Fluids, electrolytes, acid-base & nutrition

• Water is 50–60% of an adult's body weight.
• Osmosis: water moves across a membrane from the weaker (more dilute) side to the stronger (more concentrated) side. No energy needed.
• Diffusion: solutes (like electrolytes) spread from high concentration to low. No energy needed.
• Active transport: uses energy (ATP, adenosine triphosphate) to move solutes from low concentration to high, like the sodium–potassium pump.
• Filtration: pressure pushes fluid out of the capillaries into the tissues.
• Sensible losses can be measured (urine, sweat, liquid stool). Insensible losses can't (breathing, evaporation from the skin, water in formed stool).
• Third spacing: fluid gets trapped in a body space where the body can't use it (burns, cirrhosis, pancreatitis). It's still in the body, but blood volume drops.

Measure all I&O in mL: 1 oz = 30 mL (an 8-oz cup is 240 mL). Intake includes foods that melt at room temperature, IV flushes and IV medications, tube feedings and irrigants. Output includes blood, emesis, diarrhea, and wound or tube drainage. Report urine output under 30 mL/hr.

Measure with calibrated containers, read at eye level. Total I&O at least every 8 hours: intake minus output; a negative number means a deficit. For incontinence briefs, weigh them: 1 g = 1 mL. Weigh the client daily at the same time, after voiding, in the same type of clothes (same linens on a bed scale).

Hct (hematocrit) and BUN rise with fluid deficit (hemoconcentration) and fall with overload (hemodilution). Older adults are at higher risk for both: less body water, a weaker thirst sense, and kidneys and heart that handle shifts less well. Skin turgor is less reliable in them.

Fluid restriction tips: remove the water pitcher, serve fluids in small cups so they look full, set short 1–2 hour goals, tell dietary staff and every shift how much the client may have, and record all oral intake.

One slide lists magnesium as 1.3–2.1 mg/dL, but the magnesium slides and ATI use mEq/L. This guide uses mEq/L.

• More normal ranges: chloride 98–106 mEq/L, phosphorus 3–4.5 mg/dL
• Sodium is the main electrolyte outside the cells (ECF); potassium is the main one inside the cells (ICF)
• Positive ions (cations): sodium, potassium, calcium, magnesium
• Negative ions (anions): chloride, phosphate, bicarbonate
• Highest risk for imbalances: older adults and clients with chronic illness or cognitive disorders

Both imbalances affect the brain because water shifts in or out of brain cells.

• Hyponatremia (brain cells swell): also caused by SIADH, heart failure, NG suction, tap-water enemas and diuretics. Headache, muscle twitching, decreased deep tendon reflexes, seizures. Fluid restriction for water excess; 3% saline only for severe cases. Change positions slowly; watch breathing if muscles are weak.
• Hypernatremia (brain cells shrink): also caused by fever, heavy sweating, burns, watery diarrhea, NPO status, hypertonic tube feedings. Thirst, dry sticky mucous membranes, warm flushed skin, fever, brisk reflexes, oliguria. Oral care to ease thirst, low-sodium diet, safety for confusion.

Foods high in potassium: baked potatoes, bananas, oranges, spinach, avocado, cantaloupe, salmon. Salt substitutes contain potassium, so clients with hyperkalemia should avoid them. Insulin pushes potassium into the cells, so check blood glucose (risk of hypoglycemia). Hypokalemia raises the risk of digoxin toxicity. Continuous ECG (electrocardiogram) monitoring for both.

• More hypocalcemia risks: thyroid or neck surgery (the parathyroid glands sit behind the thyroid), low magnesium, low albumin, many transfusions (the preservative in stored blood binds calcium), pancreatitis, kidney disease, long-term steroids, and acid-reducing medications.
• Ionized calcium (the active, unbound part, about half the total) is low under 4.5 mg/dL. It needs its own lab order; the CMP gives only total calcium.
• Hypocalcemia also brings hyperactive reflexes, prolonged QT on the ECG, and diarrhea. Nursing: seizure and fall precautions, emergency equipment nearby (laryngeal spasm), calcium and vitamin D. Calcium supplements absorb best in doses under 500 mg at a time.
• Hypercalcemia can also come from thiazide diuretics, lithium, too much vitamin D, and prolonged bed rest (bones release calcium). It brings decreased reflexes, thirst and polyuria. Nursing: more fluids, limit calcium, get the client moving, and watch for fractures.

