The Best of EM:RAP
presented by Mel Herbert, MD
edited by Veronica Vasquez, MD
1. Toxic Alcohols: A Review by Dr. Mel Herbert and Dr. Stuart Swadron
In general, toxic alcohols can be divided into two groups based on similarity in symptoms, pathophysiology, and treatment: isopropyl alcohol and ethanol in one group, methanol and ethylene glycol in the other. Isopropyl alcohol can be considered a “super alcohol” with more profound intoxication effects than ethanol and greater propensity for gastrointestinal bleeding from hemorrhagic gastritis. In addition, hypotension is more commonly seen with isopropyl ingestion due to its cardiodepressant effects. In the metabolism of both isopropyl and ethanol, ketones are the end product rather than acid metabolites. Isopropyl alcohol ingestion will result in ketosis with no concomitant increase in anion gap. In the case of methanol and ethylene glycol, both are metabolized into acids. Methanol is metabolized into formaldehyde and formic acid, which can accumulate in the retina causing edema and optic papillitis. Glycolic and oxalic acid are the toxic metabolites of ethylene glycol and may lead to acute tubular necrosis and renal failure. With all toxic alcohol ingestions, the osmolal gap will be increased (>10 mosm/L) secondary to unmeasured osmols. It is important to note that as osmolality decreases, acid metabolites increase resulting in an increased anion gap. Therefore, in patients with a suggested ingestion and increased anion gap, a prior elevated osmolal gap should be considered.
The mainstays of treatment in toxic alcohol treatment are as follows:
1) Prevent formation of toxic metabolites by inhibiting alcohol dehydrogenase
Ethanol and fomepizole (4-MP) are both efficacious in the treatment of methanol and ethylene glycol ingestion. Comparison studies indicate treatment with fomepizole results in fewer side effects and complications.
(Ann Emerg Med. 2009 Apr;53(4):439-450)
2) Elimination of alcohol and toxic metabolites
Hemodialysis eliminates the alcohol, toxic metabolite and normalizes acidosis. It should always be considered as a treatment option in methanol and ethylene glycol ingestion.
3) Correct the acidosis
Consider administering bicarbonate. In toxic alcohol ingestion, the acid burden cannot be converted back to bicarbonate. In severely acidotic patients requiring rapid sequence intubation, the pH may drop abruptly and may precipitate cardiac arrest as the patient can no longer compensate via hyperventilation.
4) Replenish co-factors
Administer folic acid in methanol ingestion (used as a co-factor in the conversion of formic acid to carbon dioxide) and thiamine, pyridoxine and magnesium in ethylene glycol ingestion (preventing glycolic and oxalic acid formation.)
Lastly, look for other clues of an ethylene glycol ingestion by fluorescing facial hair and urine with a Wood’s lamp and checking for calcium oxalate crystals in the urine.
2. Abdominal Pain in the Elderly with Robert McNamara, MD
Emergency physicians have rated abdominal pain in the elderly as one of the most difficult clinical scenarios. The overall mortality rate of this chief complaint in the elderly is approximately 8-14%. This percentage is greatly increased if it is misdiagnosed in the emergency department and admitted to the wrong service. Approximately half of all elderly patients with abdominal pain will be admitted and one third will later require surgical intervention.
Acute appendicitis is frequently misdiagnosed in the elderly due to delayed and atypical presentation. Up to 8% of elderly patients with acute appendicitis wait more than 7 days before presenting. Most will present with right lower quadrant pain, but migration of pain may not be reported. Many elderly patients lack the common signs and symptoms associated with acute appendicitis. Up to 30% will have no fever and as many as 56% will report no anorexia. Nausea and vomiting are also uncommon and WBC count is typically less than 10,000. An elevated bilirubin (17%) may be a misleading indication of biliary disease. In addition, plain films may also be misleading as air-fluid levels secondary to ileus may be interpreted as a bowel obstruction. In one study of appendicitis in the elderly, only 51% were correctly diagnosed at time of admission and 72% were found to have frank perforation at time of surgery. (Am J Surg. 1990;160(3):291-3)
In contrast to the atypical presentation of appendicitis, elderly patients do present with the typical findings of right upper quadrant pain, fever, vomiting and an elevated WBC count. The difficulty with acute cholecystitis in the elderly is not diagnosis, but management. Acute cholecystitis is the commonest surgical emergency in the elderly. The mortality rate of acute cholecystitis in the elderly is an astounding 10-14%. The elderly are more likely to have an emphysematous or gangrenous gallbladder and more likely to develop sepsis. This therefore requires greater vigilance by emergency physicians to expedite surgical intervention. Be aware of altered mental status with acute cholecystitis. Altered mental status may be a symptom of advanced disease such as with an emphysematous or gangrenous gallbladder.
Abdominal aortic aneurysm:
Abdominal aortic aneurysms in the elderly are commonly missed in the emergency department. Up to 30% of abdominal aortic aneurysms are misdiagnosed. The number one misdiagnosis by far is presumed “renal colic.” This is frequently the case in elderly patients presenting with abdominal or back pain and evidence of blood on a urine dip. In a study by Marston, et al. in 1992, almost all patients with misdiagnosed ruptured AAA experienced at least one episode of hypotension while in the emergency department.
These episodes were attributed as “vagal” secondary to pain or “urosepsis” from an infected stone. Hypotension in the elderly individual with abdominal or back pain must prompt further inquiry into the possibility of AAA. The increasing rate of obesity in our population may further limit our ability to recognize AAA on physical exam. Consider posterior ultrasound if the aorta is not visible anteriorly. If computed tomography is unavailable, plain films may be useful in diagnosing AAA. A radiologic review in 1986 found that 90% of patients with AAA had evidence on a flat plate including apparent calcific outline, loss of psoas or renal shadow and evidence of a soft tissue mass. (Clin Radiol.1986;37(4):383)
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