Download Dannemiller Lecture on Down Syndrome

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ANESTHETIC CONSIDERATIONS IN THE PATIENT
WITH
DOWN SYNDROME
Melissa A. Ehlers, M.D.
Assistant Professor of Anesthesiology
Director of Pediatric Anesthesia
Albany Medical Center
Albany, NY
Address correspondence to:
Melissa A. Ehlers, M.D.
47 New Scotland Ave.
Albany Medical Center
PO Box 131
Albany, NY 12208
(518) 262-4305
(518) 262-4736 (fax)
[email protected]
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Learning Objectives
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Appreciate commonly found disease states in the population with Down syndrome (DS)
Understand how to quickly evaluate these common diseases
Learn how to evaluate a potentially unstable cervical spine
Be aware of the significantly increased mortality from pulmonary infection in the
patient with DS
Recognize common forms of congenital heart disease (CHD) in this population
Understand some of the potential complications in the patient with CHD presenting
for non-cardiac surgery
Be aware of differences in determination of tracheal tube size
Decide whether endocarditis prophylaxis is necessary
Evaluate the best method of post-operative pain control
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Anesthetic care of the patient with Down syndrome (also known as Trisomy 21) can
present a challenge to even the most seasoned practitioner. These patients may have a
wide range of serious medical problems in combination with varied ability to realize that
they are sick. Unfortunately, they rarely understand why the anesthesia caregivers must
poke and prod them in an effort to “make them better.” In order to provide the best
possible care for them the caregiver must understand the various physical and emotional
characteristics of the patient with DS and be prepared for the special challenges that they
may present.
Pre-operative considerations
Frequently the preoperative screen may be the most challenging part of the entire
anesthetic. The intelligence quotient (IQ) in individuals with DS ranges from 20 to 70,1
therefore commonly little or no detailed information may be obtained from the patient.
Instead, a parent, sibling, other relative or caretaker must frequently be relied upon to
furnish the medical history. Because this may be incomplete or abbreviated, the
anesthesia provider must keep the common disease states associated with DS in mind and
attempt to rule out or further explore as many as possible (see Table 1).
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Mental Retardation
The IQ usually ranges from 20 to 70 in these patients and cooperation can be difficult to
obtain. This is further compounded by a 30% incidence of mental illness in the DS
population2 that can make communication even more difficult. For those patients able to
understand, a calm, quiet explanation of the anesthetic plan can be reassuring; appropriate
use of oral or intravenous sedative premedication may make the experience much more
pleasant for everyone involved. With the extremely agitated, uncooperative patient, one
must occasionally resort to intramuscular or rectal sedatives in order to sedate him/her to
the point where the rest of the anesthetic plan can occur smoothly and safely.
Hypo-/hyper- thyroidism
Hypothyroidism may be seen in as many as 10 to 40% of patients with DS, and this
population also has a higher-than-average prevalence of hyperthyroidism.2 Many
patients will have routine screening tests for this condition, but a well-directed history
may elucidate symptoms (i.e., constipation, recent weight gain, sluggishness vs. diarrhea,
heat intolerance, palpitations) that warrant further workup.
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Diabetes Mellitus
The prevalence of type 1 diabetes mellitus is as high as 10.6% in patients with DS.3
These patients are often treated with once daily insulin regimens that are surprisingly
efficacious when compared to diabetics without DS who are matched for other variables
(i.e., duration of diabetes, sex, age). If screening for diabetes has not been done recently
in the patient, a history of prolonged flu-like illness, polyuria, polyphagia, and/or weight
loss should raise the suspicion of diabetes.
Obesity
Although infants with DS typically follow height and weight curves lower than those of
the rest of the population, by the age of 2 to 3 years they commonly start to exhibit
excessive weight gain.4 Upon reaching adulthood, as many as 50% of individuals with
DS may be overweight in spite of evidence that their caloric intake may even be
reduced.5 Obesity in these patients may contribute to worsening of pre-existing
conditions (i.e., diabetes, sleep apnea, pulmonary hypertension) or may cause new health
conditions unrelated to the presence of DS, such as hypertension, arthritis, and
gallbladder disease. Additionally, practitioners should be cognizant of the airway,
ventilatory, and positioning challenges posed by the overweight patient.
