Flail chest is a clinical finding defined by paradoxical movement of a chest wall segment during respiration, resulting from ≥3 consecutive ribs fractured in ≥2 places, creating a free-floating segment. [1-2] It represents the most severe form of blunt chest wall injury, with mortality rates of 10–20% and is a marker of high kinetic energy absorption with frequent associated injuries. [3-4]
1. History
- Mechanism: High-energy blunt thoracic trauma — motor vehicle collisions (most common), falls from height, crush injuries, assaults, occupational injuries [2]
- Symptom characterization: Severe pleuritic chest wall pain, dyspnea, splinting with respirations, inability to take a deep breath or cough effectively
- Timing: Paradoxical motion may not be immediately apparent due to chest wall edema, muscle splinting, or subcutaneous emphysema — can present in a delayed fashion [2]
- Associated symptoms: Hemoptysis (pulmonary contusion), shoulder pain (diaphragmatic injury), abdominal pain (associated abdominal injuries)
- Important negatives: Loss of consciousness (concurrent TBI in ~66%), neck/back pain (spinal fractures), abdominal tenderness
2. Alarm Features
- Respiratory distress with tachypnea, accessory muscle use, hypoxia (SpO₂ <90%)
- Hemodynamic instability — suggests massive hemothorax, cardiac tamponade, or tension pneumothorax
- Subcutaneous emphysema — may indicate pneumothorax or tracheobronchial injury
- Tracheal deviation — tension pneumothorax
- Worsening respiratory status over 24–72 hours — evolving pulmonary contusion or ARDS (develops in ~27% of flail chest patients) [4]
- Bilateral flail segments — extremely high mortality
3. Medications
- Multimodal analgesia is the cornerstone of management: [5-6]
- Scheduled acetaminophen + scheduled NSAIDs (COX-2 inhibitor preferred if regional block planned)
- Muscle relaxants (reduce LOS and respiratory complications) [5]
- Opioids: oral first-line with IV breakthrough; escalate to PCA if needed
- Low-dose ketamine (0.3 mg/kg IV over 15 min) as opioid-sparing adjunct, especially in elderly [7]
- Regional analgesia (see Special Tests below)
- Contraindicated: Steroids should NOT be used in pulmonary contusion-flail chest [3]
- Caution: Excessive opioids in elderly → delirium, respiratory depression, falls [8]
4. Diet
- No specific dietary triggers
- Avoid excessive fluid administration — resuscitate to adequate perfusion, then meticulously avoid unnecessary fluids (worsens pulmonary contusion) [3]
- Adequate nutrition is critical for healing; early enteral nutrition preferred in ICU patients
5. Review of Systems
- Pulmonary: Dyspnea, cough, hemoptysis, pleuritic pain
- Cardiovascular: Chest pain, palpitations (myocardial contusion)
- Neurologic: Headache, LOC, confusion (concurrent TBI in 66%) [2]
- MSK: Extremity pain, back pain (skeletal fractures in 64%) [2]
- GI/Abdominal: Abdominal pain, distension (abdominal injuries in 34%) [2]
- GU: Hematuria (pelvic/renal injury)
6. Collateral History and Family History
- Collateral: Mechanism details from EMS — speed, ejection, steering wheel deformity, seatbelt use, airbag deployment
- Witnesses: Duration of LOC, extrication time
- Social: Anticoagulant/antiplatelet use (increases hemorrhage risk), alcohol/substance use at time of injury
- Family history: Generally not relevant in acute trauma setting
- PMH from family/records: Cardiopulmonary comorbidities, bleeding disorders
7. Risk Factors
- High-speed MVC, especially unrestrained occupants
- Falls from height (particularly elderly)
- Age >65 — doubled mortality and morbidity compared to younger patients with similar injuries [7-8]
- Osteoporosis — lower energy mechanism can produce flail segments
- Pre-existing cardiopulmonary disease — reduced physiologic reserve
- Anticoagulation — increased risk of hemothorax
- Obesity — may mask clinical findings on exam
8. Differential Diagnosis
- Simple multiple rib fractures without flail segment — no paradoxical motion
- Sternal fracture — midline tenderness, different mechanism of instability
- Pulmonary contusion without flail — hypoxia without chest wall instability
- Tension pneumothorax — unilateral absent breath sounds, tracheal deviation, hypotension (cannot-miss)
- Massive hemothorax — dullness to percussion, hypotension (cannot-miss)
- Cardiac tamponade — Beck's triad, muffled heart sounds (cannot-miss)
- Traumatic aortic injury — widened mediastinum, mechanism-dependent (cannot-miss)
- Diaphragmatic rupture — bowel sounds in chest, elevated hemidiaphragm
9. Past Medical History
- COPD/asthma — significantly increases risk of respiratory failure
- CHF — fluid management becomes more complex
- Prior thoracic surgery — altered anatomy, adhesions
- Osteoporosis — lower threshold for flail from lesser mechanisms
- Coagulopathy or anticoagulant use — increased bleeding risk
- Prior rib fractures — may complicate healing and fixation
