E L I M I N A T I O N a n d G A S E X C H A N G E / O X Y G E N A T I O N
Normal Anatomy and Physiology of Elimination
Urinary System Anatomy
Humans typically possess two kidneys (right and left).
There are two ureters (right and left) connecting each kidney to the bladder.
The bladder is a single organ used for urine storage.
Urine exits the body through a single urethra.
Sexual Dimorphism in Urinary Anatomy:
The female urethra is significantly shorter than the male urethra.
This shorter distance provides a narrower "highway" for pathogens (bacteria and bugs) to travel to the bladder and ureters, resulting in a higher incidence of Urinary Tract Infections (UTIs) in females.
In clinical practice (e.g., catheter insertion), urine output is often achieved more quickly in females due to the short urethra.
For male patients, it is recommended to insert an indwelling catheter to the Y-bifurcation to ensure proper placement.
Gastrointestinal (GI) System Anatomy
The GI tract is a long, continuous tube beginning at the mouth and ending at the anus.
Mouth and Esophagus: Site of chewing and swallowing, which initiates the digestive process.
Stomach: Highly acidic environment where enzymes and acids mix with food. The stomach lining is critical for protection against these acids.
Small Intestine: Primary site for nutrient absorption. Stool here is typically very liquidy.
Large Intestine: Responsible for removing water from waste. As stool travels through the large intestine, it becomes more formed.
Rectum and Anus: Terminal end where stool is excreted.
Digestion Speed: If waste moves through the system too quickly (peristalsis is accelerated), there is insufficient time for water absorption, resulting in diarrhea.
Expected Elimination Findings and Standards
Expected Urinary Findings
Color: Ranges on a spectrum, but the ideal color is light yellow, frequently referred to as "straw."
Clarity: Should be clear. Cloudiness, particles, or sediment are abnormal.
Odor: Should be virtually odorless (malodorous/foul-smelling is abnormal).
Urinary Output (UOP) Benchmarks:
Normal adult output should be approximately .
In a clinical setting, an output of less than is deemed concerning and must be reported to a provider.
Expected Bowel Findings
Process: Movement occurs via peristalsis, an involuntary muscle contraction. Defecation is triggered when stool reaches the rectum, creating a sensation of need.
Frequency: Highly variable between individuals; a normal range is between three times per day to three times per week (approximately every other day).
Pain: Bowel movements should never be painful or difficult.
Assessment: It is essential to ask the patient about their personal "normal" baseline to identify deviations.
Bristol Stool Chart (Objective Tool)
Used to categorize stool morphology objectively to ensure consistent communication between healthcare providers.
Type 3 and Type 4 are considered the ideal and expected normal stool shapes.
Pediatric versions often use kid-friendly terms to help children describe their elimination.
Risks and Factors Influencing Elimination
Vulnerable Populations
Young Children: Bodies are still maturing and growing; children may have picky eating habits or high activity levels affecting elimination.
Older Adults: Renal function naturally declines over 70–80 years. Bladder and bowel muscle tone may decrease. Mobility often declines, which slows the GI system.
Pregnant Women: High levels of progesterone slow down GI motility. Displacement of organs and changes in diet/activity also contribute to issues.
External and Lifestyle Risk Factors
Medications:
Diuretics increase urine production.
Opioid pain medications frequently cause constipation.
Drying agents can decrease urinary frequency.
Dietary Restrictions: Celiac disease, religious preferences (e.g., Kosher or avoiding pork), NPO status (nothing by mouth), or fluid restrictions (e.g., Chronic Kidney Disease limited to daily).
Privacy: Patients often struggle to eliminate in non-private clinical settings; lack of privacy can cause voluntary retention.
Activity: High activity outside (sweating) can lead to concentrated, darker urine.
Pathological Alterations in Elimination
Urinary Incontinence (Types)
Stress Incontinence: Leakage triggered by physical pressure such as coughing, laughing, sneezing, jumping, or running.
