Physiological AdaptationLesson 8.1
Alterations in Body Systems
When a body system fails, priorities change fast. Recognize the pattern, pick the first action, and see the next domino coming.
By the end you can
- Choose the right isolation and act first in seizures, rising ICP, and autonomic dysreflexia
- Manage magnesium, bleeding in pregnancy, postpartum hemorrhage, and each type of shock
- Treat DKA, HHS, thyroid and adrenal crises, AKI, GI bleeding, and radiation safely
Your case
Postpartum · 2 hours after birth · severe preeclampsia
Mrs. G, 31. Vaginal birth 2 hours ago. Severe preeclampsia, on IV magnesium sulfate. No history of asthma.
Her fundus is boggy, 2 cm above the umbilicus, and pushed to the right. She has not voided since before delivery. Her pad is soaked.
HR 108BP 98/64RR 14Lochia heavy, with clots
Hold that thought
- Why won't her uterus stay firm?
- Which uterotonic would be dangerous for her?
- What would tell you the magnesium has become toxic?
You will answer all three at the end of the lesson.
Concept 1 · Isolation precautions
Follow the route, not the diagnosis
- Airborne
- Fit-tested N95, negative-pressure room, door closed
- Droplet
- Surgical mask, private room preferred
- Contact
- Gown and gloves for every entry, equipment stays in the room
- Transport
- Airborne or droplet: the client wears a surgical mask
Sort by how it spreads
Tap a disease, then tap the box it belongs in.
Also: disseminated zoster is airborne. Mumps and rubella are droplet. VRE, scabies, and RSV are contact. Standard precautions apply to every client.
Concept 2 · Key infections
TB, meningitis, C. diff, HIV
- Active TB: cough over 3 weeks, night sweats, weight loss, hemoptysis, low-grade fever
- Skin test: read at 48 to 72 hours. Positive: 5 mm if immunocompromised, 10 mm high risk, 15 mm others
- Diagnose: 3 sputum AFB samples, 8 to 24 hours apart, early morning
- RIPE: rifampin, isoniazid, pyrazinamide, ethambutol for 2 months, then rifampin and isoniazid for 4
- Rifampin turns body fluids orange. Isoniazid: watch the liver, give vitamin B6
- Triad: fever, stiff neck, altered mental status
- Brudzinski: flex the neck, and the hips and knees flex
- Kernig: with the hip at 90 degrees, extending the knee causes pain
- Petechial rash: meningococcal. A medical emergency
- Treat: IV antibiotics STAT plus dexamethasone. Droplet until 24 hours of antibiotics
- Close contacts get prophylaxis: rifampin or ciprofloxacin
- Cause: antibiotics wipe out the normal gut flora
- Signs: frequent foul, watery stools, cramping, fever
- Treat: oral vancomycin or fidaxomicin. Stop the offending antibiotic if possible
- Nursing: contact precautions, soap and water, bleach disinfectant
- CD4: normal 500 to 1,500. Under 200 is AIDS: start infection prophylaxis
- Viral load: undetectable means untransmittable
- ART adherence: missed doses breed resistance
- PEP: start within 72 hours of exposure, the sooner the better
Quick check 1 of 4
Productive cough for 4 weeks, night sweats, 15 lb weight loss, upper lobe cavitation on X-ray. AFB results are pending. Which precautions now?
This is suspected active TB, which is airborne. Start a negative-pressure room and a fit-tested N95 on suspicion, because cultures take weeks. A surgical mask does not filter the tiny particles.
Concept 3 · Seizures
Protect, turn, time it
During a seizure
- Protect: clear the area, pad the rails, lower the bed
- Turn to the side to protect the airway. Suction ready
- Never restrain or put anything in the mouth
- Time it from onset. Note the movements, body parts, LOC, incontinence
- Nothing by mouth until fully alert
Status epilepticus: over 5 minutes, or repeated seizures without waking. IV lorazepam (or diazepam) first, then fosphenytoin or phenytoin, then phenobarbital or a propofol or midazolam drip. Check glucose.
Tonic-clonic: stiffening, then rhythmic jerking, loss of consciousness, postictal confusion. Absence: brief staring spells, common in children, no postictal state. Myoclonic: sudden brief jerks. Focal: starts in one area with one-sided signs, consciousness may or may not be lost, and it can spread to bilateral tonic-clonic.
Padded side rails up, bed in the lowest position, suction and oxygen at the bedside, IV access, and rescue medication ready (rectal diazepam or intranasal midazolam).