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Sleep Apnea
Obstructive sleep apnea (OSA) has a reported prevalence of 54% to 100% in the
population with DS compared with only 2% in the rest of the population.6 Typical
characteristics of the DS patient, which include midface hypoplasia, micrognathia, small
larynx, obesity and muscular hypotonia, all predispose them to potentially significant
OSA. Besides these potential causes of mechanical obstruction, there is evidence that
some individuals with DS may have centrally mediated sleep apnea, perhaps secondary to
an abnormal respiratory drive with hypoxic stimulation (Ondine’s curse).7 If
adenotonsillar hypertrophy is present, their removal may improve symptoms, but quite
often these patients have relative hypoplasia of these structures and other surgical
alternatives would include uvulopalatopharyngoplasty and/or possible partial tongue-base
resection or genioglossal advancement. Nonsurgical therapy may include continuous
positive airway pressure (CPAP), weight loss programs, and occasionally, medications to
stimulate respiratory drive.6 The consequences of undiagnosed/untreated OSA may
include “minor” symptoms such as daytime sleepiness or behavioral difficulties, but
major problems such as cor pulmonale (especially in this population which is more
susceptible to pulmonary hypertension) or arrhythmias may develop. Obviously, because
of the high prevalence in this population, one should assume the DS patient has OSA and
try to rule it out by a history of surgical or non-surgical treatment or a negative
polysomnography test. Otherwise, anesthetic preparation should include the assumption
that some degree of obstruction may be encountered during most anesthetics, and
pulmonary hypertension may also be present.
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Otitis Media/ Hearing Loss
Patients with DS are predisposed to frequent middle ear infections and/or effusions
because of abnormal eustachian tube architecture (including hypotonicity of the
musculature, a decreased diameter, and abnormal cartilage). Stasis within the eustachian
tube permits bacteria to migrate from the nasopharynx.7 Recurrent infections along with
an increased incidence of inner ear abnormalities (progressive ossification of the basal
spiral tract, shortened organ of Corti, decreased spiral ganglion cells) all contribute to the
increased incidence of hearing loss in individuals with DS which may be as high as 78%.8
Whether presenting for middle/inner ear surgery or some other procedure, these patients
may find communication even more difficult because of their hearing loss. Also, they
may be more prone to post-operative nausea and vomiting if their vestibular pathways
have been affected.
Gastrointestinal Disorders
Newborns with DS have up to a 12% prevalence of various gastrointestinal (GI)
atresias,1 which usually necessitate surgery within the first few days of life. Other
frequent GI abnormalities include pyloric stenosis, imperforate anus, tracheo-esophageal
fistula, and Hirschsprung’s Disease. In addition, patients with DS are prone to develop
celiac disease (occurs in 7 to 16%9) that requires lifelong adherence to a special diet in
order to prevent small bowel mucosal damage.
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Hematologic Abnormalities
Children with DS are known to have a 10-to 20-fold increase in their risk of developing
acute leukemia,10 although it is still only found in less than 1% of individuals with DS.1
With chemotherapy, the long-term prognosis for acute lymphocytic leukemia (ALL) is
similar to that for non-DS patients, but interestingly, patients with DS have higher
survival rates for the various myeloid leukemias. This has led some authors to speculate
that there may be increased expression of a gene on chromosome 21 that allows improved
chemosensitivity of the dysplastic cells.11 In contrast to the increased risk of ALL, the
risk of developing most solid tumors is lower in the DS population, and breast cancer is
rarely seen.
