Post-Polio Health (ISSN 1066-5331)
Vol. 11, No. 4, Fall 1995
Considerations Before Surgery
Oscar A. Schwartz, MD, FCCP, Saint Louis, Missouri
Preparing for Surgery
Kathleen Navarre, PhD, Essexville, Michigan
Arranging for Anesthesia
Judi Cox, Springfield, Illinois
Dealing with Breast Cancer Surgery
Ellen Fay Peak, Birmingham, Alabama
New Breathing Problems in Aging Polio Survivors: Respiratory Muscle Weakness
Ann Romaker, MD, Kansas City, Missouri
Post-Polio Breathing and Sleep Problems
Judith R. Fischer and Joan L. Headley
Panel Recommends New Preferred Polio Schedule for US
Post-Polio Related Research
Augusta Alba, MD, DNP-N, DPM&R, Goldwater Memorial Hospital, New York, New York
How does scoliosis affect breathing? Consider a typical, moderate curve of the spine of an individual. We usually look at the outside of the body to determine what is happening to the inside of the body, to the lungs and the heart. The twisting of the ribs backwards causes the lung to be similarly twisted into that shape and partially compressed. Distortion of the lung happens not only on the side of the convexity, but on the other side as well, the side of concavity.
When considering breathing, we are particularly interested in the cervicothoracic curve (apex at C7-T1), the thoracic curve (apex between T2-T11), and the thoracolumbar curve (apex at T12-L1). These are the ones that can affect cardiopulmonary function. Curves are classified by the number of degrees of lateral curvature. Curves in group III (31-50°) and group IV (51-70°) and beyond are the ones that cause more problems insofar as anesthesia and surgery are concerned.
There are several specific neuromuscular diseases which can cause curvatures including muscular dystrophies, spinal muscular atrophy, cerebral palsy, spinal cord injury, spina bifida, and arthrogryposis. Post-polio scoliosis is probably most similar to the scoliosis associated with spinal muscular atrophy. For the person with neuromuscular scoliosis, it is important to know specific management techniques when the curve is the result of muscle weakness.
The surgical treatment of scoliosis has already been discussed (Polio Network News, Vol. 11, Nos. 2 & 3). Non-surgical treatments include observation, bracing, custom seating, and electrical stimulation which for the most part has fallen out of favor, because it has not proved to prevent further progression of the curve. Postural exercises, exercises to maintain spinal flexibility, and other exercise routines are helpful and must be individualized. Physical therapists specializing in the treatment of scoliosis can provide this training.
For polio survivors with scoliosis, the main problem is a reduction of the biggest breath one can take. When the ability to breathe in deeply is impaired, the tidal volume (volume inspired with each breath) becomes smaller. Respiratory rate then becomes more rapid in order to maintain adequate ventilation. When a person is breathing more rapidly, the amount of air that actually reaches into the distal parts of the lungs where gas exchange occurs, the alveoli, is less. The work of breathing is increased because the flexibility of the chest wall is decreased due to the scoliosis. If the work is increased, the oxygen cost of breathing is also increased.
What is the result of inadequate ventilation due to a scoliotic chest wall? One develops an increased resistance in the circulatory system of the lung which leads to hypertension of the pulmonary artery system – the system which sends blood to the lungs from the heart. If pressure in the pulmonary artery increases, the right side of the heart becomes enlarged and hypertrophied. The heart muscle becomes thicker in an effort to pump blood against a higher pressure. If the scoliosis is not corrected, the heart eventually dilates. This condition is known as cor pulmonale.
With a scoliotic curve there can be a displacement of the heart within the chest, with it sometimes appearing to be on the right side of the chest. The aorta, which is the major blood vessel of the body, may also be twisted to follow the scoliotic curve. It is rarely kinked. The ultimate outcome with inadequate ventilation is congestive heart failure.
What recommendations can be made when polio survivors with breathing problems are facing surgery? There is no special pre-op or post-op care if the vital capacity is 70 to 100% of normal, with a good ability to cough, and if expiratory peak flow, hemoglobin and EKG are normal.
If curvature and neuromuscular weakness have decreased the vital capacity to 50 to 70% of normal, the expiratory flow is slightly reduced, and hemoglobin is slightly elevated but EKG is normal, pre-op management is regular. However, post-op management should include intermittent positive pressure breathing treatments on a regular basis with assisted coughing.
When vital capacity is further decreased to 30 to 50%, there are more serious problems affecting the heart and lungs. Expiratory flow is markedly reduced, and hemoglobin is elevated above normal. With the secondary complication of increased hemoglobin, the blood is more viscous which increases the chance of thrombosis. The EKG reflects the increased size and hypertrophy of the right side of the heart. Pre-op management must include assisted ventilation on a regular basis and, if improvement occurs, then surgery can be considered.
If assisted ventilation helps pre-op, continue it post-op on an indefinite basis so that hemoglobin and carbon dioxide will not be elevated and oxygen will not be depressed.
In post-op management, artificial ventilation should continue until the individual has regained at least 75% of pre-op vital capacity (VC). Aerosol mists with assisted cough; frequent turning to prevent atelectasis (small mucus plugs in the lung); and a limit on post-op sedation, which reduces the ability to breathe deeply and to cough, are recommended.
Persons with scoliosis with 10 to 30% of predicted VC may have a greater degree of cor pulmonale, a further increase of hemoglobin and will need even more assisted ventilation. If the person is helped by assisted ventilation, then proceed with surgery. In some cases with vital capacity in the 10 to 30% range and the 30 to 50% range, consider a pre-op tracheostomy.
The post-op treatment of people with 10 to 30% of predicted VC is the same as that for persons with 30 to 50%.