Unit 1: Ventriculoperitoneal Shunts Flashcards

1
Q

Implanted cerebrospinal fluid (CSF) shunt system

A

diverts excess CSF from the brain to another part of the body

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2
Q

What is the most common type of implanted CSF shunt system?

A

Ventriculoperitoneal shunt (VPS)

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3
Q

Indications for CSF shunting

A
  • signs and symptoms of clinical deterioration due to an increase in CSF volume within the brain, often leading to increased ICP
  • conditions that result in obstruction of CSF circulation and/or absorption
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4
Q

What happens if there is overproduction or obstruction of CSF flow and/or impaired absorption?

A

Leads to:

  • ventricular dilation (ventricles in the brain)
  • hydrocephalus
  • increased ICP
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5
Q

Normal ICP Range

A

0-15 mmHg

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6
Q

Hydrocephalus

A

active and progressive dilation of the ventricular system in the brain

  • noncommunicating or communicating
  • occurs when CSF production exceeds the absorption rate
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7
Q

How can Hydrocephalus Develop?

A

can result from:

  • CSF overproduction
  • Obstruction of CSF circulation
  • Decreased CSF reabsorption
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8
Q

Noncommunicating Hydrocephalus

A

“obstructive” hydrocephalus

  • the flow of CSF between the ventricles is obstructed or blocked
  • brain tumor common cause
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9
Q

Communicating Hydrocephalus

A

occurs when there is a defect in the sites of absorption of CSF
-CSF can still flow between the ventricles
-due to subarachnoid hemorrhage (SAH), infection (meningitis), or gradual dysfunction due to aging
>debris from blood breakdown in SAH, or exudate associated with meningitis can obstruct the arachnoid villi and prevent them from absorbing CSF normally

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10
Q

Normal Pressure Hydrocephalus (NPH)

A

cerebral ventricular dilation seen on brain imaging and normal CSF pressure on lumbar puncture

  • Triad: Gait disturbance, cognitive impairment, and urinary incontinence
  • idiopathic or develop as a complication of SAH, head trauma, infection, or a tumor
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11
Q

Peritoneal Cavity

A

most common extracranial site for distal shunt catheter termination in ventricular shunting

  • easy to access
  • provides most reliable absorption of the diverted CSF
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12
Q

4 Basic Components of the Ventriculoperitoneal shunt Systems

A
  • the proximal catheter
  • reservoir
  • one-way valve
  • distal valve
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13
Q

VPS: 4 Components and their roles

A
  1. The proximal catheter: drains CSF from the ventricle
  2. Reservoir: provides support to the proximal catheter, which can prevent kinking as it curves exciting the skull; access to obtain CSF samples for ICP monitoring
  3. One-Way Valve: controls CSF flow into the distal catheter
  4. Distal Catheter: tunneled subcutaneously; terminates into the peritoneal cavity via separate incision; shunted CSF is then absorbed by the peritoneal cavity
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14
Q

CSF Shunt Valves

A

functions as a flow-resistance mechanism

  • engineered to control ICP over a range of postural positions and pressures
  • can be fixed or programmable (adjustable) pressure settings
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15
Q

CSF Fixed Shunt Valves

A

not programmable

  • have opening and closing pressures set by the manufacturer
  • fewer complications
  • if rate needs to be adjusted, the patient will need another surgical procedure
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16
Q

CSF Programmable Shunt Valves

A

opening and closing pressures can be adjusted without the need for surgical procedure

  • uses magnetic tools
  • more expensive
  • fewer surgeries
  • settings must be checked and confirmed following an MRI
17
Q

Siphoning of CSF

A

posture related “suction” effect on CSF flow dynamics through the shunt system

  • caused by increased hydrostatic pressure with patient in an upright position
  • siphoning can cause rapid over-drainage of CSF from the brain
  • over drainage can cause collapse of the ventricles and tear blood vessels
18
Q

Goal of Cerebral Ventricular Shunting

A

regulate the flow of CSF in order to control the volume of CSF; ventricular dilation, and ICP

19
Q

What happens in CSF Overdrainage

A

result in the cerebral ventricles shrinking or collapsing, causing the meninges to pull away from the inner surface of the skull
-causes slit-ventricle syndrome; slit-ventricle syndrome can cause severe but intermittent headaches that are relieved only by lying down

