Mechanisms of Injury in Trauma. Frank Wright, MD Trauma, Acute Care Surgery, and Surgical Critical Care University of Colorado Hospital

Transcription

1 Mechanisms of Injury in Trauma Frank Wright, MD Trauma, Acute Care Surgery, and Surgical Critical Care University of Colorado Hospital

2 Overview Review Penetrating GSW Stabbing Blunt MVC/MCC/auto-ped Fall Blast Disclosures: None

3 Penetrating GSW Shotgun Handgun Rifle

4 Penetrating GSW Shotgun Massive destruction if short range If pattern > 25cm, lower risk of internal injury At ~15-20 meters distance, often only penetrate skin/muscle

5 Penetrating - GSW Handgun Rifle Size Matters

6 Penetrating - GSW 3 Zones of Injury Laceration/Crush Permanent Cavity Stretch/Cavitation Temporary Cavity Shock waves Can reach up to 200atm with high velocity projectiles

7 Penetrating - GSW Internal ballistics longer barrel fires with greater velocity Kinetic Energy = mass * velocity 2 / 2 Ballistic Gelatin Model

8 Penetrating - Stabbing Location Matters Anterior abdominal wall 50-75% do not need operation Flank CT A/P Chest Tube thoracostomy is definitive management for hemothorax 85% of the time Cardiac Box Mid-clavicular line from clavicle to costal margin Thoraco-abdominal Extremity

9 Special Consideration - Neck Vital structures Caution with intubation May be safer to transport without intubation Penetrating Allow them to tripod, lean forward Controlled intubation in ED or OR with neck prepped and full exploration tray available Fiberoptic?, glide?, prepped and draped?

10 Blunt Trauma Transfer of energy MVC Falls Auto pedestrian MCC

11 Blunt Trauma Transfer of energy MVC mortality Head-on 60% Side impact 20-35% Rollovers 8-15% Rear-end 3-5% Ejection traveling at speed of vehicle, hit immobile object, no protection 4x more likely to have ICU admission 5x higher ISS 5x higher mortality Lateral impact Less protection higher rate of thorax and abdominal injuries

12 Blunt Trauma Falls LD50 48ft (4 stories) 34ft if head/chest injury 68ft if no injuries to head/chest LD90 84ft (7 stories) 76.2% orthopedic injuries 19-22% spinal fractures

13 Auto-pedestrian Auto-pedestrian Lower extremity impact (tibia/fibula) Fulcrum with thorax and head forced onto hood Tibia/Fibula fx, rib fx, TBI, spleen/liver

14 Auto-pedestrian 35 mph Mortality Speed

15 Auto-pedestrian 45 mph Mortality Speed

16 Unadjusted Comparison Light bar Helmeted v Unhelmeted Regression Analysis Helmeted v Unhelmeted (reference)

17 Specific Blunt Trauma Injury Patterns BCVI Aortic Injury Flail Chest Diaphragm Trauma Pelvic Fractures

18 BCVI Risk Factors for BCVI High-energy transfer mechanism with: LeForte II or III fracture Cervical-spine fracture patterns: subluxation, fractures extending into the Hyperextension mechanism Carotid or Vertebral artery Majority manifest within 72h Treated with heparin drip vs antiplatelet Re-image in 7 days Transverse foramen, fractures of C1-C3 Basilar skull fracture with carotid canal involvement Diffuse axonal injury with a Glascow Coma Scale (GCS) score < 6 Near hanging with anoxic brain injury

19 Denver Grading Scale 3% 11% 33% 44% 20% Grade I: irregularity of the vessel wall or a dissection/intramural hematoma with less than 25% luminal stenosis Grade II: intraluminal thrombus or raised intimal flap is visualized, or dissection/intramural hematoma with 25% or more luminal narrowing Grade III: pseudoaneurysm Grade IV: vessel occlusion Grade V: vessel transection < 1% rate CVA with ASA or low heparin

