Pulmonary Function Tests (PFT’s) (see Pulmonary Function Tests, [[Pulmonary Function Tests]])

• Restrictive Pattern: may be mild in adolescents with kyphoscoliosis
  • Normal FEV1/FVC (about 80% predicted)
  • Decreased VC (in adults: decreased in propor-tion to deformity/ uniformly decreased in patients with scoliosis >90 degrees): due to inspiratory muscle weakness, mechanical disadvantage of respiratory muscles
  • Decreased TLC (in adults: decreased in proportion to deformity/ uniformly decreased in patients with scoliosis >90 degrees): due to decreased lung compliance
  • Decreased FRC (due to decreased end-expira-tory position of chest wall due to decreased lung compliance)
  • Relatively preserved RV
  • Increased RV/ TLC ratio (as high as 50%)
  • Decreased lung compliance (due to decreased chest wall compliance and breathing at low lung volumes/ worsens with aging due to unknown structural changes): usually normal compliance in children, even with severe kyphoscoliosis
  • Decreased MIPS/MEPS: occurs independent of thoracic curvature/ probably due to mechanical disadvantage of muscles (MIP is typically about 50% of predicted in eucapnic cases, 25% of predicted in hypercapnic cases)
  • Decreased MVV (typically 40% of predicted)

Exercise Test (see xxxx, [[xxxx]])

• Decreased VO2max: typically to 60-85% of normal
  • Due to deconditioning

Chest X-Ray (CXR) (see Chest X-Ray, [[Chest X-Ray]])

• Reveals the deformity of spine (quantified by Cobb angle) and ribs

Chest CT (see Chest Computed Tomography, [[Chest Computed Tomography]])

• Assesses deformity, lung parenchyma

Ventilation/Perfusion (V/Q) Scan (see Ventilation-Perfusion Scan, [[Ventilation-Perfusion Scan]])

• Mismatch occurs when Cobb scoliosis angle is >65 degrees

Sleep Study (see Sleep Study, [[Sleep Study]])

• xxx

Clinical Manifestations

Pulmonary manifestations

Dyspnea (see Dyspnea, [[Dyspnea]])

• xxx

Rapid, Shallow Respiration (see Tachypnea, [[Tachypnea]])

• Physiology:

Pulmonary Hypertension/Cor Pulmonale (see Pulmonary Hypertension, [[Pulmonary Hypertension]]): predicts death within one year without treatment

• Physiology
  • Low Lung Volumes with Compression of Pulmonary Arteries
  • Decreased Chest Wall Compliance, Resulting in Hypoventilation
  • Hypoxic Pulmonary Vasoconstriction
  • Medial Proliferation
• Clinical
  • xxx

Respiratory Muscle Fatigue

• Physiology: respiratory muscle weakness and decreased lung compliance

Acute or Chronic Hypoventilation/Respiratory Failure (see Respiratory Failure, [[Respiratory Failure]])

• Risk Factors for Respiratory Failure
  • Advanced Age of Onset
  • Cobb Angle >100 Degrees
  • Decreased Inspiratory Muscle Strength
  • Degree of Spinal Deformity
  • Presence of Paralysis: controversial
  • Sleep-Disordered Breathing

Nocturnal Hypoventilation

• Physiology
  • Mechanism of NREM-Associated Hypoventilation: decreased respiratory drive during NREM
  • Mechanism of REM-Associated Hypoventilation: inhibition of intercostal and accessory muscles during RME
• Clinical: worse during REM

Central Sleep Apnea (CSA) (see Central Sleep Apnea, [[Central Sleep Apnea]])

• Physiology:

Obstructive Sleep Apnea (OSA) (see Obstructive Sleep Apnea, [[Obstructive Sleep Apnea]])

• Physiology: due to distorted upper airway

Rheumatologic/Orthopedic Manifestations

• Kyphosis: may be isolated deformity (when associated with vertebral destruction)
• Scoliosis: almost always involves some degree of kyphosis

Treatment

General Measures

• Chest Physical Therapy (CPT): as required
• Oxygen (see Oxygen, [[Oxygen]]): improves survival in kyphoscoliosis (best results in patients <65 y/o and with pCO2 >55)
• Prompt Treatment of Respiratory Infections
• Treatment of Airway Obstruction: if present
  • Bronchodilators
• Treatment of Concomitant Congestive Heart Failure (CHF) (see Congestive Heart Failure, [[Congestive Heart Failure]]): if present
• Vaccination
  • Influenza (see Influenza Virus, [[Influenza Virus]])
  • Pneumococcus (see Streptococcus Pneumoniae, [[Streptococcus Pneumoniae]])

Intermittent Positive Pressure Ventilation

• Benefit lasts up to 3 hours after a 5 minute treatment (decreases atelectasis, etc.)

Treatment of Nocturnal Hypoventilation

Nocturnal Non-Invasive Positive Pressure Ventilation (NIPPV) (see Non-Invasive Positive Pressure Ventilation, [[Non-Invasive Positive Pressure Ventilation]])

• General Comments
  • Systematic Review of Nocturnal NIPPV in Patients with Neuromuscular Disease and Chest Wall Disorders (2000) [MEDLINE]
    • Nocturnal ventilation improved short-term clinical symptoms and may prolong survival
    • However, comparison of efficacy between NIPPV vs mechanical ventilation could not be made from the available data
• Average Volume Assured Pressure Support (VAPS) (see Volume Assured Pressure Support, [[Volume Assured Pressure Support]]) [MEDLINE]
  • Technique: set a target tidal volume, and the machine will maintain that tidal volume by varying the degree of pressure support delivered
  • Clinical Efficacy
    • VAPS may be more comfortable than bilevel ventilation (BiPAP) with a backup rate, as BiPAP provides a fixed amount of pressure support that is not affected by the patient’s effort

Tracheostomy with Nocturnal Mechanical Ventilation (see Tracheostomy, [[Tracheostomy]])

• May Be Required in Severe Cases

Treatment of Obstructive Sleep Apnea (OSA) (see Obstructive Sleep Apnea, [[Obstructive Sleep Apnea]])

• xxx

Surgical Intervention

• High Surgical Complication Rates: >50% complication rate (in patients >20 y/o) with typically little clinical benefit

References

• Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders. Cochrane Database Syst Rev. 2000;(2):CD001941 [MEDLINE]
• Therapy for sleep hypoventilation and central apnea syndromes. Curr Treat Options Neurol 2012;14(5):427-437 [MEDLINE]