Deep Vein Thrombosis & Pulmonary Embolus – Comprehensive Study Notes- מאמר 2.13

Objectives

• Identify patients at increased risk for developing a Deep Vein Thrombosis (DVT).
• Recognize clinical manifestations (signs & symptoms) at early vs. middle/late stages.
• Accurately apply and interpret the Wells DVT Clinical Prediction Rule for early-stage screening.

Key Terminology

• Thrombosis – Intravascular formation of a clot (platelets + fibrin network + cells) within a vein.
• Embolus – A fragment of a clot that breaks free, travels through the circulation, and lodges distally, potentially occluding blood flow.
• Pulmonary Embolus (PE) – An embolus that lodges in the pulmonary arterial tree, causing potentially fatal obstruction.
• Superficial vs. Deep Veins
  • Superficial thrombosis (often tied to varicose veins): painful, unsightly but does NOT lead to PE.
  • Deep venous system (iliac, femoral, popliteal, tibial, etc.): carries PE risk – primary focus of this lecture.

Epidemiology & Key Statistics

• DVT is the most common cause of hospital readmission & death after total knee or hip arthroplasty.
• Incidence following major general surgery: $30\%\text{ – }60\%$ will develop symptomatic DVT within $4\text{ weeks}$ post-op.
• Approximately $50\%$ of patients with a confirmed DVT already have an occult PE at time of diagnosis.
• Distribution:
  • Lower extremity: $80\text{ – }90\%$ of cases.
  • Upper extremity: $10\text{ – }20\%$ (subclavian & axillary most common).

Pathophysiology (Virchow’s Triad Re-emphasized)

1. Venous Stasis – Prolonged immobility diminishes calf-muscle pump action, slowing blood flow.
2. Endothelial (Venous Wall) Injury – Surgery, fractures, indwelling catheters, injections, trauma.
3. Hypercoagulability – Malignancy, inherited thrombophilia, pregnancy/post-partum, estrogen therapy, lifestyle factors (e.g., smoking).

Sequence:

\text{Endothelial damage} \rightarrow \text{Platelet adhesion} \rightarrow \text{Fibrin accumulation} \rightarrow \text{Clot formation}

If fibrinolysis < clot growth OR clot fragments break off:

\text{DVT} \rightarrow \text{Embolus} \rightarrow \text{Heart} \rightarrow \text{Pulmonary arteries} \rightarrow \text{PE}

Major Risk-Factor Categories (Lower & Upper Limb)

1. Immobility / Venous Stasis

• Hospital bed-rest $\ge 3\text{ days}$.
• Long car or plane travel.
• Spinal-cord injury.

2. Venous Wall Injury

• Recent surgery (THR, TKR, ACL reconstruction, ORIF fractures).
• Indwelling central venous catheters (CVC), PICC lines.
• Intravenous injections, fracture–dislocations.

3. Hypercoagulability

• Active cancer or treatment within $6\text{ months}$.
• Hereditary thrombophilia.
• Pregnancy & $6\text{-week}$ postpartum window.
• Oral contraceptives, hormone-replacement therapy, Tamoxifen.

4. Lifestyle / Miscellaneous

• Smoking.
• Age >60 yrs.
• Obesity, Diabetes mellitus.
• Prior DVT/PE.
• Positive family history.

Clinical Manifestations – LOWER Extremity DVT

Wells Clinical Prediction Rule for LOWER Extremity DVT

(Philip Wells et al., $\text{1997}$)

Interpretation:

• Score ≥$2$ ⇒ DVT likely → ultrasound & D-dimer; urgent MD contact if unmanaged.
• Score <$2$ ⇒ DVT unlikely. If D-dimer negative, probability ≈ <1\%.

Clinical Manifestations – UPPER Extremity DVT

• Same "dull diffuse ache / tightness / heaviness" in shoulder, arm, forearm or hand.
• Unilateral arm swelling or pitting edema.
• Skin warmth, erythema or cyanosis.
• Prominent superficial veins over delto-pectoral groove or arm.
• Low-grade fever, malaise.
• Effort-induced (primary) vs. secondary (CVC, PICC, pacemaker, dialysis, infection, malignancy).

CONSTANS Criteria (Upper-Extremity CPR)

Interpretation:

• Score ≥$2$ ⇒ UE-DVT likely → D-dimer + ultrasound.
• Score ≤$1$ ⇒ UE-DVT unlikely. If D-dimer negative, UE-DVT effectively ruled out.

Pulmonary Embolus (PE) – Signs & Symptoms

• Pleuritic chest pain (sharp, ↑ with inspiration/expiration/cough).
• Possible diffuse chest discomfort.
• Dyspnea, tachypnea (rapid breathing).
• Tachycardia.
• Hemoptysis (coughing up blood) or persistent dry cough.
• Anxiety, sense of doom.
• Syncope (large embolus).

Rule-Out & Prediction Tools

1. PERC (Pulmonary Embolism Rule-Out Criteria)

Patient is low risk only if ALL are NO:

1. Age <50 yrs.
2. Pulse <100\,\text{bpm}.
3. SpO_2 >95\% at room air.
4. No unilateral leg swelling.
5. No hemoptysis.
6. No recent surgery/trauma.
7. No prior DVT/PE.
8. No estrogen use.

If satisfied → PE probability extremely low; no further testing typically required.

2. Revised Geneva Score

Interpretation: $0\text{–}1$ low, $2\text{–}4$ intermediate, ≥$5$ high probability.

Physical-Therapy Implications & Best Practices

• High Vigilance: PTs often see post-op patients during the critical $0\text{–}4\text{ wk}$ window when DVT incidence peaks.
• Routine Screening: Apply Wells (LE) or CONSTANS (UE) at initial eval & when new calf/arm symptoms arise.
• Early MD communication: Score ≥$2$ or intermediate/high Geneva → urgent call; patient may need duplex ultrasonography & anticoagulation.
• Document Thoroughly: Record all positive and negative findings for medicolegal clarity – shows DVT/PE was considered.
• Educate Patients & Families: Recognize warning signs; encourage mobility, hydration, compression, proper positioning, adherence to anticoagulant regimen.
• Contraindications: Avoid aggressive soft-tissue mobilization, vigorous ROM, or modalities (e.g., heat) over suspected DVT site until ruled out.

Summary “Take-Home” Points

• DVT risk spans all settings & age groups – especially orthopedic, cancer, immobilized, pregnant/post-partum populations.
• Half of DVTs are silent; thus risk stratification tools are indispensable.
• Wells Score + D-dimer for LE; CONSTANS for UE; PERC & Revised Geneva for PE.
• Prompt identification & referral are critical to prevent fatal PE and reduce hospital readmissions.
• Consistent documentation supports best practice & legal protection.