20 Blunt Aortic Injury LTC. Parmley Circulation 1958 Autopsy study 275 cases of blunt aortic injury 85% fatal, 15% arrive to ED Variable extent of aortic injury Clinical presentation Early Diagnosis

21 Blunt Aortic Injury Trauma of energy: Deceleration Compression Intra-luminal hypertension

22 Blunt Aortic Injury Deceleration Shear Forces

23 Blunt Aortic Injury Deceleration Compression 382 M. Scaglione et al. / European Journal of Radiology 65 (2008) ble segment of chest wall (Fig. 6). In this context, MDCT may be useful, since it offers important spatial details for the optimal surgical approach. Thoracic compression may frequently cause lung parenchyma (contusion and laceration) and pleura (pneumothorax and hemothorax) injuries. Furthermore, relatively uncommon but potentially life-threatening injuries include fractures, lacerations, and disruptions of the tracheobronchial tree and the diaphragm. It is important to underline that compression chest injuries may not be necessarily confined to the chest but also involve the homolateral abdominal side right and left-sided thoracoabdominal injury, causing abdominal solid-organ and/or very serious vessels injuries (Figs. 7 and 8). In this context, the flexibility of acquisition protocols, the increased efficiency and speed of MDCT scanners and the optimal multiplanar reconstruction view from isotropic-voxel data sets allow a 386 quick and accurate evaluation of M. all Scaglione trauma injuries, et al. / European providing necessary details for optimal and timely management Journal of Rad approach Deceleration injuries Intra-luminal hypertension Fig. 5. A 57-year-old trauma patient having a midline thoracic trauma after a violent motorcycle crash. (a) Sagittal multiplanar reconstruction shows multiple fractures of the sternal body (small arrows), retrosternal hematoma (asterisk) and vertebral fractures (large arrows) along the course of a vector force anteroporsteriorly directed, fromhightolow. Moredistally, (b) axialctimage depicts open-book pelvic fracture associated with diffuse extraperitoneal hematoma Deceleration injuries are the most common and lethal injuries in our part of the world. This mechanism is responsible for major airways injuries, cardiac contusions, aortic lesions, diaphragmatic rupture. High-speed motor-vehicle accidents (MVAs) are the major cause ofblunt thoracic aortic injuries and blunt injuries of the major thoracic arteries. Blunt aortic injuries follow closely behind head injury as a cause of death after blunt trauma. Falls from heights and MVAs involving a pedestrian are other recognized causes. The mechanisms of injury are rapid deceleration, production of shearing forces, and direct luminal compression against points of fixation (especially at the ligamentum arteriosum). Many of these patients die from vessel rupture and rapid exsanguination at the scene of the injury or before reaching definitive care. However, it should be emphasized that in these patients death usually occurs when trauma causes complete tear of the three layers constituting the aortic wall. Conversely, when trauma causes incomplete vessel injury (i.e. small injuries confined to the intima or involving the intima and media layers) patients may survive the initial trauma for days, months or even years without receiving any treatment. In this patient group, aortic injury is often discovered incidentally or may cause delayed symptoms (such as dysphonia, dyshagia) that only subsequently are connected to a past traumatic episode. In the emergency setting, MDCT is the best diagnostic tool to quickly and accurately evaluate the aorta while requiring only intravenous contrast material. MDCT allows not only to diagnose (or exclude!) aortic injuries butalso showappropriate grade of injuries which correlates to the need of urgent treatment [27]. This is of particular importance in the acute setting because these patients usually have more than one problem to solve at the same time: stabilizing the patient before taking any treat- Fig. 1. A 25-year-old male patients with suspected chest injury after direct hammer blow. (a window setting) show localized chest wall injury (arrow). (d f) Corresponding images (lun quality images thereby improving diagnostic accuracy for the lesions of all anatomical chest components (chest cage, lungs, tracheo-bronchial tree, blood vessels, diaphragm) [13 30]. After initial clinical assessment which must take place during the stabilization of the traumatized patient, including X-ray chest film and abdominal ultrasound performed by the Radiologist during intubation and insertion of central venous and avail have supe to de radio hemo In

