What Evaluation Should be Done for Carbon Monoxide Poisoning?

Patient Presentation
A 14-year-old male was brought to the emergency room by ambulance after he was found sitting in his room groaning in pain in the early morning after his mother returned from her overnight work shift.
The adolescent was lethargic but could answer questions. His mother quickly checked on other people in the home who were also either unarousable or in pain.
The mother suspected carbon monoxide poisoning, tried to move all the family out of the home, and called for emergency services.
With later questioning, the history revealed that a fireplace fire was lit in the late evening the previous night and was lit throughout the night.
No carbon monoxide detector was in the home.
Upon the ambulance’s arrival, he was placed on 100% oxygen. In the emergency room he complained of headache, nausea and vomitted once.
The pertinent physical exam showed a lethargic but appropriate adolescent with a Glascow Coma Scale of 13. His heart rate was 145, respiratory rate was 22 and he had normal blood pressure.
He was described as having reddish skin with bluish fingernail beds. He complained of muscle pain but had normal strength and tone. The rest of his examination was normal.
The work-up included an electrocardiogram which showed sinus tachycardia.
The radiologic evaluation showed a normal chest x-ray.
The laboratory evaluation revealed an arterial blood gas of 7.4/40/300/-1 (pH/Carbon Dioxide/Oxygen/Base excess).
The hemoglobin was 16.2 mg/dl, hematocrit of 47% with a white blood cell count of 25.6 WBC x 1000/mm2 with predominant polymorphonuclear cells.
A creatinine phosphokinase level was 580 U/L (normal 40-200 U/L).
The carboxyhemoglobin level was 26% (normal 1-3%) confirming the diagnosis of carbon monoxide poisoning.
During the patient’s clinical course he was transferred to a regional children’s hospital which had hyperbaric oxygen treatment available and he received two treatments because of continued confusion and lethargy. His carboxyhemoglobin decreased to 0.5% with treatment.
A consultation for neuropsychiatric testing was completed and showed some discrepancy between verbal and non-verbal testing but no memory problems.
There was no previous testing available for comparison.
He was discharged to home after the fireplace was fixed and the furnace also inspected. Other family members were discharged to home after appropriate treatment also. He was to follow-up with neurology and have repeated neuropsychiatric testing in 1-2 months.

Discussion
Carbon monoxide (CO) is a by-product of incomplete burning of carbon fuels.
It is colorless and odorless and therefore difficult to detect.
Common causes of CO poisoning are faulty or inadequately ventilated home heating sources (e.g. furnaces, fireplaces, kerosene heaters, etc.), automobiles with obstructed exhaust systems, gas-powered generators, home fires or tobacco smoke.
Other sources may be recreational or employment related including propane-fueled forklifts, gas-powered concrete saws, swimming behind motorboats, being in enclosed spaces with ice-cleaning machines (i.e. Zamboni&reg) or automobiles (e.g. indoor tractor pulls, demolition derbys). Inhalation of methylene chloride vapors also can cause CO poisoning.

CO binds to hemoglobin significantly more readily than oxygen (230-270 times more) and therefore, it causes toxicity by cellular hypoxia. CO can cause problems whether it is a chronic or acute exposure.
CO binds to myocardial tissue even more readily than hemoglobin and therefore the heart is at high risk. Obviously the brain is also at high risk because of its need for a consistent oxygen supply.
CO is eliminated through the lungs with a half-life at room air of 3-4 hours.
Supplemental oxygen reduces the half-life to 30-90 minutes and hyperbaric oxygen (2.5 atmospheres at 100% oxygen) reduces it to 15-23 minutes.

Chronic CO poisoning may present with the same symptoms but often presents with new changes in cognitive ability or gradual onset of neuropsychiatric symptoms.