Approximately 10% of newborns with DS will exhibit transient abnormal myelopoiesis
(TAM) that almost always spontaneously resolves within 3 months.12 Characteristics of
this condition include megakaryocytes in peripheral blood, variable thrombocytopenia,
and rare progression to hydrops fetalis or hepatic fibrosis.13 This disorder is considered
to be indistinguishable from acute megakaryocytic leukemia (AML-M7), and only its
spontaneous regression points to the diagnosis of TAM. Of these patients, approximately
25% will go on to develop AML in the first four years of life, which is fatal if left
untreated.12
Other common hematologic anomalies of the newborn with DS are thrombocytopenia
and thrombocytosis.14 Both appear to spontaneously regress, but severe or symptomatic
thrombocytopenia may need to be treated with transfusion.
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Atlanto-axial Instability
Up to 20 % of children with DS have radiographic evidence of atlantoaxial instability
(AAI), but only approximately 1% of all patients with DS will exhibit any symptoms15
(see Table 2).
Pre-operative evaluation of the individual with DS for AAI remains controversial. All
patients should have annual neurologic exams and certainly a patient who exhibits any of
the above symptoms should have neck radiographs taken. Lateral views in extension,
neutral position, and flexion are termed a “Down series”16. A distance 4.5 mm or greater
between the anterior arch of the atlas and odontoid process of the axis is regarded as
potentially unstable.17 The asymptomatic child with DS without previous screening
presenting for tonsillectomy is a common workup dilemma for many practitioners. If the
patient has competed in Special Olympics, screening for AAI is required before
participation and any evidence of AAI should have been communicated to the caregivers.
Otherwise, a brief inquiry as to any evidence of ligamentous laxity or instability
elsewhere (i.e. frequent patellar dislocation, ability to fold thumb back to touch wrist)
should alert one to a greater likelihood that some degree of AAI is present. Regardless,
without overt neurological symptoms, it does not seem reasonable to recommend
radiographs in these asymptomatic patients as long as some standard precautions are
taken, such as minimal manipulation of the head for intubation (ideally one has an
assistant stabilize the head/neck in the neutral position) as well as avoidance of further
surgical manipulation of the head and neck whenever possible. Although many people
assume that extension of the head is most compromising to the spinal cord, lateral or
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axial rotation can also cause damage18 and this should be kept in mind when placing
internal jugular venous lines. For those patients who already have diagnosed AAI,
consideration should be given to placing a hard or soft collar perioperatively to protect
the cervical spine.
Recurrent Pulmonary Infections
Numerous studies have found the lungs of patients with DS to be abnormal; grossly they
exhibit a sponge-like appearance due to enlargement of alveoli and terminal bronchioles
that is accompanied by a reduction in the overall number of alveoli.19 Although some
investigators feel that these abnormalities are present antenatally,20 others have found that
these differences only start to occur after birth.21 This has led to the hypothesis that
intrauterine pulmonary development may be mediated by maternal-placental factors,
while post-natal development is mainly genetic in nature.22 Another unusual feature in
these patients is the presence of a double capillary network around the alveoli, a normal
feature of all human fetuses, but abnormal in its persistence into adult life.21
Another abnormality in patients with DS is their state of relative immunodeficiency due
to decreases in both cell and antibody-mediated immunity.23 All of the above factors,
combined with reduced mucociliary clearance and the presence of heart disease in many
patients (which can increase interstitial fluid in the lungs, cause compression of the leftmainstem bronchus, etc.) all contribute to a mortality from respiratory infection that is
124 times greater than that of the non-DS population.22 For this reason, the presence of
any pulmonary infection in a patient with DS presenting for surgery should be treated
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with careful consideration, and the threshold for postponement of an elective case may be
much lower than usual.
