Course Authors

Robert Brown, M.D., and Martin Carey, M.D.

Dr. Robert Brown, a native of Fayetteville, Arkansas, is in the second year of the emergency medicine residency program at University of Arkansas for Medical Sciences at Little Rock. His interests include toxicology and patients' perceptions of emergencies.

Drs. Brown and Carey report no commercial conflict of interest.

Estimated course time: 1 hour(s).

Albert Einstein College of Medicine – Montefiore Medical Center designates this enduring material activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

In support of improving patient care, this activity has been planned and implemented by Albert Einstein College of Medicine-Montefiore Medical Center and InterMDnet. Albert Einstein College of Medicine – Montefiore Medical Center is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

 

Learning Objectives

Upon completion of this Cyberounds^®, you should be able to:

• Discuss the differential diagnosis of a sudden collapse in a young person

• Describe the immediate management of a young person with loss of consciousness

• Understand the importance of a full past history, including drug history.

 

It is nearing 7:00 PM on a Friday night and, as usual, the Emergency Department is hopping. You have seen three patients with chronic low back pain, six patients with headache that turned out to be nothing more than tension and/or migraine and three cases of gastroenteritis. You are just beginning to wonder why you even bother reading journals or committing time to continuing education when a call comes over the radio from the local ambulance service. They are bringing in a 17-year-old white male who collapsed and experienced about 45 seconds of seizure activity while nearing the end of basketball practice at the local high school. He has been comatose since that time.

The EMT reports that his vital signs are stable: temperature 99^oF, blood pressure 125/78, pulse 70 beats per minute and respiration rate 16 breaths per minute. Rapid blood glucose determination was 145mg/dL so no dextrose was given. 2 mg of naloxone given per EMS protocol had no effect. No past medical history is known because the patient is comatose and his mother is out of town. While the coach went to call the patient's mother, a fellow athlete agreed to ride to the hospital with the patient. A 20-gauge IV has been started on the patient by the paramedic. Estimated time to hospital is four minutes.

Q. What differential diagnosis is running through your mind as you prepare yourself for the arrival of the patient?

A. Several things should come to mind. This list is in no way inclusive or in any particular order:

• Seizure Disorder - the patient could well be postictal.
• Substance Abuse - should always be a consideration in comatose or seizure patients.
• CNS Infection - not as likely with a normal temperature but should be kept in mind.
• Intracranial Mass or Bleed - did he fall on the court and strike his head or has he had a spontaneous bleed?

The ambulance bay doors burst open and the paramedics bring in a young man in basketball shorts and a tee shirt bearing the name of the local high school. You point them to one of your department's monitored beds and, being the fine emergency physician that you are, corner the accompanying Bulldog (the local high school's mascot) for any additional information that he can provide.

You are told that the patient's Mom is on her way in by car from out of town, approximately 30 minutes away. The friend tells you that the basketball team has been having "two-a days" for the past week and that Ken has been busting it harder than anybody, trying to make it as a starting guard. He has been running wind sprints through breaks and is the first one to arrive and the last one to leave the court everyday. Over the past couple of days, Ken's hands have gotten kind of shaky and he has become progressively more clumsy. The team and coaches had put this off to exhaustion from the long hours that Ken had been putting in. Ken refused to slow down, however, always being one to excel in all that he did. As long as your historian had known him, he had always been "a bundle of energy." Today, at practice, Ken stumbled to the ground during a practice game, experienced a seizure for about 45 seconds and then remained comatose. As far as your historian knows, Ken takes no medications and has no medical problems.

Q. What is your differential diagnosis now? Check the diagnosis you think is most likely:

A.

• Seizure Disorder - very unlikely now, with what appears to be a history of progressive symptoms. This would now be a diagnosis of exclusion. Need to talk to Mom.
• Substance Abuse - possible but, again, unlikely in view of Ken's obvious commitment to make the team.
• CNS Infection - not the classic history but should be kept in mind.
• Intracranial Mass or Bleed - a slow bleed could cause this type of picture.

Your patient has been moved to the monitored bed and hooked to the monitor. Even though the pulse oximeter measures his saturation as 97%, you place a nasal canula and give him 2 liters of O₂. The monitor reveals normal sinus rhythm at a rate of 75 beats per minute. Pulses are intact and equal. Having finished your initial assessment of the airway breathing and circulation, you proceed with the rest of your physical examination. Vital signs are: blood pressure 125/82, pulse 75, respirations 16 and temperature 98.6�^oF. The patient's Glascow Coma Scale score is 3. The rest of the physical exam is negative, except for a mild psoriatic-type eruption at the patient's hairline and on his elbows bilaterally, moderate fasciculation of his upper extremity musculature and 4+ reflexes in all limbs. His mucous membranes are a little dry.

