Anesthesia Considerations in Thoracic Trauma Patients 張婉玲 醫師 嘉義長庚醫院 麻醉科 2009.11.21.

Introduction Mortality from chest injuries is around 10% The majority of patients with thoracic trauma can be managed conservatively Require thoracotomy： Blunt trauma：10 % Penetrating trauma：15 %～30 %

Initial Management Plan Airway maintenance with cervical spine protection Breathing: ventilation and oxygenation Circulation with hemorrhage control

Initial Assessment Primary Survey: –AIRWAY •Always assume a cervical spine injury exists until proven Jaw-thrust maneuver

Initial Assessment ALWAYS ASSUME FULL STOMACH PRECAUTIONS---RAPID SEQUENCE INTUBATION

Indications for intubation: –Airway obstruction –PaO2 < 80 mmHg or SpO2 < 90% with O2 –Shock with SBP < 90 mmHg –Severe head injury or unconscious (GCS <9) –Anticipated surgery with multisystem injury

Initial Assessment Awake intubation: local, topical superior laryngeal nerve blocks Awake fiberoptic: may be too bloody Awake cricothyrotomy/tracheostomy Know your difficult airway algorithm!

Initial Assessment BREATHING –100 % O2 –Always verify correct position of ETT.

Initial Assessment Circulation –Control hemorrhage first! –Crystalloids vs. colloids vs. blood products?

Secondary survey After primary survey complete, attempt to complete a head-to-toe assessment

Preop assessment Cardiac: S/S shock, EKG changes Respiratory: Breath sounds, crepitus, respiratory patterns/distress, CXR Neurologic: GCS, LOC; assume C-spine injury until ruled outLateral C-spine Xray, palpate neck Renal: monitor urine output, amount and color

Preop assessment Gastrointestional: FULL STOMACH!!!! Endocrine: release of stress hormones (catecholaminesand glucose) Hematologic: hypovolemicshock; coagulopathies

Laboratory/diagnostic tests CBC, electrolytes, urinalysis, PT/PTT, lactate, baseline ABG (as condition permits) CXR, lateral C-spine, CT/MRI 12 lead EKG FAST: focused abdominal sonography for trauma

INJURIES TO IDENTIFY DURING PRE-OPERATIVE ASSESSMENT

AIRWAY INJURY/OBSTRUCTION Intrathoracic tracheobronchial injuries are less common than upper airway injuries. High mortality. A definitive airway can usually be secured using a fiber-optic bronchoscope

Pneumothorax Accumulation of air between parietal and visceral pleura Results in severe V/Q mismatch and hypoxia S/S: –chest wall hyperresonant to percussion –Breath sounds decreased or absent unilaterally –Subcutaneous emphysema –CXR confirms

Tension pneumothorax Diagnosis of tension pneumothorax is clinical rather than radiological - Absent breath sounds - Hyper-resonant percussion - No chest movement - Tracheal deviation to the injured side - Distended neck veins (may not be seen if the patient is hypovolaemic). - Severe dyspnoea, tachycardia and hypotension

Tension pneumothorax Immediate chest decompression is required. During anaesthesia In pressure controlled modes: ↓ tidal volume In volume controlled modes: ↑ peak airway pressure

OPEN PNEUMOTHORAX >2/3rd the diameter of the trachea. This results in paradoxical breathing with collapse of the lung on the affected side during inspiration. This results in increased intra-pulmonary shunt, decreased venous return and progressive hypoxaemia and hypercapnia. Administration of oxygen, covering the wound and chest drain insertion.

Hemothorax Can be caused from bleeding of intercostal vessels, pulmonary arteries or veins, avulsion of mediastinal vessels or penetrating cardiac injury. Differentiated from pneumothorax by dullness to percussion with absent breath sounds

Hemothorax The choice and dose of anaesthetic induction agent is determined by the severity of the shock and any preexisting medical co-morbidity Fluid load before chest tube placement Thoracotomy may be needed if drainage is more than 250 mls per hour, or the patient’s physiological status continues to deteriorate despite fluid replacement.