Congenital Heart Disease
Cardiac defects are recognized in 40-50% of the population with DS while alive, and in
up to 66% of these patients at autopsy. Additionally, subtle abnormalities of morphology
or cardiovascular function can be seen in almost everyone with DS.24 The most common
type of congenital heart disease (CHD) in this population is complete atrioventricular
septal defect (cAVSD) where the lower part of the atrial septum and the upper part of the
ventricular septum are missing, and there is a common atrioventricular valve that must be
divided into the tricuspid and mitral valves. CAVSD has a prevalence of approximately
50-60% of all CHD cases with DS.25 Ventricular septal defects (VSD) account for about
12%, and Tetralogy of Fallot (TOF) is the third most common being found in
approximately 8% of cases. Interestingly, Chinese and Mexican DS patients are more
likely to have a VSD than cAVSD suggesting that trisomy of the 21st chromosome does
not by itself account for the constellation of heart diseases seen, and instead, there are
other genetic and environmental factors that must be important as well.26 Because the
prevalence of CHD is so high in this population, almost all infants with DS will be
evaluated at birth, preferably by a pediatric cardiologist, for the presence of heart disease.
Since most forms of CHD in the population with DS involve a large left-to-right shunt
(especially with CAVSD and VSDs), signs of pulmonary overcirculation develop quite
quickly. For this reason, these patients tend to have repair fairly early (i.e., within the
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first year of life) since morphologic differences in their lung parenchyma make them
much more susceptible to the development of irreversible pulmonary vascular occlusive
disease.27 Even the adult patient with DS and no history of CHD is at greater risk of
acquired heart disease; mitral valve prolapse is found in 50 – 60% of these patients while
valvular incompetence is seen in 17%.2 It is of interest that coronary artery disease is
much less prevalent in individuals with DS than the rest of the population. Recently, a
group from the University of Vermont demonstrated that adult patients with DS have
reduced plasminogen activator type-1 in their blood compared with control subjects, and
they theorize that this may explain the decreased incidence of coronary plaque formation
and rupture in this population.28-
Intraoperative Considerations
In 1957, McKusick29 was the first person to report a hypersensitivity to atropine in the
population with DS and several other authors reported similar findings. Based on these
papers, pediatric manuals for many years warned of the potentially fatal effect of atropine
use in these patients. Starting in 1973, however, other authors30 have shown that there is
no difference in the cardio-acceleratory effects of atropine in the patient with DS
compared to the rest of the population. Interestingly, ophthalmic instillation of atropine
drops does cause a more rapid mydriasis in the patient with DS but the duration and
degree of papillary dilation are the same as in the patient without DS.
13
If the anesthetic plan includes tracheal intubation, one special consideration in the patient
with DS is the appropriate size of tracheal tube (TT). This population has a higher
incidence of congenital narrowing of the subglottis, and they are also more likely to
develop significant subglottic stenosis following tracheal intubation.6 In a study
performed at the Children’s Hospital Medical Center in Cincinnati, Ohio, Shott31
determined the proper size of TT in 42 children with DS compared to 32 control subjects,
using an audible air leak around the TT between 10 and 30 cm of H2O pressure as the
guide.
In addition, the author assessed the tracheal diameter found on MRI of another
18 patients with DS. Shott’s conclusions led her to recommend that for the patient with
DS, the initial intubation should be performed with a TT that is two half-sizes smaller
than that normally used as determined by the standard formula TT size = 4 + age/4.
Since numerous other authors have found very high rates of post-extubation croup (Kobel
et al32) or stridor (Sherry33) in the population with DS, it would seem prudent to follow
these recommendations.
The patient with DS and uncorrected CHD presenting for non-cardiac surgery may be
intimidating for many anesthesiologists. Keeping a few simple things in mind, however,
can enable one to deliver a safe anesthetic. First, one must make sure that the cardiac
anatomy and the direction of any intracardiac shunts are understood. Second, if
intracardiac shunts are present, one must be hypervigilant about not allowing air in the
intravenous line to enter the patient as this may find its way to the left side of the heart
and out into the systemic circulation to possibly cause myocardial or cerebral ischemia.
