A catheter tube is a hollow tube that can be inserted into a body cavity to drain or inject fluids. These are usually thin and flexible, and are often used to drain urine from the bladder, open a vein or artery in or near the heart, or to drain fluids from abscesses in other body cavities and organs. Doctors may also place catheter tubes to measure blood pressure or intracranial pressure in the skull.
In one form or another, catheters have been used since ancient times. The Syrians used reeds — while the Greeks used metal tubes — inserted in the urethra to drain the bladder. The tubes have been used in modern medicine since the 1860s. The first modern, disposable catheter was invented in the 1940s.
Heart catheters are usually inserted into either side of the heart from the groin or arm. Doctors guide the catheter into the vessels of the heart using an x-ray machine that allows them to see the process. Once the catheter tube is inserted, doctors can collect blood, measure pressure and oxygen, and examine the arteries for signs of disease or defect.
Drainage catheters are usually inserted, via needle, directly into the body where fluid has collected. Abscesses and cysts often need to be drained in this way to treat infection and clear the swelling. Doctors and surgeons also use drainage catheters to remove accumulated fluid from the lungs, chest cavity, or spinal column. Thin catheter tubes are also used to administer anesthesia and other medications, particularly in the epidural space in the spinal canal.
Urinary catheters, or Foley catheters, are extremely common — both for patients admitted to a hospital or other health facility, and for those at home. A catheter tube may be inserted in the bladder for short or long-term use due to urinary incontinence or leakage, dementia, spinal cord injury, surgery, or any other condition that makes it difficult or impossible for a patient to control urination.
Typically, a urinary catheter is inserted into the bladder through the urethra, though it can also be placed directly, through a small hole in the abdomen. The catheter tube has a small balloon at the end to prevent it from sliding out of the bladder. This can be deflated, by a valve, when it is time to remove or replace the catheter.
Some urinary catheter tubes are attached to a condom-like sheath that is placed over the penis. This type of catheter is often used for men with dementia to prevent the patient from removing the tube. Patients who use urinary catheters at home must be extremely careful to keep the tube clean and sterile, and must follow their doctors’ instructions on when to remove and change the catheter.