Quick check 2 of 4
A tonic-clonic seizure has lasted 6 minutes. The client is on the side and the area is clear. What is the priority?
Over 5 minutes is status epilepticus, an emergency that injures neurons. Safety is already done, so stop the seizure with an IV benzodiazepine. Never force anything into the mouth or restrain the client, and waiting is dangerous.
Concept 4 · ICP and autonomic dysreflexia
Lower the pressure, find the trigger
- Normal ICP
- 5 to 15 mmHg. Treat if sustained over 20
- Monro-Kellie
- Brain, blood, and CSF share a fixed skull. If one rises, ICP rises
- Earliest sign
- A change in LOC
- Late sign
- Cushing's triad: rising SBP, wide pulse pressure, slow HR, irregular breathing
HOB 30 degrees, head midline, no hip flexion over 90. Prevent Valsalva (stool softeners, no straining). Dim, quiet room, cluster care. Mannitol or 3% saline, treat fever, seizure prophylaxis, EVD drainage if placed. Posturing worsens from decorticate (arms flexed) to decerebrate (all extended) to flaccid.
Autonomic dysreflexia: injury at T6 or above
- Trigger: a stimulus below the injury. A full bladder is number 1, then impaction, tight clothes, skin
- Signs: sudden severe hypertension, pounding headache, flushing above the injury, bradycardia
Concept 5 · Preeclampsia and magnesium
Magnesium protects the brain. Watch for toxicity
- After 20 weeks: BP 140/90 or higher, twice, 4 hours apart
- Plus proteinuria (300 mg in 24 hours, or protein/creatinine 0.3 or more), or other organ damage
- Eclampsia: preeclampsia plus seizures. Before, during, or up to 6 weeks after birth
- Magnesium sulfate prevents and treats the seizures. Usually continued 24 hours after birth
- BP 160/110 or higher
- Platelets under 100,000
- Liver enzymes twice normal, RUQ or epigastric pain
- Creatinine over 1.1 mg/dL
- Pulmonary edema
- Headache or visual changes (spots, blurring)
- Hemolysis, Elevated Liver enzymes, Low Platelets
- A variant of severe preeclampsia
- RUQ pain, malaise, nausea: easy to misdiagnose
- The only cure is delivery
Magnesium safety
Therapeutic level: mEq/L.
Hold for a respiratory rate under .
Keep urine output at least mL an hour.
First sign of toxicity: .
Antidote at the bedside: .
Concept 6 · Bleeding in pregnancy
Painless or painful bleeding
Tap a finding, then tap the box it belongs in.
Previa
- Diagnose by ultrasound
- Pelvic rest, monitor bleeding
- C-section if it stays over the os
- Risk: prior C-section, multiples, older age, smoking
Abruption
- Can cause DIC, shock, fetal death
- Mild: monitor. Severe: emergency delivery
- Couvelaire uterus: blood in the muscle, may need hysterectomy
Concept 7 · Postpartum hemorrhage
Tone first: massage, empty the bladder, oxytocin
- PPH
- Blood loss of 1,000 mL or more by any route, or any blood loss with signs of hypovolemia
- Number 1 cause
- Uterine atony
- Atony steps
- Firm fundal massage, empty the bladder, oxytocin. Then other drugs, balloon tamponade, surgery
In practice now: this is the ACOG definition. Older books still print over 500 mL after a vaginal birth and over 1,000 mL after a cesarean.
The 4 T's
- Tone:
- Trauma:
- Tissue:
- Thrombin:
| Uterotonic | Key point |
|---|---|
| Oxytocin | First line. IV infusion |
| Methylergonovine | Avoid in hypertension |
| Carboprost | Avoid in asthma |
| Misoprostol | Rectal or sublingual |
Rare and catastrophic, with high mortality. Amniotic fluid enters the mother's circulation and sets off an anaphylactoid reaction during labor, birth, or right after. Sudden dyspnea, hypoxemia, cardiovascular collapse, seizures, DIC. No specific treatment: support the ABCs with intubation, vasopressors, blood products, and DIC care.
Concept 8 · Shock
Read the skin, the pulse, and the neck
Match the picture to the shock
Quick check 3 of 4
Crushing chest pain and dyspnea. BP 78/50, HR 132, SpO2 89%, crackles in both lungs, JVD. ST elevation in V1 to V4. Which shock is this?
