- Identify the major genetic disorders presented and understand their physiological impact.
- Learn the special considerations to take when treating patients with these disorders.
- Understand specific circumstances where these patients require unique treatment or transport considerations.
- Atelectasis: Deflation of the alveoli, which can lead to collapse of part of a lung.
- Cardiomegaly: Enlargement of the heart, which may be pathological but may also be natural (as in pregnancy).
- Dilated cardiomyopathy: Pathological weakening and enlargement of the heart and its chambers, which could lead to CHF.
- Portal hypertension: Hypertension in the liver due to liver disease.
- Rhabdomyolysis: The breakdown of muscle tissue, causing release of muscle proteins into the bloodstream.
- Subluxation: A partial dislocation.
You’re dispatched to the local high school gym for chest pain. Upon arrival, you see a tall, thin 18-year-old male appearing to be in significant pain and experiencing shortness of breath. He says he began to feel a tearing sensation in his upper chest while running, followed by nausea and vomiting. On assessment, you find his radial pulse is thready. His skin is pale, cool and diaphoretic. You apply oxygen and the cardiac monitor; his heart rate is in the 120s. His blood pressure remains normotensive. Your 12-lead ECG is nondiagnostic, and the patient tells you he’s beginning to feel better and wants to avoid the embarrassment of going to the hospital.
Genetic defects affect 1—2% of the population. Most people who survive through infancy with a genetic defect have relatively mild defects of the sex chromosomes.1 A large number of genetic defects are carried on the X chromosome, which codes for almost 1,900 different genes, unlike the Y chromosome that codes for a mere 450 genes.
As a result of females having two X chromosomes, genetic defects will often have mild or unrecognizable manifestations due to compensation by the non-defective X chromosome. Genetic defects may affect any organ or system, as with the musculature in muscular dystrophy and the cardiovascular system in Down syndrome.
Muscular dystrophy is an X-linked recessive genetic disorder that may be inherited or a new mutation.2 There are many types–the most common is Duchenne muscular dystrophy (DMD), which occurs once every 3,500 live births.3
In DMD the gene for dystrophin is defective. This causes a weakening of the sarcolemma, the membrane of smooth muscle cells that connects muscles to tendon. These defective fibers are replaced by connective tissue,3 creating a pseudo-hypertrophy where muscles appear large but don’t function as muscle. This is most common on the gastrocnemius as well as the triceps brachii and vastus lateralis.2
Onset of symptoms usually occurs between 2 and 6 years of age.2 Symptoms often begin with a child preferring to walk on his toes, walking with a waddling gait and using proximal instead of distal muscles. Gower’s sign is present, in which a child uses his arms to walk himself into a standing position from a squat due to leg weakness.2 Progression of the disease is rapid, with most people wheelchair-bound by their teens.3
Severe scoliosis is strongly associated with DMD. If untreated, lung function is decreased due to impaired lung expansion.3 During transport, the care provider should make all attempts to assist the DMD patient into a position that helps maximize lung expansion.
The majority of DMD patients have cardiac involvement, the extent of which, in large part, determines life expectancy.4 Half of all children with DMD will have dilated cardiomyopathy by age 15.3 The same amount of patients will experience dysrhythmias, congestive heart failure or cardiomegaly during their lifetimes.4 Seventy-five percent of DMD patients die by age 20, usually due to cardiac or respiratory failure.2
DMD patients represent a special concern when they’re sick or attain a traumatic injury. These patients have a fixed cardiac output, leaving them incapable of compensating for hypovolemia. Additionally, DMD patients are more likely to suffer dysrhythmias and respiratory insufficiency when anesthetized. Inhaled anesthetics such as nitrous oxide appear to increase rhabdomyolysis from increased plasma concentrations of calcium.3 Anesthesia should be avoided when possible to avoid these complications.
In the DMD patient, extrajunctional synapses appear, which are associated with muscular damage.5 These increase the cellular amounts of succinylcholine. Succinylcholine causes depolarization of the muscle cells, which can lead to leakage of potassium from the cell, causing hyperkalemia.6 Succinylcholine creates rhabdomyolysis, causing a malignant hyperthermia-like syndrome.7 For this reason, succinylcholine and other polarizing neuromuscular blocking agents should never be used on DMD patients to facilitate rapid sequence induction. Non-polarizing neuromuscular blocking agents can be used if absolutely necessary, but should be avoided.3
Cystic fibrosis (CF) is a recessive genetic condition that affects the body’s ability to transport salt, and therefore water, throughout the body.1 As with muscular dystrophy, the recessive nature of the genetic defect means that both parents must be carriers in order to produce a child affected by the disorder. One in every 29 Caucasians is a carrier,1 making CF the most common lethal genetic condition in Caucasians.8 While the majority of CF patients are white, the disease is known to affect all races.
