Pulmonary function in individuals with a history of poliomyelitis

Pathophysiology of Neuromuscular Respiratory Diseases

Gas exchange between the atmosphere and the human body depends on the lungs and the function of the respiratory pump. The respiratory pump consists of the respiratory control center located in the brain, bony rib cage, diaphragm, and intercostal, accessory, and abdominal muscles. A variety of muscles serve to fine-tune adjustments of ventilation to metabolic demands. Appropriate evaluation and interventions can prevent respiratory complications and prolong life in individuals with neuromuscular diseases. This article discusses normal function of the respiratory pump, general pathophysiologic issues, and abnormalities in more common neuromuscular diseases.

Currents issues in cardiorespiratory care of patients with post-polio syndrome

ABSTRACT Post-polio syndrome (PPS) is a condition that affects polio survivors years after recovery from an initial acute attack of the poliomyelitis virus. Most often, polio survivors experience a gradual new weakening in muscles that were previously affected by the polio infection. The actual incidence of cardiovascular diseases (CVDs) in individuals suffering from PPS is not known. However, there is a reason to suspect that individuals with PPS might be at increased risk. Method A search for papers was made in the databases Bireme, Scielo and Pubmed with the following keywords: post polio syndrome, cardiorespiratory and rehabilitation in English, French and Spanish languages. Although we targeted only seek current studies on the topic in question, only the relevant (double-blind, randomized-controlled and consensus articles) were considered. Results and Discussion Certain features of PPS such as generalized fatigue, generalized and specific muscle weakness, joint and/or muscle pain may result in physical inactivity deconditioning obesity and dyslipidemia. Respiratory difficulties are common and may result in hypoxemia. Conclusion Only when evaluated and treated promptly, somE patients can obtain the full benefits of the use of respiratory muscles aids as far as quality of life is concerned.

Obesity and Pulmonary Function in Polio Survivors

Objective

To examine the correlation between obesity and pulmonary function in polio survivors.

Methods

This study was conducted based on a questionnaire survey and physical examination. The questionnaire included gender, age, paralyzed regions, physical activity levels, and accompanying diseases. The physical examination included measuring body mass index, waist circumference, muscle power, total fat amount, body fat percentage, and lean body mass. In addition, pulmonary function was tested based on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), ratio of FEV1 to FVC, and chest circumference. Five university hospitals and a local health clinic participated in this study.

Results

Pearson and partial correlation coefficients that used data collected from 73 polio survivors showed that obesity had a negative correlation with pulmonary function.

Conclusion

This study found that pulmonary function has a negative correlation with obesity for polio survivors. Therefore, it is necessary to develop specialized exercise programs to help polio survivors reduce their weight and strengthen their respiratory muscles.

Lung function in post-poliomyelitis syndrome: a cross-sectional study

OBJECTIVE:

To compare lung function between patients with post-poliomyelitis syndrome and those with sequelae of paralytic poliomyelitis (without any signs or symptoms of post-poliomyelitis syndrome), as well as between patients with post-poliomyelitis syndrome and healthy controls.

METHODS:

Twenty-nine male participants were assigned to one of three groups: control; poliomyelitis (comprising patients who had had paralytic poliomyelitis but had not developed post-poliomyelitis syndrome); and post-poliomyelitis syndrome. Volunteers underwent lung function measurements (spirometry and respiratory muscle strength assessment).

RESULTS:

The results of the spirometric assessment revealed no significant differences among the groups except for an approximately 27% lower mean maximal voluntary ventilation in the post-poliomyelitis syndrome group when compared with the control group (p = 0.0127). Nevertheless, the maximal voluntary ventilation values for the post-poliomyelitis group were compared with those for the Brazilian population and were found to be normal. No significant differences were observed in respiratory muscle strength among the groups.

CONCLUSIONS:

With the exception of lower maximal voluntary ventilation, there was no significant lung function impairment in outpatients diagnosed with post-poliomyelitis syndrome when compared with healthy subjects and with patients with sequelae of poliomyelitis without post-poliomyelitis syndrome. This is an important clinical finding because it shows that patients with post-poliomyelitis syndrome can have preserved lung function.

