From the Guidelines
Difficult vein cannulation in sick and obese patients requires a systematic approach to improve success rates, and I strongly recommend using ultrasound guidance as the first-line technique whenever available, as it significantly increases first-attempt success rates and reduces complications. This approach is supported by recent guidelines and studies, including those from the European Society of Intensive Care Medicine 1, which recommend the use of ultrasound guidance for vascular cannulation in critically ill patients.
When using ultrasound guidance, it is essential to optimize patient positioning with appropriate limb dependent positioning and apply a tourniquet 10-15 cm above the intended insertion site. For enhanced vein visibility, use warm compresses for 5-10 minutes to promote vasodilation, and consider using vein illumination devices like VeinViewers or AccuVein if available.
Some key points to consider when performing difficult vein cannulation include:
- Prioritizing the forearm or upper arm veins over hand veins in obese patients, as these are typically more stable and less likely to infiltrate
- Using smaller gauge catheters (22G or 24G) initially to increase success probability
- Considering alternative access methods such as intraosseous access (using devices like EZ-IO) for emergent situations, or midline or central venous catheters for longer-term access
- Being aware of the potential for vasopressor use to cause peripheral vasoconstriction, further complicating peripheral access, and considering early central access in critically ill patients
The use of ultrasound guidance is supported by studies such as those published in the Journal of Critical Care Medicine 1 and Intensive Care Medicine 1, which demonstrate the effectiveness of ultrasound guidance in improving success rates and reducing complications. Additionally, guidelines from the Association of Anaesthetists of Great Britain and Ireland 1 and the American Journal of Kidney Diseases 1 also recommend the use of ultrasound guidance for vascular access.
Overall, the use of ultrasound guidance for difficult vein cannulation in sick and obese patients is a recommended approach, and its use should be considered as a first-line technique whenever available.
From the Research
Difficult Vein Cannulation in Sick and Obese Patients
- Difficult vein cannulation is a common issue in critically ill patients, particularly in those who are obese or have generalized edemas 2.
- Ultrasound-guided peripheral venous cannulation has been shown to have a high success rate in patients with difficult intravenous access, improving patient satisfaction and reducing the need for central venous lines 2, 3.
- However, ultrasound-guided cannulation can also result in a high rate of premature catheter failure, highlighting the need for comprehensive knowledge of the procedure to improve cannulation success and avoid complications 2.
Ultrasound-Guided Cannulation Techniques
- The use of longer-than-normal catheters has been shown to provide a solution to low survival rates of standard-length catheters in obese patients 4.
- A study comparing standard-length catheters with long catheters in ultrasound-guided peripheral vein cannulation found that both had high success rates, but long catheters had a lower risk of catheter failure 4.
- Ultrasound-guided internal jugular vein cannulation can be successful in obese patients, even in a forced semi-sitting position, using a lateral-oblique probe position 5.
Challenges in Obese Patients
- Central venous cannulation can be difficult in morbidly obese patients due to the increased risk of carotid artery puncture and overlapping of the internal jugular vein and carotid artery 6.
- However, a study found no statistically significant difference in the success rate of internal jugular vein puncture between morbidly obese patients and nonobese patients, highlighting the importance of using ultrasound guidance to minimize complications 6.
- Keeping the head in a neutral position in morbidly obese patients can help minimize the overlapping of the internal jugular vein and carotid artery, reducing the risk of carotid artery puncture 6.