Pathophysiology & Risk Factors

Sickle cell disease is an autosomal recessive disorder from a beta-globin point mutation (chromosome 11) substituting valine for glutamic acid, producing hemoglobin S. HbS polymerizes when deoxygenated, forcing red cells into rigid, sticky crescents that adhere to endothelium and occlude vessels. Sickled cells survive only 10-20 days (vs 120), causing chronic hemolytic anemia. Vaso-occlusion is the single mechanism behind nearly every complication.

Sickling cascade: trigger to crisis

Triggerhypoxia, dehydration, infection, cold, acidosis, high altitude
HbS polymerizesdeoxygenated S-hemoglobin stiffens RBC into crescent
Vaso-occlusionsticky cells adhere to endothelium, obstruct vessels
Tissue ischemiadownstream hypoxia, infarction
Pain crisisvaso-occlusive crisis + organ damage

Signs & Symptoms

EarlyProgresses →

Splenomegaly

early; functional asplenia develops later

Late / Severe

Functional asplenia

repeated splenic infarction over time

Other findings

Chronic hemolytic anemia Hallmark

baseline Hgb often 6-8 g/dL

Vaso-occlusive pain crisis Hallmark

severe extremity, back, chest, abdominal pain

Jaundice

from hemolysis, indirect bilirubin

Fatigue

chronic anemia

Pallor

Diagnostics & Labs

Diagnostic

Hemoglobin electrophoresis Hallmark

confirmatory; predominantly HbS

Newborn screening

identifies disease early

Peripheral smear sickled cells

Howell-Jolly bodies

reflect functional asplenia

Monitor

Elevated reticulocyte count

hemolytic anemia profile

Elevated indirect bilirubin

from hemolysis

Elevated LDH

hemolysis marker

Interventions & Priorities

IV opioid analgesia

first priority; morphine or hydromorphone, scheduled or PCA, not PRN-only

Aggressive IV hydration

normal saline reduces viscosity; oral fluids insufficient in crisis

Supplemental oxygen for SpO2 below 95%SpO2 < 95%

not routine if saturation adequate

Warm compresses Hallmark

promote vasodilation; NEVER apply ice

Incentive spirometry every 2 hours

while awake; prevents atelectasis and acute chest syndrome

Reassess pain and titrate opioid

consistent scale; advocate against under-dosing

Treatments & Medications

IV morphine

scheduled opioid for crisis pain

IV hydromorphone

PCA option

IV normal saline

aggressive hydration to lower viscosity

RBC transfusion

for severe anemia (Hgb below 6 g/dL) or acute chest syndrome; not routine

Pneumococcal vaccine

functional asplenia raises encapsulated-organism risk

Influenza vaccine

infection is a major crisis trigger

Patient Teaching

Maintain daily hydration 2-3 L Hallmark

every day, not only when symptoms start

Avoid cold exposure

wear wetsuit; avoid unheated pools/lakes

Avoid high altitude

low ambient oxygen triggers sickling

Avoid strenuous oxygen-depleting exercise

moderate activity is still encouraged

Stay current on vaccinations

pneumococcal and influenza

Treat infections promptly

infection precipitates crises

Opioid tolerance is not addiction

do not under-report crisis pain

Complications

Late / SevereProgresses →

Chronic organ damage

cumulative ischemic injury

Other findings

Aplastic crisis

parvovirus B19; transfusion-focused, distinct from VOC

Priapism

sustained painful erection; emergency after 4 hours

Renal papillary necrosis

hematuria with flank pain

Report Nowescalate immediately

Acute chest syndrome Hallmark

fever, chest pain, new infiltrate, tachypnea, hypoxia; leading cause of death

Splenic sequestration

rapidly falling Hgb, LUQ fullness/pain, hypovolemic shock

Stroke

sudden focal neuro deficit, slurred speech, weakness

Rapid hemoglobin drop

signals sequestration or severe anemia

Prolonged priapism

erection beyond 4 hours; urologic emergency

Clinical Pearl

Sickling traces to one event: HbS polymerizes when oxygen drops, so cells turn STICKY and STIFF and starve tissue downstream. Treat the crisis with H-O-W: Hydration, Opioids, Warmth. Cold is the enemy.