CHALLENGING CASE

Anterior Approach to Low Cervical and High Thoracic Tumors: Anesthetic Challenges

Evan Shao MD, FRCPC
Department of Anesthesia and Pain
Toronto Western Hospital, University Health Network
Toronto, Canada

Atul Prabhu MD, FRCPC
Department of Anesthesia and Pain
Toronto Western Hospital, University Health Network
Toronto, Canada

Tumul Chowdhury MD, DM, FRCPC
Department of Anesthesia and Pain
Toronto Western Hospital, University Health Network
Toronto, Canada

Dr. Shao
Evan Shao MD, FRCPC
Dr. Prabhu
Atul Prabhu MD, FRCPC
Dr. Chowdhury
Tumul Chowdhury MD, DM, FRCPC

Introduction
The anterior low cervical and high thoracic spine is a complex and challenging location to access surgically due to various anatomical constraints. The surgical exposure requires dissection around critical structures, including the esophagus, trachea, brachiocephalic artery, and brachiocephalic vein. However, the anterior approach is the only approach that allows direct visualization of the anterior theca 1. Previous case studies have shown that the mini-transsternal approach is safe for various infective, metastatic, traumatic, and degenerative lesions 1. However, this approach requires lung isolation for optimal surgical exposure, and lung isolation in spine surgery has its unique considerations and pitfalls that differ from typical thoracic surgery. Written informed consent was taken from the patient for this educational, challenging case report.

Case Description
A previously healthy 25-year-old female presented to the spine clinic with a large cervical giant cell tumor. She initially presented with a 1-year history of worsening neck pain, bilateral arm weakness, and paresthesia. Imaging revealed the tumor as a complex mass extending from C7 to T2 centered on the T1 vertebral body. There was also a large, ossified mass in the paravertebral soft tissue extending from C7 to the superior aspect of T2. On physical exam, her upper motor strength was 5/5 bilaterally and electromyography (EMG) of the upper limb was also normal. After neoadjuvant chemotherapy treatment, a posterior en-bloc resection of tumor at C7 - T2 and anterior C3 - T6 instrumented fusion with mini-sternotomy was planned. A combined spine and thoracic surgery team was needed, as the anterior resection required a mini-sternotomy and dissection into the thoracic cavity and mediastinum to access the tumor.

Fig 1

Figure 1: C-spine 1.5T MRI with contrast showing T1 giant cell tumor

Anesthetic Description
Pre-operatively, the patient was calm, awake, and alert. Her airway examination was unremarkable with Mallampati Grade I, adequate mouth opening, and a full C-spine range of motion. The rest of her physical examination, including the vital parameters, were normal.

An 18G IV was inserted into the right hand, and the patient was brought into the operating room. The patient was then transferred onto a Jackson table; standard Canadian Anesthesiologists' Society monitor and Entropy were applied. She was pre-oxygenated, and a standard IV induction was done with fentanyl 2 mcg/kg, lidocaine 1 mg/kg, propofol 2 mg/kg, and rocuronium 0.6 mg/kg. A Storz C-Mac #3 blade was used to insert a size 37 left-sided double-lumen tube (DLT), and its position was confirmed with a bronchoscope. Only the tracheal cuff was inflated initially. A post-induction arterial line was placed in the right radial artery along with a right femoral cordis central line and a left hand 16G IV line. The patient was repositioned prone using the Jackson table uneventfully. Anesthesia was maintained using total intravenous anesthesia (TIVA); the patient was monitored for SSEP and MEP throughout the surgery. IV fluid infusion was kept to minimum throughout the procedure. The posterior approach to the surgery was completed uneventfully 14 hours after incision.

The patient was then flipped supine, and the position of the DLT was re-confirmed using a bronchoscope. The right lung was isolated, and one-lung ventilation (OLV) was initiated with a tidal volume of 325 mL (5 mL/kg) with a PEEP of 5 cm H2O and FiO2 of 1.0. Unfortunately, the patient did not tolerate OLV, and her saturation dropped to 88% before temporarily returning to two-lung ventilation (TLV). The placement of the DLT was checked, and ventilation was further optimized. OLV was re-attempted with the addition of intermittent insufflation of O2 through a suction cannula at 2 L/min to the non-ventilated lung. It allowed adequate lung collapse while maintaining O2 saturation above 95%.

