertion of catheters or tubes into the body.
• Ensuring the correct size and type of stylet for the cannula, and using it in a manner that minimizes trauma and prevents infection, are critical aspects of medical practice.
• Guidelines such as those for central venous catheters 1 and airway management 1 provide valuable insights into the best practices for these procedures.

From the Research

Stylet Introduction Through Cannula

• The use of a stylet during endotracheal intubation has been studied in various settings, including intensive care units and prehospital environments 2, 3, 4, 5.
• A study published in 2020 proposed a randomized controlled trial to evaluate the effect of using an endotracheal tube with a stylet versus an endotracheal tube alone on first-attempt intubation success in critically ill patients 2.
• Another study published in 2022 found that tracheal tube introducers and stylets are efficacious aids to intubation in the prehospital environment, with bougies offering a statistically significant advantage in terms of first-pass intubation success when video technology is available 3.
• A multicentre, randomised clinical trial published in 2021 found that using a stylet improves first-attempt intubation success in critically ill adults undergoing tracheal intubation 4.
• The use of a video-intubating stylet, such as the Trachway, has been shown to reduce the incidence of difficult intubation and improve EMG tube placement in patients undergoing monitored thyroidectomy 5.
• In contrast, a systematic review and meta-analysis published in 2019 found that the use of a stylet in endoscopic ultrasound with fine-needle aspiration does not confer a significant advantage in diagnostic adequacy, accuracy, yield, contamination, bloodiness, or cellularity over no stylet use 6.

Key Findings

• The use of a stylet can improve first-attempt intubation success in critically ill adults 4.
• Tracheal tube introducers and stylets are efficacious aids to intubation in the prehospital environment 3.
• The Trachway video-intubating stylet can reduce the incidence of difficult intubation and improve EMG tube placement in patients undergoing monitored thyroidectomy 5.
• The use of a stylet in endoscopic ultrasound with fine-needle aspiration does not confer a significant advantage over no stylet use 6.

Stylet Use in Different Settings

• Intensive care units: the use of a stylet can improve first-attempt intubation success in critically ill adults 4.
• Prehospital environments: tracheal tube introducers and stylets are efficacious aids to intubation, with bougies offering a statistically significant advantage in terms of first-pass intubation success when video technology is available 3.
• Monitored thyroidectomy: the Trachway video-intubating stylet can reduce the incidence of difficult intubation and improve EMG tube placement 5.
• Endoscopic ultrasound with fine-needle aspiration: the use of a stylet does not confer a significant advantage over no stylet use 6.