New breathing problems in aging polio survivors can be slowly progressive and thus be insidious and often not recognized by either polio survivors or health care professionals. Individuals who used an iron lung, or barely escaped one, during the acute phase should be aware of potential problems to avoid underventilation and possible respiratory failure. Those survivors who did not receive ventilatory assistance during the acute phase, especially those who had high spinal polio and who have upper body weakness and/or diaphragm weakness, are at higher risk.
Underventilation (hypoventilation) is most prevalent during sleep when there is posture change and less effective accessory muscle availability. This results in an elevation of CO2 levels and a decrease in oxygen levels in the blood (Romaker, 1995). Causes include chest wall deformities such as scoliosis/kyphoscoliosis, respiratory muscle weakness, and sleep apnea, either central, obstructive, or mixed (see Sleep Apnea).
Other contributing factors include smoking, obesity, and diminished vital capacity (VC). A diminished VC is common in everyone who is aging. Polio survivors who have impairment of the diaphragmatic and/or intercostal (rib) muscles, or scoliosis, combined with the normal changes due to aging may lose VC at a rate of 60-90% greater than normal, thus exacerbating the development of underventilation (Bach, 1994).
Signs and symptoms include: daytime sleepiness, morning headaches, not feeling rested in the morning, need to sleep sitting up, sleep disturbances (including dreams of being smothered, nightmares, restless sleep, interrupted sleep), snoring, fatigue or exhaustion from normal activities, poor concentration and impaired intellectual function, shortness of breath on exertion, claustrophobia and/or feeling that the air in the room is somehow bad, anxiety, difficulty in speaking for more than a short time, quiet speech with fewer words per breath, use of accessory muscles to breathe, and a weak cough with increased susceptibility to respiratory infections and pneumonias.
An individual experiencing a combination of any of the above should immediately seek a respiratory evaluation by a pulmonologist (see Pulmonary Function Tests), preferably one experienced in neuromuscular disease, and preferably an in-lab sleep study. When VC declines from examination to examination to a range under 1 L (liter), assistance with ventilation must be considered (Bach, 1994). At altitude, especially above 5,000 feet, persons with a VC below 1.5 liters may need assistance with ventilation (Eulberg, personal communication, 2023).
Management of underventilation can be achieved using noninvasive positive pressure ventilation (see Ventilators). Often nocturnal use is enough to correct the condition. Those who begin using nocturnal ventilation may find themselves gradually adding periods of ventilator use during the daytime. In some cases, invasive tracheostomy positive pressure ventilation may be necessary. Underventilation can be aggravated by the use of oxygen therapy alone because it can result in decreased respiratory drive and increased CO2 levels (see Oxygen). Underventilation is a very serious condition which, if ignored and left untreated, can lead to death (see Diastolic Heart Failure).
References
Bach, J.R. (1994). Evaluation and management of post-polio respiratory sequelae: noninvasive options. In LS. Halstead & G. Grimby (Eds.), Post-polio syndrome. Philadelphia, PA: Hanley & Belfus, Inc.
Romaker, A (1995). New breathing problems in aging polio survivors. Polio Network News, 11(4), 1, 7-8.