The fundamental defect occurs on the cystic fibrosis transmembrane regulator gene, which affects the chloride channels.9 Chloride ions aren’t transported efficiently, decreasing the body’s ability to produce fluid secretions and increasing the viscosity of those secretions.9 This causes airway problems as well as blockages of smaller ducts such as those in the pancreas and liver, and electrolyte imbalances.9
CF is characterized by a triad of increased concentration of chloride in sweat, pancreatic insufficiency and chronic pulmonary disease.9 The major organs affected by CF are the lungs, sweat glands and the GI tract, especially the pancreas.10
X-ray showing hyperinflation and predominantly upper lobe bronchiectasis in a patient with cystic fibrosis. Photo courtesy Edward T. Dickinson
Respiratory infections are the most prominent manifestations of CF and often start before the patient is 1 year old.10 The viscosity of airway secretions in the CF patient make it difficult for cilia to clear the patient’s airway. Mucus keeps bacteria in place, allowing it to colonize, leading to biofilm development and chronic respiratory infections. High amounts of sodium reabsorption in the CF patient increase the inflammatory response and further diminish the body’s ability to fight infections. Air trapping and bronchiectasis lead to atelectasis, chronic hypoxia and cor pulmonale, which eventually lead to respiratory failure.8
Mortality in CF usually results from pneumonia, hypoxia, cor pulmonale or respiratory failure.10 Lung transplants are withheld until the CF patient has end-stage pulmonary disease with an expected two-year survival on supplemental oxygen of less than 50%.11 CF patients, even those who are in late stages, may undergo home therapy instead of in-hospital therapy due to the risk of nosocomial infections.8 For the EMS worker, this means you may encounter a CF patient in the home-care environment who’s very sick. It’s important to distinguish the patient’s chronic situation from his emergency complaint.
Thick secretions that block the pancreatic ducts lead to frequent and varied digestive problems.1 Almost 90% of CF sufferers experience pancreatic insufficiency,10 often leading to insulin-dependent diabetes.8 Additionally, bile duct blockages may lead to focal biliary cirrhosis and portal hypertension. Diabetes, portal hypertension and liver disease are highly significant in morbidity and mortality in CF.8 Following lung disease-related issues, most CF mortality is caused by cirrhosis of the liver.8
Excess salt excretions through the skin can lead to electrolyte imbalances, which can cause three major problems. First, dysrhythmias are a common concern. The care provider should keep in mind that dysrhythmias in the CF patient may be related to an electrolyte imbalance. Second, electrolyte imbalances may lead to heat exhaustion in weather that others may not define as “hot,” especially in younger patients. Finally, electrolyte imbalances increase the likelihood of shock, especially in younger children.10 Hypothermia related to shock can lead to significant respiratory depression.8
CF patients may be especially fragile when involved in a traumatic incident. Malabsorption of vitamin K may create coagulation issues. Low bone densities can lead to osteoporosis, increasing the likelihood of fracture from injuries that may not appear significant.8
Home treatments for the CF patient are fairly standardized. It’s not unusual for CF patients of any age group to have a peripherally inserted central catheter or portacath in place. When possible, accessing one of these devices will save the patient the pain and potential infections associated with additional IV access. One nebulized medication, dornase alfa (Pulmozyne), has been shown to decrease the number of respiratory infections experienced by the patient. It’s believed that this medication hydrolyzes the DNA in the sputum to reduce sputum viscosity. Almost half of CF patients are also on corticosteroids.8 Most CF patients in the United States use a combination of airway-clearance devices, percussion of the thorax and postural drainage to help clear secretions.8
CF patients may present a special difficulty for EMS. Along with the 6% of patients on home oxygen,8 bi-level positive airway pressure (BiPAP) is frequently used. If in protocols or available with a base order, the care provider may want to consider the potential benefits of continuous positive airway pressure/BiPAP use on a CF patient in respiratory distress when appropriate. Additionally, inhaled hypertonic saline has been shown to increase the clearance of mucus in CF, and it should be considered if accessible to the provider.
