Urinary Tract Physiology and Common Issues
Physiology of the Urinary Tract
Urine is formed in the nephrons. The urinary tract is not involved in urine formation; it only stores the urine and facilitates its elimination. The kidney uses the following mechanisms:
1. Filtration
The first step in urine formation. Blood reaches the kidney capillaries, and plasma, along with small dissolved molecules like Na+, passes through the thin wall of Bowman’s capsule. Approximately 900 liters of plasma pass through the capillaries daily, with 180 liters being filtered, resulting in urine.
2. Reabsorption
After filtration, the resulting liquid passes through the tubules. Normally, only about 1.5 liters of urine are excreted daily, meaning 99% of the filtered fluid is reabsorbed as it travels through the nephron. This process involves penetrating and eliminating unnecessary substances in the urine. Hormones regulate the absorption and elimination of water and electrolytes according to the body’s needs.
3. Excretion
As urine forms, it drips into the renal calyces via the collecting tubules. From there, it goes to the renal pelvis, the ureters, and finally to the bladder, where it is stored. When the bladder fills, the pressure exerted by the urine on the bladder walls stimulates nerve endings, triggering the urge to urinate. The second sphincter then opens, and urine is expelled.
Urinary Retention
Urinary retention causes severe pain and can lead to infection due to urine stagnation. Before resorting to a catheter, it is appropriate to encourage certain techniques to facilitate urination:
- Ensure adequate fluid intake.
- Apply heat to the bladder area to relax the muscles.
- Pour warm water over the perineal area or run tap water.
- Ask the patient to sit on the toilet, leaning forward to press their belly with their hands.
Urinary Incontinence
Urinary incontinence is the inability to control urine. It is important to try to solve or improve the situation because:
- It affects the patient’s self-esteem.
- Contact with urine can promote the proliferation of germs and pressure ulcers.
- It can cause unpleasant odors.
- The patient’s independence decreases.
Solutions for Urinary Incontinence
- Training program: Teach the patient a series of exercises to strengthen the perineal muscles. The patient should sit in a chair with their feet flat on the floor and knees apart, then contract and relax the perineal muscles ten times. This exercise should be performed several times a day. Start by taking small amounts of liquid every 2 hours while performing a massage on the bladder during urination.
- Use of external urine collection devices: For men, an adhesive tape is placed around the penis to hold the collector and position the urine collection bag. For women, waterproof diapers or panties can be used.
- Intermittent catheterization.
- Permanent catheterization.
Catheterization
Catheterization involves inserting a tube into the bladder to evacuate urine.
Frequent Reasons for Catheterization
- Urinary retention
- Diuresis control
- Urinary incontinence
Most catheterizations are conducted at the urethral meatus. The duration of catheterization varies: it can be temporary (the patient is catheterized for short periods, sometimes only minutes) or permanent (the catheter remains in place for extended periods, days, or months).
Auxiliary Personnel Responsibilities (APR) in Catheterization
- Assemble the equipment and prepare materials.
- Prepare, position, and reassure the patient.
- Collaborate during the procedure.
- Gather materials.