Classification and use of medical catheters

Medical catheters are widely used and are indispensable tools in modern medicine. Their classification is complex, with various approaches based on various dimensions (such as application site, function, and material). Classification by application site and function is the most core clinical classification method, directly related to the catheter's intended use.

· Central venous catheter: inserted into a large central vein (such as the subclavian vein and internal jugular vein) for infusion, blood transfusion, measurement of central venous pressure, long-term nutritional support, etc.
- A peripherally inserted central venous catheter (PICC) is inserted through a peripheral vein in the upper arm, with the distal end reaching the superior vena cava. It is suitable for medium- to long-term (weeks to months) intravenous treatment.
- Tunneled central venous catheters: Some catheters are routed through a subcutaneous tunnel before entering the blood vessels, which can reduce the risk of infection, such as the cuffed catheters used by hemodialysis patients.
- Implantable infusion tube: completely implanted under the skin, infusion is performed through non-destructive needle puncture of the port, with the lowest risk of infection, suitable for long-term, intermittent chemotherapy or infusion.

· Peripheral intravenous catheter: The most common cannula, used for short-term (usually a few days) intravenous infusion and medication.
· Arterial catheter: Inserted into an artery (such as the radial artery) and used to continuously monitor arterial blood pressure or to collect frequent arterial blood samples.
· Pulmonary artery catheter: A special, long, thin catheter that enters the central vein, passes through the right heart, and finally reaches the pulmonary artery. It is used to monitor hemodynamic parameters such as heart function and cardiac output.
· Angiography catheter: used for angiography, which injects contrast agent into specific blood vessels (such as coronary arteries and cerebral blood vessels) to show their morphology under X-ray fluoroscopy.

· Balloon catheter: A catheter with a balloon at the tip that is used to widen narrowed blood vessels or heart valves.
-Percutaneous coronary angioplasty balloon catheter: used to dilate the coronary arteries.
-Peripheral balloon catheter: used to dilate limb or renal arteries, etc.

· Catheter: Inserted through the urethra into the bladder to drain urine.
-Foley catheter: The most commonly used, with a balloon, fixed in the bladder, used for indwelling catheterization.
-Intermittent urinary catheter: It is used once and is removed after emptying the bladder. It is mainly used for patients who need regular catheterization.

3. Airway tube
· Endotracheal intubation: Insertion of a tube into the trachea through the mouth or nose to create an artificial airway for anesthesia or mechanical ventilation.
· Tracheostomy tube: inserted through the tracheostomy opening in the neck and used for patients who require an artificial airway for a long time.

4. Digestive tract catheter
· Nasogastric tube: inserted into the stomach cavity through the nose for tube feeding or drainage of gastric contents.
· Nasoenteric tube: inserted through the nose, with the tip passing through the pylorus into the duodenum or jejunum for enteral nutrition.
· T-tube: A T-shaped catheter placed in the common bile duct after biliary surgery to drain bile and support the duct.

5. Body cavity drainage tube
· Chest tube: Inserted into the chest cavity to drain air (pneumothorax) or fluid (pleural effusion, hemothorax).
· Abdominal drain: Placed in the abdominal cavity to drain fluid, blood, or pus, such as a drain after surgery.
· Ventricular drain: Inserted into the ventricles of the brain to drain cerebrospinal fluid and reduce pressure within the skull.

6. Other special catheters
· Radiofrequency ablation catheter: used for cardiac electrophysiological examinations, using radiofrequency energy to ablate abnormal electrical pathways (such as for the treatment of atrial fibrillation).
· Thrombectomy catheter: used to mechanically remove a blood clot from a blood vessel.
· Stent delivery system catheter: used to precisely deliver vascular stents to the lesion site and release them.
· Hysterosalpingography catheter: used to inject contrast agent into the uterus and fallopian tubes to check their patency.