Anesthetic Considerations

Anesthetic Considerations

• Neuraxial anesthesia is usually impractical and inappropriate in hemodynamically unstable patients with life-threatening injuries.
• If the patient arrives in the operating room already intubated, correct positioning of the endotracheal tube must be verified. Patients with suspected head trauma are hyperventilated (moderate/controlled) to decrease intracranial pressure.
• Ventilation may be compromised by pneumothorax, flail chest, obstruction of the endotracheal tube, or direct pulmonary injury.
• If the patient is not intubated:
Consider rapid sequence induction.
Be prepared for an emergency tracheotomy.
Stabilize the neck if a cervical spine injury is suspected.
Check the intravenous cannula to make sure they are functional.
• If time permits, hypovolemia should be at least partially corrected prior to induction of general anesthesia. Fluid resuscitation and transfusion should continue throughout induction and maintenance of anesthesia.
• Commonly used induction agents for trauma patients include ketamine (1-2 mg/kg) and etomidate (.2-.4mg/kg) followed by suxamethonium (1-2 mg/kg) after pre-oxygenation. Ketamine should be avoided, when possible, in patients with head injuries (Thiopentone 1-4 mg/kg). A non-depolarizing muscle relaxant should be used if the patient has a contraindication to succinylcholine. The induction dose requirements reduced in patients with major trauma. Even drugs such as ketamine, which normally indirectly stimulate cardiac function, can display cardio-depressant properties in patients who are in end stage shock and already have maximal sympathetic stimulation. Hypotension may also be encountered following etomidate induction.
• Maintenance of anesthesia in unstable patients may consist primarily of the use of muscle relaxants called neuromuscular blocking agents), with general anesthetic agents titrated as tolerated (mean arterial pressure > 50-60 mm Hg) in an effort to provide at least amnesia. Intermittent small doses of ketamine (25 mg every 15 min) are often well tolerated and may help reduce the incidence of recall. The key to the safe anesthetic management of shock patients is to administer small incremental doses of whichever agents are selected.
• Each time you add a new drug, be sure to monitor the patients' vital signs carefully before you add another drug.
• Monitor the urine:
Output: Try to maintain a rate greater than 0.5ml/kg/hr.
Color: Tea color means myoglobin is present from damaged muscle. Red color usually means damage to the kidneys or bladder.
• Communicate with the surgeon(s) throughout the case, and keep an eye on the surgical field so you know what is going on.
• Fat embolism is difficult to detect during anesthesia for trauma. If the patient has a chest injury and a fractured femur, it is hard to differentiate how much each one contributes to the respiratory failure. If you have an isolated fracture, i.e. femur, without lung damage, then a continual downward in respiratory function can be assumed to be fat emboli. Supportive care is given as there is no definitive treatment for fat embolism.
• Check frequently for tension pneumothorax in patients with chest trauma
• Pericardial tamponade can occur rapidly or insidiously. The blood around the heart must be removed by pericardiocentesis or via a thoracotomy.
• If you plan to extubate the patient in the operating room or the recovery room, give the airway the same intense care you did for the intubation. Do not extubate until the patient can protect their own airway and continue to administer oxygen postoperatively.

Anesthetic Management of Moribund

If the patient is moribund (that is, non-responsive to anything), the blood pressure cannot be detected by conventional means, and there is a high heart rate, then the patient is given oxygen, a fast acting muscle relaxant (succinylcholine), rapidly intubated, and the surgery started. Once the bleeding is stopped, the blood pressure usually comes up, the heart rate down, and the patient is on the way to recovery. Then add a narcotic for pain relief, and finally a very low amount of ketamine or halothane. Each drug added during the resuscitation is given in low doses at first to make sure the patient can withstand the change in physiology induced by the drug.

• If the patient is unconscious and has no detectable blood pressure and a rapid thready pulse, administer 100% oxygen, give succinylcholine, intubate, give a non-depolarizing muscle relaxant, and ventilate with 100% oxygen.
• If the patient is conscious but has no detectable blood pressure and a rapid thready pulse, while you administer 100% oxygen tell the patient he/she may have awareness during part of the anesthetic, and you will give them pain medications as soon as you can restore their vital signs. Then you can give ketamine, followed by succinylcholine, intubation, a non-depolarizing muscle relaxant, and ventilate with 100% oxygen. Ketamine (1mg/kg) may be repeated every 30 minutes.
• Combating awareness during general anesthesia: In many cases awareness must be accepted as a necessary element of the anesthetic technique. Take time to let the patient know they may be awake long enough for you to stabilize their vital signs. Then you will give them pain medications and anesthesia. Talk to the patient during the induction and throughout the case. Tell them they are getting fluid and blood to stabilize their vital signs. Let them know when you are giving them drugs for sleep and pain. Be sure and ask them after the surgery what they remembered, and assure them it was absolutely necessary to do what you did to save their lives. They will almost universally thank you for your efforts.