Common acute signs and symptoms:

  • Dermatologic
    • Cherry-red skin - is the classic description, often remembered by the saying, “cherry-red, you’re dead!”
    • Pallor

    • Cyanosis
  • Cardiac
    • Chest pain
    • Hypotension
    • Palpitations
    • Tachycardia
  • Gastrointestinal
    • Abdominal pain
    • Diarrhea
    • Emesis
    • Nausea
  • Musculoskeletal
    • Muscle pain secondary to rhabdomyolysis
  • Neurologic
    • Ataxia
    • Aggitation
    • Amnesia
    • Coma
    • Confabulation
    • Confusion
    • Depression
    • Distractability
    • Dizziness
    • Emotional lability
    • Gait disturbances
    • Hallucination
    • Headache – one of the earliest signs
    • Hearing and vestibular problems
    • Impaired cognition
    • Impaired judgement
    • Impulsivenss
    • Increased reflexes
    • Memory impairment – the most common neuropsychiatric finding
    • Papilledema
    • Psychosis
    • Seizures
    • Retinal hemorrhages
    • Visual acuity changes including hemianopsia
  • Respiratory
    • Dyspnea on exertion
    • Tachypnea (mild generally)
    • Pulmonary edema
  • Other
    • Fatigue

Treatment includes:

  • Oxygen – 100% at room air begun immediately and possibly hyperbaric oxygen. The Undersea and Hyperbaric Medical Society offers a directory of locations where hyperbaric oxygen is available at: http://www.uhms.org/Chambers/Chambersearch.asp or Divers Alert Network (DAN) at Duke University can be contacted at (919) 684-2948.
  • Intensive care unit admission for management of neurological, cardiac, respiratory, renal or muscular disease
  • Outpatients who are asymptomatic with a carboxyhemoglobin levels less than 10% generally can be discharged home but with early follow-up and reduced activity for 2-4 weeks.
  • Prevention should be discussed at health maintenance visits including the importance of CO detectors with audible alarms in the home and proper maintenance of home heating equipment. In areas with snow fall, reminding parents to keep the exhaust system clear if stranded and running the motor for heat is important.

Patients usually (~67%) have a full recovery. Variability of clinical severity, lab values, and outcome all limit prognostic accuracy.
Poor outcomes are associated with cardiac arrest, coma, metabolic acidosis, extremely high carboxyhemoglobin levels, and head imaging abnormalities.
Neuropsychiatric testing may have some prognostic ability in determining delayed cognitive problems.

Learning Point

Workup for CO poisoning often includes:

    Laboratory
    • Carboxyhemoglobin – confirmation of disease process and treatment indications
    • Arterial blood gas – screening for acid/base deficit, metabolic and respiratory status
    • Creatine kinase with MB fraction – screening for rhabdomyolysis and myocardial injury
    • Myoglobin – screening for rhabdomyolysis
    • Complete blood count – usually mild leukocytosis
    • Electrolytes and glucose screening for lactic acidosis, hypokalemia, and hyperglycemia seen in severe poisoning
    • BUN and creatinine – screening for acute renal failure secondary to myoglobinuria.
    • Liver function tests – screening for hepatic failure
    • Urine analysis – screening for chronic poisoning which may show albumin and glucose
    • Cyanide levels – screening if industrial fire or other possible exposure
    • Blood alcohol levels – screening for intentional and unintentional injury
    • Toxicology screens – screening for possible suicide attempt or co-toxicity

    Imaging Studies are sometimes done

    • Chest x-ray – usually normal
    • Computed tomography scan or magnetic resonance imaging of the head – looking for cerebral edema and focal lesions, most typically of the basil ganglia.
      Other tests

      • Electrocardiogram – screening for arrhythmias
      • Neuropsychologic testing – screening for cognitive deficits

Questions for Further Discussion
1. What are the components of the Glascow Coma Scale?
2. What are the indications for hyperbaric oxygen treatment?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Information prescriptions for patients can be found at MEDLINEplus for this topic: Carbon Monoxide Poisoning
and at Pediatric Common Questions, Quick Answers for this topic: Fire Safety.

