Trauma anesthesia

1

Outline and prioritize the initial assessment and management of a trauma patient.

The American College of Surgeons Committee on Trauma has developed a systematic and concise guideline for management of trauma patients and is taught as Advanced Trauma Life Support (ATLS). Initial assessment includes:

• Primary survey (ABCDEs)

• Resuscitation

• Secondary survey

• Continued postresuscitation monitoring and reevaluation

• Definitive care

The goal of the primary survey is to identify and manage immediately life-threatening conditions.

The primary survey is carried out in the following sequence:

• A irway—establish and maintain a patent airway using advanced airway management if needed (such as endotracheal intubation, cricothyrotomy, or tracheostomy)

• B reathing—ensure adequate gas exchange and assist with ventilation if needed

• C irculation—control external hemorrhage and replace intravascular volume

• D isability—perform a rapid neurological evaluation

• E xposure/ E nvironmental control—undress to evaluate for other injuries, then cover to avoid hypothermia

The secondary survey begins once the ABCs are stabilized and includes a head to toe evaluation of the trauma patient, as well as indicated diagnostic studies (radiographs, focused sonography, laboratory tests, and invasive diagnostic procedures).

2

Using the aforementioned guideline, describe the specific assessment and management of an unconscious, hemodynamically unstable trauma patient arriving in the operating room.

First priorities are always the ABCs (airway, breathing, and circulation). An unconscious trauma patient requires prompt securement of the airway, best accomplished with rapid-sequence induction (RSI) and tracheal intubation. RSI means minimizing the time between loss of consciousness and establishment of a secure endotracheal airway. RSI is performed to minimize risk of pulmonary aspiration of gastric contents. Succinylcholine is the preferred paralytic agent because of its rapid onset. The Sellick maneuver (firm pressure applied to cricoid ring) may prevent regurgitation of gastric contents during induction of anesthesia.

The next priority should be establishing appropriate intravenous access, using short, large bore (14 or 16 gauge) peripheral catheters, rapid infusion catheters (RICs) or central access, using 9F introducers (internal jugular, subclavian, or femoral veins). Arterial cannulation is then obtained for continuous blood pressure monitoring and for frequent blood analysis (arterial blood gases, hematocrit, platelet count, coagulation studies, and blood chemistry).

3

Describe the specific concerns during airway management of trauma patient with known or suspected cervical spine injury.

The incidence of cervical spine injury in a trauma patient is 2% to 5%, and this increases to 10% in the presence of a severe head injury. In these situations, airway management must be performed without excessive movement of the cervical spine. There are, unfortunately, no airway management techniques that result in complete cervical immobility, but attempts are made to minimize neck movement. A jaw-thrust maneuver is used to establish a patent airway, while avoiding neck hyperextension. Manual in-line stabilization (MILS) should be used to stabilize the neck during laryngoscopy. MILS is performed by an assistant placing his/her hands on each side of the patient’s head and neck to immobilize the cervical spine. Use of video laryngoscopy or fiberoptic bronchoscopy can improve success of intubation in these patients.

In the setting of a known cervical spinal cord injury, awake fiberoptic intubation using topicalization and carefully titrated sedation may be the safest way to secure the airway and may allow for postintubation assessment of neurological status before induction of anesthesia. A bloody airway and/or an uncooperative patient, however, may reduce the utility of this technique during initial airway management.

4

How is the American Society of Anesthesiologists difficult airway algorithm altered in trauma?

See Figure 57.1 .

5

When is emergency invasive airway access indicated? How is it performed?

When ventilation is inadequate and intubation attempts are unsuccessful, invasive airway management is indicated. In the setting of trauma, oropharyngeal hemorrhage, neck hematoma, glottic edema, or laryngeal injury, conventional methods of achieving tracheal intubation may not work and emergency invasive airway access is indicated.

Options for invasive airway access include needle cricothyroidotomy and open surgical cricothyroidotomy. Cricothyroidotomy is preferable to tracheostomy because it is faster to perform and does not require neck extension.

Needle cricothyroidotomy is performed by inserting a large gauge (14-G) plastic cannula through the cricothyroid membrane beyond the level of obstruction. Oxygen is then delivered via jet insufflation, until a definitive airway can be established.

Surgical cricothyroidotomy is performed with either a percutaneous or open technique.

Percutaneous cricothyroidotomy is performed using commercially available kits, in which the Seldinger technique is used to convert a needle cricothyroidotomy over a wire and dilator to a 6.0 cuffed airway catheter.

Open cricothyroidotomy is performed by making a midline 4-cm vertical skin incision starting just below the thyroid cartilage prominence, followed by palpation, identification, and a horizontal cut through the cricothyroid membrane. A curved hemostat can be inserted to dilate the opening and a small endotracheal or tracheostomy tube (5–7 mm) can be inserted into the airway.

This open technique may be faster and more successful than percutaneous, but is dependent on the skills and training of the proceduralist.

6

Which anesthetic induction agents are best for trauma patients?

In the setting of hypovolemia, choosing an induction agent that has the lowest cardiovascular depressant effect is vital. More important than the specific drug chosen, is reduction of dose to minimize hypotension through loss of sympathetic tone.

Ketamine is the preferred induction agent in a hypovolemic patient because it usually maintains blood pressure via direct stimulation of the sympathetic nervous system. It is the only agent that increases peripheral vascular resistance. Ketamine can, however, have direct myocardial depressant effects that may result in hypotension, in the setting of severely ill patients with depleted adrenal reserves.

Etomidate is another induction agent commonly used in trauma patients because of its minimal effects on hemodynamics. The dose should be reduced by 25% to 50% in hypovolemic patients and caution should be used in patients relying on sympathetic tone to maintain cardiac output. In addition, etomidate inhibits cortisol synthesis by the adrenal gland, resulting in adrenal suppression, even after a single induction dose. The clinical significance of this short-term adrenal suppression is unclear.

7

Review the ATLS classifications of hemorrhagic shock (class 1–IV)

See Figure 57.2 .

8

In addition to vital signs listed in Figure 57.2 , are there other clinical indicators of the severity of hemorrhagic shock?

Markers of organ perfusion, such as serum lactate and base deficit indicate severity of shock and can be used during early management to demonstrate adequacy of resuscitation. Base deficit on arterial blood gas indicates changes in oxygen delivery in the setting of hypoperfusion. Base deficit is superior to the ATLS classification of hemodynamic shock in predicting transfusion need and mortality. A base deficit greater than 6 mmol/L on admission indicates moderate shock and predicts increased mortality. Base deficit greater than 6 mmol/L also predicts the likely presence of trauma-induced coagulopathy (TIC) and hypofibrinogenemia, both of which contribute to ongoing blood loss.

Serum lactate is a less specific marker of organ hypoperfusion and tissue hypoxia compared with base deficit. Elevation may be seen in several clinical scenarios, in addition to trauma, including alcohol intoxication. Nevertheless, failure to clear elevated lactate in setting of trauma is another predictor of increased mortality.

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