Low magnesium often comes with low calcium and low potassium, and can also cause positive Trousseau's and Chvostek's signs. High magnesium can slow breathing and heart rate; check reflexes and report absent ones. Calcium gluconate treats severe high magnesium (and protects the heart in high potassium).

• Hypomagnesemia causes: alcohol use disorder, diarrhea, diuretics, PPIs (proton pump inhibitors), malnutrition
• Hypomagnesemia signs: hyperactive reflexes, tremors, tetany, high BP, tachycardia, dysrhythmias. Oral magnesium can cause diarrhea.
• IV magnesium is a high-alert medication: double-check the dose with another nurse. Given too fast, it causes flushing, sweating and slowed breathing.
• Hypermagnesemia causes: kidney disease, and too many magnesium laxatives or antacids
• Hypermagnesemia check: the patellar reflex; absent = high magnesium
• Severe hypermagnesemia: slow, shallow breathing, bradycardia, low BP, cardiac arrest
• Hypermagnesemia treatment: stop magnesium sources; loop diuretics, calcium gluconate, dialysis if the kidneys can't clear it

The slides also list D5W (dextrose 5% in water) as isotonic, but your instructor said it isn't a focus for now.

• Hypotonic (0.45% saline): watch for low BP; avoid with burns, liver disease, trauma, or increased intracranial pressure (swelling brain cells make it worse).
• Hypertonic: watch for fluid overload; may be avoided with heart or kidney disease. D10W can irritate veins, so a central line is preferred.
• Lactated Ringer's: common for burns and trauma; use with caution in kidney failure.
• Colloids: albumin (natural; counts as a blood product) and synthetic dextran and hetastarch. They pull fluid into the vessels, so watch for fluid overload and allergic reactions. Albumin must finish within 4 hours of opening.

Larger gauges (16–18) for trauma, surgery, rapid fluids and blood; 20–24 for routine or fragile veins. Start distal on the nondominant arm. Avoid veins on the side of a mastectomy, an AV (arteriovenous) fistula, or recent infiltration. Clip hair; never shave. Insert bevel up at 10–30°. Older adults or clients on anticoagulants: use a BP cuff instead of a tourniquet and a smaller catheter.

Needlestick prevention: use needleless systems and safety devices, never recap, and drop needles in a sharps container right away.

The slides only name the midline. In ATI, it's a longer peripheral catheter that can stay in place longer than a regular peripheral IV. The provider may consider a midline (or a CVAD) when therapy is expected to last more than about 5 days or the fluid irritates small veins. A short peripheral IV is enough for short-term therapy, such as fluids or medications for less than a week.

• PICC: put in through an arm vein; the tip sits in the vena cava
• Nontunneled central catheter: put straight into the jugular, subclavian or femoral vein
• Tunneled catheter: runs under the skin before entering the vein and can stay for years; keep scissors and other sharp objects away from it
• Implanted port: placed under the skin, usually on the chest, and accessed with a special noncoring needle
• CVADs are flushed with saline or heparin per facility policy to keep them from clotting. Clients who are unstable or getting intensive treatment such as chemotherapy may need one

A blood type is the letter (A, B, AB or O) plus the Rh factor: positive (+) if the Rh protein is present, negative (–) if not. Matching matters because the immune system attacks red cells with markers it doesn't have.

Most common: O+. Least common: AB–. O– is used in emergencies when the client's type isn't known yet.

• Consent first; 18–20 gauge IV already in place
• Two nurses check the unit against the client at the bedside
• Only 0.9% normal saline runs with blood
• Stay with the client the first 15 minutes (most reactions happen then); vital signs before, at 15 min, and per policy
• Finish within 4 hours
• Reaction (fever, chills, back pain, hives, dyspnea, low BP): stop the transfusion, keep the vein open with normal saline through new tubing, notify the provider, send the bag back to the blood bank

• Blood is typed and crossmatched first. PRBCs are usually given when Hgb (hemoglobin) drops to 7–8 g/dL; each unit raises Hgb about 1 g/dL and Hct about 3%
• Change blood tubing after every unit or every 4 hours. Never give IV medications through a line running blood

Metabolic acidosis (diabetic ketoacidosis, diarrhea, kidney failure) brings deep, rapid Kussmaul breathing. Metabolic alkalosis comes from prolonged vomiting, gastric suction, or too many antacids.