Third, one must be conscious of the increased propensity in these patients to have a
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pulmonary hypertensive crisis that may cause a left-to-right shunt to become right-to-left,
which leads to cyanosis and possibly acidosis. Immediate measures that should be taken
to reverse pulmonary hypertension include increasing the PaO2 and decreasing the PaCO2
(but avoid overdistension of the lungs which can also increase pulmonary vascular
resistance or PVR). In addition, one should consider administration of volume to
increase preload, sodium bicarbonate to reverse any acidosis that may have developed,
phenylephrine to increase the systemic vascular resistance (SVR), or opioids to reduce
sympathetic outflow to the pulmonary bed (care must be taken as this may decrease the
SVR as well). Table 3 shows a more comprehensive list of common causes of an
increase in the PVR, and methods of treatment. Finally, one must not forget to administer
subacute bacterial endocarditis (SBE) prophylaxis when indicated (see Table 4).
Post-operative considerations
Certainly no patient with DS should be denied adequate pain control; however, it must be
recognized that these patients can rarely be treated for pain similarly to their age-matched
counterparts without DS. While formulating the pain control plan, one must keep in mind
the patient’s ability to request pain medications or to use a patient-controlled analgesia
button. When using opioids, it is important to consider the potential need to avoid any
degree of hypercarbia in the patient who has episodes of pulmonary hypertension.
Alternatively, one should consider if the patient is cooperative enough for a nerve-block
technique or if it is possible to incorporate this during a general anesthetic. Another
consideration is the need for a sitter (if no family member will be available) in order to
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prevent the patient from possibly injuring him/herself (i.e., pulling out the IV, falling out
of bed, eating something they should not).
Other problems frequently encountered in the immediate post-operative period are airway
obstruction (again, up to 100% may have sleep apnea), agitation from pain as well as the
unfamiliar environment, and control of blood sugar in those patients who have diabetes
mellitus.
Conclusion
Although caring for the patient with DS may cause some anxiety among
anesthesiologists, it usually is a rewarding experience to interact with these typically
happy, warm and outgoing individuals. As our ability to treat congenital heart disease
and pulmonary hypertension improves, we can expect to see more patients with DS
present for surgery.
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Table 1. Common Medical Conditions in the Patient with Down Syndrome
Mental Retardation
Hypo/hyper-thyroidism
Diabetes
Obesity
Sleep Apnea
Otitis Media/Hearing Loss
Gastrointestinal Disorders
Hematologic Disorders
Atlantoaxial Instability
Recurrent Pulmonary Infections
Congenital Heart Disease
17
Table 2. Symptoms of Atlantoaxial Instability
Neck Pain
Gait Disturbance
Incontinence (urinary/fecal)
Motor Weakness
Torticollis
Ataxia
18
Table 3. Factors that increase PVR
Acidosis
Hypoxia
Hypercarbia
Increased airway pressure
Sympathetic stimulation
Potential Treatment
Reverse cause of acidosis, sodium bicarbonate
Increase PaO2 with supplemental O2, FIO2, etc.
Decrease PaCO2 by RR and TV, etc.
Avoid high airway pressures by adjusting
ventilation
Opioids, deepen anesthesia
19
Table 4. Indications for Endocarditis Prophylaxis
Artificial valve
> 1+ (trace) valvular regurgitation
Presence of any shunt (except an atrial septal defect)
Congenital heart disease surgery within the past 6 months
Previous history of endocarditis
> Mild coarctation of the aorta
20
References:
1
American Academy of Pediatrics: Health supervision for children with Down syndrome; Committee on
Genetics. Pediatrics 2001;107:442-449
2
Smith D: Health care management of adults with Down syndrome. Am Fam Physician 2001;64:1031-8