The anterior approach to the surgery was also completed uneventfully. Upon completion of the surgery, the DLT was exchanged for a #7.5 single lumen tube (SLT). The Storz C-MAC #3 was reinserted into the patient, and the vocal cord was visualized prior to performing the airway exchange using a Cook Airway Exchange catheter. The patient was then transferred to the intensive care unit (ICU) with the tracheal tube in-situ.

Discussion
Major anesthetic considerations for this case include challenges during surgical exposure, the potential for significant bleeding and requirement for massive transfusion, maintaining spinal cord perfusion, prolonged surgery in the prone position, change in position mid procedure, the potential for pneumothorax, lung isolation, intubation in a patient with potentially unstable C-spine, complications during tracheal extubation, and postoperative pain management. Due to the approach taken during surgery and its proximity to major thoracic vessels, a central line was placed below the diaphragm for potential massive blood loss and disruption of the SVC. One major anesthetic conflict was between the need for more restrictive fluid management and maintaining adequate perfusion in the spinal cord and other vital organs. Avoiding excessive fluids throughout the case is critical, considering the patient will require OLV after prolonged prone positioning, and pulmonary edema will increase the chance of hypoxia with OLV. Restricting fluids would also limit airway and facial edema, which would decrease the chance of airway obstruction after extubation.

Extra care was needed while positioning the patient to avoid direct pressure and peripheral nerve injuries. Furthermore, careful planning of IV and arterial lines tubing placement avoided tangles and inadvertent disconnect during the repositioning back to supine; this was especially important as the patient’s anesthesia was maintained with TIVA. The patient was also at risk for postoperative visual loss with surgery in a prolonged prone position with the potential for massive blood loss.

The discussion will now mostly focus on methods of lung isolation, hypoxemia during one-lung ventilation, and methods of lung isolation in a patient with unstable c-spine.

Lung Isolation
The options for lung isolation, in this case, included 2:

  • Double lumen tube
  • Single lumen tube with a bronchial blocker
  • Endobronchial tube

The advantages of using a DLT, in this case, included ease of placement, ability to suction and bronchoscopy to isolated lung, CPAP to operative lung, and alternate OLV to either lung. The disadvantages include the difficulty of postoperative ventilation in the ICU and potential airway trauma during placement.

The advantages of using a bronchial blocker include easier placement with difficult airways, selective lobar lung isolation, and no manipulation needed before ICU transfer. The disadvantages include more difficulty to place the blocker in the correct position, easier dislodging of the blocker during the case, suction not being possible, and difficulty alternating OLV to the other lung.

The advantages of using an endobronchial tube would be easier to place during emergencies and easier placement with difficult airways. However, the disadvantages would be the inability to perform bronchoscopy, suction, and CPAP in the isolated lung.

A DLT was chosen in this case over bronchial blocker due to ease of insertion and obtaining lung isolation, less likelihood of dislodging and losing lung isolation, and ability to easily isolate the other lung. Although potential airway trauma was a concern during insertion, this patient did not have an unstable C-Spine or risk above baseline for a normal DLT insertion. However, a real concern would have been the risk of performing an airway exchange to change a DLT to an SLT before transfer to ICU. The long duration of the surgery, potential for massive transfusion, and prolonged time in a prone position all potentially predisposes the patient to airway swelling, which could have increased the risk of an airway exchange. In a cohort study of 1177 patients, McLean et al3 found an overall failure rate of 13.8% for airway exchange using Cook airway exchange catheter, however, the failure rate of DLT to SLT was zero. However, failures of DLT to SLT exchanges have been reported in literature 4. Combining the use of airway exchange catheters and videolaryngoscope can reduce the risk of complications during airway exchanges 5. Another consideration for inserting the DLT was that if a significant pneumothorax was to develop during the case, rapid lung isolation could have been achieved by inflating the bronchial cuff.

Hypoxia During OLV
Risk factors for hypoxia during OLV include right-sided surgery, normal PFT, supine position, low PaO2 during two lung ventilation, morbid obesity (BMI >30kg/m2), previous lobectomy, and contralateral lung collapse surgery 6. Of these six risk factors, our patient had three (right-side surgery, normal PFT, and supine position) and was at a higher risk for hypoxia during OLV. After the initial desaturation with OLV, the patient was put back on TLV to temporize, followed by optimization of OLV. This included checking the position of the DLT, optimizing the hemodynamics, and performing a recruitment maneuver. Despite all these interventions, the patient still desaturated upon the second attempt at OLV. A suction cannula was inserted into the right lung, and intermittent O2 was insufflated into the right lung. This allowed the patient to maintain her O2 saturation at 96% with minimal interference to the surgical field.

