Emergency Airway Management for Trauma Patients

Emergency Airway Management for Trauma Patients

• Traumatic airway injury requires rapid assessment and emergency management in critically ill patients.
• Rapid sequence induction (RSI) is a vital and fundamental skill for anesthesia providers in airway management.

Endotracheal Intubation and Airway Management

• Endotracheal intubation is a mainstay of anesthesia practice.
• Difficult tracheal intubation is the third most common respiratory-related event that leads to brain damage and death.
• RSI is the preferred method for traumatic airway management.

Muscle Relaxants and Airway Management

• Muscle relaxation is associated with the highest overall rate of successful airway management.
• The use of muscle relaxants in RSI increases the risk of a "can't intubate/ can't ventilate" scenario.

Emergency Intubation for Trauma Patients

• Emergency intubation should adhere to the American Society of Anesthesiologists (ASA) difficult airway algorithm.
• Trauma patients are assumed to have delayed gastric emptying and are at increased risk for aspiration.
• Anesthesia providers must be skilled in utilizing airway adjuncts, including video laryngoscopy and cricothyroidotomy.

Cervical Spine Injuries

• Patients with blunt or penetrating neck and face injuries should be considered to have cervical spine instability.
• The incidence of cervical spine injury after trauma is approximately 3% to 6% of all trauma patients and approximately 10% for patients with traumatic brain injury.
• In-line manual axial stabilization is essential for immobilizing the neck during airway management.
• Cricoid pressure (Sellick maneuver) assists the anesthetist by displacing the larynx posteriorly and providing an improved view of the vocal cords.
• Cricoid pressure may be contraindicated in patients with cervical spine injuries due to the risk of spinal cord and vascular injury.
• Patients with actual or suspected cervical spine injuries should be intubated using in-line manual axial stabilization.

Rapid Sequence Induction (RSI)

• RSI is used to rapidly control a patient's airway while reducing the likelihood of gastric aspiration in patients with traumatic injuries.
• Indications for endotracheal intubation include inadequate oxygenation/ventilation, loss of airway reflexes, decreased level of consciousness, and the need to secure the airway for sedation during painful procedures.

Preoxygenation

• Preoxygenation is essential before inducing anesthesia for RSI.
• The goal is to increase the concentration of oxygen in the functional residual capacity, providing an increased period before hypoxemia ensues.
• Administration of 100% high-flow (10 to 15 L/min) oxygen via a nonrebreathing facemask or bag-valve facemask is required.
• Four to eight tidal volume breaths provide an adequate degree of preoxygenation.
• Quantifying the adequacy of preoxygenation by observing the ETO (end-tidal oxygen) is recommended.

Cricoid Pressure

• Cricoid pressure was first described by Sellick in 1961.
• The goal is to reduce the risk of pulmonary aspiration of gastric contents by compressing the esophagus against the cricoid cartilage and cervical vertebrae.
• Cricoid pressure is maintained throughout the RSI and is not released until endotracheal tube (ETT) placement has been confirmed to be bilaterally equal.
• Contraindications for cricoid pressure include patients with confirmed or suspected cervical spine injury, patients with tracheal and/or cricoid cartilage injury, and patients who are actively vomiting.

Induction Agents

• The anesthetic induction for RSI can be achieved using various agents.
• Initial dose selection should be cautious, as any induction agent can cause a dramatic decrease in blood pressure, especially in hypovolemic patients.
• The precise dose of induction agent is variable and highly individualized.
• Induction agents should be titrated to response, realizing that sympathetic nervous system (SNS) inhibition can have dramatic cardiovascular effects in patients with hypovolemic shock.

Apneic Oxygenation

• Apneic oxygenation is the concept of providing pulmonary ventilation using high-flow oxygen.
• The purpose is to reduce the risk of gastric distension and pulmonary aspiration from positive pressure ventilation while preventing hypoxemia.
• The principle is based on the Boyle law, where gas leaves the facemask, fills the lungs, and exchanges within the lungs based on the concentration gradient of gases in the alveoli.
• Clinical modifications to RSI include bag-valve-mask ventilation through cricoid pressure, which does not appear to increase the risk of aspiration.

Laryngoscopy for RSI

• There is no optimal laryngoscope blade or size for successful RSI; anesthetists should use the equipment they are most comfortable with.
• Confirmation of successful ETT placement includes:
  • Presence of carbon dioxide
  • Bilateral equal and clear breath sounds
  • Absence of sounds over the stomach
  • Chest rise and fall

Approach to Unsuccessful Laryngoscopy

• If the initial attempt is unsuccessful, a second attempt should incorporate a change in technique, including:
  • Change of operator
  • Change of laryngoscope blade
  • Change in patient position

Video Laryngoscopy

• Video laryngoscopy provides superior visualization compared to direct laryngoscopy, especially in patients with cervical spine injury during intubation.
• Video laryngoscopy does not reduce cervical spine movement during intubation.

Airway Management

• Supporting oxygenation throughout the intubation process is crucial.
• Proficiency in airway management adjuncts is essential for safe patient care.