To view current news articles on this topic check Google News.

Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:363-364.

Lucchesi M, Schochat G. Toxicity, Carbon Monoxide. eMedicine.
Available from the Internet at http://www.emedicine.com/ped/topic315.htm (rev. 11/1/2004, cited 12/12/05).

ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    5. Patients and their families are counseled and educated.
    7. All medical and invasive procedures considered essential for the area of practice are competency performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    February 13, 2006

  • What is the Differential Diagnosis of Hypokalemia?

    Patient Presentation
    A 14-year-old male came to the emergency room after he had an episode of loss of consciousness for 1-2 minutes.
    He regained consciousness on the way to the emergency room.
    He said he felt his heart racing and then loss consciousness. He has had 1 previous episode 9-12 months ago where he felt “shaky and weak”. Over the past month he has complained of general “weakness” but cannot describe it further. he says he has had fatigue for 4-5 years.
    He has missed some school because of the weakness. He has also had some muscle cramps that were short-lived.
    The family history was positive for heart attacks at an advanced age and some anxiety and depression. No arrhythmias or neurological problems were in the family.
    The review of systems was negative including fever, recent illnesses, travel, unusual diets or eating behaviors, and sexual activity.
    The pertinent physical exam reveals a well-developed adolescent with normal vital signs and growth parameters. He has normal skin and subcutaneous fat. HEENT had a normal dental examination. His heart had a normal rate and rhythm with no murmurs and good pulses.
    He had a normal neurological evaluation. His mood revealed some minor symptoms of depression. The rest of his examination was normal.
    The laboratory evaluation in the emergency room showed a potassium level of 2.6 mEq/L (normal 3.4-4.7 mEq/L) and magnesium of 1.0 mEq/L (normal 1.3-2.0 mEq/L).
    He received potassium and magnesium supplementation by IV. An electrocardiogram was normal and his beta-HCG was negative. The rest of his laboratory evaluation was normal at that time including electrolytes, BUN, creatinine, phosphorous, glucose, liver and pancreatic enzymes.
    He was hospitalized and repeated electrolytes, BUN, creatinine, glucose, creatinine phosphokinase, urinalysis, urine electrolytes and osmolality were negative.
    An abdominal ultrasound and urine toxicology screen were also normal.
    Consultation with cardiology and neurology were negative.
    A screening evaluation for psychiatric illness confirmed some concerns for depression but a fuller evaluation was needed.
    A nephrology consult was obtained and the diagnosis of Gitelman’s syndrome was considered.
    As the patient’s clinical course had shown no abnormalities since initial presentation, he was discharged to home on oral potassium and magnesium.
    He was to follow up with his local physician, psychiatrist and nephrologist for further evaluation and monitoring.

    Discussion
    Gitelman syndrome is a renal salt-wasting disorder that causes volume contraction and hypokalemia alkalosis. Hypomagnesemia occurs in ~50% of patients. It is an autosomal recessive disorder. Patients are born full term without polyhydramnios have normal weight gain and usually present in late childhood. They often crave salt. They may present with tetany or weakness secondary to hypomagnesemia. They also have low urinary calcium excretion.
    Treatment is potassium and magnesium supplementation.

    Bartter syndrome is often confused with Gitelman syndrome. Bartter syndrome also is a renal salt-wasting disorder that is autosomal recessive. These patients often have a history of polyhydramnios and prematurity. They commonly have failure to thrive in the first year of life. Older children also crave salt and may complain of muscle cramps or constipation because of chronic volume depletion secondary to renal salt losses.
    Treatment is centered on electrolyte supplementation but hypotonia and failiure to thrive can be difficult to treat.

