Case Study of Spinal Decompression Surgery with Fusion and Instrumentation
Philip F. Hess BSN
University of Pennsylvania
Anticipated Date of Graduation: May 2015
Email Address: philhess@nursing.upenn.edu
Keywords: Spinal decompression, prone position, brachial plexus, post-operative vision loss,
and ischemic optic neuropathy
Spinal decompression surgery is performed when osseous structures of the spine impinge upon
the spinal cord or nerve roots. Spinal fusion with instrumentation may be necessary after
decompression surgery if the spinal column becomes unstable or if there is a primary spinal
instability which has developed as a result of degenerative disc disease or trauma1. Prone
positioning is often necessary in spinal surgery but may be associated with such complications as
post-operative vision loss (POVL), nerve injury, and delayed extubation.2,3,4,5 The complications
of prone positioning may be avoided; however, through proper patient positioning and sound
anesthetic technique.
Case Report
A 42 year old, 157 cm, 52 kg female presented for multi-level spinal decompression with fusion
and instrumentation. Her medical history was significant for scoliosis, hyperlipidemia, and
depression. Her surgical history included cholecystectomy and open reduction with internal
fixation of a right fibula fracture, none of which were associated with anesthetic complications.
Her current medications included simvastatin and citalopram daily.
In the operating suite, intravenous (IV) midazolam 2 mg and glycopyrrolate 0.1mg were
administered. American Association of Anesthesiology (ASA) monitors were applied and preoxygenation was initiated via facemask at a rate of 10 L/min flow.
General anesthesia was induced with 2% Lidocaine 80 mg IV and Propofol 160 mg IV. Mask
ventilation was performed during which neurophysiology monitoring leads were applied and
baseline motor and somatosensory evoked potentials were obtained. Succinylcholine 80 mg was
administered intravenously and fasciculation was observed. Direct laryngoscopy with a Mac 3
laryngoscope was performed and a Grade I view was obtained. A 7.0 mm endotracheal tube was
advanced through the glottis; the high-volume, low-pressure cuff was inflated. Bilateral breath
sounds were auscultated and a positive ETCO2 tracing was elicited confirming endotracheal
placement. The patient’s respirations were maintained with mechanical ventilation using volume
control mode which delivered a tidal volume of 525ml at a rate of 10 breaths per minute. General
anesthesia was maintained using total intravenous anesthesia (TIVA). This was provided by
infusing propofol at 125 mcg/kg/min and remifentanil at 0.3 mcg/kg/min.
Once a stable anesthetic plane was established, the patient was turned prone and positioned on
the Jackson spinal surgery table (Allen Medical Systems Inc., Acton, MA). Her eyes, ears, and
nose were assured to be free of pressure by using a Prone View pillow and helmet system
(Dupaco Inc., San Diego, CA). After the patient’s extremities were padded, a warming blanket
was applied and the table was placed in ten degree reverse Trendelenburg position.
During the surgery, arterial blood gases were drawn and trends in hemoglobin and hematocrit
were monitored. 6 units of packed red blood cells and 2 units of fresh frozen plasma were
infused to replace intraoperative blood loss. Crystalloid fluids were infused to replace
maintenance requirements, fluid deficits, and to compensate for insensitive losses from the
surgical exposure. Dexamethasone 10 mg IV and ondansetron 4 mg IV was administered prior to
closure for post-operative nausea and vomiting (PONV) prophylaxis.
At the conclusion of surgery, TIVA was discontinued and general anesthesia was maintained
with desflurane 3% inspired concentration in a mixture of oxygen 1 L/min and air 1 L/min. The
patient was disconnected from the ventilator circuit, turned supine and ventilation was
reestablished. Once the patient resumed spontaneous ventilation, mechanical ventilation was
discontinued. When she was able to maintain adequate spontaneous respiration and follow
commands, the endotracheal tube was removed using positive pressure. O2 was administered via
nasal cannula at 4L/min flow. The patient was transported to the post anesthesia recovery unit
where she remained stable and denied any pain.
Discussion
Prone positioning for spinal surgery is commonly performed but is not without inherent risks.
Complications such as POVL, nerve injury, and delayed extubation have been reported in proneposition spinal surgeries but these complications may be avoided through proper positioning and
anesthetic technique.2,3,4,5
It is estimated that POVL occurs in approximately 1:1,100 prone spine surgeries.2 Several
factors have been cited as being possible causes of POVL; among them ischemic optic
neuropathy (ION), central retinal artery occlusion (CRAO), and increased intra-ocular pressure
(IOP) from horizontal positioning or direct pressure against the eye.2,3 A 2014 randomized
controlled study examined the effects of reverse Trendelenburg positioning on intra-ocular
pressure during prone spine surgery. It was determined that five degree reverse Trendelenburg
decreased IOP as much as 11% in prone positioned patients and ten degree positioning decreased
IOP an additional 7%.2 No complications were found with this positioning.