20
Q

What happens in CSF Underdrainage

A

cerebral ventricles enlarge in conjunction with S/S of hydrocephalus
-valve needs to be revised or externally adjusted

21
Q

Ventriculoperitoneal Shunt (VPS) Complications

A
  • shunt malfunction (from obstruction)
  • infection
  • abscess
  • pseudocyst
  • subdural hematoma (SDH)
  • peritonitis
  • bowel perforation
  • pain
  • seizures
  • intracranial hemorrhage
  • abdominal injury (ascites, peritonitis, abdominal perforations)
22
Q

Complications: Shunt Malfunction

A
  • obstructions causing shunt malfunction are due to CSF protein or debris buildup
  • can become obstructed at any time
  • obstruction leads to increased ICP; headache, vomiting, lethargy, irritability, and confusion
  • malfunction if the catheter disconnects, migrates, or fractures
23
Q

Complications: Infection

A

when shunt is colonized by skin flora

-skin infection can lead to abscess formation or shunt occlusion

24
Q

Complications: Abscess

A

abdominal abscesses can occur from shunt contamination or from the shunt migrating into the bowel
-if complains of abdominal pain, must be assessed for formation of an abdominal abscess

25
Q

Complications: Pseudocyst

A

develops when the body walls off CSF around the terminal portion of the peritoneal catheter

  • thin-walled cystic mass around the shunt tip, which is filled with cerebrospinal fluid
  • CSFoma is hallmark of shunt infection
  • necessitate removal of the VPS and treatment with antibiotics prior to replacement
26
Q

Complications: Subdural Hematoma (SDH)

A

collection of blood between the dura and the arachnoid membranes

27
Q

Complications: Peritonitis

A

causes general signs and symptoms of infection in conjunction with abdominal pain

28
Q

Complications: Bowel Perforation

A

by the peritoneal section of the distal shunt catheter

29
Q

Immediate Post-Operative Care

A
  • positioning
  • managing pain
  • ensuring proper functioning of the shunt device
  • monitoring neurological status
  • assessing for complications
  • caring for the surgical sites
30
Q

Caring for Surgical Sites

A

assess both proximal (head) and distal (abdominal) shunt catheter site incisions:

  • bleeding
  • drainage
  • signs of wound infection
31
Q

Signs of Wound Infection

A

-erythema or edema at the incision site or along the catheter pathway
-fever
-lethargy or irritability
-abdominal pain
-anorexia
-headache
-nuchal rigidity
-low-grade fever
-elevated white cell count
>after a CSF specimen for culture has been obtained, start treatment with a broad-spectrum antibiotic (vancomycin)

32
Q

Nursing Care

A
  • Elevate the head of the bed 30-45 Degrees; optimize CSF drainage
  • Perform Frequent Neurologic and other Organ System Assessments
  • Assess for abdominal pain or tenderness, erythema, and warmth and tenderness over the shunt tubing (for peritonitis b/c it may develop as a response to foreign object)
  • CSF malabsorption from the peritoneal cavity can lead to abdominal distension, discomfort, and frank ascites
  • Report S/S of increased ICP (change in LOC, headache, vomiting, lethargy, confusion); incase of shunt malfunction
  • Monitor for Signs of Bleeding from delayed intracranial hemorrhage that is a result of erosion of vasculature by catheter cannulation or sudden ICP reduction after VPS placement (pallor, tachycardia, hypotension; notify team immediately)
  • Confirm correct pressure setting after MRI
  • Inform appropriate personnel that the patient has a VPS in place
33
Q

Discharge Teachings

A
  • visible staples or sutures generally removed within 1 to 2 weeks post-op
  • head should not be showered or shampooed until staples or stitches removed
  • do not submerge or soak surgical wound before it is completely healed
  • once post-op edema resolves, a raised area at the scalp and abdominal insertion site will remain visible; protect these areas; when hair regrows, the raised area is unnoticeable
  • educate about potential complications associated with the CSF shunt (over- and/or underdrainage, infection, and S/S of increasing ICP)
  • use caution with devices (cell phones containing magnets) that could alter the programmed shunt valve; use ear opposite the shunt
  • know S/S that indicate shunt failure or infection
  • call assigned clinic if suspect any problems