    Learning Point
    Potassium is important for cellular homeostasis and is the most common intracellular cation. Most potassium is intracellular and total body potassium is ~50 meq/kg of body weight. The kidney is the final homeostatic mechanism for total body potassium.
    Potassium is filtered in the kidney and ~80% is reabsortion in the proximal tubule. Potassium is secreted in the descending limb of Henle
    with reabsorbing in the ascending limb. Potassium is again secreted in the distal tubules and collecting duct. Overall renal handing of potassium is affected by urine flow rate, plasma and luminal potassium concentration, delivery of sodium and chloride, availability of other nonabsorbable ions (e.g. sulfate, phosphate) and diuretics.

    The differential diagnosis of hypokalemia includes:

    • Gastrointestinal losses – normally the bowel secretes potassium into the lumen and reabsorbs sodium chloride
      • Stomach
        • Emesis
        • Nasogastric suctioning
        • Pyloric stenosis
      • Intestine
        • Diarrhea
        • Enema and laxatives
        • Enteric fistula
        • Malabsorption
        • Villous adenoma
      • Biliary system
        • Biliary drainage
    • Renal losses
      • Electrolyte abnormalities
        • Hypomagnesemia
      • Endocrine abnormalities
        • Cushing disease or syndrome
        • Congenital adrenal hyperplasia
        • Hyperaldosteronism
        • High renin states
        • Increased mineralocorticoid – medications such as Florinef&reg, chewing tobacco, licorice
      • Intrinsic renal abnormalities
        • Bartter’s Syndrome
        • Gitelman’s Syndrome
        • Renal tubular acidosis, types I or II
      • Medications
        • Antibiotics – e.g. amphotericin B, carbenicillin
        • Diuretics – especially thiazide, loop diuretics, osmotic diuretics
    • Shift to Intracellular space
      • Alkalosis
      • Barium intoxication
      • Familial hypokalemia Periodic Paralysis
      • Hypothismia
      • Na-K-ATPase stimulation – e.g. beta-2 agonists, catecholamines, insulin
    • Othis
      • Excessive sweating
      • Inadequate intake – e.g. anorexia nervosa or abnormal diets, over long time periods only 10 meq/L/day of K is sufficient to sustain life

    Questions for Further Discussion
    1. What is the laboratory evaluation for hypokalemia?
    2. What is the differential diagnosis for hyperkalemia?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topic: Metabolic Disorders

    To view current news articles on this topic check Google News.

    Bakerman S. Bakerman’s ABC’s of Interpretive Laboratory Data. 3rd Edit. Interpretive Laboratory Data, Inc. Myrtle Beach, SC. 412.

    Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1652-53,1713.

    ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients is gathised.
    3. Informed decisions about diagnostic and thisapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from othis disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.
    25. Quality patient care and assisting patients in dealing with system complexities is advocated.
    26. Partnering with health care managers and health care providers to assess, coordinate, and improve health care and how these activities can affect system performance are known.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    February 6, 2006

  • What is in the Differential Diagnosis of an Abdominal Mass?

    Patient Presentation
    A 3-year-old male came to clinic because his parents noted that his abdomen was hard on the right side when they squeezed his abdomen while they were playing 2 days ago.
    The past medical history was normal.
    The family history was negative.
    The review of systems was negative including weight loss, chills, fever, sweats, bone or other pain, adenopathy, bleeding, bruising or change in bowel or bladder habits. He also had normal satiety and was eating well.
    The pertinent physical exam with normal vital signs, growth and development. Abdomen reveals a diffuse solid mass in the right mid- to upper quadrant. No splenomegaly was noted. Shoddy anterior cervical and inguinal nodes were noted. Skin examination was normal.
    The work-up showed normal complete blood count, erythrocyte sedimentation rate, lactate dehydrogenase, liver enzymes, and total bilirubin.
    The radiologic evaluation revealed a large mass that appeared adherent to the liver that did not appear to be arising from the kidney or the adrenal grand. The patient then had an alpha-fetoprotein level drawn that was significantly elevated and a surgical biopsy confirmed a
    diagnosis of hepatoblastoma. The child is undergoing chemotherapy to shrink the tumor and surgical resection is planned for the future.


