Case 75 - Thoracic trauma Flashcards
What are some physiologic derangements from chest injuries (card, pulm, heme)?
Pulmonary Failure
- hypoxia and hypercarbia
- causes:
- lung laceration
- lung contusion
- airway injury
- chest wall splinting
- diaphragmatic injury
Heme (hypovolemic shock)
- hemorrhage
- DIC
Cardiac Failure (cardiogenic shock)
- pericardial tamponade
- cardiac rupture
- myocardial contusion
How do you diagnose pneumothorax?
- CXR in sitting position
- CT
- may consider in patients that cannot sit up for CXR 2/2 c spine injury or hd instability
- Ultrasound
- absence of lung sliding
- absence of comet-tail artifact
- comet-tail artifact = multiple reverbations off the pleural line thought to be created when ultrasound waves hit the interface between the apposing pleural and visceral layers of the lung.
- when air gets in between apposing layers, lose “comet-tail artifacts”
what are s/sx of pneumothorax under anesthesia?
- increase peak airway pressure
- decrease lung complicance
- absent unilateral breath sounds
- decrease SaO2
- severe hypotension / HD instability
What may be a ddx of pneumothorax in a chest trauma patient?
- atelectasis
- bronchial obstruction
- traumatic diaphragamtic defect with herniation of abdominal contents into thorax
What are symptoms of hemothorax and what are indications for thoracotomy (as opposed to VATS)?
Symptoms of hemothorax
- hemorrhagic shock
- mediastinal shift
indications for thoracotomy
- volume and rate of blood drained via CT determine VATS vs thoracotomy:
- drain > 1200 mL of blood on initial CT placement
- > 200 mL/hr for 4 hours.
What is flail chest?
- fracture of several ribs at two or more sites
how does flail chest contribute to respiratory impairment?
- Flail chest can lead to resp impairment –> arterial hypoxemia and hypoercarbia
- 2 mechanism: paradoxical ventilation and pulmonary contusion
Paradoxical ventilation
- caving of flail segment on inspiration and bulgin on exhalation
- this is dyssynchrous with movement of contralateral chest wall and diaphragm.
- flail segment may inc work of breathing
Pulmonary contusion
- primary cause of M&M after blunt chest trauma
- blood in alveoli and interstital space cause increase in elastic recoil –> difficult for lung to expand –> inc work of breathing, dec FRC, dec lung compliance
What is the pathophysiology of lung contusion?
- interstital and intraalveolar hemorrhage, alveolar disruption, and atelectasis
- v/q mismatch, intrapulm shunting, pulm edema -> result is hypoxemia, hypercarbia, tachypnea, shallow breathing
- can develop inflammation –> ARDS
How do you diagnose flail chest and pulmonary contusion (what are the clinical symptoms, PE findings, radiological exam, lab findings)
- flail chest is associated with pulmonary contusion
- diagnosis involves: 1) clinical symptoms, 2) physical exam, 3) radiologic studies, 4) lab studies
1) clinical symptoms
- dyspnea, tachypnea
- intercostal muscle retractions
- use of accessory muscles of respiration
2)PE
- chest wall bruising
- rib cage deformity - paradoxical ventilation
- crepitus / pain on palpation of thorax
3) radiology
- CXR –> underestimates contusion volume
- CT
4) labs
* serial ABGs - progressive hypoxia, hypercarbia, resp acidosis
how will you manage a patient with flail chest and pulm contusion?
Managament
Goal - decrease elastic recoil and work of breathing, improve blood gases w/o adverse hemodynamic effect
- NIPPV
- many patients do well with NIPPV
- intubation
- impending respiratory failure
- avoid volume overload / excessive fluid administration
- volume overload –> pulm edema –> increase size of contusion and worsen repiratory function
- guide fluid managemnt by TEE, PAC
- Pain
- epidural if no contraindication
- paravertebral block, intercostal block, IV opioids
how would you monitor a flail chest patient with pulmonary contusion?
Monitors
- Pulse oximeter
- arterial line
- beat to beat monitoring
- serial abg
- TEE
- PAC
- calculate O2 delivery
- intrapulmonary shunt fraction to adjust optimal CPAP
What is acute cardiac tamponade?