Flail chest Results from two or more ribs fracture in two or more places Accompanied by hemothorax or pulmonary contusion Patients with 3 or more rib fractures have greater likelihood of hepatic or splenicinjury

Flail chest S/S –Paradoxical chest wall movement Treatment –O2 –Pain control

Cardiac tamponade Life-threatening emergency Bleeding into pericardial space, which restricts cardiac filling during diastole and creates a low cardiac output state Initial symptoms - Dyspnea – Orthopnea – tachycardia

Cardiac tamponade Classic symptoms –Beck’s triad neck vein distention, hypotension, muffled heart sounds –Pulsus paradoxus: > 10 mmHg decrease in blood pressure during spontaneous inspiration May not be evident in hypovolemia

Cardiac tamponade Echocardiography provides the definitive diagnosis.

ANAESTHESIA FOR RESUSCITATIVE THORACOTOMY Penetrating cardiac injury may rapidly lead to cardiac arrest. Induction of anaesthesia may lead to a dramatic loss of blood pressure and care should be taken with the choice of induction agent.

AORTIC DISRUPTION A wide mediastinum on chest X-ray may be the only indication that the injury has occurred Spiral contrast CT is now performed more frequently than angiography

TRACHEOBRONCHIAL INJURY high mortality In blunt trauma the majority of injuries occur within a 2 – 3 cm of the carina Signs include haemoptysis, subcutaneous emphysema and persisting pneumothorax or broncho-pleural fistula following chest drain insertion.

TRACHEOBRONCHIAL INJURY Low tidal volume, permissive hypercapnia ventilatory strategies are required until surgical intervention has occurred. Once intubated fibre optic bronchoscopy is needed to identify the site of the leak.

OESOPHAGEAL DISRUPTION very rare most frequently occurring in the lower oesophagus

DIAPHRAGMATIC RUPTURE most commonly after blunt abdominal trauma. Usually on the left side. Classically the stomach, nasogastric tube or colon is noted to be in the left side of the chest on chest X-ray.

Pulmonary contusion Intra-alveolar hemorrhage and edema resulting from sudden increase in intra-alveolar pressure and rupture of alveolar-capillary interface Difficult to diagnosis

ARDS Later pulmonary complication Attributed to direct thoracic injury, sepsis, aspiration, head injury, massive transfusion, oxygen toxicity, and fat embolism Mortality rate reaching 50%

INTRA-OPERATIVE LUNG PROTECTIVE STRATEGIES LUNG PROTECTIVE VENTILATION tidal volume 6 - 8 mls/kg trans alveolar pressure is kept below 35 cm of water (plateau airway pressure of 35 - 45 cm of water).

INTRA-OPERATIVE LUNG PROTECTIVE STRATEGIES INTRA-OPERATIVE LUNG RECRUITMENT Extrinsic PEEP a single large tidal breath and holding end inspiration for 20 seconds

Myocardial contusion Associated with blunt trauma Contusion most often right ventricle since lies directly posterior to sternum S/S –Dysrhythmias: heart block to Vfib; ST segment elevation –Elevated CPK-MB; ? Troponin elevation –CHF –Anginal pain which may or may not respond to nitrates

Anesthetic management The general principles of trauma anesthesia such as oxygenation, restoration of circulating volume, correction of hypothermia and coagulopathy.

Anesthetic management Induction Standard monitors Preoxygenation direct laryngoscopy + RSI Invasive monitors as indicated

Induction agents Thiopental 3-4 mg/kg; reduce doses in unstable patients Ketamine 0.5-1 mg/kg; useful for burn and hypovolemic patients; avoid with head injuried Etomidate 0.1-0.3 mg/kg; reduce doses with hypovolemia Propofol 1-2 mg/kg in stable patients; reduce doses in hypovolemia

Muscle relaxants Succinylcholine: 1-2 mg/kg; useful for RSI Rocuronium: 1 mg/kg

ONE LUNG ANAESTHESIA Double-lumen tubes are often difficult to insert during rapid sequence intubation and are commonlyassociated with malposition.

Maintenance Low-dose volatile agent with fentanyl and nondepolarizing muscle relaxant is usually suitable. Avoid Nitrous oxide. Bispectral index monitor

Conclusion Blunt or penetrating thoracic injuries present a particular challenge as a result of complex, dynamic and lifethreatening injuries The roles of the anesthesiologist and anesthetist are critical.