    Figure 33 – Axial image from a CT scan of the abdomen performed with intravenous and oral contrast. A large, inhomogenous mass is seen on the right side of the abdomen, compressing the right kidney posteriorly. The mass did not appear to arise from the right adrenal gland or right kidney.

    Discussion
    Approximately 70% of liver tumors are malignant with hepatoblastoma predominating in those < 3 years and hepatocellular carcinoma becoming more common in older children.
    Hepatoendothelioma is the most common benign tumor. Liver tumors usually present as a painless abdominal mass but they can also cause weight loss, anorexia, fever or jaundice.
    Alpha-fetoprotein levels are elevated in hepatoblastoma and hepatocellular carcinoma. Hepatoblastoma is more common in children with Beckwith-Wiedemann syndrome and hemihypertrophy.
    Resection is the mainstay of treatment but chemotherapy to shrink a large tumor or after resection is also used. Favorable factors for prognosis are decreasing alpha-fetoprotein levels and complete resections.
    Overall disease free survival is 70% except for those patients presenting with initial metastatic disease.

    Learning Point
    The differential diagnosis of an abdominal mass depends on the location, age of the patient, and imaging results but includes:

    • Abdominal organs that are normal but are mistaken as a mass – e.g. liver, spleen, kidney, aorta, bladder, uterus, etc.
    • Organ enlargement – e.g. storage disease, congestive heart failure, infection, etc.
    • Gastrointestinal anatomic abnormality – e.g. bowel duplication, stenosis, appendiceal abscess, etc.
    • Renal abnormalitiy – e.g. hydronephrosis, megaureter, polycystic kidney disease, renal vein thrombosis, etc.
    • Tumors – primary or metastatic, but most commonly neuroblastoma, Wilm’s tumor, and lymphoma. Other malignancies include hepatocellular carcinoma, hepatoblastoma, rhabdomyosarcoma,
      ovarian or testicular germ cell tumors, and primary neuroectodermal tumors. Benign tumors may also occur such as teratomas.

    • Cysts – e.g. choledochal cyst, mesenteric cyst, pancreatic pseudocyst, omental cyst, ovarian cyst, meconium pseudocyst, urachal cyst, etc.
    • Miscellaneous – e.g. abscess, fecal mass, hydrops of gall bladder, intussusception, pregnancy, pyloric stenosis, hydrometrocolpos, adrenal hemorrhaage, etc.

    Questions for Further Discussion
    1. What should be included in the workup of an abdominal mass? Why?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topic: Liver Cancer

    To view current news articles on this topic check Google News.

    Sheldon SH Levy HB. Pediatric Differential Diagnosis. Second Edition. Raven Press: New York. 1985:1-4.

    Woodhead JC. Pediatric Clerkship Guide. Mosby. St. Louis MO, 2003:115-120.

    Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1375-1376, 1620-21.

    ACGME Competencies Highlighted by Case

  • Patient Care
    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    7. All medical and invasive procedures considered essential for the area of practice are competency performed.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa

    Date
    January 30, 2006

  • When Do Cyanotic Congenital Heart Diseases Present?

