Book 2, Case 2-Scoliosis repair Flashcards
What is the Cobb angle, and how is it measured? What degrees are abnormal? What degree needs surgery? At what point do pts get Pul HTN?
The Cobb angle is used to measure the severity of scoliosis. It is a
measure of the angle of perpendicular lines drawn from the upper surface of the most
cephalad tilted vertebrae and the lower surface of the most caudad tilted vertebrae.
Angles greater than 10 degrees are considered abnormal and surgery is recommended
for angles greater than 40-50 degrees. Pulmonary dysfunction is associated with
angles greater than 60-65 degrees. Cobb, angles around 70 degrees often result in
pulmonary hypertension during exercise, while angles around 110 degrees lead to
pulmonary hypertension at rest.
SOB in scoliosis pt with Duchenne’s but without asthma-are you concerned? Why?
Yes,because his progressively increasing shortness of
breath potentially represents significant cardiopulmonary dysfunction secondary to
neuromuscular scoliosis and/or DMD.
The chest wall deformity associated with
significant kyphoscoliosis can lead to impaired pulmonary development (occurs when
scoliosis develops before 5 years of age, impairing normal lung development),
restrictive lung disease with increased work of breathing (decreased chest wall
compliance), and ventilation/perfusion mismatching. Subsequent hypoxia, hypoxic
pulmonary vasoconstriction, and hypercapnia eventually lead to pulmonary
hypertension and right ventricular failure.
As far as DMD: Moreover, the abnormal production of
dystrophin that occurs with DMD may lead to: (1) cardiomyopathy, ventricular
dysrhythmias, and mitral regurgitation secondary to the replacement of myocardium
with connective tissue and/or fat; (2) decreased pulmonary reserves, an ineffective
cough, retained pulmonary secretions, and recurrent pneumonia secondary to chronic
respiratory muscle weakness; (3) chronic aspiration, secondary to impaired laryngeal
reflexes; ( 4) nocturnal oxygen desaturation and sleep apnea, which may contribute to
pulmonary hypertension and cor pulmonale.
How do you want to evaluate the pt with scoliosis (wheelchair bound) and Duchenne’s?
I would begin by obtaining a thorough history concerning his exercise
tolerance, the progression and severity of his shortness of breath, any cardiac
dysrhythmias (the loss of myocardial tissue associated with DMD can lead to
dysrhythmias as well as cardiomyopathy and mitral valve regurgitation), and the
onset and progression of his DMD and kyphoscoliosis. I would then identify the
location, extent, and severity of his spinal deformity, and focus on a careful
assessment of his airway, neurologic function, and cardiopulmonary status.
To further evaluate his cardiopulmonary status I would examine him for dyspnea,
wheezing, pulmonary edema, heart murmurs (scoliosis is associated with mitral valve
prolapse and DMD can lead to mitral valve regurgitation), jugular venous distension,
enlarged liver, and lower extremity edema. I would also obtain an ECG (DMD is
associated with tachycardia, tall R waves in VI, prominent Q waves in the limb leads,
a shortened PR wave, and inverted T waves), pulmonary function tests (helps to
determine the severity of the patient’s restrictive lung disease and facilitates decisions
regarding post-operative ventilatory support), an ABG (helpful to identify any
hypoxemia or acidosis that may be contributing to pulmonary hypertension), and a
CXR (helpful in identifying cardiomegaly or pneumonia). Finally, for this
wheelchair-bound patient, I would order a stress echocardiogram to identify any
pulmonary hypertension (right ventricular and/or atrial hypertrophy),
cardiomyopathy, or mitral valve prolapse (10-25% of patients with DMD).
Further evaluation would include: (1) a careful airway exam focusing on neck
mobility (the presence of cervical scoliosis may compromise airway management),
size of the tongue (30% of patients with DMD exhibit macroglossia), and difficultly
swallowing (patients with DMD often have diminished airwayreflexes and an
increased risk for aspiration); (2) a complete blood count; and (3) a neurologic
assessment to identify preexisting neurologic deficits (to avoid confusion should
neurologic deficits be observed postoperatively).
Which heart conditions are associated with scoliosis? DMD?
Scoliosis: MVP
DMD: Mitral valve regurgitation
The surgeon says he may wish to perform a “wake-up” test. He has mentioned
this to the patient who is now very nervous. What would you say to this 11-year-
old boy?
I would tell him that sometime during the case I would whisper his
name in his ear and ask him to wiggle his fingers and toes. I would let him know that
he would probably not remember anything about waking up, but if he did, he would
be very sleepy, would not feel any pain, and would go right back to sleep after
wiggling his toes.