In addition, frequent sinus infections in the CF patient may lead to nasal polyps, complicating nasal intubation.10 Further, anesthetics and opioids may lead to significant respiratory depression–opioids should be used modestly and the care provider should be prepared to secure the patient’s airway.8 Finally, chronic respiratory infections mean that many CF patients are on constant prophylactic antibiotics. This constant antibiotic use causes problems with antibiotic resistance and chronic immunosuppression.1
The quality of life of the CF patient has been improved greatly over the decades.8 The lifespan has increased in the U.S. from 14 years in 1969 to 32 years in 2000 and more than 50 years in patients born after the year 2000.11 These variations are related to treatment, to the individual’s particular genetic mutation and other comorbidities.
Some studies have shown that chronically ill adolescents have more risk-taking behaviors than their healthy counterparts in an attempt to appear “normal.” These behaviors may extend to medication compliance; about half of CF adolescents are not fully compliant with their medications.11 Adolescents responsible for taking their own medications should be asked, away from parents, about compliance.
CF leads to physical abnormalities, such as delayed puberty, discolored teeth (from antibiotic use) and gastrointestinal problems.11 These embarrassing issues, along with the fear of a possible early death, lead to problems with depression (present in a quarter to half of all CF adolescents). This creates a risk for suicide attempts and further increases the likelihood of risk-taking behavior.11
Adolescents often have difficulty understanding the long-term consequences of their risky behaviors. Smoking greatly decreases lung function over the long term in the CF patient. Alcohol use increases the likelihood of pancreatitis and liver problems, which have a detrimental effect on the patient’s lifespan.11 Due to the acute risks of pancreatitis, CF patients who have been drinking alcohol with associated vomiting or abdominal pain must be checked for hypoglycemia and transported to the ED.11
Girls with CF have been traditionally told they’re likely to be infertile. However, while increased viscosity of cervical mucus may decrease fertility, women with CF are fertile.11 But because these women may not believe they can become pregnant, prenatal care is often delayed. Women who are on systemic birth control hormones face an increased risk of embolism and interactions with their antibiotics. Pregnant women with CF experience increased difficulties maintaining adequate nutrition and pulmonary function, and the possibility of premature birth of their infants.11
Marfan syndrome is a hypotonia syndrome,2 where muscle tone is decreased. It’s autosomal dominant and occurs once every 3,000—5,000 live births.12 Unfortunately, these statistics vary significantly because the disease remains undiagnosed in many patients until after death.
First described in 1896, Marfan syndrome comes from a mutation in the gene FBN1. This gene codes a protein that assists with cellular adhesion and forms the microfibrils that create the extracellular matrix. Though largely hereditary, up to one third of cases may be new mutations. There are more than 1,000 different known mutations of FBN1,12 causing a spectrum of problems and severities.
Marfan syndrome is characterized by the overgrowth of long bones (a tall patient, especially with long arms), skeletal issues such as scoliosis, pneumothorax, dislocated lens of the eye and dilated aortic root. These patients also commonly experience dilation of the pulmonary artery, prolapsed or sclerosed atrioventricular (AV) valve (50—80% of Marfan patients have prolapsed mitral valves), and calcification of the mitral annulus (the ring surrounding the leaflets of the mitral valve).12
Cardiovascular complications account for 90% of Marfan deaths. Photo Matthew Strauss
Cardiovascular complications account for 90% of Marfan deaths. Of these, 80% are from aortic rupture. The most common location of aneurism in these patients is the ascending aorta.13 Moderate to severe mitral regurgitations occur in 12—15% of those with prolapse. Valvular regurgitation and dysrhythmias are also causes of sudden death in the Marfan patient. Common dysrhythmias come from prolonged AV conduction, creating a delay in conduction from the atria to the ventricles, shown on the ECG as first, second or third-degree heart blocks and a prolonged PQ interval. The Marfan patient may also experience issues related to ventricular repolarization, with ST segment abnormalities, prolonged QT intervals, the presence of U waves, and other ventricular dysrhythmias. Twenty-one percent of Marfan patients will experience a ventricular dysrhythmia during their lifetimes, with 4% experiencing sudden cardiac arrest due to this dysrhythmia.12