    Patient Presentation
    An 6 week old male came to his local pediatrician’s office with 2 days of nasal congestion that was clear. He was formula feeding without problems and had started daycare several days ago. He had no fevers.
    The past medical and social history revealed that he was a previously well, full-term baby.
    The family history was negative.
    The pertinent physical exam revealed a vigorous male with weight, length and head circumference in the 25-75% and growing appropriately. His heart rate = 135, respiratory rate = 30 and normal blood pressure. He was afebrile.
    He was noted to have purplish lips, hands and feet. He had clear nasal discharge.
    On heart examination, he had a grade III/VI systolic murmur loudest at the lower left sternal border that was described as high frequency. It was not holosystolic but occured through most of systole.
    There was a normal S1, S2 with a normal split of S2. There was no other murmurs or thrills.
    The liver was 1.5 cm below the right costal margin and a normal spleen was palpable. The peripheral pulses were equal in the upper and lower extremities. There was a 1.5 second capillary refill.
    The work-up after being transferred to the local hospital revealed a saturation of 68% and a hyperoxia test showed an increased in the saturation to 80%.
    The chest radiograph showed clear lung fields andno cardiomegaly.
    The electrocardiogram showed upright T waves in V1 and V2 and mild right ventricular hypertrophy.
    An arterial blood gas was normal. a dignosis of of cyanotic congenital heart disease was made, but the patient was also placed on intravenous antibiotics because of his age and possible co-existing sepsis.
    He was transported to a regional children’s hospital where an echocardiogram revealed the specific diagnosis of Tetralogy of Fallot. A cardiac catheterization was planned to determine anatomy, pressures and to plan probable surgery to increase pulmonary blood flow.

    Discussion
    Cyanosis is a blue coloring of the skin and mucous membranes caused by an increase concentration of reduced hemoglobin. This occurs at a critical level of about 5 g/100 ml of reduced hemoglobin.

    Cyanosis is caused by

    • Decreased arterial oxygen saturation
      • Inadequate alveolar ventilation
        • Airway obstruction
        • Structural changes in the lungs (e.g. pneumonia, hyaline membrane disease, etc.)
        • Central nervous system hypoventilation
        • Weakness of the respiratory muscles
      • Desaturated blood bypassing the lungs
        • Cyanotic congenital heart disease
        • Pulmonary arterio-venous fistulas
    • Increased capillary deoxygenation
      • Acrocyanosis of the newborn
      • Congestive heart failure
      • Shock
    • Abnormal hemoglobin
      • Carbon monoxide poisoning
      • Methemoglobinemia

    The hyperoxia test is a screening diagnostic test used to often determine if the cyanosis is caused by the circulatory or pulmonary systems. The infant is placed in room air and the saturation measured. The infant is then placed in 100% oxygen environment and the saturation is again measured.
    If the problem is in the lungs, the saturation should increase with supplemental oxygen.
    If the problem is caused by cardiac disease, the saturation should not improve with the supplemental oxygen. This is because there is still mixing of saturated and desaturated blood in the heart. The hyperoxia test is useful as a general test, but as each child’s cardiac anatomy may be different, the test may not show these results every time.

    Congenital heart disease occurs in ~10 /1000 live-born children. The incidence is higher in stillborn and spontaneous abortuses. The most common congenital heart disease is a ventricular septal defect and the most common cyanotic congenital heart defect is transposition of the great vessels.

    Common congenital heart disease incidence as a percentage of all congenital heart disease

    	Ventricular septal defect		27.1-42
    Atrial septal defect 6.8-11.7
    Patent ductus arteriosus 5.3-11 (excluding preterm infants)
    Transposition of the great vessels 3.5-5.3
    Tetralogy of Fallot 3.9-6.8
    Truncus arteriosus 0.7-1.7
    Total Anomalous Pulmonary Venous Return 0.6-1.7
    Hypoplastic right heart 1.4-3.2 (mainly tricuspid atresia and pulmonary atresia with intact ventricular septum)

    Learning Point
    As noted before, the anatomy of an child is highly individualized. But time courses for general symptom presentation can be considered for various congenital heart disease.

    Presents Almost Immediately at Birth

    • Transposition of the great vessels (D-transposition) – The aorta arises from the right ventricle and the pulmonary artery arises from the left ventricle forming parallel systemic and pulmonary systems. Communication between the systems is required for the infant to survive. These communications can be an atrial septal defect, patent foramen ovale, patent ductus arteriosus or combinations of these.
      D-transposition usually presents with severe cyanosis at birth.

