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Unexpected Killers in Primary Care

Paul Simmons, MD and Joe Martinez, MD

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How are your anxiety levels? Because we’re about to ratchet them up to an 11. In this segment, EM/IM physician Dr. Joe Martinez teaches Paul about 4 patients with deadly diagnoses who presented with seemingly benign findings. Let’s heighten our awareness of do-not-miss pathology that can masquerade as run-of-the-mill disease processes.


  • We cover carbon monoxide poisoning, heterotopic pregnancy, mesenteric ischemia and syncope related to Brugada’s and hypertrophic cardiomyopathy.

  • Keep your radar up for these and other dangerous causes by digging into symptom patterns, identifying risk factors and taking the time to do physical exam maneuvers that may make the diagnosis.


  • Carbon monoxide poisoning:

    • Case 1: 30 year old woman who just got a new stressful job has headaches, nausea and dizziness. The headaches get better 4-5 hours after she arrives at work but then return in the evening. She is diagnosed with tension headaches. Two weeks later, she has a car accident and ends up dying in the trauma center from her injuries. They find she was getting carbon monoxide poisoning from her car where she was now spending an hour each day commuting. On the fateful day of her accident, she passed out from the carbon monoxide poisoning, crashed into a tree and later died.

    • Case 2: A family of 5 come to the emergency department with flu-like symptoms of myalgias, fatigue and headache with non-specific physical exam findings. They were counseled on supportive care. Days later a neighbor finds them all dead except the oldest son who survives in a persistent vegetative state. Their power had been out so they were heating it with a gas-powered generator located inside the house.

    • Clues:

      • Patterns to the symptoms that point to an exposure

        • Headaches that were coming on before work, getting better and then back again in the evening point to an exposure pattern while driving in the car

        • The family all got the “flu” at the same time

      • Pets also affected

        • Animals are particularly sensitive to carbon monoxide because they have higher respiratory rates

    • Patterns are key:

      • Are your headaches better or worse at certain times of day or in certain environments?

      • Are they always happening at home versus at work.

      • Are they always happening in the car?

      • Is there anybody else sick at home?

      • Do you have carbon monoxide detectors at home?

    • Epidemiology:

      • More common during flu season when people are inside and using heaters

      • 15,000 ED visits per year

      • Leading cause of accidental poisoning deaths in the US

        • 500 deaths per year

    • Diagnosis:

      • Carboxyhemoglobin level

        • Venous blood

        • Co-oximeters (measure oxygen and carboxyhemoglobin)

    • Treatment:

      • Remove them from the environment

      • Give them oxygen

        • Hyperbaric oxygen reduces the half-life of carboxyhemoglobin → may help prevent neurologic sequelae

  • Heterotopic pregnancy:

    • Case: 37yo woman G1P0 presents to ED with vaginal spotting and pelvic pain. Ultrasound shows single intrauterine pregnancy with some free fluid in cul-de-sac and likely ruptured corpus luteum cyst. Two days later she is back in hemorrhagic shock and dies. Turns out this pregnancy was through in-vitro fertilization and that she had a heterotopic pregnancy (ie: intrauterine + ectopic pregnancy).

    • Epidemiology:

      • Rare in the general population

        • 1 in every 30,000 gestations

      • Much more common in pregnant population

        • 1 in ever 300-500 gestations

    • Diagnosis:

      • Very difficult diagnosis to make

      • Ultrasound

        • May look to radiologist like a ruptured corpus luteum cyst that is very common in early pregnancy

        • Pearl: Giving the clinical context that the pregnancy was from in vitro fertilization is key to potentially NOT missing the diagnosis as the radiologist may then be clued into the possibility of an ectopic

      • Laparoscopy may be required by OB/GYN

  • Acute mesenteric ischemia:

    • Case: 76yo man with diabetes, hypertension, atrial fibrillation, history of stroke comes in with abdominal pain, vomiting, diarrhea. Though he is ill-appearing, his abdominal exam is benign. He is discharged with a case of gastroenteritis. Later that day, he comes back in shock and dies of mesenteric ischemia.

    • Clues:

      • Older patients

      • Vascular disease

      • Prior history of stroke

      • “Pain out of proportion to exam”

      • Intestinal angina: eating a large meal causes pain because your gut isn’t getting the blood flow it needs. Leads to weight loss and food fear.

    • Diagnosis:

      • Mesenteric ultrasound

  • Brugada syndrome and hypertrophic cardiomyopathy

    • Case 1: 30yo man who passes out. Non-exertional. No seizure activity. Normal exam. EKG with automatic read of incomplete right bundle branch block. Normal echo. Several years later the patient dies.

    • Case 2: 21yo man with palpitations and lightheadedness while playing soccer. During exam time, he drinks a bunch of caffeine and has lightheadedness. At his doctor’s visit, his exam is normal and his EKG is read has left ventricular hypertrophy. At his next soccer game, he collapses and dies.

    • Brugada syndrome:

      • Described by a pair of Spanish cardiologists - the Brugada brothers

      • Sodium channelopathy that's inherited and leads to ventricular tachycardia in structurally normal hearts

      • ECG patterns:

        • Type one -  incomplete right bundle branch block with some ST segment elevation that then transitions into a coved T-wave inversion

        • Type two - the saddleback variant, incomplete right bundle branch block again, ST elevation

        • Patterns are variable and often times only seen during times of stress (ie: febrile illness, sports)

      • Treatment:

        • Cardiac electrophysiologist referral

        • Implantable cardiac defibrillator

    • Hypertrophic cardiomyopathy:

      • One of the most common reasons for otherwise healthy people to die during athletic endeavors

      • Pearl: It is hypertrophic cardiomyopathy, no hypertrophic obstructive cardiomyopathy (HOCM), because not all variants are obstructive

      • The murmur may be provoked through the Valsalva maneuver

      • ECG patterns:

        • Tall R waves in the septal lead V1 and V2

        • Dagger-like Q waves often in the inferior or lateral leads



  1. Roderique JD, et al. A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement. Toxicology 2015; 334:45-58. PMID: 25997893

  2. Rose JJ, et al. Carbon monoxide poisoning: pathogenesis, management, and future directions of therapy. Am J Respir Crit Care 2017; 195(5):596-606. PMID: 27753502

  3. Letsas KP, et al. Prognosis, risk stratification, and management of asymptomatic individuals with Brugada syndrome: a systematic review. Pacing Clin Electrophysiol 2017; 40:1332–1345. PMID: 28994463

  4. Wu W, et al. Risk factors for cardiac events in patients with Brugada syndrome; a PRISMA-compliant meta-analysis and systematic review. Medicine 2016; 95(30):e4214. PMID: 27472692

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