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presented by Mel Herbert, MD
edited by Veronica Vasquez, MD
 
 
At a recent All L.A. Conference, a panel of guest speakers from several emergency departments throughout Southern California discussed a few current updates and controversies in the management of trauma patients:

Permissive Hypotension
 
Does the use of permissive hypotension in trauma patients with likely hemorrhagic shock represent the current state of the art for the hypotensive trauma patient?

The goals of permissive hypotension in trauma are to limit hemorrhage, limit hemodilution and limit the disruption of the clotting process. Large volume crystalloid may actually harm patients by inducing acidosis and coagulopathy. Studies have shown that permissive hypotension in penetrating trauma patients without severe hypotension may be useful, but there is a paucity of data in blunt trauma. The concept of delayed resuscitation in one study comparing immediate vs. delayed resuscitation revealed differences in systolic BP (79 vs. 72 mm Hg,) Hemoglobin (11.2 vs. 12.9,) and prothrombin time (14.1 vs. 11.4 secs) suggesting a different physiological profile at time of surgery. There is no clear answer to date and it may be more important to consider clinical context and time to definitive care.
Source: N Engl J Med 1994;331:1105-9

In pediatric patients with severe closed head injuries (GCS<8) and presumed increased ICP on mechanical ventilation, what are the resuscitation targets in hypotensive & hypertensive patients?
In patients with closed head injuries, there are many unknowns which make management difficult. Cerebral blood flow is equal to (cerebral perfusion pressure - ICP)/cerebral vascular resistance. Without an ICP and a cerebral perfusion pressure, we are left in the dark in terms of target points. We know that we must aggressively resuscitate hypotensive patients to perfuse the brain and that decreasing blood pressure in the elderly may result in ischemic stroke. It may therefore be wise to judiciously decrease blood pressure in hypertensive pediatric patients as well. In absence of a known ICP, the Brain Trauma Foundation Guidelines recommend a systolic BP ≥ 90 mm Hg in adults, and a systolic BP ≥ 70 + (2 x age) in children. We may not be able to measure all these indices, but we can certainly affect them by maintaining adequate oxygenation, avoiding hypercarbia and limiting hyperventilation to the point of ischemia. As children are more responsive to minor changes, our goal should be to prevent secondary insult.

Additional information related to Trauma 
 
1. Acetaminophen toxicity:
Dr. Tim Erickson and Dr. Stuart Swadron review the toxicology of acetaminophen and answer some common questions that puzzle providers. Acetaminophen continues to be the most common tablet overdose in the U.S.  Acetaminophen is metabolized by the liver via 3 pathways: glucuronidaton and sulfation, resulting in nontoxic metabolites, and a third pathway utilizing hepatic P450. It is this pathway that results in the build up of the toxic metabolite, n-acetyl-p-benzoquinoneimine (NAPQI.)  NAPQI combines with hepatic glutathione to form a nontoxic compound which is renally excreted. In an overdose, glucuronidation and sulfation are quickly saturated, resulting in increased NAPQI and glutathione depletion, ultimately resulting in hepatocellular injury. N-acetylcysteine (NAC) acts as glutathione substitute and also acts as a co-factor in sulfation, shunting acetaminophen away from the P450 system. NAC is now believed to have a late effect in hepatic necrosis by minimizing damage via binding free radicals. This may translate into NAC having a therapeutic role after the initial “8 hour window.”  Of note, NAC is now FDA approved in the IV form, Acetadote, which is given over a shorter period of time (< 24 hrs vs. PO x 72 hrs) and without the unpleasant sulfuric odor. Remember to consider charcoal early for possible co-ingestions and dialysis as a treatment choice.

Is it a chronic overdose?  In a patient with a normal APAP level and elevated transaminases, the Rumack-Matthew nomogram does not apply. These findings may be an indication of encephalopathy and fulminant liver failure.  Acetadote beyond 24 hours may help reverse failure according to the King’s College Criteria from the U.K. Patients given Acetadote showed improvement whereas those who were not had a near 100% fatality.

Is a single level enough in a well patient? Yes, if it is an accurate history and the APAP level is below the hepatotoxic line on the nomogram. If it is an unreliable history, a second level 2-4 hours later is acceptable. If there is any question, start NAC. Modify later as levels return.

Is there any downfall to empiric NAC? Aside from cost, there is little downside to empiric NAC. NAC will not interfere with the APAP level (unlike Digibind in digoxin toxicity.) Conversely, if NAC is withheld and it is a true ingestion, NAC is the standard of care.

How do cirrhotic patients differ? Have a lower threshold for toxicity in these patients. They may have elevated transaminases at baseline. Consider empiric treatment.

Sustained release acetaminophen? Behaves similarly and may still use the nomogram. If the patient is co-ingesting opioids or anticholinergic drugs, there may be a slower release.

Management in trauma patients discovered to be secondary to an overdose? If there is a detectable APAP level, check transaminases. If elevated, start NAC empirically & track LFTs. Late presenters will have low APAP levels but high LFTs. Consider measuring prothrombin time. When in doubt, treat with NAC.
“Rules of 140” in acetaminophen OD:
    •    Toxic dose = 140 mg/kg in a single ingestion
    •    Hepatotoxic APAP level at 4hrs  140 g/mL
    •    First NAC dose = 140 mg/kg

2. Pain management in the ED
Dr. Jim Ducharme presents a USC Grand Rounds talk on pain management in the emergency department. Emergency physicians do a poor job at pain control. This is due to the fact that our decisions are based on our personal beliefs and biases. We tend not to believe our patients.  If a patient is witnessed eating, sleeping or watching TV, “they aren’t in pain.” In addition, referral bias results in ED physicians seeing the patients who are in severe pain. Statistics show that 80% of our patients present with moderate to severe pain, yet only 50% actually receive pain medication. Of those, only 15% receive adequate analgesia prior to discharge.  Sadly, this is best exemplified by our sickle cell patients. In a study in the Annals of Internal Medicine, sickle cell patients reported experiencing pain 55% of the time. Of those, 29% reported experiencing pain on 95% of their days. These patients reported seeing a provider only 15% of the time, and were undoubtedly met by opposition when seeking analgesia. How do we go about change?