10. Physical Exam
- Inspection: Paradoxical chest wall movement (segment moves inward on inspiration, outward on expiration) — pathognomonic but may be masked early by splinting/edema [2]
- Palpation: Crepitus over fracture sites, bony step-offs, subcutaneous emphysema, chest wall instability
- Auscultation: Decreased breath sounds (hemothorax/pneumothorax), crackles (contusion)
- Vital signs: Tachypnea, tachycardia, hypoxia; hypotension suggests associated hemorrhage
- Full trauma exam: ATLS primary and secondary survey — assess for TBI, abdominal injuries, pelvic/long bone fractures (extrathoracic injuries in ~90%) [2]
11. Lab Studies
- ABG/VBG: Assess oxygenation, ventilation, A-a gradient (correlates with contusion severity) [3]
- CBC: Baseline hemoglobin (serial for hemorrhage monitoring)
- Type and screen/crossmatch: Anticipate transfusion needs
- Lactate: Tissue perfusion marker
- Coagulation studies: PT/INR, PTT (especially if on anticoagulants)
- Troponin: Rule out myocardial contusion
- BMP: Baseline renal function for fluid management
- Ethanol level/UDS: If altered mental status
12. Imaging
- Chest X-ray (CXR): First-line in unstable patients; can detect flail chest, large pneumothorax/hemothorax, mispositioned tubes — but sensitivity is limited [9]
- CT chest with IV contrast: Gold standard for defining injury extent — detects rib fractures (including occult), pulmonary contusion volume, pneumothorax, hemothorax, and vascular injuries with higher sensitivity than CXR. 3D reconstructions are essential for surgical planning [9-11]
- CT of the chest is essential for pre-operative planning of surgical stabilization [9]
- E-FAST: Rapid bedside assessment for pneumothorax, hemothorax, hemopericardium in unstable patients [9]
- CXR may be unnecessary if CT is being performed in a stable patient with suspected chest trauma
13. Special Tests
- Regional analgesia techniques: [3][5-6]
- Thoracic epidural: Preferred for bilateral rib fractures and severe flail chest — gold standard for pain control
- Paravertebral block: Alternative when epidural is contraindicated (coagulopathy, spine fractures)
- Serratus anterior plane block (SAPB): Emerging technique, feasible in ED, safe in anticoagulated patients and those in spinal precautions [8]
- Erector spinae plane (ESP) block: Promising ease of administration and safety profile [6]
- Intercostal nerve blocks with liposomal bupivacaine: Option when other regional techniques are contraindicated [5]
- Pulmonary contusion volume quantification on CT — correlates with ARDS risk [9]
- Incentive spirometry: Objective measure of respiratory effort and tidal volume trending
- Bronchoscopy: If tracheobronchial injury suspected (90% sensitivity) [9]
14. ECG
- Obtain ECG in all blunt chest trauma to evaluate for:
- Myocardial contusion: ST changes, new arrhythmias (sinus tachycardia, atrial fibrillation, PVCs, bundle branch blocks)
- Right heart strain pattern (if tension pneumothorax or massive PE)
- Pericardial effusion/tamponade: Low voltage, electrical alternans
- Continuous telemetry monitoring recommended for at least 24 hours if ECG abnormalities present
15. Assessment
- Flail chest is a clinical diagnosis confirmed by paradoxical chest wall motion on exam and ≥3 consecutive ribs fractured in ≥2 places on imaging [1]
- Severity depends on: extent of flail segment, degree of pulmonary contusion, associated injuries, patient age, and comorbidities [2-3]
- Respiratory compromise is driven primarily by the underlying pulmonary contusion (not the mechanical flail itself), with secondary contributions from pain-induced splinting and chest wall instability [3]
- Pulmonary contusion coexists in 40–60%; pneumothorax/hemothorax in ~70% [2][4]
- ARDS develops in ~27% of flail chest patients [4]
- Long-term morbidity is significant: 46% have abnormal chest wall expansion, 24% obstructive changes, 20% restrictive changes on spirometry at follow-up [3]
16. Treatment Plan
Initial Stabilization (ED)
- ATLS primary survey — address airway, breathing, circulation
- Supplemental O₂, pulse oximetry, continuous monitoring
- Chest tube for pneumothorax or hemothorax
- Do NOT intubate solely for chest wall instability — intubate only for respiratory failure [3]
- If intubated: include PEEP/CPAP in ventilatory regimen [3]
- Trial of mask CPAP in alert, compliant patients with marginal respiratory status combined with regional anesthesia [3]
Pain Management (see Medications above)
- Initiate multimodal analgesia immediately [5]
- Early regional analgesia consultation — epidural is preferred for severe flail chest [3]
Fluid Management
- meticulously avoid unnecessary fluids[3]
Surgical Stabilization of Rib Fractures (SSRF)
- Should be considered in all hemodynamically stable patients with flail chest (WSES-AAST, Moderate GoR) [9]
