Pediatric emergency medicine trisk 1162

might indicate an intratracheal granuloma, which should be evaluated by direct
visualization, typically performed by an otorhinolaryngologist.
A large amount of bleeding is a surgical emergency. IV access should be
obtained immediately and volume replacement should be initiated. The
tracheostomy tube should not be removed because it may be the best way to
ensure an airway. Frequent suctioning aids in preventing aspiration. If the site of
bleeding can be identified, direct pressure should be applied to the area.
Overinflating the cuff may tamponade a bleeding vessel and provide a temporary
treatment until it can be ligated.
Peristomal granulomas can usually be treated with topical antibiotics. In
refractory cases, cauterization with silver nitrate is indicated.
Home Ventilators
Some patients with tracheostomies will require home mechanical ventilation.
Caregivers may come in to the ED because the ventilator is alarming at home or
the patient is requiring higher levels of support or oxygen. Understanding the
basics of home ventilators is useful in the workup and management of
complications.
The low pressure alarm on the ventilator will sound if two consecutive breaths
do not reach the pressure limit; this is usually caused by a leak or disconnect. The
physician should start at the patient and work toward the ventilator, checking for
loose connections. Finally, the tracheostomy cuff should be evaluated for leaks
and the low pressure alarm should be confirmed to be set at the correct setting.
The high pressure alarm on the ventilator will sound when the pressure in the
circuit has increased. This can be caused by frequent coughing, tracheostomy
tube obstruction, kinks in the tubing, and water in the circuit. Because
tracheostomy tube obstruction is so common, the tube should be changed or
suctioned and the inner cannula of the tracheostomy tube changed as needed.
Increased oxygen or ventilator requirements suggest an infectious process and
appropriate testing should be obtained, including a chest radiograph and tracheal
secretion Gram stain and cultures. Hospital admission is often indicated for more
aggressive treatment.

If a patient with a tracheostomy tube and home ventilator is stable to be
discharged from the ED, it must be confirmed with the caregivers that they have
adequate battery life and oxygen for the drive home.

CEREBROSPINAL FLUID SHUNTS
Background


CSF shunt placement is the most common neurosurgical procedure performed in
children. More than 4,400 CSF shunts were placed in 2003; CSF shunt–related
problems accounted for almost 15,000 hospital admissions and almost $300
million in charges for shunt malfunctions. CSF shunts are placed to divert CSF
from the brain to another area of the body, most commonly the peritoneal cavity.
The clinician evaluating a child with a CSF shunt should be aware of associated
complications such as infection, obstruction, and overdrainage, because certain
complications can be disastrous if unrecognized and untreated. However, children
with CSF shunts may often exhibit symptoms of their chronic illnesses that are
unrelated to shunt malfunction.

Pathophysiology
CSF is an ultrafiltrate of plasma produced at a rate of 500 mL/day in a 70-kg
adult and proportionally less in children and infants. The fluid is mainly produced
by the choroid plexus and various extrachoroidal sites within the brain. CSF
travels from the lateral ventricles into the third ventricle through the foramen of
Monro and then again through the aqueduct of Sylvius to the fourth ventricle. The
CSF then enters the subarachnoid space via the foramina of Luschka and
Magendie and travels through the brain and spinal canal. CSF is reabsorbed and
enters the venous system through the “one-way valves” of arachnoid villi that
penetrate the dura.
Hydrocephalus can result from oversecretion, impaired absorption, or blockage

of CSF pathways. Oversecretion can occur in some choroid plexus tumors.
Impaired absorption can occur as a result of increased CSF protein, often a result
of perinatal hemorrhage or meningitis or less commonly etiologies such as
subarachnoid hemorrhage, or Guillain–Barré syndrome. Severe congestive heart
failure or any other condition that raises venous pressure may impair CSF
absorption as well. Impaired absorption is the cause of communicating
hydrocephalus, in which flow from the lateral ventricles to the foramina of
Luschka and Magendie is not obstructed. Blockage of CSF pathways , or
obstructive hydrocephalus, is the most common cause of hydrocephalus in
children. This is often located at the narrow aqueduct of Sylvius proximal to the
fourth ventricle and is referred to commonly as aqueductal stenosis. Conditions
that can cause obstruction are intraventricular bleeding or scarring, tumors, or
congenital malformations. Dandy–Walker cysts cause obstruction of the foramina
of Luschka and Magendie and therefore may result in enlargement of all four
ventricles.

Equipment


Different types of CSF shunts vary mostly by the location of the distal tubing and
the type of reservoir or valve system. The choice of CSF shunt type and the
method of placement (endoscopically or nonendoscopically) depend on the
individual patient’s anatomy and cause of hydrocephalus and the experiences and
preferences of the neurosurgeon performing the procedure. Commonly, the
patient or caregiver knows the location and type of shunt and is able to provide
details regarding prior shunt placement and problems. Palpation of the hardware
and plain radiographs may be used to acquire more information regarding the
specific location of the shunt components. Most CSF shunts have the following
components: (1) proximal shunt tubing, (2) reservoir system, and (3) distal shunt
tubing ( Fig. 135.3 ). Occasionally, the system will not contain a reservoir and

instead will have a one-way valve.
The proximal shunt tubing has a fenestrated tip that is usually located in the
ventricle but may also be located inside a communicating cyst or in the lumbar
subarachnoid space. This tip allows free passage of CSF into the shunt system
unless it becomes occluded. More than one proximal catheter may be present if
multiple, noncommunicating areas of the brain require shunting. The reservoir
system consists of one or two “domes” or “bubbles.” Reservoirs may be placed
directly over or slightly distal to the burr hole. This information is crucial when
emergent access to the burr hole is needed. The distal shunt tubing leads from the
reservoir unit to a part of the body that can accept the drained CSF, usually the
peritoneum. The distal tubing may also be located in the vascular system or
pleural cavity. Ventricular–atrial shunts are less commonly inserted because of the
serious infectious complications that have occurred with these types of shunts, but
may be necessary due to severe scarring in the peritoneum. All modern shunt
tubing is made of 1/8-in diameter Silastic elastomer, which causes minimal
omental reaction and is resistant to cracking.


FIGURE 135.3 Diagram of typical ventriculoperitoneal shunt.

CSF shunt systems contain a one-way valve to prevent backflow of CSF into
the ventricles. These valves are designed to operate at high, medium, or low
pressure. Externally programmable valves, which can vary the opening pressure
setting, are also available. An antisiphon device may be inserted into the distal
portion of the system to prevent overdrainage of CSF and concomitant lowpressure complications.

Clinical Findings/Management
Mechanical Malfunction
Malfunction of a CSF shunt can be caused by the obstruction of the catheter
lumen or disconnection of the various components. The proximal catheter lumen