The body compensates with the other system: the lungs respond in minutes to hours, the kidneys in hours to days. Kussmaul breathing is the lungs blowing off CO2 to raise the pH.

No more than 35% of calories should come from fat. Extra glucose is stored as glycogen in the liver and muscles as backup energy. A healthy weight-loss pace is 1–2 lb a week, and losing just 5–10% of body weight improves BP, blood glucose and cholesterol. Adults need 150 minutes of moderate activity a week plus 2 days of muscle strengthening.

Supplements don't replace a healthy diet, and the FDA (Food and Drug Administration) doesn't approve them before they're sold. Ask about them in every nutrition assessment, and clients should check with their provider first.

• St. John's wort weakens birth control, heart medications and antidepressants
• Vitamin K weakens warfarin (raises clot risk); keep vitamin K intake steady
• Antioxidant supplements (vitamins C and E) can weaken chemotherapy
• Too much iron: nausea, vomiting, liver damage. Too much vitamin A: headaches, weaker bones

• Everything on the label is per serving. Eat two servings, double every number.
• %DV (percent Daily Value): 5% or less = low, 20% or more = high. Choose high %DV for fiber, vitamin D, calcium, potassium and iron; low %DV for sodium, added sugars and saturated fat.
• Added sugars are counted inside total sugars.
• Net carbs = total carbohydrates − fiber (and sugar alcohols). 10 g carbs with 5 g fiber = 5 g net carbs.
• Sodium: no more than 2,300 mg a day (about 1 teaspoon of salt) for healthy adults, less with heart disease. About 70% comes from processed and restaurant food.
• Fiber: women 19–30 need 28 g a day, men 19–30 need 34 g; needs go down with age.

BMI = weight (kg) ÷ height (m)². Example: 80 kg and 1.6 m tall → 1.6 × 1.6 = 2.56 → 80 ÷ 2.56 = 31.3 (obese).

In pounds and inches: weight ÷ height ÷ height × 703. Example: 170 lb, 64 in → 170 ÷ 64 ÷ 64 × 703 = 29.2 (overweight).

Signs of poor nutrition: dry, brittle hair and nails; dry, scaly skin; loss of fat under the skin; flaccid muscles, weakness and fatigue; swollen or bleeding gums; dry, dull eyes; poor posture; mental status changes; changes in weight and bowel pattern; frequent infections. Low vitamin C → irritated gums.

Purging by vomiting, laxatives or diuretics ties back to this week: low potassium and fluid volume deficit.

• NPO means nothing at all, not even ice chips; clarify with the provider whether medications are allowed. Restarting food needs a provider's order.
• Mechanical soft: diced or ground foods. Dysphagia diet: pureed food and thickened liquids.
• Low sodium: no added salt, or 1–2 g sodium a day. Low cholesterol: no more than 300 mg a day.
• Diabetic: balanced protein, fat and carbohydrate, about 1,800 calories.
• The nurse's job: make sure the client gets the prescribed diet and help advance it as ordered.

Taught by a speech therapist after a swallow evaluation. Risk factors for aspiration: stroke, acid reflux, mouth sores, dental problems.

Also: support the head, neck and upper back; watch for coughing, choking, gagging and drooling; oral care after meals and snacks.

Fasting glucose (nothing by mouth for at least 8 hours): 74–106 mg/dL. Two hours after a meal, blood glucose should be back under 140 mg/dL.

Hypoglycemia (glucose under 70 mg/dL): give something with sugar that raises glucose quickly (glucose tablets or gel, regular soda, juice, honey, or hard candy), recheck in 15 minutes, and repeat until it's at least 70. Then a meal or snack.

Check glucose before giving insulin. Inject at 90° (45° if the client has little fat under the skin), at least 2 in from the navel, away from scars or bruised, lumpy or numb skin.

Nasal tubes are for under about 4 weeks. Small-bore feeding tubes are 8–12 French for adults; large-bore tubes (12–18 French) are for suction, lavage (washing out the stomach) and decompression.

Enteral feeding is preferred over parenteral: fewer infections and shorter hospital stays. It's not used with GI bleeding, bowel obstruction, or a bowel without enough blood flow. A client is NPO at least 8 hours before a G-tube is placed.

Don't rely on listening over the stomach while pushing air: you can hear air even if the tube is in the lung. Capnography (CO2 detection) means the tube is in the airway: remove it. No fluid? Turn the client side to side and try more air.

