Anesthetic considerations in the patient with down syndrome

Published on 07/02/2015 by admin

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Last modified 22/04/2025

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Anesthetic considerations in the patient with down syndrome

Michael J. Murray, MD, PhD and Jennifer A. Rabbitts, MB, ChB

Trisomy 21 (three copies of chromosome 21) accounts for 95% of the cases of Down syndrome (DS), the most common chromosomal abnormality (1:691 live births, according to the Centers for Disease Prevention and Control) and also the most common genetic cause of intellectual disability. The other 5% of patients have DS due to mosaicism (two populations of cells in the same individual, some with two copies of chromosome 21, the rest with three copies of chromosome 21) or due to translocation of part of chromosome 21 onto another chromosome such that there are triplicate copies of a sufficient number of genes to produce the syndrome.

How trisomy 21 causes the multiple genetic deficits associated with DS is not known, but progress is being made. Chromosome 21 is the smallest of the human chromosomes, but it is a very small part of the chromosome that is most likely involved in the genesis of DS. Because of areas of synteny (the correspondence of genes located on the same chromosome in several species) between the human and mouse genomes, researchers have been able to use mouse models to pinpoint the specific genes on human chromosome 21 that are most likely involved in producing symptoms of DS. The Ts65Dn mouse, which carries 132 genes that are syntenic with human chromosome 21, has facial characteristics, memory and learning problems, and age-related changes in the forebrain similar to what is seen in human DS. Studies in other animal models suggest that more than 400 genes are triplicated in DS. Scientists are of the opinion that the deficits seen in DS are not due to a single triplicate copy of one gene but, rather, to several genes or the interaction of several genes. Most recently, investigators have developed a pluripotent stem cell line that contains triplicate copies of genes of interest; the investigators have been able to transform some of these cells into neurons that display reduced synaptic activity, affecting excitatory and inhibitory synapses equally, deficits that are consistent with the cognitive deficits seen in individuals with DS.

The most significant risk factor for trisomy 21—maternal age—was thought more than a century ago to be due to “uterine exhaustion.” However, we now know that older mothers have more babies with DS because the frequency of meiotic nondisjunction increases with increasing maternal age. The American College of Obstetricians and Gynecologists recommends that all pregnant women undergo nuchal translucency ultrasound, amniocentesis, or chorionic villus sampling during the first few months of pregnancy to check for DS.

Clinical manifestations

Abnormalities associated with DS, including abnormalities of the nasal structures and decreased blood flow into the right atrium, are apparent in utero via ultrasound by about 12 weeks. At birth, infants with DS have hypotonia, characteristic oblique palpebral fissures, flat faces, inner canthal folds, hyperflexible joints, a single palmar crease, and dysplastic middle phalanx of the fifth digit. More than half will have congenital cardiac malformations (about half have endocardial cushion defects and another 25% have ventricular septal defects). Although DS is universally associated with mental impairment, the degree of impairment varies.

Neurologic manifestations

In addition to the delayed mental development, social development is also delayed, resulting in common problems such as impulsive behavior, poor judgment, short attention span, and slow learning. As the child ages and becomes aware of his or her limitations, behavior may become increasingly unmanageable, with frequent outbursts noted. Independent of the degree of mental impairment early in life, those individuals with DS who survive into later adulthood are at increased risk for developing dementia, compared with individuals who do not have DS.

Head and neck abnormalities

Because patients with DS often have abnormalities of the head and neck, the anesthesia provider should assess any patient with DS seen in the preoperative clinic for these abnormalities (Box 207-1). Despite the many airway abnormalities described, patients with DS are typically not difficult to intubate, though they may be difficult to ventilate by mask. Cervical spinal malformations have been reported in association with trisomy 21, with 10% of patients having cervical spinal stenosis and 30% having atlantoaxial instability, although only 1% to 2% of these patients will become symptomatic.

Cardiac abnormalities

As previously mentioned, patients with DS have a high incidence of congenital cardiac abnormalities, the most prevalent of which are atrial septal defects and ventricular septal defects. If the child has not had a previous echocardiogram, depending on the nature of the procedure for which the anesthesia provider is seeing the child, obtaining a cardiac consultation or performing an echocardiogram should be considered. Any child with uncorrected or corrected cardiac abnormalities should be considered a candidate for endocarditis prophylaxis, again depending on the nature of the surgery, and in keeping with American Heart Association guidelines.

Respiratory manifestations

Because of the prevalence of cardiac abnormalities in patients with DS, insufficient attention is typically given to the pulmonary problems that children and adolescents with DS can have. Common pulmonary problems include recurrent bronchitis or pneumonia, sleep-disordered breathing, laryngomalacia, tracheobronchomalacia, tracheal bronchus (a bronchus that originates above the carina, more commonly on the right), pulmonary hypertension, subpleural cysts, and subglottic stenosis. Less common abnormalities include complete tracheal rings and interstitial lung disease.