Airway Management Considerations for Trauma Patient

• Patient exhibits signs of significant respiratory distress: respiratory rate 32 breaths/min, audible stridor, oxygen saturation 88%, and oxygen delivered by non-rebreathing oxygen facemask
• Respiratory compensation: increased minute ventilation to compensate for hypoxia
• despite supraphysiologic concentration of inhaled oxygen, oxygen saturation remains low, indicating arterial hypoxemia

Physiologic Response to Hypoxia and Hypovolemic Shock

• Physiologic compensatory response to hypoxia and hypovolemic shock: increased cardiac output and systemic vascular resistance to increase blood pressure and systemic perfusion
• However, patient's blood pressure remains low, suggesting moderate to severe hypovolemic shock

Airway Complications

• Intraoral or pharyngeal laceration suspected due to blood coming out of mouth, which will complicate direct laryngoscopy by obscuring anesthetist's vision and distorting airway anatomy
• Pulmonary contusion and active bleeding may require lung isolation using double-lumen ETT or bronchial blocker

Acute Airway Management

• Safest and most efficient method: rapid sequence intubation (RSI) with in-line manual axial stabilization
• Patient should be allowed to sit upright and suction oral pharynx as tolerated to facilitate fluid movement from airway by gravity
• High-flow oxygen should be supplied via non-rebreathing facemask, face tent, or blow-by oxygen to optimize pulmonary reserve prior to induction
• Preparation for immediate surgical airway intervention is warranted

Succinylcholine vs Rocuronium for Intubation

• Succinylcholine (1.5 mg/kg) provides the most rapid onset of muscle relaxation for intubation and is the preferred agent without specific contraindications.
• Contraindications for succinylcholine include life-threatening hyperkalemia in patients with neurologic deficits caused by spinal cord injuries, especially after 24-48 hours post-injury.
• High-dose rocuronium (1.2 mg/kg) can also be used for RSI, with adequate intubating conditions within 1 minute.

Management Strategy for Failed Direct Laryngoscopy

• The anesthetist must have alternative plans for airway management in case of failed intubation.
• The ASA difficult airway algorithm helps organize a plan, but alternative strategies may be required for trauma patients.
• The gum elastic bougie can facilitate nearly blind passage of the ETT.
• Prolonged apnea may require bag-valve-mask ventilation with cricoid pressure, and in rare cases, creation of a surgical airway.

Physiologic Implications of Prolonged Apnea

• Failure to secure a patent airway rapidly results in physiologic decompensation in trauma patients.
• Apnea and hypoventilation cause pathologic responses, including increases in PaCO2 and decreases in PaO2, exacerbated by increased metabolic demands in trauma patients.
• Decreased PaO2, increased PaCO2, and decreased pH stimulate an increase in sympathetic nervous system (SNS) outflow, leading to cardiac excitation and vasoconstriction.
• Hypercarbia, hypoxemia, and increased 2,3 DPG cause a rightward shift of the oxyhemoglobin dissociation curve, leading to decreased affinity between oxygen and hemoglobin.
• The rate of PaCO2 accumulation during apnea is predictable, with an average increase of 6 mm Hg in the first minute and 3-4 mm Hg for each additional minute.

Tension Pneumothorax

• Occurs when air becomes trapped in the thorax due to a defect or rupture in lung tissue
• Gas escapes from the lung into the pleural cavity during inspiration, but is trapped in the thoracic cage due to a one-way flap valve
• Increasing pressure in the thoracic cavity impinges on the heart and major vasculature, reducing cardiac filling and output

Signs and Management of Tension Pneumothorax

• Typically occurs shortly after implementing positive pressure ventilation
• Anesthetist should be aware of associated signs and release thoracic tension via chest tube thoracoscopy or needle decompression
• Needle decompression involves placing a 2- to 3-inch angiocatheter into the second intercostal space at the midclavicular line on the affected side of the chest
• If cardiac function does not improve, decompress the other side of the chest and initiate advanced cardiac life support protocol
• After needle decompression, the angiocatheter must remain in place until a chest tube is placed to prevent reaccumulation of air

Signs of Tension Pneumothorax

• Hypoxemia and hypercarbia are pulmonary manifestations of tension pneumothorax
• Increased peak inspiratory pressures and decreased pulmonary compliance are also signs of tension pneumothorax
• Absence of breath sound on the affected side and tracheal deviation in the opposite direction of the pneumothorax are key pulmonary manifestations
• Hypotension, tachycardia, and mediastinal shift in the opposite direction of the pneumothorax are cardiac manifestations of tension pneumothorax
• Distended neck veins are another sign of tension pneumothorax

Contraindications for Succinylcholine

• Malignant hyperthermia is a contraindication for the use of succinylcholine
• Hyperkalemia, spinal cord injury (except for acute airway management within 24 hours of trauma), and crush injury are contraindications
• Stroke, Guillain-Barré syndrome, and burn injury (>24 hours) are also contraindications
• Muscular dystrophy, motor neuron disease, and mitochondrial myopathies are contraindications
• Hyperkalemic periodic paralysis and pseudocholinesterase deficiency are contraindications for the use of succinylcholine