Pulmonary issues in patients with chronic neuromuscular disease

Patients with chronic neuromuscular diseases such as spinal cord injury, amyotrophic lateral sclerosis, and muscular dystrophies experience respiratory complications that are cared for by the respiratory practitioner. An organized anatomical approach for evaluation and treatment is helpful to provide appropriate clinical care. Effective noninvasive strategies for management of hypoventilation, sleep-disordered breathing, and cough insufficiency are available for these patients.

Respiratory failure in a patient with antecedent poliomyelitis: Amyotrophic lateral sclerosis or post-polio syndrome?

We report a 69-year-old man who developed paralytic poliomyelitis in childhood and then decades later suffered from fatal respiratory failure. Six months before this event, he had progressive weight loss and shortness of breath. He had severe muscular atrophy of the entire right leg as a sequela of the paralytic poliomyelitis. He showed mild weakness of the facial muscle and tongue, dysarthria, and severe muscle atrophy from the neck to proximal upper extremities and trunk, but no obvious pyramidal signs. Electromyogram revealed neurogenic changes in the right leg, and in the paraspinal, sternocleidomastoid, and lingual muscles. There was a slight increase in central motor conduction time from the motor cortex to the lumbar anterior horn. Pulmonary function showed restrictive ventilation dysfunction, which was the eventual cause of death. Some neuropathological features were suggestive of amyotrophic lateral sclerosis (ALS), namely Bunina bodies. In patients with a history of paralytic poliomyelitis who present after a long stable period with advanced fatal respiratory failure, one may consider not only respiratory impairment from post-polio syndrome but also the onset of ALS.

EFNS guideline on diagnosis and management of post-polio syndrome. Report of an EFNS task force

Post-polio syndrome (PPS) is characterized by new or increased muscular weakness, atrophy, muscle pain and fatigue several years after acute polio. The aim of the article is to prepare diagnostic criteria for PPS, and to evaluate the existing evidence for therapeutic interventions. The Medline, EMBASE and ISI databases were searched. Consensus in the group was reached after discussion by e-mail. We recommend Halstead's definition of PPS from 1991 as diagnostic criteria. Supervised, aerobic muscular training, both isokinetic and isometric, is a safe and effective way to prevent further decline for patients with moderate weakness (Level B). Muscular training can also improve muscular fatigue, muscle weakness and pain. Training in a warm climate and non-swimming water exercises are particularly useful (Level B). Respiratory muscle training can improve pulmonary function. Recognition of respiratory impairment and early introduction of non-invasive ventilatory aids prevent or delay further respiratory decline and the need for invasive respiratory aid (Level C). Group training, regular follow-up and patient education are useful for the patients' mental status and well-being. Weight loss, adjustment and introduction of properly fitted assistive devices should be considered (good practice points). A small number of controlled studies of potential-specific treatments for PPS have been completed, but no definitive therapeutic effect has been reported for the agents evaluated (pyridostigmine, corticosteroids, amantadine). Future randomized trials should particularly address the treatment of pain, which is commonly reported by PPS patients. There is also a need for studies evaluating the long-term effects of muscular training.

The Relation Between Walking Capacity and Clinical Correlates in Survivors of Chronic Spinal Poliomyelitis

OBJECTIVES

To examine (1) common clinical measures that may influence walking performance in the six-minute walk test (6MWT) in people with chronic poliomyelitis and (2) the test-retest reliability of the 6MWT distance, lower-extremity muscle strength, balance, and balance confidence on separate trials.

DESIGN

A prospective quasi-experimental study.

SETTING

University-based postpolio clinic.

PARTICIPANTS

Nineteen survivors of poliomyelitis (mean age, 62.2+/-1.9y; time since polio onset, 54.4+/-8.79y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

6MWT distance, rate-pressure product (RPP), Physiological Cost Index (PCI), ratings of perceived exertion (RPE), pain, fatigue, strength, standing balance, balance confidence, limb-length discrepancy, and lung function.

RESULTS

The 6MWT distance correlated with PCI, pretest pain, lower-extremity muscle strength, balance, balance confidence, corrected leg-length discrepancy, and lung function but not with RPP, RPE, posttest pain, or pretest and posttest fatigue. The PCI correlated with balance confidence and lung function. About 68% of the variance in 6MWT distance was accounted for by balance and pretest pain. The P value was set at .05.