3
Anwar AJ, Walker JD, Frier BM: Type 1 diabetes mellitus and Down's syndrome: prevalence,
management and diabetic complications. Diabet Med 1998;15:160-3
4
Prasher, VP:Overweight and obesity among Down syndrome adults. J of Intel Dis Res 1995; 35:437-441
5
Luke AH, Sutton M, Schoeller DS, Roizen NJ: Nutrient intake and obesity in prepubescent children with
Down syndrome. J Am Diet Assoc 1996; 96:1265-7
6
Kanamori G, Witter M, Brown J, Williams-Smith L: Syndromic and other congenital anomalies of the
head and neck: Otolaryngologic manifestations of Down Syndrome. Otolaryngol Clin North Am 2000;33:
1285-92
7
Bower CM, Gungor A: Pediatric obstructive sleep apnea syndrome. Otolaryngol Clin North Am
2000;33:49-73
8
Shott SR, Joseph A, Heithaus D: Hearing loss in children with Down syndrome. Int J Pediatr
Otorhinolaryngol 2001;61:199-205
9
Van Riper M, Cohen W: Caring for children with Down Syndrome and their families. J Pediatr Health
Care 2001;15:123-131
10
Fong CT, Brodeur G: Down’s syndrome and leukemia; epidemiology, genetics, cytogenetics and
mechanisms of leukemogenesis. Cancer Genet Cytogenet 1987;28:55
21
11
Hasle H: Pattern of malignant disorders in individuals with Down’s syndrome. The Lancet Oncol 2001;
2:429-436
12
Zipursky A, Brown EJ, Christensen H, Sutherland R, Doyle J: Leukemia and/or myeloproliferative
syndrome in neonates with Down syndrome. Semin Perinatol 1997: 21:97-101
13
Zipursky A, Brown EJ, Christensen H, Doyle J: Transient myeloproliferative disorder (transient
leukemia) and hematologic manifestations of Down syndrome. Clin Lab Med 1999; 19:157-67, vii
14
http://www.ds-health.com/hemat.htm
15
Harley EH, Collins MD: Neurologic sequelae secondary to atlantoaxial instability in Down Syndrome.
Arch of Otolaryn 1994: 120;159-165.
16
Motoyama EK, Davis PJ, ed. Smith’s Anesthesia for Infants and Children, 6 th edition. New York,
Mosby, 1996. p 868
17
Behrman: Nelson Textbook of Pediatrics, 16th ed. W. B. Saunders Company, 2000. Section 613.2
18
Williams JP, Somerville GM, Miner ME, Reilly D: Atlanto-axial subluxation and Trisomy-21: Another
perioperative complication. Anes 1987;67:253-254
19
Cooney TP, Thurlbeck WM: Pulmonary hypoplasia in Down’s syndrome. N Engl J Med 1982;
307:1170-3
20
Schloo BL, Vawter GF, Reid LM: Down syndrome: patterns of disturbed lung growth. Hum Pathol
1991;22:919-923
21
Cooney TP, Wentworth PJ, Thurlbeck WM: Diminished radial count is found only postnatally in
Down’s syndrome. Pediatr Pulmonol 1988;5:204-9
22
Marino B, and Pueschel S, ed. Heart Disease in Persons with Down syndrome. Baltimore, Paul H
Brookes Publishing Co., 1996, p. 122
23
Ugazio AG, Lanzavecchia A, Jayakar S, Plebani A, Duse M, Burgio R: Immunodeficiency in Down’s
syndrome. Acta Paediatr Scand 1978;67:705-708
22
24
Marino B, and Pueschel S, eds. Heart Disease in persons with Down syndrome. Copyright 1996 Paul H
Brookes Publishing Co., pp. 22 and 49.
25
Greenwood RD, Nadas AS: The clinical course of cardiac disease in Down’s synrome. Pediatrics
1976;58:893-897
26
Marino B, and Pueschel S, ed. Heart Disease in persons with Down syndrome. Copyright 1996 Paul H
Brookes Publishing Co. p. 134
27
Marino B, and Pueschel S, ed. Heart Disease in persons with Down syndrome. Copyright 1996 Paul H
Brookes Publishing Co. p. 116
28
Hopkins WE, Fukagawa NK, Sobel BE, Schneider DJ. Plasminogen activator inhibitor type 1 in adults
with Down syndrome and protection against macrovascular disease. Am J Cardiol 2000;85:784-6, A9
29
McKusick VA: Mechanisms in genetic diseases of man. Am J of Med 1957;22;676-86
30
Mir GH, Cumming GR: Response to atropine in Down’s syndrome. Arch Dis Child 1971;46:61-5
31
Shott S: Down syndrome: Analysis of airway size and a guide for appropriate intubation. Laryngoscope
2000;110:585-592
32
Kobel M, Creighton RE, Steward DJ: Anaesthetic considerations in Down’s syndrome: experience with
100 patients and a review of the literature. Can Anaesth Soc J 1982;29:593-598
33
Sherry KM: Post-extubation stridor in Down’s syndrome. Br J Anaesth 1983;55:53-55