- rapid accumulation of fluid or blood in the pericardial sac
-
external compression of pericardial blood results in
- 1) inflow occlusion of atrioventricular valves (valves are pushed inwards, creating small orifice area)
- 2) decrease ventricular filling
-
Equalization of intrapericardial pressure with myocardium filling presures
- Diastolic underfilling results in CO becoming rate dependent
- does not give time for heart to compensate
- Emergent
how do you diagnosis cardiac tamponade?
diagnosis based on clinical signs, EKG, and Echo (gold standard)
Clinical Signs
- CVD
- hypotension
- muffled heart sounds
- paradoxical pulse
- exaggerated respiratory variation
- > 10 mm Hg decline in systolic pressure during inspiration in a spont breathing pt
Ekg
- diminished QRS voltage (due to fluid accum)
- electrical alterans (phasic alteration of R wave amplitude as heart swings back and forth in pericardial sac)
TEE
- RV diastolic collapse
- early diastole, indicating that intrapericardial pressure is transiently exceeding RV filling pressure during diastole.
- pericardial fluid
PAC
- equalization of cardiac chamber pressure
what is the mech of action of pulsus paradoxus in cardiac tamponade pts?
In spont breathing pts, inspiration provides negative intrathoracic pressure…
1) increae in transmural aortic pressure and in LV ventricular afterload
* (dec ejection of blood in face of higher afterload)
2) ** has RV fills during inspiration, intraventricual septum bulges into LV, decreasing its cavity –> LV underfilling**
how would you manage cardiac tamponade?
1) Is this patient cardiovascularly unstable?
* emergent pericardiocentesis
2) stabilize till surgery
- Volume replacement
- Fast Full Strong
- Fast HR
- Full Volume
- avoid drugs that cause myocardial depression
- Increase SVR to maintain coronary perfusion
- spontaneous ventilation
3) anesthesia
- volume!!!
- fast full strong
- ketamine induction to maintain sympathetic system and spont vent
-
Spont Ventilation preferred to prevent a reduction in venous return
- if PPV necessary, low airway pressure, no PEEP (Avoid increasing intrathoracic pressure –> at risk for dec venous return)
- Avoid myocardial depresion and bradycardia
what is the mechanism of injur, site of injury, and clinical features of traumatic thoracic aortic injury?
Mechanism of injury
- sudden body deceleration
- compression of thoracic vessels between spine and ribs/sternum
Site
- most common = aortic isthmus
- junction between distal arch and descending thoracic aorta. Just distal to subclavian A
- rarely ascending aorta or arch
Clinical features
- unexplained hypotension
- evidence of direct chest injury
- pulse deficits (b/w R and L upper extremity and upper and lower extremities)
- retrosternal pain
- hoarseness (recurrent laryngeal N. injured)
- LE neurologic deficits
What method can be used to definitively dx blunt aortic injury?
- CT angiography
- indicates location and type of lesion
Other methods of detection of aortic injury
- CXR
- mediastinal widening
- right deviation of esophagus and trachea
- displaced left main stem
- blurred aortic contours
- CT
- TEE
What are the current management strategies for blunt aortic injury?
Anesthesia
- PREVENT RUPTURE
- decrease shearing force or viscous drag of blood flow on injured wall
- 1) dec myocardial contractility
-
2) maintain lowest BP acceptable for tissue perfusion and oxygenation
- BB (esmolol infusion), CCB, NTG
Surgical
-
endovascular approach
- decreased blood loss, reduce mortality, avoid GENA and double lumen tube, lower risk of paraplegia, shorter ICU stay
- low grade injury –> CT scan, BP control, manage conservatively
What are potential airway management problems associated with thoracic aorta injuries?
1) prevertebral space
- bleeding from aorta can reach preertebral spce
- hematoma in this area can shift larynx and trachea anteriorly –> difficult laryngoscopy view
2) C-spine collar
- trauma pts usually in cervical collar
- limited neck extension during laryngoscopy
3) pseudoaneurysm and left main stem
- pseudoaneurysm or subadventital hematoma can compress Left Main Stem bronchus
- causes narrowing of lumen
-
forcing left-sided DLT and inflating cuff can result in rupture of aneurysm
- FOB –> look for pulsating area of left main stem bronchi.
Patient undergoes thoracic abdominal repair following a MVA c/b thoracic aortic injury. After surgery, he wakes up and complains of not moving his legs. What may be some causes?
Anatomy
- blood supply to spinal cord –> 1 anterior and 2 posterior spinal arteries
- originate from vertebral A
- ant spinal A supplies anterior 2/3 of spinal cord (motor area)
- posterior spinal A supplies post 1/2 of spinal cord (vibration, proprioception, sensory area)
Mechanism of spinal cord ischemia
1) occlusion of subclaivan A
- Vertebral A comes off subclavian A.
- vertebral A forms ant and post spinal artery
- injury or surgical clamp of subclavian A
2) injury to Artery of Adamkiewicz
* typicall found T8-T12
3) hypotension
* Spinal cord Perf Pres = MAP - CVP (or ICP)