CONCLUSIONS

With stringent standardization of the 6MWT applied to survivors of poliomyelitis (a neuromuscular condition with a musculoskeletal component), reproducibility was high; hence, test validity and interpretation were enhanced. The 6MWT distance was useful in elucidating the relation between impairment and a functional activity-namely, walking-in survivors of poliomyelitis.

Post-Polio Syndrome

Post-polio syndrome (PPS) is the term used for the new late manifestations that occur in patients 30 to 40 years after the occurrence of acute poliomyelitis. PPS has been recognized for over 100 years, but is more common at the present time because of the large epidemics of poliomyelitis in the 1940s and 1950s. PPS is manifested by neurologic, musculoskeletal, and general manifestations. Neurologic manifestations include new weakness, muscle atrophy, dysphagia, dysphonia, and respiratory failure. Musculoskeletal manifestations include muscle pain, joint pain, spinal spondylosis and scoliosis, and secondary root and peripheral nerve compression. General manifestations include generalized fatigue and cold intolerance. New muscle weakness of a mild-to-moderate degree responds well to a nonfatiguing exercise program and pacing of activity with rest periods to avoid muscle overuse. Generalized fatigue may be treated with energy conservation and weight loss programs and lower extremity orthoses. Pharmacologic agents also may be helpful, but have not been beneficial in controlled trials. Bulbar muscle weakness includes dysphagia, dysphonia, sleep disorders, and chronic respiratory failure. Dysphagia may be improved with instruction on compensatory swallowing techniques. Dysphonia is treated with voice exercise therapy and voice amplification devices. Sleep disorders are treated similarly to sleep disorders in non-PPS patients. Respiratory failure may be treated with continuous positive airway pressure, bilevel positive airway pressure, and nasal ventilation, or tracheotomy and permanent ventilation if necessary. Musculoskeletal (muscle and joint) pain is treated with weight loss, pacing of activities, use of assistive devices, and prescribing anti-inflammatory medications and physical therapy techniques. Cardiopulmonary conditioning can be improved without muscle overuse with cycle or arm ergometer exercise or dynamic aquatic exercise.

Disorders of the respiratory muscles

The act of breathing depends on coordinated activity of the respiratory muscles to generate subatmospheric pressure. This action is compromised by disease states affecting anatomical sites ranging from the cerebral cortex to the alveolar sac. Weakness of the respiratory muscles can dominate the clinical manifestations in the later stages of several primary neurologic and neuromuscular disorders in a manner unique to each disease state. Structural abnormalities of the thoracic cage, such as scoliosis or flail chest, interfere with the action of the respiratory muscles-again in a manner unique to each disease state. The hyperinflation that accompanies diseases of the airways interferes with the ability of the respiratory muscles to generate subatmospheric pressure and it increases the load on the respiratory muscles. Impaired respiratory muscle function is the most severe consequence of several newly described syndromes affecting critically ill patients. Research on the respiratory muscles embraces techniques of molecular biology, integrative physiology, and controlled clinical trials. A detailed understanding of disease states affecting the respiratory muscles is necessary for every physician who practices pulmonary medicine or critical care medicine.

Pulmonary complications of chronic neuromuscular diseases and their management

Chronic neuromuscular diseases may affect all major respiratory muscles groups including inspiratory, expiratory, and bulbar, and respiratory complications are the major cause of morbidity and mortality. Untreated, many of these diseases lead inexorably to hypercapnic respiratory failure, precipitated in some cases by chronic aspiration and secretion retention or pneumonia, related to impairment of cough and swallowing mechanisms. Many measures are helpful including inhibition of salivation, cough-assist techniques, devices to enhance communication, and physical therapy. In addition, ventilatory assistance is an important part of disease management for patients with advanced neuromuscular disease. Because of its comfort, convenience, and portability advantages, noninvasive positive pressure ventilation (NPPV) has become the modality of first choice for most patients. Patients to receive NPPV should be selected using consensus guidelines, and initiation should be gradual to maximize the chances for success. Attention should be paid to individual preferences for interfaces and early identification of cough impairment that necessitates the use of cough-assist devices. For patients considered unsuitable for noninvasive ventilation, invasive mechanical ventilation should be considered, but only after a frank but compassionate discussion between the patient, family, physician, and other caregivers.