Urge Incontinence: A sudden, intense need to urinate followed by involuntary leakage before reaching a toilet.
Reflex Incontinence: Urine loss due to nerve damage, often seen in spinal cord injuries or neurological disorders.
Overflow Incontinence: Incomplete bladder emptying leads to the bladder reaching capacity and leaking.
Functional Incontinence: Physical or cognitive inability to reach the toilet in time (e.g., Parkinson’s disease, hip fractures, or stroke).
Nocturnal Enuresis: Nighttime bedwetting; common in pediatrics but abnormal in adults.
Urinary Retention
Failure to empty the bladder completely, which can be acute or chronic.
Symptoms include abdominal distension, pain, and frequent "dribbling" (voiding small amounts often).
Urinary Hesitancy: A delayed or weak start to the urinary stream.
BPH (Benign Prostatic Hyperplasia): In aging males, the prostate hypertrophies and compresses the urethra, narrowing the pathway for urine.
Bowel Alterations
Constipation: Defined as fewer than three bowel movements per week. Stool becomes hard and dry as water is continuously absorbed in the large intestine.
Fecal Impaction: A severe blockage of stool. Paradoxically, liquid stool may leak around the impaction, appearing like diarrhea.
Diarrhea: Loose, watery stools occurring more than three times in 24 hours.
Acute: 1–2 days.
Persistent: > 2 weeks.
Chronic: > 4 weeks.
Bowel Incontinence (Fecal Incontinence): Involuntary passage of stool. Urge (unable to reach toilet) or Passive (unaware of leakage).
Urinary and Bowel Diversions
Urinary Diversions
Indwelling Catheter (Foley): A tube remaining in the bladder; risk of CAUTI (Catheter-Associated Urinary Tract Infection).
Intermittent Catheter (Red Robin): "In and out" procedure to empty the bladder and then removed.
Ureteral Stent: A hollow cylinder placed in the ureter to keep it open for urine flow.
Urostomy (Ileal Conduit): Surgical creation of a stoma on the abdomen; urine flows from kidneys/ureters into an external collection bag.
Nephrostomy: A tube placed directly into the kidney to drain urine.
Cystostomy (Suprapubic Catheter): A tube placed surgically through the abdominal wall directly into the bladder.
Bowel Diversions
Bowel Management System (Rectal Tube): A non-surgical system for liquid stool. Risk of injuring the rectal sphincter if the retention balloon is overinflated.
Ileostomy: Placed in the ileum (small intestine). Output is liquid, watery, and high volume. High risk for dehydration.
Colostomy: Placed in the colon (large intestine). Depending on the site (ascending, transverse, descending), stool becomes increasingly solid and formed as it nears the rectum.
Stoma Assessment: A healthy stoma is "beefy red" and moist (perfused). Abnormal findings include stomas that are dusky, pale, blue, black, or dry.
WOCN: Certified Wound Ostomy Continence Nurses are specialized resources for troubleshooting and patient education.
Diagnostic Procedures
Urinary Testing
Post-Void Residual (PVR): Use of a non-invasive bladder scanner at the bedside to measure the volume of urine remaining in the bladder after the patient voids.
Urinalysis (UA): Visual and chemical examination (color, clarity, sediment). Bedside dipsticks can provide immediate results.
Urine Culture: Takes 24–48 hours to grow organisms; used to determine specific bacterial growth and appropriate antibiotics.
24-Hour Urine Collection: All urine over a 24-hour period is collected in one container and must be kept refrigerated or on ice to preserve chemical integrity.
Clean Catch Midstream: Nursing responsibility to educate the patient to void a small amount into the toilet first, then catch the "midstream" sample to avoid skin flora contamination.
Bowel Testing
Fecal Occult Blood Test (Hemoccult): Detects microscopic blood in stool.
Melena: Term for dark, tarry, black stools indicating potential upper GI bleeding.