Standardizing approaches in triage is one option. Implementing early analgesia via nursing protocols has proven effective in Australia, with no subsequent increase in patients leaving before being seen and analgesia wait times down to  60% were pain free in Group 3. You must support and believe in what you are doing.

In patients with polytrauma, we are consumed by life threatening injuries and less likely to pay attention to pain. Consider a sub-dissociative dose of ketamine for analgesia, 0.2-0.3mg/kg IV over 10 minutes then an infusion of 0.3mg/kg/hr. Realize that propofol or etomidate for sedation have no impact on dorsal horn-spinothalamic tracks and do not stop painful stimuli. Propofol alone actually augments hyperalgesic states, making pain worse.

Remember, not a single procedure in the ED has to hurt. Consider fentanyl for disimpaction, EMLA for pediatric IVs, and sedation for NGT placement. If nurses are too busy to repeat dosing, consider nerve blocks or PCA pumps. Intramuscular injections are painful, so don’t do them. Oral opioid dosing is no different than IV in terms of pain relief at 30-40 minutes. Do not forget to simply ask the patient if they would like pain medication – treat the patient, not the pain score. The majority of our patients in pain are not drug seeking - only 12% of our patients have abuse problems. Lastly ask yourself this: would you rather risk withholding pain medication to someone truly in pain or treat a suspected addict?
Sources: Ann Intern Med 2008;148:94, CJEM 2005;7:149-154, BMJ 2008;336:999-1003

3. Trauma updates
At a recent All L.A. Conference, a panel of guest speakers from several emergency departments throughout Southern California discussed a few current updates and controversies in the management of trauma patients:

What is the current role of plain radiography for the evaluation of c-spine in the non-critically injured patient whose c-spine cannot be cleared clinically alone?   
There is no question that the sensitivity and specificity of plain x-ray are inferior to other definitive tests such as CT or MRI. However, the associated costs and risk of malignant transformation are cause for reconsideration of the utility of plain radiography. High risk patients will get a CT, low risk will be cleared clinically, but the problem arises in those in between. According to the quantitative data from NEXUS, of 34,818 patients with apparent spinal cord injury, 320 had c-spine injuries missed on plain films. Of these, 83 were based on “bad” films, 47 had plain films read as “normal, ” and most of these patients had SCIWORA with neurological deficits later identified by exam and MRI. Only 3 potentially unstable injuries were missed, translating to 1 potentially unstable injury missed for 333 years of clinical practice for the average ED physician. When used appropriately, flexion/extension views may be useful when MRI is not readily available in patients with an abnormal c-spine series followed by a normal CT and a clinically suspected ligamentous injury. Yes, obtaining adequate plain films is often difficult and tedious, but certainly worth minimizing long-term radiation risks and short-term costs.
Source: N Engl J Med 2000:343;94-99

Does the use of permissive hypotension in trauma patients with likely hemorrhagic shock represent the current state of the art for the hypotensive trauma patient?
The goals of permissive hypotension in trauma are to limit hemorrhage, limit hemodilution and limit the disruption of the clotting process. Large volume crystalloid may actually harm patients by inducing acidosis and coagulopathy. Studies have shown that permissive hypotension in penetrating trauma patients without severe hypotension may be useful, but there is a paucity of data in blunt trauma.  The concept of delayed resuscitation in one study comparing immediate vs. delayed resuscitation revealed differences in systolic BP (79 vs. 72 mm Hg,) Hemoglobin (11.2 vs. 12.9,) and prothrombin time (14.1 vs. 11.4 secs) suggesting a different physiological profile at time of surgery. There is no clear answer to date and it may be more important to consider clinical context and time to definitive care.
Source: N Engl J Med 1994;331:1105-9

In pediatric patients with severe closed head injuries (GCS<8) and presumed increased ICP on mechanical ventilation, what are the resuscitation targets in hypotensive & hypertensive patients?
In patients with closed head injuries, there are many unknowns which make management difficult. Cerebral blood flow is equal to (cerebral perfusion pressure - ICP)/cerebral vascular resistance. Without an ICP and a cerebral perfusion pressure, we are left in the dark in terms of target points. We know that we must aggressively resuscitate hypotensive patients to perfuse the brain and that decreasing blood pressure in the elderly may result in ischemic stroke. It may therefore be wise to judiciously decrease blood pressure in hypertensive pediatric patients as well.  In absence of a known ICP, the Brain Trauma Foundation Guidelines recommend a systolic BP ≥ 90 mm Hg in adults, and a systolic BP ≥ 70 + (2 x age) in children. We may not be able to measure all these indices, but we can certainly affect them by maintaining adequate oxygenation, avoiding hypercarbia and limiting hyperventilation to the point of ischemia. As children are more responsive to minor changes, our goal should be to prevent secondary insult.

to find more EM:RAP educational materials, go to www.emrap.org
 

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