    • Tricuspid atresia – There is no direct communication between the right atria and right ventricle. Blood must go from the right atrium to the left atrium by an atrial septal defect or patent foramen ovale. A patent ductus arteriosus is the source of blood flow to lungs. There are several variants of tricuspid atresia and associated lesions may determine the presentation.

    Presents in the Perinatal Period

    • Truncus arteriosus – A single great vessel leaves the heart to supply coronary artery flow, aortic flow and pulmonary flow. There is almost complete mixing of the systemic and pulmonary blood. The degree of cyanosis is dependent on the size of the pulmonary arteries and the magnitude of pulmonary blood flow.
    • Total anomalous pulmonary venous return – The pulmonary veins fail to connect normally to the left atrium. Alternate pathways direct flow to the right atrium and then across an atrial communication. The admixture of blood at the atrial level and the right to left atrial shunt result in the cyanosis. When this lesion presents at birth, it is because of obstruction to the pulmonary veins.
    • Tetralogy of Fallot (also known as a “TET” or “blue TET”) – The are four abnormalities are: ventricular septal defect, pulmonic stenosis, right ventricular hypertrophy and an overriding aorta. The amount of restriction through the right ventricular outflow tract determines the amount of pulmonary flow and influences the amount of right to left shunt across the ventricular septal defect. The degree of cyanosis is a reflection of the amount of pulmonary flow.

    Presents after the Perinatal Period

    • Tetralogy of Fallot (also known as a “pink Tetralogy” or “pink TET”) – The amount of restriction through the pulmonary valve and right ventricular outflow tract is less severe and there may be left-to-right shunting through the ventricular septal defect until pulmonary stenosis progresses.
      “Tet spells” occur when there is a provocation of a fall in systemic resistance and fixed pulmonary obstruction is present. At these times, the flow across the ventricular septal defect fecomes right to left and the patient has a cyanotic spell.
      The spells are characterized by tachypnea, cyanosis and a shorter outflow murmur. Treatment includes calming the child, and increasing the systemic vascular resistance (i.e. knee-to-chest position, volume influsion or sedation) by slowing the heart rate (beta-blocker therapy) to allow longer diastolic filling. Oxygen can also be administered to the infant but if resisted can actually be counterproductive.

    Questions for Further Discussion
    1. What are the common chest radiographic signs of congenital heart disease?
    2. What congenital heart diseases are associated with chromosomal abnormalities?
    3. What congenital heart diseases are associated with maternal medications?

    Related Cases

    To Learn More
    To view pediatric review articles on this topic from the past year check PubMed.

    Information prescriptions for patients can be found at MEDLINEplus for this topic: Congenital Heart Disease
    and at Pediatric Common Questions, Quick Answers for these topics:
    Congenital Heart Disease and Heart Murmurs and Arrhythmias.

    To view current news articles on this topic check Google News.

    Rudolph CD, et. al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:1780-81.

    Robertson J, Shilkofski N. The Harriet Lane Handbook. 17th edition. Elsevier Mosby Philadelphia, PA. 2005:159-210.

    Park MK. Pediatric Cardiology for Practitioners. 3rd edition. Mosby. St. Louis, MO. 1996;114-128.

    ACGME Competencies Highlighted by Case

  • Patient Care
    1. When interacting with patients and their families, the health care professional communicates effecively and demonstrates caring and respectful behaviors.
    2. Essential and accurate information about the patients is gathered.
    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    7. All medical and invasive procedures considered essential for the area of practice are competency performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused case is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Interpersonal and Communication Skills
    19. The health professional works effectively with others as a member or leader of a health care team or other professional group.

  • Systems Based Practice
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.

    Author
    Donna M. D’Alessandro, MD
    Associate Professor of Pediatrics, Children’s Hospital of Iowa
    Dr. D’Alessandro would also like to thank Dr. Jill Morriss, Professor of Clinical Pediatrics for her helpful suggestions in reviewing and improving this case.

    Date
    January 23, 2006