Gastrointestinal manifestations

Anesthesia providers involved in the resuscitation of a neonate with DS should be aware that early and massive vomiting may be a sign of gastrointestinal obstruction due to esophageal atresia or duodenal atresia. Adolescents and adults with DS may have problems with constipation.

Endocrinologic considerations

Older children, adolescents, and adults with DS are frequently obese (which may increase their likelihood of developing obstructive sleep apnea) and may have metabolic syndrome (obesity, hypertension, diabetes). Patients with DS also are at increased risk of developing hypothyroidism.

Musculoskeletal abnormalities

As mentioned previously, patients with DS are at increased risk of having spinal abnormalities, including atlanto-occipatal subluxation and spinal stenosis. Other musculoskeletal abnormalities include separated joints between the bones of the skull (sutures), a single crease in the palm of the hand, wide short hands with short fingers, and a dysplastic middle phalanx of the fifth digit. Physical development is often slower than normal. Most children with DS never reach average adult height.

Perioperative management

Preoperative evaluation

Because of the many problems these children have, they frequently undergo surgical procedures. Educating and preparing them for surgery, ensuring that they have not eaten for the requisite period of time prior to surgery, and assessing their pain postoperatively can be a challenge.

As with any other patient, a complete history and physical examination should be performed in compliance with the American Society of Anesthesiologists guidelines and third-party requirements. The primary reason for doing so, however, is and always should be for the effect on patient outcome. The five most important items in the preoperative assessment of a patient with DS are evaluation of the airway, of the cardiac system, and of the pulmonary system; assessment of the cervical spine; and discussion of postoperative pain management.

The preoperative assessment should focus on a number of factors related to atlantoaxial instability. The anesthesia provider should conduct a thorough history and physical examination looking for symptoms or signs suggestive of cord compression and should particularly focus on identifying abnormal range of motion or tenderness in the neck, gait abnormalities, and weakness, spasticity, increased deep tendon reflexes, or clonus of the lower extremities. All patients with trisomy 21 who are to undergo a surgical procedure that includes an anesthetic should have their cervical spines radiographically evaluated if this evaluation has not previously taken place. Examining the patient’s joints for laxity will help to identify those patients who are at risk for developing atlanto-occipital dislocation. Any patient who is identified during the preoperative assessment as having evidence of atlantoaxial instability should be referred for further evaluation of neck stabilization. Elective procedures should be postponed until this determination is made.

Finally, depending on how independent the patient is, postoperative pain management should be discussed with the patient and the patient’s care provider. If the patient’s intellectual functioning is insufficient, plans for managing the patient’s pain postoperatively should be discussed, with the patient’s assent and the care provider’s consent.

Operative management

Anesthetic management in patients with DS is dictated by the patient’s cognitive abilities and associated abnormalities, especially congenital cardiac anomalies and atlantoaxial instability. Patients with DS have an increased incidence of hip problems, the most significant of which is subluxation due to laxity of ligaments and tendons. This needs to be borne in mind when positioning the patient for any procedure, but especially for procedures performed with the patient in the lithotomy position or on the lower extremities.

Atropine premedication, the use of which was previously thought to be inadvisable in patients with DS, is now considered safe but would be dependent on the surgical procedure, the evaluation of the patient, and the degree of preoperative salivation and in keeping with the anesthesia department’s practice. Response to preoperative sedation varies in patients with DS because of their different levels of cognitive functioning.

Induction of anesthesia may be accomplished using either inhalation or intravenous techniques, although difficulty in obtaining intravenous access should be anticipated, especially in patients who are obese and who are uncooperative. The minimum alveolar concentration of inhalation anesthetic agents is not reported to differ in patients with DS, as compared with the general population, and maintenance of anesthesia may be achieved with either inhalation or intravenous agents. Care must be taken in choosing an appropriately sized tracheal tube, with awareness of the possibility of subglottic narrowing. Intubation should be performed with care taken to not hyperextend the cervical spine and to avoid undue pressure with the laryngoscope blade on malpositioned teeth. Though these patients have small mouths and large tongues, most should be considered to be candidates for direct laryngoscopy or videolaryngoscopy to secure the airway. If a fiberoptic bronchoscope must be used, it would probably best be performed with the patient receiving monitored anesthesia care, obtaining a view of the airway with a videolaryngoscope, and then passing the bronchoscope into the glottic opening and sliding a tracheal tube of appropriate size off the bronchoscope and into the trachea.

Due caution should be exercised on extubation, and the possibility of upper airway obstruction and postextubation stridor should be anticipated.

Postanesthesia care

At this juncture, if a plan has not already been developed for addressing the issue of obstructive sleep apnea, the patient’s preoperative status, hospital policy, and how the patient does in the postanesthesia care unit will dictate whether intervention is necessary. Per the American Society of Anesthesiologists guidelines, there are no firm recommendations whether or not the patient should be admitted to the hospital overnight or should be discharged, but one must consider the patient’s history, appropriately evaluate the patient, and proceed accordingly.

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