Case Report

Age: 13 years

Sex: Female

Diagnosis: Severe thoracic scoliosis (Cobb angle 80°) and severe lumbar scoliosis (Cobb angle 90°)

Procedure: Posterior spinal fusion

Baseline Findings

The patient had a respiratory rate of 18 per minute, oxygen saturation of 99 percent on room air, and an end-tidal carbon dioxide of 32 mmHg. She demonstrated good activity tolerance and was able to perform daily tasks and play without limitation. Despite being advised, she declined formal pulmonary function testing.

Post-Intubation Ventilation

Following intubation with a 6.5 mm endotracheal tube, ventilatory measurements showed compliance of 19 ml/cm H₂O, peak inspiratory pressure of 22 cm H₂O, mean airway pressure of 9 cm H₂O, a tidal volume of 325 ml, and a respiratory rate of 18 per minute.

BackgroundThoracic and Lumbar Scoliosis

Scoliosis is a three-dimensional deformity of the spine characterized by lateral curvature and vertebral rotation. A Cobb angle greater than 70° represents severe disease. This patient presented with an 80° thoracic curve and a 90° lumbar curve, both of which severely compromise respiratory and biomechanical function.

Thoracic scoliosis distorts rib cage geometry, restricts diaphragmatic excursion, and reduces lung volumes, resulting in restrictive physiology. Lumbar scoliosis alters pelvic alignment, increases intra-abdominal pressure, and compresses abdominal organs, which worsens respiratory restriction and decreases venous return.

Relevance to Anesthesia:

Thoracic deformity reduces compliance and necessitates higher airway pressures, increasing the risk of barotrauma. Prone positioning and corrective maneuvers exacerbate ventilation-perfusion mismatch and complicate ventilation. Lumbar deformity increases intra-abdominal pressure in the prone position, leading to inferior vena cava compression and hypotension. Dual-curve correction increases surgical time, blood loss, fluid shifts, and hypothermia risk.

References:

Vitale MG, et al. J Bone Joint Surg Am. 2008;90(5):1022-8.

Koumbourlis AC. Paediatr Respir Rev. 2006;7(2):152-60.

Lung Compliance

Compliance, defined as the change in volume divided by the change in pressure, normally ranges from 30 to 50 ml/cm H₂O in children. In this patient, compliance was calculated as tidal volume divided by (peak pressure minus PEEP), which equaled 325 ml divided by (22 – 5), yielding approximately 19 ml/cm H₂O. This reflects reduced distensibility due to restrictive physiology from scoliosis.

Relevance to Anesthesia:

Low compliance requires higher airway pressures, placing the patient at risk of barotrauma. Pressure-controlled ventilation or low tidal volumes should be employed. Continuous monitoring of peak pressures and compliance throughout thoracic and lumbar correction is essential to detect dynamic changes and allow ventilatory adjustments.

References:

Coté CJ, et al. A practice of anesthesia for infants and children. 6th ed. Elsevier; 2019.

Sharma G, Goodwin J. Clin Interv Aging. 2006;1(3):253-60.

Surrogate Pulmonary Markers

Although pulmonary function tests were not performed, surrogate markers indicated preserved baseline function. The patient’s respiratory rate was 18 per minute, oxygen saturation was 99 percent on room air, end-tidal carbon dioxide was 32 mmHg, and her activity tolerance was good.

Relevance to Anesthesia:

These markers serve as baseline guides for intraoperative ventilation and postoperative extubation decisions. While good preoperative function suggests potential for early extubation, anesthesiologists must remain vigilant for intraoperative deterioration due to thoracic and lumbar manipulation.

References:

Motoyama EK, Davis PJ. Smith’s anesthesia for infants and children. 9th ed. Elsevier; 2017.

Reames DL, et al. Spine (Phila Pa 1976). 2011;36(18):1484-91.

Biomechanics of Spinal Correction

Posterior spinal fusion employs distraction and derotation to correct curvature. Thoracic correction expands compressed lung zones and alters chest wall mechanics. Lumbar correction restores pelvic alignment and reduces intra-abdominal pressure, though it can impose stress on adjacent segments. Dual-curve correction increases overall surgical complexity.