ST elevation in V1 to V4 is an anterior MI, and crackles plus JVD mean the failing left ventricle is backing up. That is cardiogenic shock: inotropes and reperfusion, not large fluid boluses. Hypovolemia has flat neck veins, and tamponade has muffled heart sounds with clear lungs.
Concept 9 · Treat the type
Fix the cause of the shock
- Hypovolemic
- Replace volume: crystalloids, blood
- Cardiogenic
- Inotropes (dobutamine), IABP, treat the cause. Avoid large fluid boluses
- Septic
- Warm early, cold and mottled late. Antibiotics, fluids, norepinephrine
- Anaphylactic
- IM epinephrine in the outer thigh first. Then fluids, antihistamines, steroids
- Neurogenic
- Fluids, vasopressors, atropine for the bradycardia
- Obstructive
- Remove the block: needle decompression, pericardiocentesis, thrombolytics
Acute pulmonary edema
- Signs: severe dyspnea, pink frothy sputum, crackles throughout, anxiety, sweating
- Position: high Fowler's, legs dangling
- Oxygen to SpO2 94% or higher. BiPAP or intubation if needed
- Drugs: IV furosemide, nitroglycerin, morphine with caution
- Working if: fewer crackles, lower RR, higher SpO2, more urine, weight down
Left backs into the lungs: dyspnea, orthopnea, PND, crackles, pink frothy sputum, S3, BNP over 100. Right backs into the body: JVD, leg edema, hepatomegaly, ascites, weight gain. Left failure is the most common cause of right failure.
Concept 10 · DKA and HHS
Fluids first, and respect the potassium
| Feature | DKA | HHS |
|---|---|---|
| Who, onset | Mostly type 1, over hours | Mostly type 2, older, over days to weeks |
| Labs | Glucose over 250, pH under 7.30, HCO3 under 18 | Glucose over 600, pH over 7.30 |
| Clues | Ketones, Kussmaul breathing, fruity breath | Little or no ketones, osmolality over 320, severe dehydration |
| Treat | NS bolus, insulin drip, potassium | Aggressive fluids, then insulin. Higher mortality |
In practice now: the 2024 ADA consensus diagnoses DKA at glucose 200 or higher, or at any glucose in someone with known diabetes.
The potassium lies. Acidosis pushes K out of cells, so serum K looks high while total body K is low. Insulin drives it back in. K under 3.3: hold the insulin and replace K first.
In practice now: the 2024 ADA consensus starts insulin once K+ is 3.5 or higher; most NCLEX books still say 3.3.
Pearl: check glucose every hour. When it falls to about 200 to 250, add dextrose (D5 0.45% NS) and keep the insulin running until the acidosis clears.
Concept 11 · Endocrine crises
Too fast, too slow, or no cortisol
- Everything speeds up: high fever, severe tachycardia, agitation or delirium, vomiting, diarrhea, HF
- Triggers: surgery, infection, trauma, stopping antithyroid drugs, iodine contrast
- Beta blocker (propranolol) for the heart rate
- PTU or methimazole blocks new hormone. Iodine goes in only after them
- Steroids block T4 to T3 conversion. Cool the client, but no aspirin
- Everything slows: hypothermia, bradycardia, hypotension, hypoventilation, coma, low sodium
- Triggers: cold, infection, sedatives, stopping thyroid replacement
- Treat: IV levothyroxine, IV steroids, passive rewarming, ventilation support
- Handle gently: the heart is irritable
- Cause: stopping long-term steroids abruptly (number 1), adrenal damage, pituitary failure
- No cortisol: low glucose, low BP, weak stress response
- No aldosterone: low sodium, high potassium, dehydration
- Treat: IV hydrocortisone STAT, NS, dextrose if glucose is low
- Prevent: never stop steroids abruptly. Taper
Quick check 4 of 4
A client stopped long-term prednisone abruptly a week ago. BP 74/40, glucose 52 mg/dL, sodium 128, potassium 6.0. What does the nurse anticipate first?
Low BP, low glucose, low sodium, and high potassium after stopping steroids abruptly is adrenal crisis. Replace cortisol with IV hydrocortisone and restore volume with NS, plus dextrose for the glucose. Fluid restriction or a diuretic would deepen the shock.
Concept 12 · Acute kidney injury
Before, inside, or after the kidney
Tap a cause, then tap the box it belongs in.