False Positives: Can be caused by red meat, beets, broccoli, aspirin, ibuprofen, or excessive Vitamin C.
Stool Culture: Used to detect organisms like C. diff (Clostridium difficile).
Nursing Interventions for Elimination
Facilitating Urinary Elimination
Tools: Bedpan, urinal (for males), toilet hat (for I&O measurement), and bedside commode (feels most like a natural toilet).
Bladder Training: Scheduled voiding (e.g., every 15 minutes, gradually increasing to hourly) to regain control over frequency.
External Catheters: Condom catheters (males) and PureWick (females) provide non-invasive alternatives to indwelling catheters.
Bladder Irrigation: Flushing the bladder (often post-prostate surgery) to prevent blood clots.
Calculation: Must subtract the irrigation fluid from the total output to find the "True Urine" ().
Facilitating Bowel Elimination
Enemas: Instillation of solution (soap suds, mineral oil, saline) into the rectum.
Positioning: Left lateral Sims position (left side with right leg flexed toward chest).
Height: Hang the enema bag no higher than 18 inches above the anus to control the speed of gravity flow.
Lifestyle: Increase dietary fiber and fluid intake.
Medications: Laxatives and stool softeners should only be used as a short-term solution to avoid physiological dependency.
Oxygenation and Gas Exchange
Respiratory Physiology
Surfactant: A chemical lubricant that keeps alveoli (air sacs) plump. Without it, alveoli collapse.
Atelectasis: The medical term for the collapse of alveoli.
Ventilation vs. Perfusion (VQ):
Ventilation (V): The actual flow of air in and out of the alveoli.
Perfusion (Q): The blood flow through the alveolar space where actual gas exchange happens (O2 in, CO2 out).
Oxygen Transport: Oxygen attaches to hemoglobin on red blood cells. Conditions like sickle cell disease or low RBC counts impair this transport.
Risk Factors for Respiratory Issues
Modifiable: Smoking, drug use, dietary habits, sedentary lifestyle, and stress.
Non-Modifiable: Genetics and chronological age.
Oxygen Delivery Devices
Nasal Cannula: Least invasive, low flow, does not obstruct the mouth. Supplemental oxygen starts above room air (21% FiO2).
High Flow Nasal Cannula: Provides precise, humidified oxygen to prevent dry membranes and epistaxis (nosebleeds).
Simple Face Mask: Fits over nose and mouth; can cause anxiety in some patients.
Non-Rebreather Mask: Used for higher oxygen needs; requires flow meter settings of 10–15 liters.
Venturi Mask: Color-coded valves allow for highly prescriptive, specific FiO2 delivery (e.g., Red valve = 40% FiO2 at 8 liters).
Chronic Considerations (COPD): Patients with chronic conditions like COPD often live with lower oxygen saturations (87–91%). Over-oxygenating these patients can dangerously lower their respiratory drive.
Home Oxygen Safety
Oxygen is a flammable drug; strictly no smoking or open flames (stoves, candles).
Patients must have enough portable oxygen to cover all travel/errands.
Place "Oxygen in Use" signs in the home.
Nursing Interventions for Respiratory Support
Positioning: Raise the head of the bed (Fowler’s position); encourage tripod positioning (hunching over a bedside table).
Sputum Collection: Best collected first thing in the morning before eating or drinking.
Coughing and Splinting: Use a pillow to hold against abdominal/thoracic incisions to reduce pain during coughing. Use "huff coughing" (short, back-to-back exhales) as an alternative to one forceful cough.
Incentive Spirometer: Measures voluntary inhale (inspiratory volume).
Instruction: "Like drinking a milkshake through a thin straw."
Frequency: 10 times per hour.
Technique: Inhale, hold for 3–5 seconds, then exhale.
Pursed Lip Breathing: Breathe in through the nose for a count of two; breathe out through pursed lips for a count of four. This slows the respiratory rate and alleviates breathlessness.