Degeneration of the muscle in the aorta is caused by smooth muscle shrinking, thick basement membranes and issues associated with the collagen and lamellae of the aorta. Additionally, Marfan syndrome increases the activation of TGF-beta, a protein involved in immunity and cellular differentiation. This causes an increase in inflammation and fibrosis in the Marfan patient, exacerbating vascular and pulmonary problems.12 Decreased elasticity in the tunica media worsens aortic stenosis. Proximal aortic dilation further weakens the vessel, increasing disposition to dissect.12 Hemodynamic stress from problems such as hypertension and aortic regurgitation further damages the aorta by putting pressure on the aortic wall. The already thin, stiff, dilated aorta attempts to dilate further, worsening aortic regurgitation. This cycle carries a high risk for dissection and rupture.12
Dissection and aortic regurgitation used to be responsible for 90% of Marfan deaths;12 with modern treatment, prophylactic surgeries and, on rare occasion, heart transplants, diagnosed Marfan syndrome patients have almost normal lifespans with a median age of 61 as of 1995.13 The majority of those who experience sudden death at a young age are undiagnosed–without proper diagnosis, death frequently occurs in the patient’s 20s or 30s.12 A relatively young patient experiencing sharp chest pain should be questioned about family history. A family history of aortic aneurism or sudden death may suggest undiagnosed Marfan syndrome.12
Along with thoracic aortic aneurism dissection, care providers must also consider the possibility of dissections in unusual locations–especially the internal carotid, pulmonary artery and the renal artery. However, dissection of peripheral arteries is unusual.13
The patient with Marfan syndrome may know he has an aneurism or dissection. Type A dissection, involving the ascending aorta, is a surgical emergency just as it would be in the non-Marfan patient. These patients will normally appear normotensive or hypotensive.14 Type B dissections, accounting for 10% of Marfan dissections, are usually in the proximal descending thoracic aorta; these dissections may be stable and chronic.12 Type B dissections generally cause the patient to become hypertensive.14 Both types of dissections may cause migratory pain and may be worse at the onset than minutes later,14 which could lead the patient to attempt to avoid hospital evaluation. Twelve-lead ECGs are generally nondiagnostic.14 The patient will likely know approximately when he will need surgery (generally after approximately 5 cm diameter); however, a rapid increase in aortic size, even in the normal range, increases the risk for dissection.12
Prior dissections increase a patient’s risk of a new dissection. In Marfan patients with uncontrolled hypertension, the patient has a 46% likelihood of developing a second dissection. If hypertension is controlled, this risk drops to 17%. Smoking greatly increases these risks.13
The majority of Marfan syndrome patients are on beta blockers, even if they aren’t hypertensive. Beta blocker use appears to improve elasticity and decrease stress on the walls of the aorta, which decreases the rate of aortic dilation. Generally the patient will be on atenolol titrated to a heart rate of less than 60, blood pressure permitting.12 This means these patients will normally be in a bradycardic rhythm. Some hypertensive Marfan patients will take an ACE inhibitor. Those who are unable to tolerate beta blockers are given verapamil.12
Strenuous anaerobic exercises, such as weightlifting, are contraindicated in the Marfan patient due to the higher aortic wall stress from increased blood pressure. Sports involving direct impacts or collisions should be avoided because of the risk of arterial trauma and tears. Sports involving rapid pressure changes, such as scuba diving, can lead to pneumothorax. Aerobic exercise decreases peripheral vascular resistance and diastolic blood pressure, which compensates for the increased wall pressures. However, aerobic activity should be moderate with the Marfan athlete maintaining exertion at 50% or less of his maximum.12 Marfan syndrome should be considered in any athlete who experiences sudden cardiac symptoms or arrest and dissection should be considered.
Pregnancy presents a special risk to women with Marfan syndrome. Increased cardiac output, heart rate, stroke volume and circulating volume put pressure on the aortic walls, especially in the third trimester of pregnancy. These concerns continue several days after delivery, with one fifth of aortic problems in pregnancy occuring two days after delivery or later. Prophylactic beta blockers are regularly given, and the patient may also have prophylactic aortic root repair prior to or early into pregnancy.12
Though aortic and cardiac problems are the most life-threatening for the Marfan patient, other less dramatic problems associated with the disease may lead to the patient calling EMS. Vision problems are common, especially lens dislocation; if the dislocation is complete, the patient may develop sudden blurred vision. Additionally, 15% will develop gallstones, 14% will have a herniated or ruptured disc, 10% will have a bladder prolapse, and 10% of females will suffer uterine prolapse.13 Along with these problems, 11% of Marfan patients have a deviated nasal septum,13 which may complicate nasal intubation.