- BUN:Cr over 20:1
- Pre-renal. Restore perfusion
- BUN:Cr about 10:1
- Intrarenal
- Oliguric phase
- Under 400 mL a day, high K, fluid overload, acidosis
- Diuretic phase
- 3 to 5 L a day. Watch for dehydration and low K
- Recovery
- Back to baseline, can take months
Concept 13 · GI bleeding and encephalopathy
Upper bleeds turn black. A sick liver leaks ammonia
Upper GI
- Above the ligament of Treitz
- Bloody or coffee-ground vomit, black tarry stool
- Peptic ulcer (number 1), varices, Mallory-Weiss tear
- Varices: octreotide, vasopressin, banding, balloon tamponade
Lower GI
- Below the ligament of Treitz
- Bright red blood per rectum
- Diverticulosis (number 1 in older adults), hemorrhoids, colorectal cancer, IBD
Hepatic encephalopathy
- Why: the liver can't clear ammonia, and it reaches the brain
- Signs: confusion, asterixis (flapping tremor), musty breath, personality change, coma
- Lactulose: goal 2 to 3 soft stools a day. Rifaximin cuts ammonia-making gut bacteria
- Monitor: ammonia, LOC, I&O
Concept 14 · Radiation and recovery
Internal sources make the client radioactive
- Not radioactive. Like an X-ray, it stops when the machine stops
- Skin: no lotion, powder, or deodorant on the area. Loose cotton, no sun
- Leave the markings: they line up the beam
- Side effects: fatigue (most common), redness to peeling, hair loss in the field, mucositis
- The client is radioactive while the sealed source is in
- Time: limit time in the room, typically about 30 minutes per nurse per shift
- Distance: work efficiently, step back when not giving care
- Shielding: lead apron or portable shield
- Private room with a radiation sign. No pregnant staff or visitors, no children. Linens stay in the room
Source fell out? Never touch it, even gloved. Long-handled forceps into the lead container, then call the radiation safety officer.
Neutropenic precautions (ANC under 500)
- No crowds, sick visitors, raw foods, fresh flowers, or standing water
- Fever may be the only sign. Report 100.4 F (38 C) or higher
- No rectal temps, suppositories, or enemas. Soft toothbrush
Head and neck: mucositis, dry mouth, taste changes, dental problems. Chest: esophagitis, pneumonitis, cough. Abdomen and pelvis: nausea, vomiting, diarrhea, cystitis. Any site: bone marrow suppression, so watch the CBC.
Use teach-back, plus written instructions. Book follow-up before discharge and complete medication reconciliation. Check home safety, especially after a neuro event. Teach warning signs, meds, diet changes (fluid and sodium limits in HF, renal diet, low residue during radiation), activity progression, and self-monitoring (daily weight, glucose, wound, temperature).
Decide it
Two systems, one client
Back to Mrs. G · 2 hours postpartum · on magnesium
You massage the fundus. It firms for a moment, then goes boggy again. Bleeding continues.
The fundus will not stay firm. It sits high and to the right. What next?
Too slow. HR 108 and BP 98/64 are early shock signs. Act now.
Right. A full bladder pushes the uterus up and to the side and keeps it from contracting. Oxytocin is the first-line uterotonic.
Surgery is the last resort, after uterotonics and balloon tamponade fail.
Oxytocin is running, and the uterus is still soft. Which new order do you question?
Carboprost is off-limits in asthma, which she does not have. It is a reasonable next drug for her.
Misoprostol has no hypertension warning. It is a reasonable choice here.
Right. Methylergonovine raises blood pressure and is contraindicated in hypertension and preeclampsia.
The bleeding slows. An hour later: RR 10, reflexes absent, urine 20 mL in the last hour. What do you do?
Right. Absent reflexes and RR under 12 are magnesium toxicity. Low urine output lets it build up, because the kidneys clear it.
That does not address the toxicity, and she has just bled. Stop the infusion first.
Waiting risks respiratory arrest. Absent reflexes come before breathing stops.
How it ends
- A straight cath drained a full bladder. Her fundus firmed at the umbilicus, midline
- The methylergonovine order was changed. Carboprost was given and the bleeding slowed
- Magnesium stopped, calcium gluconate given. Reflexes return and her RR is back to 16
Lock it in
Three hooks to carry into the exam
Two more
- Previa painless, abruption painful: painless bright red bleeding means no vaginal exam
- In DKA the potassium lies: high on the lab, low in the body. Under 3.3, hold the insulin
Rapid fire
Suspected TB needs an N95 and a negative-pressure room before the cultures are back.