Inspiratory muscle training in patients with prior polio who use part-time assisted ventilation

OBJECTIVE

To evaluate whether inspiratory muscle training in patients with prior poliomyelitis (and with symptoms and signs of hypoventilation) who use part-time assisted ventilation could improve symptoms and respiratory muscle function without adverse effects.

DESIGN

Intervention study with before-after trial.

SETTING

Training was performed in the patients' homes; assessments were performed at the hospital.

PATIENTS

Ten prior-polio patients were included. Three of them did not complete the trial, and their data were not included in results of training.

INTERVENTION

Ten weeks of daily inspiratory muscle training.

MAIN OUTCOME MEASURES

Spirometry, maximal inspiratory and expiratory pressures, inspiratory muscle endurance, and questions regarding activities of daily living were performed.

RESULTS

Inspiratory endurance capacity over 5 minutes improved from 10.7 to 16.7cm H2O (p < .05) assessed at 15 on the Borg scale, and most patients improved in activities of daily living. The whole-body endurance capacity remained stable over the studied period.

CONCLUSION

Inspiratory muscle training and close supervision can increase respiratory muscle endurance and improve well-being in patients with prior polio who use part-time assisted ventilation.

Respiratory response to exercise in postpolio patients with severe inspiratory muscle dysfunction

OBJECTIVES

To evaluate the limiting factors of exercise performance and to analyze the respiratory strategies adopted during exercise in postpolio patients with severe inspiratory muscle dysfunction.

PATIENTS

Five patients with prior poliomyelitis associated with scoliosis and with respiratory muscle dysfunction (mean vital capacity, 1.74L [range, 1.1 to 2.4]) were studied at rest and during leg or arm cycle exercise.

METHODS

Gas exchange was examined by arterial blood gases and mass spectrometry of expired air. Ventilatory mechanics were studied by measurement of esophageal and gastric pressures.

RESULTS

Blood gases at rest were normal, except for subnormal PO2 levels in three patients. In all but one patient, ventilatory insufficiency was the limiting factor for exercise. A compensatory breathing pattern with abdominal muscle recruitment during expiration was present already at rest in three of the patients. The pressures generated by the diaphragm were below fatiguing margins, ie, levels that in healthy subjects can be sustained for at least 45 minutes.

CONCLUSIONS

The extent of ventilatory dysfunction was not evident in blood gas values at rest; however, it was revealed by blood gas values during the exercise test. Diaphragm fatigue seems to be avoided at the cost of impaired blood gases.

Sleep apnea in patients with postpolio syndrome

We studied sleep architecture and sleep apnea pattern in patients with postpolio syndrome (PPS). Ten patients with clinical signs of PPS underwent polysomnographic recording for two consecutive nights. Although sleep efficiency and proportions of sleep stages were within the normal range, sleep architecture was disrupted owing to sleep apnea. Patients with bulbar involvement had more frequent sleep apnea (mean sleep apnea index, 11.09) than patients without (apnea index, 5.88). The former also had significantly more central apnea, which occurred more commonly during non-rapid-eye-movement (NREM) than rapid-eye-movement (REM) sleep, than those without bulbar signs. This finding suggests reduction in forebrain control of compromised bulbar respiratory centers during NREM sleep in PPS.

Dyspnea in a patient years after severe poliomyelitis. The role of cardiopulmonary exercise testing