Extra risk of a misplaced tube: decreased LOC, weak cough or gag, recently removed breathing tube, agitation.

Check residuals every 4–6 hours for tubes in the stomach; return the residual unless it's large (over 250 mL: follow protocol). Use a 50–60 mL syringe on small-bore tubes (smaller syringes can collapse them). Hang only 4 hours of formula at a time (the NG chapter says to follow the manufacturer's hang time and to discard refrigerated unused formula after 24 hours); formula at room temperature; wipe the can top with alcohol; label the bag and tubing. Check blood glucose every 4–6 hours until the full rate is tolerated for 24 hours. Don't delegate tube feedings. Flush with water before and after each intermittent feeding, every 4 hours during continuous feeds, and after medications and residual checks. The skills module allows 30–50 mL; the flagged steps above use 30 mL. Listen for bowel sounds first as a baseline (absent sounds alone don't stop a feeding).

Schedules: intermittent (bolus, by syringe or pump), continuous (pump only), or cyclic (a set block each day, such as 2100 to 0900).

• Most common complications: displaced tube, aspiration, diarrhea
• Diarrhea: ask about a slower rate, diluting or changing the formula, fiber, or lactose-free formula; keep the formula and tubing clean
• Skin: protect the nose with a skin adhesive under the tape and shift the tube's position often
• Feelings: tube feeding can bring isolation and body-image worries; offer privacy or company during feedings, listen, and teach the family

NG tube uses: decompression, feeding, lavage (washing out the stomach for bleeding or poisoning), and compression (a balloon to stop bleeding).

Tube duration: nasal tubes short-term; surgical gastrostomy or jejunostomy for more than about 6 weeks; PEG or PEJ (endoscopic) for more than 30 days. Intestinal placement is preferred with gastroparesis, reflux or past aspiration pneumonia.

Complications: suspected aspiration → stop the feeding first, turn to the side, suction, oxygen, notify, chest X-ray. Diarrhea 3+ times in 24 hours → slow the rate, notify, dietitian, skin care, ask about antibiotics. Nausea → slow the rate, head of bed 30°, room-temperature formula, turn to the side, check patency and residual.

NG comfort: sore nares → water-soluble lubricant, try the other nostril; dry mouth → rinses, lozenges, oral care; not draining → irrigate per protocol, reposition, check the suction.

ATI measures nose → earlobe → xiphoid process and stops there. This guide follows the extra 10 cm your instructor gave.

Insertion

• Check the order, nares and gag reflex; agree on a stop signal; suction at the bedside
• High-Fowler's position
• Measure nose tip → earlobe → xiphoid process and mark it (add 20–30 cm for duodenal or jejunal tubes)
• Water-soluble lubricant; advance toward the back of the throat, then head tilted forward (chin down) and sips of water as you advance
• Stop and pull back for respiratory distress, inability to speak, heavy nosebleed, or resistance
• Confirm placement (X-ray), then tape to the nose and pin to the gown with slack

Decompression (suction)

• Removes air and fluid for bowel obstruction, paralytic ileus, or GI surgery; stays until bowel sounds or flatus return
• Single-lumen (Levin) tube: low intermittent suction to protect the stomach lining
• Double-lumen sump (Salem) tube: the blue air vent is never clamped, connected to suction, or used for irrigation; keep it above the stomach
• Irrigate with 20–30 mL of normal saline or water and count it as intake; frequent oral care; water-soluble (not petroleum) lubricant for the nares
• Heavy NG output loses fluid and electrolytes: watch for fluid volume deficit and metabolic alkalosis

Removal

• Verify the order; turn off suction; flush with 10 mL of saline or 30–50 mL of air
• Client takes a deep breath and holds it (closes the airway)
• Pinch the tube and withdraw it steadily; never force it; then mouth care

Gastric lavage (irrigating the stomach) uses a large-bore tube, mostly in the emergency department. It isn't routine for poisoning anymore. Never leave the client alone during it.

Parenteral nutrition holds dextrose, amino acids (protein), lipids, electrolytes, vitamins and minerals, mixed for each client. High blood glucose is the common problem: check glucose often; insulin can be added to the bag or given under the skin. Labs also track electrolytes and kidney and liver function. Never give other IV medications through the parenteral nutrition line. Lipid tubing is changed every 12 hours and with each new container.