24 Blunt Aortic Injury Deceleration Compression Intra-luminal hypertension

25 J Trauma Jan;70(1):

26 Mechanism of Injury MVC 52% Auto-Ped 37% MCC 6.9% Fall 2.9%

27 Crash Injury Research Engineering Network (CIREN) 29.8 mph

28 Crash Injury Research Engineering Network (CIREN) 22.4 mph

29 Pulse-Pressure Control Augmentation of Δp/Δt Wheat et al Aortic wall tension is directly proportional to increase in pressure and inversely proportional to pulse rate 90/90 rule esmolol drip

30 Treatment Open aortic repair Generally requires cardiopulmonary bypass Why is this a problem in a trauma patient? Endovascular stent Medical management Pulse-Pressure Control

31 Flail Chest Fractures in at least 3 ribs in 2 locations Creates dissociation of chest wall from respiration Marker for underlying pulmonary contusion Intubation may lead to tension pneumothorax Paradoxical respiration

32 Diaphragmatic Trauma 3:1 Left to Right ratio Marker for high mechanism impact Associated injuries Pelvic fx 40-55% CHI 42% Hepatic/splenic injury 25-60% Thoracic aortic injury 5-10%

33 Imaging

34 Morbidity higher in blunt vs penetrating 60 vs 40% (atelectasis, lobar collapse, PNA, sepsis, MSOF, abscess, prolonged respiratory failure, empyema, rib fractures, associated organ injuries) Penetrating injury between 4 th and 12 th rib Left sided penetrating thoracoabdominal trauma 24% have diaphragmatic injury noted by 20 months post-trauma Mortality - Generally due to associated injuries

35 Pelvic Ring Injuries Exsanguinating hemorrhage Combination of osseous, venous and arterial Most commonly involves internal iliac vessels Treatment Mechanical stabilization Hemorrhage control Rectovaginal exam

36 Young-Burgess Classification J Trauma Jul;30(7):848-56

37 Neurovascular Injury Vascular injury % Neurologic injury > 20% Vertical Shear Pattern ~ 45% Lumbo-sacral plexopathy (L2-S3)

38 Mechanical Stabilization Pelvic binder T-POD Sheet External fixation C-clamp

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40 Hemorrhage Control Angiography and embolization Less timely 80% of hemorrhage is venous Increase risk of pelvic floor/gluteal ischemia/necrosis Preperitoneal pelvic packing Venous injury control (80% of bleeding) Possible arterial control Failure associated with arterial hemorrhage Can then perform IR embolization

41 191 patients requiring transfusion DAY (7:30 AM-5:30 PM, weekdays) AHR (5:30 PM-7:30 AM and weekends/holidays) 88 pts (32 DAY, 56 AHR) survived to IR 16 pts died while awaiting IR (all AHR group) J Trauma Acute Care Surg AHR group 94% increased risk of mortality

42 Pelvic packing

43 Blast Injury

44 Blast Injury Primary Direct effect of high pressure wave air and fluid containing organs ear/lung/eye/bowel Tympanic membrane rupture sensitive marker for proximity to blast Blast lung injury 5-8% of live casualties in urban bombings Penetrating head/torso injury, burn, skull fx indicate high risk of BLI Extent of BLI most important determinant of subsequent mortality Range: pulmonary contusion to severe ARDS Barotrauma (PTX and broncho-alveolar fistula), air embolism, upper airway mucosal damage Treat as severe ARDS Up to 60% mortality

45 Blast Injury Secondary blast injury penetrating trauma Tertiary blast injury Blunt trauma Thrown by blast, strike objects or fall Quaternary blast injury Burn/Crush Enclosed space detonation Increased mortality and injury severity Reflected/amplified blast wave 4-6x increased mortality

46 Questions?