Overview
Defined as prolonged bed rest or restricted mobility due to critical illness, major surgery, trauma, cast application, or spinal cord injury (SCI).
Leads to rapid multi-system deconditioning and metabolic alterations.
High-yield USMLE focus is on identifying and preventing complications (e.g., thromboembolism, hypercalcemia, pressure ulcers).
Bone Resorption : Absence of mechanical loading increases osteoclastic activity and decreases osteoblastic activity.
Leads to hypercalciuria and hypercalcemia . c
Venous Stasis : Lack of skeletal muscle pump action in the lower extremities causes blood pooling.Muscle Atrophy : Rapid loss of muscle mass (especially postural muscles) and strength within days of bed rest.Respiratory Alterations : Decreased diaphragmatic excursion, shallow breathing, and impaired ciliary clearance.
Systemic Complications
Endocrine & Renal
Hypercalcemia of Immobilization :
Risk factors: Pts with high baseline bone turnover (e.g., adolescents/young adults, Paget disease).
Clinical onset: Typically 4 weeks post-immobilization (can be earlier in SCI).
Presentation: Constipation, polyuria, polydipsia, lethargy.
Key Labs: ↑ Serum Ca , ↓ PTH , ↓ or normal 1,25-dihydroxyvitamin D .
Renal: Nephrolithiasis (due to hypercalciuria) and UTIs (secondary to urinary stasis).
Cardiovascular
Thromboembolism (DVT/PE) : High risk due to Virchow’s triad (venous stasis + endothelial damage/hypercoagulability post-injury/surgery).Orthostatic Hypotension : Blunted baroreceptor response and plasma volume contraction upon re-mobilization.
Integumentary
Pressure Ulcers (Decubitus Ulcers) :
Common locations: Sacrum, heels, ischial tuberosities, greater trochanter.
Staging:
Stage 1 : Non-blanchable erythema of intact skin.Stage 2 : Partial-thickness skin loss with exposed dermis (or intact/ruptured serum-filled blister).Stage 3 : Full-thickness skin loss; adipose tissue is visible, but muscle/bone/tendon is NOT exposed.Stage 4 : Full-thickness skin and tissue loss w/ exposed fascia, muscle, tendon, ligament, or bone.Unstageable : Obscured by slough or eschar (must debride to stage, unless on heels/dry eschar).Deep Tissue Pressure Injury : Persistent non-blanchable deep red/maroon/purple discoloration.
Pulmonary
Atelectasis : Basal alveolar collapse due to shallow breathing; predisposes to hypostatic pneumonia .Aspiration : Increased risk in supine pts, particularly with concurrent neurologic deficits.
Gastrointestinal
Constipation and fecal impaction due to decreased gut motility and loss of gravity-assisted defecation.
Musculoskeletal
Joint contractures (especially foot drop/plantarflexion contracture).
Disuse osteoporosis.
Prevention & Management Strategies
DVT Prophylaxis
First-line : Pharmacologic prophylaxis with LMWH (e.g., enoxaparin) or UFH .Alternative : Mechanical prophylaxis (Sequential Compression Devices [SCDs] / Intermittent Pneumatic Compression [IPC]) only if pharmacologic options are contraindicated (e.g., active hemorrhage, severe thrombocytopenia).
Pressure Ulcer Prevention & Care
Repositioning at least every 2 hours (Q2h).
Use of pressure-redistributing mattresses/overlays.
Nutrition optimization (adequate protein and caloric intake).
Wound care:
Stage 1/2: Occlusive/semipermeable dressing (e.g., hydrocolloid).
Stage 3/4: Debridement of necrotic tissue, moist wound healing, pressure relief.
Management of Immobilization Hypercalcemia
First-line : Aggressive volume expansion with 0.9% Normal Saline (NS) to promote calciuria.Refractory/Severe : Bisphosphonates (e.g., pamidronate or zoledronic acid) to inhibit osteoclast-mediated bone resorption.
Note : Loop diuretics (e.g., furosemide) are only used after volume status is fully restored to prevent volume depletion.
Pulmonary & Musculoskeletal Care
Incentive spirometry and frequent coughing/deep breathing exercises.Early physical therapy (PT) and occupational therapy (OT).
Range of motion (ROM) exercises and splinting (e.g., multi-podus boots to prevent foot drop).