What causes arm swelling and shortness of breath when laying down?

Arm Swelling and Shortness of Breath When Laying Down

This combination of unilateral arm swelling with orthopnea (shortness of breath when lying down) demands immediate evaluation for upper extremity deep vein thrombosis (UEDVT) with potential pulmonary embolism, or alternatively superior vena cava (SVC) syndrome—both are life-threatening conditions requiring urgent imaging and treatment. 1

Immediate Life-Threatening Considerations

Upper Extremity Deep Vein Thrombosis (UEDVT)

• Unilateral arm swelling indicates an obstructive process at the brachiocephalic, subclavian, or axillary vein level and requires urgent evaluation 1
• UEDVT accounts for up to 10% of all DVTs and can lead to pulmonary embolism, which would explain the shortness of breath 1
• The combination of arm swelling with dyspnea should raise immediate concern for pulmonary embolism as a complication of UEDVT 2

Superior Vena Cava (SVC) Syndrome

• SVC obstruction presents with neck swelling, arm swelling (unilateral or bilateral), facial swelling, and dyspnea 3
• Orthopnea (shortness of breath when lying down) occurs because the supine position increases venous return and worsens cerebral venous hypertension 3
• Headache from cerebral venous hypertension is common with SVC syndrome 3
• In approximately 60% of cases, SVC compression is the presenting symptom for lung cancer diagnosis 3

Cardiac Causes

• Arm pain and shortness of breath are recognized symptoms of acute coronary syndrome, though typically bilateral rather than unilateral 3
• Pulmonary edema from heart failure causes orthopnea and may present with peripheral edema 3

Urgent Diagnostic Approach

First-Line Imaging

• Obtain urgent duplex ultrasound of the upper extremity to exclude UEDVT 1
• Duplex ultrasound has sensitivity and specificity above 80% for UEDVT 1
• Perform grayscale imaging to visualize echogenic thrombus and assess vein compressibility—lack of compression indicates acute or chronic thrombus 1
• Use Doppler assessment to evaluate blood flow patterns, cardiac pulsatility, and respiratory variation—dampening indicates central venous obstruction 1
• Test for central vein collapse with rapid inspiration ("sniffing maneuver")—impaired collapse suggests central obstruction from thrombus, mass, or stricture 1

Additional Imaging if Ultrasound Negative

• If ultrasound is negative but clinical suspicion remains high for central venous obstruction, obtain CT venography or conventional venography 1
• Ultrasound has limitations in the thoracic cavity for evaluating central veins 1
• CT imaging can identify mediastinal masses causing SVC syndrome 3

Critical Risk Factors to Assess

• History of dialysis access (AV fistula or graft) is a high-risk feature for UEDVT 1
• Central venous catheters (current or previous) increase UEDVT risk 1
• Malignancy, particularly lung cancer (72% of SVC syndrome cases) 3
• Recent trauma or immobilization 2

Immediate Management

If UEDVT Confirmed

• Initiate therapeutic anticoagulation immediately following standard DVT treatment protocols 1
• Investigate lower extremities if UEDVT confirmed without local cause, as correlation between upper and lower extremity DVT exists 1

If SVC Syndrome Suspected

• Elevate the head of the bed to decrease hydrostatic pressure and cerebral edema 3
• Consider loop diuretics if cerebral edema is severe 3
• Obtain histologic diagnosis before treatment when possible, as SVC syndrome is no longer considered a medical emergency requiring immediate radiation 3
• Small cell lung cancer responds well to chemotherapy, while non-small cell lung cancer requires different treatment including radiotherapy 3

Symptomatic Management

• Topical NSAIDs are first-choice for mild to moderate pain given superior safety profile 1

Critical Pitfalls to Avoid

• Do not dismiss unilateral swelling as benign—it indicates obstruction requiring urgent evaluation, unlike bilateral swelling which suggests systemic causes 1
• Never label acute shortness of breath as "hysteria" or "panic" without excluding serious causes like pulmonary embolism 2
• Pulmonary embolism can present without chest pain, with shortness of breath as the major symptom 2
• Recognize that catheter-associated UEDVT may be asymptomatic, manifesting only as catheter dysfunction 1
• In dialysis patients, persistent arm swelling beyond 2-6 weeks post-access creation warrants investigation for central venous stenosis 1

Follow-Up Protocol

• Reassess within 48-72 hours to evaluate response to initial management and ensure no progression 1
• Schedule formal evaluation at 6 weeks if edema persists to detect delayed complications or underlying pathology 1
• In dialysis patients with persistent swelling beyond 2 weeks after access placement, perform venography or CT venography to evaluate central veins 1