Although it has been postulated that anemia, hemodilution, and hypotension may play a role in
the occurrence of ION and POVL, no definitive causal relationship has been established.3 While
the causative factors of POVL may not be determined, it may be reversed through the
administration of erythropoietin (EPO) in the post op period.6 It is believed that EPO released
during times of hypoxia may have anti- apoptotic effects on retinal ganglion cells.7 In a 2014
published case report, Hasani et al. describe the administration of EPO to a patient who seemed
to have no predisposition to acquiring POVL but emerged from anesthesia blind in his right eye.
EPO was administered for 3 consecutive days at a dose of 40,000 IU IV daily, and his vision was
restored to 20/20 on the third day.6
Prone positioning creates the conditions for eye injuries other than those caused by ischemia or
nerve damage. Corneal injuries are the most common ocular injuries in non-eye surgeries8; in
many cases the cause of the injury is not known. Other injuries such as Valsalva retinopathy may
occur as a result of coughing, bucking, and retching during emergence and in the post op period.8
Gayer (2014) proposes that some patients; although not diagnosed with narrow angle glaucoma,
may be experiencing near closed angle conditions and are thus predisposed to acute angle closure
when placed in the prone position or administered drugs such as ephedrine. The result of acute
angle closure is a lack of drainage of aqueous humor from the eye and an increase in IOP.8
Improper patient positioning during prone spine cases is a factor in the development of nerve
injuries.3,4 Brachial plexus injury is the most common peripheral nerve injury incurred during
spinal surgery but may be prevented through careful positioning, proper padding, and
electrophysiological monitoring.4 The nerves of the brachial plexus course superficially through
the area of the axilla, therefore; reducing the pressure in this area through proper padding and
positioning may reduce the likelihood of injury.3,4 This is accomplished by using padding
beneath the chest and arms and abducting the arms less than ninety degrees from the body when
using the swimmers position.3,4 Electrophysiological monitoring may alert the anesthetist to
nerve impingement which may be relieved through repositioning before the damage becomes
permanent. 4
In their 2014 correlational study, Zirka et al. examined factors which closely correlate with
delayed extubation after prone spine surgery. The authors studied such variables as age, ASA
class, duration of surgery, crystalloid infusion, and blood administration. The study results
showed a strong correlation between all of these variables and delayed extubation.5 By properly
calculating fluid volume requirements and closely monitoring hemoglobin levels, the anesthetist
may avoid hemodilution and induced anemia which may result in delayed extubation after prone
spine surgery.3,5
In this case, we prevented increased IOP when we kept the bed in ten degree reverse
Trendelenburg position and administered PONV prophylaxis.2,8 We avoided retinal hypoxemia
by maintaining our patient’s blood pressure within twenty percent of baseline.3 Properly padding
and positioning our patient with her arms in the swimmers position and keeping her neck in a
neutral position prevented the nerve injuries and tracheal edema described by Uribe et al. (2010).
And finally, by avoiding hemodilution and induced anemia through the prudent administration of
IV fluids and blood products and close intra-operative monitoring of hemoglobin and arterial
blood gases, we were able to avoid introducing those factors which Zirka et al. (2014) describe
as being closely correlated with the delayed extubation of the patient undergoing this type of
procedure.
In conclusion, this case serves as an example of how perioperative complications may be
avoided through the use of proper positioning and anesthetic technique in prone spinal surgery.
Although correlations exist between several factors and the occurrence of POVL and delayed
extubation,2,3,5,8 further research is needed to establish causal relationships between these factors
and the perioperative complications of prone positioning in spinal surgery.
References
1. Tuttle P. Anesthesia for orthopedics and podiatry. In Naglehout JJ, Klaus KL, eds. Nurse
Anesthesia. 4th ed. St. Louis: Elsevier; 2010:999-1014
2. Carey TW, Shaw KA, Weber ML, Devine JG. Effect of the degree of reverse
Trendelenburg position on intraocular pressure during prone spine surgery: a randomized
controlled trial. Spine J. 2014. PMID: 24456677 [Epub ahead of print].
3. Practice advisory for perioperative visual loss associated with spine surgery: an updated
report by the American Society of Anesthesiologists Task Force on Perioperative Visual
Loss. Anesthesiology. 2012;116(2):274-285. PMID: 22227790.
4. Uribe JS, Kolla J, Omar H, et al. Brachial plexus injury following spinal surgery. J
Neurosurg Spine. 2010;13(4):552-558. PMID: 20887154.
5. Zerka AH, Gaudet JG, Levitt LC, et al. Factors that correlate with the decision to delay
extubation after multilevel prone spine surgery. J Neurosurg Anesthesiol.
2014;26(2):167-171. PMID: 24296539.
6. Hassani V, Homei MM, Shahbazi A, et al. Human erythropoietin effect in post-operative
visual loss following spine surgery: A case report. Anesth Pain Med. 2014 May;4(2).
PMID: 24790903.
7. Junk AK, Mammis A, Savitz SI, et al. Erythropoietin administration protects retinal
neurons from acute ischemia-reperfusion injury. Proc Natl Acad Sci. 2002;99(16):1065910664. PMID: 12130665.
8. Gayer S. Prone to blindness: Answers to postoperative vision loss. Anesth. Analg.
2011Jan;112(1):11-12. PMID: 21173205.