23
Multiple Choice Questions
1. Which of the following is true about weight in the patient with Down syndrome (DS)?
a. Infants with DS tend to follow height and weight curves that are slightly higher
than the rest of the population
b. Once they reach the age of 3, patients with DS start to exhibit a fall off of the
normal weight and height curves
*
c. Up to 50% of adult patients with DS are overweight
d. Obesity in the patient with DS rarely contributes to worsening of other preexisting conditions
2. Post-operative pain control in the patient with DS
a. is best accomplished with prn opioid administration
*
b. might include use of PCA
c. should not include consideration of pulmonary hypertension issues since they
are unlikely to occur
d. is best accomplished with non-opioids since this population is much more
sensitive to opioids
3. Problems frequently encountered in the post-operative period include:
*
a. airway obstruction
b. hypothyroidism
c. poor control of blood sugar
d. excessive salivation after use of atropine (paradoxical effect)
4. Obstructive sleep apnea
a. is seen in approximately 25% of the population with DS
b. may be centrally mediated in some patients with DS
c. is almost always cured by adenotonsillectomy in the patient with DS
*
d. may be treated nonsurgically by CPAP or weight loss programs
5. Typical airway characteristics of the patient with DS include:
*
a. midface hypoplasia
b. macrognathia
c. muscular hypertonia
d. normal-sized larynx but small pharynx
24
6. GI abnormalities frequently found in the newborn with DS include:
a. volvulus
*
b. pyloric stenosis
c. diarrhea
d. lower esophageal sphincter incompetence
7. Transient abnormal myelopoiesis (TAM) of the newborn with DS
a. spontaneously resolves after approximately one year
b. is differentiated from AML by megakaryocyte count
c. frequently progresses to hydrops fetalis
*
d. is characterized by megakaryocytes in peripheral blood
8. All patients with DS should have
a. annual radiographs taken of the c-spine
*
b. annual neurological exams
c. evaluation by a neurosurgeon for prophylactic atlantoaxial fusion
d. a soft cervical collar placed before surgery
9. The lungs of patients with DS
a. are usually relatively normal
*
b. have a double capillary network around the alveoli
c. display hypoplastic alveoli
d. show increased numbers of alveoli
10. The second most common congenital heart defect seen in the patient with DS is
*
a. ventricular septal defect
b. atrial septal defect
c. Tetralogy of Fallot
d. hypoplastic left heart syndrome
11. Most patients with DS and a congenital heart defect
a. have a large right-to-left shunt
b. have definitive surgical repair only after the age of 5 years
*
c. have signs of pulmonary overcirculation
d. are resistant to pulmonary vascular occlusive disease
12. In the older adult patient with DS
a. accelerated coronary artery disease is commonly seen
b. valvular incompetence is rarely seen
c. atrial arrythmias are almost always found
*
d. mitral valve prolapse is found in at least 50% of patients
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13. According to Shott, the proper size tracheal tube for the patient with DS can be
determined by the formula:
a. (16+age)/4
b. 4 + age/4
*
c. age/4 + 3
d. (2+age)/2
14. Factors that increase pulmonary vascular resistance include:
a. hyperpnea
*
b. hypercarbia
c. decreased sympathetic stimulation
d. hyperoxia
15. Maneuvers to decrease pulmonary vascular resistance include:
*
a. increasing the PaO2
b. adjusting airway pressures to the highest tolerated without barotrauma
c. permissive hypercapnia
d. avoiding opioids
26