Even with no localizing signs, you are worried about intracranial pathology, so you send your patient for a CT of the head. Before he goes, you draw a range of laboratory bloods and intubate him, secondary to aspiration concerns. The CT is stone-cold normal. Laboratory values (electrolytes, complete blood count, calcium, magnesium, phosphorus, toxicology screen) are all normal, except for a white blood cell count of 20 (103/mm³) and a sodium of 127mmol. Sure of your diagnosis now, you are just about to perform a lumbar puncture when the nurse comes in to tell you that the mother has arrived. Realizing that a signed consent form beats informed consent any day, you stop your lumbar puncture and go to talk to the mother.

The first words out of the mother's mouth are "Lithium! Did you check his lithium?" OOPS!.

Ken's mother tells you that Ken was diagnosed with bipolar disorder two years ago and currently takes lithium, propranolol and synthroid.

Q. Why would Ken be taking propranolol?

A. One of the most common side effects of lithium is a fine tremor of the hands. This often is responsive to beta-blocker medication.

Q. And why Synthroid^®?

A. Another common side effect of lithium is hypothyroidism. This seldom requires discontinuation of lithium therapy but will usually respond to hormone replacement therapy.

Q. What are other side effects of lithium, and what are the signs of lithium toxicity?

A.

• GI - nausea, vomiting and diarrhea are common side-effect of treatment and these symptoms are common at all levels of toxicity.
• Dermatologic - psoriasis, acne and acneiform eruptions are sometimes seen.
• Renal - mild polyuria and polydipsia that may progress to frank diabetes insipidus.
• Endocrine - hypothyroidism and hyperparathyroidism.
• Cardiovascular - flattening or inversion of T waves (fatal events very unlikely).
• Hematologic - benign leuckocytosis (as much as 1.5x) with unaffected function of leukocytes.
• CNS - mild lithium toxicity may show fine tremor, apathy, fatigue, muscle weakness and hyperreflexia.

Moderate toxicity manifests with a coarsening tremor, dysarthria, tinnitus, ataxia, hypertonia and myoclonus.

Stupor, seizures, coma, fasciculation's, spasticity, rigidity, choreathetosis, paresis, paralysis and death mark severe toxicity. CNS toxicity is the hallmark of lithium toxicity.

Realizing that your patient's picture is classic, you frantically call the lab and request that a lithium level be added to the bloodwork. The lab tells you that it will take approximately 15 minutes for the test to be run. Fifteen minutes pass and you call the lab. Ken's lithium level is 3.1 mEq/L!

Q. What is a normal lithium level?

A. A normal lithium level is 0.6-1.2mEq/L. Levels above 1.5mEq/L are often toxic and levels above 3.5-4.0 mEq/L are considered, by most, to be life threatening.

Q. What do you do now?

A. Hydrate and replace sodium deficit. Remember that lithium is a monovalent cation that looks and acts just like sodium in the body. Fluid and/or sodium deficits cause the body to retain sodium (and, therefore, lithium) in the kidney. Overhydration is of no benefit.

Hemodialysis. Lithium is one of the most dialysable substances in the body. If hemodialysis is unavailable, peritoneal dialysis is an option but it is not nearly as effective as hemodialyisis. Dialysis should be carried out for any level greater than 4.0 mEq/L or any chronic toxicity with moderate or severe symptoms. Dialysis should be continued until the lithium level is <1mEq/L (this may be > 12 hrs.).

Contact the ICU. This patient will require admission to an intensive care unit.

Q. What's the big deal? Someone taking lithium long-term should be able to tolerate a higher level, shouldn't they? Just like alcoholics?

A. Incorrect. Chronic toxicity is much worse than acute toxicity (as in a suicide attempt) due to higher tissue levels of drug and more prolonged exposure to elevated levels.

Your patient is whisked off to dialysis and the critical care doctor who will be assuming control of this patient comes in to talk to you. "Gee, I've always wanted to get to take care of a lithium toxicity!" he says, instilling you with very little confidence. "I'd better go do a Medline^® search."

Q. What should you tell him about this patient's care until he can find time to log on to the Web?

A. The patient may well require additional courses of hemodialysis. Even if the lithium level is brought down to 1.0 mEq/L during his first course, tissue levels will equilibrate over the next couple of hours and the level will rise again. A repeat level should be checked after 6-8 hours and, if appropriate (level > 1.0 mEq/L), dialysis done again.

Q. What should you tell the mother about Ken's prognosis?

A. Death from lithium toxicity is pretty uncommon but this young man is a particularly bad case. Neurologic signs may take weeks to resolve and may even be permanent.

Your patient has gone to dialysis. The Emergency Department has slowed to a trickle. Your double coverage partner has picked up your slack while you toiled with this patient. You stop to reflect. There's really no way you could have known earlier. "A bundle of energy," the other basketball player had said. The dehydration from "two-a-days." Shaky hands. Clumsiness. It would have taken a psychic to have pieced it all together. Wouldn't it?