A Foley catheter is a flexible tube inserted through the urethra into the bladder for continuous urine drainage. It is an indwelling medical device designed to remain in place for an extended period. The catheter system has two separate channels, or lumens: one drains urine into a collection bag, and the other is solely for inflating the retention balloon at the tip. The balloon’s purpose is to anchor the catheter securely within the bladder, preventing accidental slippage or migration.
Determining the Exact Volume Needed
The amount of fluid needed to inflate the retention balloon is not a universal standard but is specific to the catheter being used. This required volume is determined by the manufacturer and is typically printed on the catheter shaft, near the inflation port, and listed on the product packaging. Ignoring this specified volume can lead to complications, making it necessary to always check the device itself rather than relying on general rules.
Common adult Foley catheters typically feature balloon volumes of 5 milliliters (mL) or 10 mL. Specialized catheters, such as those used after certain urological surgeries, may have larger capacities, sometimes up to 30 mL. Using the exact volume specified ensures the balloon is inflated to the correct size and shape for optimal retention, allowing the device to perform its function safely and effectively.
Step-by-Step Inflation Technique
The process of balloon inflation requires using the correct materials and following a specific technique. The material of choice is sterile water, which should be drawn up into an appropriately sized syringe. The syringe must be the correct size to hold the exact volume specified by the manufacturer, ensuring precise measurement and delivery.
The use of sterile water is mandated because other solutions, particularly saline, can lead to complications over time. If saline is used, the salt crystals can precipitate out of the solution within the narrow inflation channel as water slowly escapes via osmosis. This crystallization can ultimately block the channel, making it difficult or impossible to deflate the balloon when the catheter needs to be removed.
To begin the inflation, the syringe is gently connected to the inflation port on the catheter. The sterile water is then injected slowly and steadily into the port. Slow injection allows the fluid to travel through the narrow lumen and fill the balloon gradually, minimizing stress on the balloon material and surrounding tissue. Any resistance or patient discomfort during this injection is a warning sign that the catheter tip may not be fully inside the bladder and that inflation should be immediately stopped.
Consequences of Under or Over-Inflation
Failing to adhere to the manufacturer’s specified volume creates distinct and significant risks for the patient. Under-inflation, where less than the recommended volume is introduced, results in poor retention and a non-spherical balloon shape. An inadequately sized balloon cannot properly anchor the catheter, increasing the likelihood of accidental dislodgement or migration into the urethra. This unintentional movement can cause significant trauma to the delicate lining of the urethra and lead to pain and bleeding.
Conversely, over-inflation, using more than the specified volume, stretches the balloon material beyond its intended capacity. This excessive volume can lead to uneven inflation and place undue pressure on the bladder neck, the sensitive area where the bladder connects to the urethra. The high pressure exerted by an over-inflated balloon can result in pressure necrosis, which is tissue damage caused by compromised blood flow. Over-inflation also increases the risk of the balloon rupturing, which complicates catheter removal.