One percent of all children have some type of mental retardation, with the majority being classified as mildly retarded.15 The most common chromosomal cause is Down syndrome. Down syndrome, also called trisomy 21, is caused by the presence of a third copy of chromosome 21. Down syndrome affects more than one in 700 infants each year and causes problems that extend well beyond intellectual deficits.1 Twenty percent of Down syndrome infants are stillborn. Of those who survive, the average life expectancy in 1929 was 9 years, mostly due to congenital heart defects. As of 1992 that has been extended to 30 years. Life span and quality of life are strongly related to treatments and underlying heart defects.1
Children with Down syndrome have delayed axonal myelination.1 The myelin sheath helps to conduct impulses and to protect the neuron, allowing regrowth and repair if damage is caused. This creates developmental and nervous system delays, including balance and all senses, such as vision. Problems extend to language and behavior, but people with Down syndrome tend to have more social aptitude than might be expected given their IQs. Additionally, those with Down syndrome show plaques on autopsy that resemble those of Alzheimer’s disease at an average of 35 years old. However, patients don’t appear to develop symptoms of dementia until their 50s.1
Coordination difficulties and late bone ossification increase the likelihood of significant trauma in the Down syndrome patient. Atlantoaxial instability occurs in almost 15% of Down syndrome patients. This instability and tendency toward hyperflexion can cause subluxation or dislocation of C1 and C2, which can increase the possibility of spinal cord injury.16 Additional degenerative changes such as narrowing of the foramina17 further increase the likelihood of compression and other damage. These possibilities should create a high index of suspicion in the case of trauma. When in doubt, Down syndrome patients should be placed in C-spine precautions with appropriate padding to maintain comfort and airway.
Down syndrome may cause developmental and nervous system delays, including balance and all senses, such as vision. Photo Kevin Link
Congenital heart defects occur in more than two thirds of Down syndrome patients and may lead to death in the first few years of life. The most common defects are prolapsed valves, ventricular septal defects, patent ductus areteriosus and vascular problems including aortic regurgitation, but many different types of cardiovascular problems are prevalent. In addition, people with Down syndrome have an increased likelihood of aortic dissection.4 Any complaint of chest pain should involve assessing for the possibility of dissection. All Down syndrome patients, of any age, who complain of chest pain or a possible anginal equivalent event, should be thoroughly examined for cardiac problems including a 12-lead ECG.
Along with the problems stated above, Down syndrome patients have a tendency toward T and B cell derangements, with resulting problems such as a high risk of leukemia and the potential to develop life-threatening respiratory infections.1 Respiratory problems pose a special concern to the EMS worker. Due to their smaller mouth openings, shortened hard palates, short necks18 and supraglottic stenosis with smaller tracheal diameter (creating a smaller trachea),19 intubation of the Down syndrome patient may be extremely difficult. If intubation is attempted the tube should be at least two sizes smaller than the care provider would normally use in a patient of the same size.19
Seizures, hip problems (including dislocation), thyroid problems and liver disease may also be present in the Down patient and should be considered and managed appropriately.1
Raising a child can be frustrating and both financially and emotionally draining for a parent. These pressures are compounded when the child is disabled, has special emotional needs or requires expensive care. Abuse occurs in 3.6% of disabled children, compared to 2.1% of the general population. Almost two thirds of abused disabled children are boys.
Abuse is especially an issue with mentally retarded children with behavior problems. Children with speech deficits are also more likely to be abused. Contrary to what many may believe, the less impaired and less obvious a mentally retarded child is, the more likely he or she is to be abused. The most common type of abuse experienced by the disabled child is neglect, though physical and sexual abuse are also a concern.15
Disabled children have almost twice the likelihood of being sexually abused than normally abled children. This likelihood is especially high with the mentally disabled. One study showed that as many as 25% of mentally retarded children are sexually abused. This is not only a problem with disabled girls; in institutions, over 75% of sexually abused kids are boys under the age of 14.15
There are many reasons for the high rate of abuse in the developmentally disabled. Caregiver stress, parental mental disabilities and parental substance abuse all increase the likelihood of abuse for the disabled child. Mentally disabled children are often raised in an environment where they are taught to depend on their caregivers instead of developing a sense of independence, further increasing caregiver stress and lowering the chances the child will feel comfortable reporting any abuse. Mentally disabled children tend to not be taught about abuse or sexual education and may not understand that what they are experiencing is wrong. Finally, disabled adolescents want to “fit in” just as much as the normally abled. These children may be more willing to tolerate abuse in an attempt to feel as though they are more “normal.”15
Aortic dissection requires immediate patient transport. Photo Matthew Strauss
Case Study Conclusion
You don’t feel right allowing your patient to refuse transport against medical advice. As part of your assessment, you check both radial pulses and find they’re unequal. You then take bilateral blood pressures and notice a significant difference. The patient hesitatingly accepts transport.
On later return to the ED you learn your patient was diagnosed with acute type A aortic dissection of the ascending aorta. He was immediately taken to surgery for aortic repair and tolerated the procedure well. Weeks later, he was discharged home with a diagnosis of aortic dissection secondary to undiagnosed Marfan syndrome.
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