Isolate on suspicion. Cultures take weeks.
Meningococcal meningitis needs droplet precautions until 24 hours of antibiotics.
And close contacts get prophylaxis.
Put a padded tongue blade in the mouth during a seizure.
Nothing in the mouth. Turn to the side and protect from injury.
Methylergonovine is a safe choice in hypertension.
It raises BP. Avoid it in hypertension and preeclampsia.
A client getting external beam radiation is radioactive.
Only an internal source makes the client radioactive.
NCLEX traps
What the exam will try to trick you with
Isolate on suspicion. Airborne precautions start the moment TB is suspected.
Sit up and find the trigger first. Check the bladder. Medication only if removing the stimulus fails.
Never. It could be previa, and an exam can cause hemorrhage. Ultrasound first.
Not cardiogenic. A failing pump can't handle the volume. Inotropes and treating the cause.
Gloves don't block radiation. Long-handled forceps, lead container, radiation safety officer.
Cheat card
The whole lesson on one card
Infection and neuro
- TB: N95, negative pressure
- C. diff: soap and water
- Over 5 minutes: IV lorazepam
- Dysreflexia: sit up, check bladder
OB
- Mag toxicity: no reflexes, RR under 12
- Antidote: calcium gluconate
- Previa painless, abruption painful
- PPH: massage, empty bladder, oxytocin
Shock
- Neurogenic: warm, slow pulse
- Cardiogenic: no big boluses
- Anaphylaxis: IM epinephrine first
- Septic: fluids, norepinephrine
Endocrine, renal, GI
- DKA: K under 3.3, hold insulin
- Adrenal crisis: IV hydrocortisone
- Pre-renal: BUN:Cr over 20:1
- Encephalopathy: lactulose
The printable version is in the Cheat Sheets library.
Lesson quiz · 1 of 5
A client with a T4 spinal cord injury suddenly has BP 210/118, a pounding headache, facial flushing, and HR 48. What does the nurse do first?
This is autonomic dysreflexia. Sitting up lowers BP right away, and a blocked catheter or full bladder is the number 1 trigger. Medication comes only if removing the trigger fails, and tests delay the fix.
Lesson quiz · 2 of 5
Type 1 diabetes: glucose 520 mg/dL, pH 7.14, ketones positive, potassium 3.0 mEq/L. NS is running and a regular insulin drip is ordered. What does the nurse do?
Insulin drives potassium into cells, so starting it at 3.0 could cause a fatal arrhythmia. Replace K to at least 3.3 first. Bicarbonate is rarely used and worsens hypokalemia, and subcutaneous insulin absorbs unpredictably in a dehydrated client.
Lesson quiz · 3 of 5
A client with cirrhosis is more confused, has asterixis, and has a high ammonia level. Which intervention is most appropriate?
This is hepatic encephalopathy. Lactulose traps ammonia in the gut and flushes it out in the stool, with a goal of 2 to 3 soft stools a day. Albumin treats ascites, sedatives can worsen encephalopathy, and dialysis is not first line.
Lesson quiz · 4 of 5
The nurse finds the sealed source of a cervical radiation implant lying on the bed linens. What does the nurse do first?
Never touch the source, even with gloves. Long-handled forceps keep distance and the lead container shields it, then the radiation safety officer is notified. Leaving it uncontained keeps exposing the client.
Lesson quiz · 5 of 5
At 32 weeks, a client has sudden painless, bright red vaginal bleeding. The uterus is soft. Which order does the nurse question?
Painless bright red bleeding with a soft uterus suggests placenta previa. A vaginal exam can disrupt the placenta and cause hemorrhage, so it waits until ultrasound rules previa out. Monitoring, ultrasound, and IV access are all appropriate.
Wrap-up
0 / 5
Quiz score
Back to Mrs. G · 3 hours postpartum
Why won't her uterus stay firm? Atony, made worse by a full bladder. A fundus that sits high and off to one side is the clue. Empty the bladder, keep massaging, and give oxytocin.
Which uterotonic is dangerous? Methylergonovine. It raises BP, and she has preeclampsia. Carboprost is off-limits only in asthma, which she does not have.
What signals magnesium toxicity? Absent reflexes first, then RR under 12, then cardiac arrest. Low urine output lets magnesium build up. Stop the infusion and give calcium gluconate.
Keep going