- Optimal timing: within 48–72 hours of injury (Strong GoR); if early intervention contraindicated, perform within 3–7 days [9]
- Nationwide data show SSRF associated with mortality of 4.2% vs 10.1% with nonoperative management in flail chest (p = 0.002) [12]
- Benefits: reduced mechanical ventilation duration (~4.5 fewer days), lower pneumonia/tracheostomy rates, shorter ICU stay, lower mortality, cost-effective [1][13]
- Best candidates: anterolateral flail chest with respiratory failure without severe pulmonary contusion; patients failing to wean from ventilator; non-intubated patients with deteriorating pulmonary function [1][9]
- Contraindication: hemodynamic instability is an absolute contraindication to SSRF [9]
- Relative contraindications: advanced age, significant cardiopulmonary comorbidities, active malignancy [9]
17. Disposition
- All flail chest patients require ICU admission — high risk of respiratory deterioration, need for continuous monitoring, and potential for mechanical ventilation
- Admission criteria: Any confirmed flail chest, respiratory distress, hypoxia, associated intrathoracic injuries, need for chest tube, hemodynamic instability
- Observation is insufficient — flail chest is not an observation-level diagnosis
- Surgical consultation triggers: All flail chest patients should have trauma surgery consultation; consider thoracic surgery for SSRF evaluation [15]
- Multidisciplinary team approach: trauma surgery, thoracic surgery (if available), anesthesia/pain service, respiratory therapy, physiotherapy [15]
18. Follow Up / Return Precautions
- Inpatient: Aggressive pulmonary toilet, incentive spirometry, early mobilization, daily respiratory assessment
- Post-discharge follow-up: Trauma clinic within 1–2 weeks; repeat imaging at 4–6 weeks to assess healing
- Return precautions: Worsening dyspnea, fever, productive cough (pneumonia), chest pain, hemoptysis
- Expected recovery: 6–12 weeks for fracture healing; significant long-term morbidity is common — persistent chest tightness, dyspnea on exertion, and chronic pain, especially with nonoperative management [1]
- Pulmonary function testing at follow-up to assess for restrictive/obstructive deficits [3]
- Return to work: Earlier with SSRF vs nonoperative management [1]
References
1. Surgical Stabilization of Rib Fractures (SSRF): The WSES and CWIS Position Paper. — Sermonesi G, Bertelli R, Pieracci FM, et al. World Journal of Emergency Surgery : WJES. 2024.
2. Surgical Versus Nonsurgical Interventions for Flail Chest. — Cataneo AJ, Cataneo DC, de Oliveira FH, et al. The Cochrane Database of Systematic Reviews. 2015.
3. Management of Pulmonary Contusion and Flail Chest: An Eastern Association for the Surgery of Trauma Practice Management Guideline. — Simon B, Ebert J, Bokhari F, et al. The Journal of Trauma and Acute Care Surgery. 2012.
4. Flail Chest as a Marker for Significant Injuries. — Ciraulo DL, Elliott D, Mitchell KA, Rodriguez A. Journal of the American College of Surgeons. 1994.
5. Best Practices Guidelines For Acute Pain Management In Trauma Patients. — Andrew Bernard, Douglas R. Oyler PharmD, Jeffrey O. Anglen MD FACS FAAOS, et al American College of Surgeons (2020). 2020.
6. Acute Pain Management of Rib Fractures: A Narrative Review. — Bresgen TU, Salinaro F, Barcella B, et al. Injury. 2025.
7. The 2023 WSES Guidelines on the Management of Trauma in Elderly and Frail Patients. — De Simone B, Chouillard E, Podda M, et al. World Journal of Emergency Surgery : WJES. 2024.
8. Serratus Anterior Plane Blocks for Early Rib Fracture Pain Management: The SABRE Randomized Clinical Trial. — Partyka C, Asha S, Berry M, et al. JAMA Surgery. 2024.
9. Thoracic Trauma WSES-AAST Guidelines. — Coccolini F, Cremonini C, Moore EE, et al. World Journal of Emergency Surgery : WJES. 2025.
10. ACR Appropriateness Criteria® Major Blunt Trauma: Update 2025. — Expert Panel on Polytrauma Imaging, Lee JT, Camacho MA, et al. Journal of the American College of Radiology : JACR. 2026.
11. ACR Appropriateness Criteria® Major Blunt Trauma. — Shyu JY, Khurana B, Soto JA, et al. Journal of the American College of Radiology : JACR. 2020.
12. Early Surgical Stabilization of Multiple Rib Fractures and Flail Chest Is Associated With Better Outcomes Compared With Nonoperative Management. — Kwon J, Zakhary B, Coimbra BC, Sarani B, Coimbra R. The Journal of Trauma and Acute Care Surgery. 2025.
13. Operative Management of Rib Fractures in the Setting of Flail Chest: A Systematic Review and Meta-Analysis. — Leinicke JA, Elmore L, Freeman BD, Colditz GA. Annals of Surgery. 2013.
14. Operative vs Nonoperative Treatment of Acute Unstable Chest Wall Injuries: A Randomized Clinical Trial. — Dehghan N, Nauth A, Schemitsch E, et al. JAMA Surgery. 2022.
15. Management of Chest Wall Injuries: An Updated Review. — Dehghan N, Nauth A, McKee M. The Journal of the American Academy of Orthopaedic Surgeons. 2026.