Relevance to Anesthesia:

Re-expansion pulmonary edema is a concern. Sudden changes in peak inspiratory pressure or end-tidal carbon dioxide may indicate pneumothorax or spinal cord hypoperfusion. Neuromonitoring is essential, and mean arterial pressure must be maintained above 65–70 mmHg to ensure spinal cord perfusion.

References:

Newton PO, et al. Spine (Phila Pa 1976). 2005;30(14):1667-71.

Wong J, et al. Paediatr Anaesth. 2005;15(6):519-23.

Cardiovascular Changes

Severe scoliosis alters cardiovascular physiology. Thoracic deformity produces right heart strain, pulmonary hypertension, and mediastinal displacement. Long-standing deformity blunts baroreflexes, and both thoracic and lumbar curves contribute to diastolic dysfunction. Lumbar scoliosis elevates intra-abdominal pressure, further reducing venous return.

Relevance to Anesthesia:

Induction hypotension is common due to reduced venous return, worsened in the prone position. Surgical distraction and derotation exacerbate preload reduction, and vasopressors are often required to maintain mean arterial pressure above 65–70 mmHg. Pulmonary hypertension heightens the risk of right heart failure, mandating careful fluid titration.

References:

Takaso M, et al. Eur Spine J. 2013;22(1):68-73.

Tsirikos AI, et al. Spine (Phila Pa 1976). 2007;32(3):297-305.

Hammer GB. Anesthesiol Clin North Am. 2001;19(2):305-25.

Intraoperative Management

Key challenges include airway management, ventilation, hemodynamic stability, neuromonitoring, fluid and temperature balance, and the complexities of lumbar correction.

Management involves pressure-controlled, lung-protective ventilation, optimization of spinal cord perfusion without controlled hypotension, and the use of total intravenous anesthesia or low concentrations of volatile anesthetics for neuromonitoring. Active warming is required to prevent hypothermia. Blood conservation includes tranexamic acid, cell salvage, and transfusion of packed red cells as indicated. Lumbar correction prolongs surgery and increases positioning and bleeding risks.

References:

Warner WC, et al. Pediatr Clin North Am. 2010;57(2):389-403.

Sathyamoorthy M, et al. J Am Acad Orthop Surg. 2020;28(1):e25-35.

Tobias JD. Paediatr Anaesth. 2007;17(1):82-7.

Causes of Intraoperative Hypotension

Hypotension in scoliosis surgery arises from prone positioning, anesthetic-induced vasodilation, surgical blood loss, distraction and derotation maneuvers, reduced anesthetic depth for neuromonitoring, pulmonary vascular changes, autonomic dysfunction, venous air embolism, and drug effects.

Relevance to Anesthesia:

The anesthesiologist must anticipate these triggers and employ vasopressors, fluids, and titrated anesthetics to maintain adequate perfusion pressures, ensuring spinal cord protection and preventing cardiovascular collapse.

References:

Jackson LL, et al. Curr Opin Anaesthesiol. 2019;32(5):610-5.

MacDonald DB. J Clin Monit Comput. 2006;20(5):347-77.

Muth CM, Shank ES. N Engl J Med. 2000;342(7):476-82.

Postoperative Respiratory Care

Postoperative risks include hypoventilation, atelectasis, respiratory fatigue, and delayed decompensation, especially after dual-curve correction.

Management includes multimodal analgesia with PCA, epidural, or regional blocks, chest physiotherapy, incentive spirometry, early ambulation, and head-up positioning. Monitoring with arterial blood gases, imaging, and readiness for non-invasive ventilation or reintubation is essential.

Relevance to Anesthesia:

Proactive respiratory support prevents deterioration in patients with limited reserve, reducing the risk of ICU readmission and prolonged ventilation.

References:

Tobias JD. Paediatr Anaesth. 2007;17(1):82-7.

Redding GJ, et al. Pediatr Pulmonol. 2008;43(7):723-30.

Discussion

This case highlights the challenges of anesthetizing a child with severe thoracic and lumbar scoliosis. The thoracic deformity compromises compliance and pulmonary function, while the lumbar deformity elevates intra-abdominal pressure and reduces venous return in the prone position. Dual-curve correction increases surgical duration, blood loss, fluid shifts, and hypothermia risk.

Anesthesiologists must individualize ventilation, hemodynamic support, and neuromonitoring strategies. The patient’s good baseline function is favorable, but meticulous intraoperative and postoperative management is essential to ensure a safe recovery.