Dyspnea after polio can occur for a variety of reasons, including neuromuscular disease and upper airway abnormalities resulting from prolonged intubation, including tracheal stenosis, tracheomalacia, and vocal cord paralysis. Routine studies such as spirometry and maximum voluntary ventilation (MVV) measurements can give similar results in these conditions. We present a 50-year-old woman who as a child developed poliomyelitis that required tracheostomy and negative pressure ventilation. Thirty-nine years later, she developed breathlessness with normal spirometry but decreased MVV. The flow volume loop showed flattening of the inspiratory and expiratory limbs, consistent with a fixed upper airway obstruction or neuromuscular weakness. Exercise testing with measurement of exercise flow volume loops and respiratory pressures was performed. The patient was ventilatory limited with increasing end-expiratory lung volume through exercise. Flow volume loops confirmed flow limitation. Respiratory pressures did not change after maximal exercise. Further evaluation confirmed left vocal cord paralysis and tracheomalacia. This patient demonstrates that the causes of dyspnea after poliomyelitis can be multifactorial, and that routine evaluation may fail to elucidate the limiting factor. In this case, exercise testing provided valuable insight into the limiting factor for this patient and provided useful data for counseling and for further management.

Movement energetics of individuals with a history of poliomyelitis

Principles for evaluating the functional capacity of, and, therefore, exercise testing, chronically-disabled populations such as individuals with a history of poliomyelitis are considerably less well established than those for able-bodied persons. Therefore, we examined the use of indexes of movement economy and cardiorespiratory conditioning based on the results of a submaximal exercise test and oxygen consumption studies in individuals with a history of poliomyelitis. Subjects (n = 48) were categorized into four distinct groups, ie, having normal movement economy and either normal (n = 12) or reduced cardiorespiratory conditioning (n = 11), or having reduced movement economy and either normal (n = 10) or reduced cardiorespiratory conditioning (n = 15). There was no relationship between the indexes of movement economy and cardiorespiratory conditioning (p > 0.05) supporting that these indexes reflected physiologically-distinct entities. Irrespective of movement economy, deconditioned subjects had a reduced forced vital capacity (% predicted) (p < 0.05) and a higher resting heart rate (HR) (p < 0.01) compared to conditioned subjects. The difference in resting HR was attributed to conditioning level rather than initial arousal because resting HR and VO2 were comparable on repeated tests (p > 0.05). Although there was no difference in steady-state HR (% predicted maximum) among the four groups (p > 0.05), VO2 (% pred max) was significantly lower for the deconditioned than the conditioned subjects (p < 0.01). We concluded that determining movement economy and cardiorespiratory conditioning with a submaximal exercise test may enhance assessment and treatment outcome evaluation, hence provide a rational basis for rehabilitation interventions in individuals with a history of poliomyelitis.

Pulmonary Manifestations of Neurological Disease

Breathing is a complicated act that requires sophisticated control mechanisms. The nervous system coordinates 3 fundamentally important components of respiration. The central nervous system has a central pattern generator that, along with appropriate feedback mechanisms, establishes both the resiratory rate and the depth of respirations. The peripheral nervous system facilitates transmission of these respiratory commands to the ventilatory muscles. The nervous system also contributes to the control of airway size. Laryngeal function is coordinated with inspiration, and local nerves in the lung have a major role in determining bronchial patency. Finally, the nervous system acts in incompletely understood ways to regulate perfusion of the lungs and to match local pulmonary blood flow with ventilation. Failure of the nervous system to adequately control these 3 different aspects of respiration may result in lifethreatening illness. Understanding how the nervous system affects control of ventilation, airway patency, and pulmonary perfusion therefore will enable intensivists to recognize and manage the pulmonary complications of neurological disease.

Effect of modified aerobic training on movement energetics in polio survivors

Given that individuals with disabilities may be unable to achieve maximal oxygen uptake in an exercise test and that maximal exercise testing may cause increased fatigue, pain, and muscle weakness, we examined the role of submaximal exercise testing and training based on objective as well as subjective parameters in polio survivors. Experimental (N = 7) and control subjects (N = 13) were tested before and after a 6-week period. The experimental subjects participated in a 6-week exercise training program for 30 to 40 minutes, three times a week. The program consisted of treadmill walking at 55% to 70% of age-predicted maximum heart rates; however, exercise intensity was modified to minimize discomfort/pain and fatigue. Neither objective nor subjective exercise responses were significantly different in the control group over the 6 weeks. No change was observed in cardiorespiratory conditioning in the experimental group. However, movement economy, which is related to the energy cost of walking, was significantly improved; and walking duration was significantly increased at the end of training. Modified aerobic training may have a role in enhancing endurance and reducing fatigue during activities of daily living in polio survivors.