What lubricant should be used for urinary catheters

Urinary catheter is a medical device used for procedures such as urine drainage and bladder irrigation. It is made of materials such as natural latex, rubber, silicone, or polyethylene terephthalate (PVC), and is mainly available in single-lumen, double-lumen, and triple-lumen models. It has a very wide range of clinical applications. When it comes to catheter lubrication, most nurses will immediately say: paraffin oil.

When asked about their selection criteria, the reasons generally fell into three categories:
- They had been using paraffin oil since starting work and had not observed any abnormalities, nor had anyone raised any objections.
- They had heard that using paraffin oil to lubricate urinary catheters could cause balloon rupture, but this only applied to latex catheters; silicone catheters were not restricted.
- Basic nursing textbooks do not explicitly prohibit the use of paraffin oil for lubrication, so using paraffin oil was not a problem.

Based on the above responses, it's clear that nursing staff have a high level of trust in traditional practices and textbooks, but pay insufficient attention to the instruction manuals. This is because both silicone-coated latex catheters and their instruction manuals explicitly state that paraffin oil should not be used to lubricate the catheter. Indeed, paraffin oil is a commonly used lubricant in routine nursing work, especially in current catheterization procedures where most use disposable catheterization kits with pre-installed lubricants. Furthermore, some of these kits don't specify the composition of the lubricant, only vaguely labeling it as lubricant, leading to the misconception that lubricant is simply paraffin oil.

Urinary catheters are mostly made of latex or silicone. According to the principle of organic compounds dissolving each other, if they come into contact with paraffin oil, they will swell, potentially causing the water-filled balloon at the end of the catheter to rupture spontaneously. This is not uncommon in clinical practice.Authoritative statistical reports indicate that latex catheters most prone to balloon rupture are due to the use of petroleum-based lubricants not as specified in the instructions.

The aforementioned report also mentions the hazards of paraffin oil in lubricating latex catheters, stating that it can cause balloon rupture. Liquid paraffin is corrosive to catheters, reducing their tightness and increasing the risk of breakage, especially for thin-walled balloons. Therefore, it should not be used for lubricating latex catheters.

So, can silicone catheters be lubricated with paraffin oil? The answer is definitely no! The instruction manual for silicone catheters explicitly prohibits the use of paraffin oil for lubrication. Furthermore, silicone catheters should not be lubricated with methyl silicone oil! This is because methyl silicone oil reduces the intermolecular forces between silicone rubber chains, thereby reducing the catheter's tensile strength and increasing the risk of catheter breakage and balloon rupture.Besides causing airbag rupture, paraffin oil itself also poses certain risks to the human body. As a colorless and odorless mixture obtained from crude oil fractionation, it can be carcinogenic if it is not properly purified or has high levels of impurities. In addition, paraffin oil is insoluble in water and easily adheres to surfaces. Patients with long-term indwelling urinary catheters are prone to complications such as urethral stricture and urinary tract infection.

What lubricants are used for different types of urinary catheters?
- Latex urinary catheters: Dimethyl silicone oil (commonly used in gastroscopy and colonoscopy), lidocaine gel, tetracaine gel, glycerol, povidone-iodine.
- Silicone urinary catheters: Lidocaine gel, tetracaine gel, glycerol, povidone-iodine.
Note: Povidone-iodine is indeed safe and effective in most cases. However, it should be noted that a very small number of people are allergic to povidone-iodine.