Pre meds in scoliosis and DMDpts? What things are you concerned for? What is a maybe?
Given the delayed gastric emptying and diminished laryngeal reflexes
associated with DMD, I would administer metoclopramide, an H2-receptor antagonist,
and a non-particulate antacid. Recognizing that this patient will be in the prone
position for an extended period of time and that airway management may be
challenging (i.e. cervical scoliosis and/or hypertrophy of the tongue secondary to
DMD), I would consider an antisialogogue to reduce oral secretions that could inhibit
airway management or loosen the tape used to secure the endotracheal tube (it would
also be reasonable to avoid this drug due to the potential for worsening tachycardia).
Moreover, if the patient were currently receiving steroids (used to increase muscle
mass in DMD), I would provide steroid supplementation. Finally, I would consider a
bronchodilator if PFTs indicated the presence of obstructive airway disease (i.e.
infection).
This increasing shortness of breath experienced by this wheelchair-bound patient
potentially represents significant cardiopulmonary compromise secondary to DMD
and kyphoscoliosis. Therefore, I would try to avoid any premedications that might
contribute to respiratory depression.
Positioning in prone surgery:
Given this child’s neuromuscular disease, I would take into account any
contractions and limitations in range of motion during positioning.The head should be in the
neutral position with frequent checks performed to ensure that the ears and eyes were
free of pressure to prevent necrosis of ear cartilage and reduce the risk of vision loss
respectively.Additionally, I would provide padding at the ulnar nerve, avoid any
direct pressure on the knees, and attempt to minimize pressure on the abdomen which
can lead to increased shunting of blood through vertebral venous plexus and
subsequently increased venous bleeding during the procedure.
Don’t forget that VAE can happen in prone cases too, and you can use TEE to detect them
Okay
Monitors in scoliosis case:
Standard ASA monitors a line 2 large bore IVs CVC TEE SSEP and MEP Foley
Pulmonary artery catheter in scoliosis with pulmonary HTN: (lets say they don’t let you use TEE)
While I recognize that there are risks with pulmonary artery catheter placement,
especially in the presence of pulmonary hypertensfon, this monitor could facilitate
intraoperative fluid management during this case where adequate spinal cord
perfusion is crucial, and where fluid overload risks exacerbating right heart failure
and pulmonary edema. Moreover, it may provide valuable information during
postoperative management.
SSEPs and MEPs-you doing both in this scoliosis case?
SSEPs directly monitor the functional integrity of the posterior
columns of the spinal cord and serve as an indirect monitor of anterior cord function
since most injuries to the spinal cord affect both posterior and anterior function.
However, given the multiple case series reporting false negatives with SSEP
monitoring alone, and considering the increased sensitivity of MEPs for detecting
motor injury, many practitioners consider MEP monitoring a useful adjunct to SSEP
monitoring during procedures that place the spinal cord at risk. While the use of
SSEP and MEP monitoring makes the routine use of a wake-up test unnecessary, it
would still be an appropriate test in the setting of significant changes in the evoked
potentials that failed to resolve with corrective action.
Do you need to do EMG in scoliosis cases?
of EMG monitoring is not universally utilized during
scoliosis surgery, it can help to avoid nerve root injury during pedicle screw
placement.
Risks of wake-up test: What will you do to prevent those risks? Why would you tell the surgeon you don’t want to perform a wake up test?
Yes. Complications of the wake-up test include inadvertent
extubation, intra-operative recall, pain, air embolism (with vigorous spontaneous
inhalation), dislodgment of surgical instruments, and removal of intravenous and
arterial lines. Therefore, if a wake-up test were required, I would make sure the
endotracheal tube and all lines were secure, provide adequate analgesia to prevent
pain, and ask the. surgeon to fill the wound with saline to reduce the risk of air
entrainment with subsequent embolism. Administer Benzes afterwards.
I don’t want to do it due to the risks that I mentioned previously.
In addition to the potential complications, the wake-up test is unlikely to detect
isolated nerve root injury and is limited to neurologically normal children who are
able to follow instructions.
When pt has DMD, why are you avoiding sux? Are you avoiding inhalational agents?
Despite his increased risk for aspiration, I would avoid succinylcholine due to the risk
of hyperkalemia, muscle rigidity, rhabdomyolysis, myoglobinuria, arrhythmias, and
cardiac arrest. It would not be necessary to avoid succinylcholine due to an
association between DMD and malignant hyperthermia, since there is no clear
evidence to substantiate this link.
So, DMD is NOT related to MH
Avoiding inhalational agents because it can also cause hyperkalemia, rhabdo
would you give NDMB to pt with DMD?
you can, but know that it will have prolonged action in these pts