Another possible intervention for the treatment of hypoxia would have been the addition of 1-5 cmH2O of CPAP to the non-ventilated lung. Although a bronchial blocker was not used, an advantage of using a bronchial blocker would be selectively isolating the right upper lobe, allowing normal ventilation in the right middle and lower lobes. Although not appropriate for this procedure, other interventions for hypoxia would include mechanical occlusion of blood flow to non-ventilated lungs and the use of extracorporeal membrane oxygenation.

Unstable C-Spine
Although our patient did not have C-Spine instability, special consideration needs to be made for patients with unstable C-Spine or difficult airways requiring lung isolation. Although both awake and asleep fiberoptic intubation with DLT has been described, it is significantly harder due to the larger outer diameter and stiffness of the tube compared to SLT 7. Furthermore, there are significant difficulties with blunting of the laryngeal and carinal stimulation during insertion due to the large size of the DLT. One alternative is to insert an SLT first, followed by an exchange to a DLT. The airway exchange procedure would have the additional risk of airway injury, and loss of airway described previously. A safer alternative would be to insert a bronchial blocker instead. It is important to note a typical 9 Fr bronchial blocker would require an SLT with an internal diameter of at least 8.0 mm 7.

Extubation
The decision to extubate the trachea should be individualized, weighing surgical, patient, and anesthetic factors. These combinations of factors include the length of surgery, blood loss, fluids administered, location of surgery, need for early neurological examination, significant cardiac or pulmonary comorbidities, patient BMI, difficulty during intubation, history of previous difficult intubation, observable facial edema, and availability of airway equipment 8. In a retrospective study, Cata et al. 9 found patients who remained intubated after prone surgery had higher ASA scores, the longer length of surgery, larger blood loss, and longer stay in hospital. The decision was made not to extubate the trachea at the end of the case due to the risk of loss of airway patency from the airway and facial/airway edema due to prolonged surgery in the prone position, location of surgery, and total fluid administered during the surgery.

Conclusion
In conclusion, en-block resection of spine tumors (low cervical and high thoracic) is a challenging but definitive treatment for such pathology. Careful perioperative anesthesia planning, monitoring, and postoperative care are keys to a favorable outcome.

References

1.

Brogna C, Thakur B, Fiengo L, et al. Mini Transsternal Approach to the Anterior High Thoracic Spine (T1–T4 Vertebrae). Biomed Res Int. 2016.

2.

Ashok V, Francis J. A practical approach to adult one-lung ventilation. BJA Educ. 2018;18(3):69-74.

3.

Mclean S, Lanam CR, Benedict W, Kirkpatrick N, Kheterpal S, Ramachandran SK. Airway Exchange Failure and Complications with the Use of the Cook Airway Exchange Catheter®: A Single Center Cohort Study of 1177 Patients. Anesth Analg. 2013;117(6):1325-1327.

4.

Hwang SM, Lee JJ, Jang JS, Lee NH. Esophageal misplacement of a single‑lumen tube after its exchange for a double‑lumen tube despite the use of an airway‑exchange catheter. Saudi J Anaesth. 2013;7(2):194 -196.

5.

Mort TC, Braffett BH. Conventional Versus Video Laryngoscopy for Tracheal Tube Exchange: Glottic Visualization, Success Rates, Complications, and Rescue Alternatives in the High-Risk Difficult Airway Patient. Anesth Analg. 2015;121(2):440 - 448.

6.

Campos J, Feider A. Hypoxia During One-Lung Ventilation - A Review and Update. J Cardiothorac Vasc Anesth. 2018;32:2330–2338.

7.

Collins SR, Titus BJ, Campos JH, Blank RS. Lung Isolation in the Patient With a Difficult Airway. Anesth Analg. 2018;126(6):1968-1978.

8.

Chui J, Crean RA. An update on the prone position: Continuing Professional Development. Can J Anesth. 2016;63:737-767.

9.

Cata JP, Saager L, Kurz A, Avitsian R. Successful Extubation in the Operating Room After Infratentorial Craniotomy. J Neurosurg Anesthesiol. 2011;23:25-29.

 

Corresponding author:
Tumul Chowdhury MD, DM, FRCPC
Staff Anesthesiologist
Department of Anesthesia and Pain Medicine
University Health Network, Toronto, Canada
Assistant Editor, Newsletter, SNACC
Email: Tumul.Chowdhury@uhn.ca

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