Principles of Physical Therapy Management

A patient with restrictive pulmonary disease secondary to neuromuscular conditions is at considerable risk of succumbing to the negative cardiovascular and pulmonary sequelae of reduced mobility and recumbency, in addition to the pathophysiological consequences of respiratory failure. Provided the patient has some residual muscle power, the balance between oxygen demand and supply will determine the degree to which mobilization can be exploited to maximize oxygen transport.⁵ The treatment goals for these patients are to maximize oxygen delivery, enhance the efficiency of oxygen uptake and usage, and thereby reduce the work of breathing. In these patients, minimizing oxygen demand overall (i.e., during mobilization as well as at rest) is a priority. Mobilization needs to be prescribed in body positions that enhance oxygen transport and its efficiency so that the benefits of mobilization can be exploited more fully without worsening arterial oxygenation. The patient requires continuous monitoring of oxygen transport and hemodynamic monitoring to ensure the exercise stimulus is optimally therapeutic and not excessive.

Although the mechanisms are different, patients with neuromuscular dysfunction, much like patients with chronic airflow limitation, can benefit from body positioning to reduce respiratory distress. Upright and lean-forward positions will reduce distress to the greatest extent.

The patient’s body position and length of time in any one position must be carefully monitored and recorded to minimize the risks of positions that are deleterious to oxygenation and ensure that a beneficial position is not assumed for too long because of the diminishing benefits over time. This is particularly important for the patient who is incapable of positioning himself or herself, who is incapable of communicating a need to turn, and in whom muscle wasting, bony prominences, and thinning of the skin may predispose the patient to skin breakdown. Educating the family and caregiver to work with the patient is an essential component of the physical therapy management of patients with neuromuscular conditions.

Patients who are hypotonic and generally weak and debilitated fail to adapt normally to position-dependent fluid shifts and thus are more prone to orthostatic intolerance.⁶ Gravitational stimulation is essential to maintain the volume-regulating mechanisms. Tilt tables should be used judiciously given the potential risks in these patients, which are compounded by the loss of the lower-extremity muscle pump mechanism. Stretcher chairs may be preferable. Because of potential adverse reactions to fluid shifts and the potential for desaturation, falling PaO₂ levels, and dysrhythmias, the patient’s hemodynamic status must be monitored closely during gravitational challenges.

The importance of chest wall mobility to optimize three-dimensional chest wall excursion in individuals with chronic neurological conditions is emphasized in Chapters 22 and 23. This goal is particularly challenging if complicated by acute respiratory insufficiency. The goal is to promote alveolar ventilation, reduce areas of atelectasis, and optimize ventilation and perfusion matching and breathing efficiency to augment and minimize reliance on respiratory support (i.e., supplemental oxygen and mechanical ventilation) while minimizing respiratory distress. This is especially important because patients with neuromuscular conditions are poor candidates for being weaned off mechanical ventilation. In addition, these patients are prone to microaspiration. Promotion of mucociliary transport is therefore essential to facilitate clearing of aspirate and minimize bacterial colonization and risk of infection.

Another major problem for patients with restrictive lung disease secondary to generalized weakness and neuromuscular disease is an ineffective cough. Cough facilitation techniques (e.g., body positioning, abdominal counter pressure, and tracheal tickle; see Chapters 22 and 23) can be used to increase intraabdominal and intrathoracic pressures and cough effectiveness. A natural cough, even when facilitated, is preferable and more effective in dislodging mucus from the sixth or seventh generation of bronchi than repeated suctioning. Even a weak, facilitated cough may be effective in dislodging secretions to the central airways for removal by suctioning or for redistribution of peripheral secretions.⁷ Huffing, a modified cough performed with the glottis open and with abdominal support, may help mobilize secretions in patients with generalized weakness. In some cases suctioning may be the only means of eliciting a cough and clearing secretions simultaneously. Coughing attempts are usually exhausting for these patients. Thus ample rest periods must be interspersed during treatment, particularly for the ventilated patient. Coughing maneuvers must be strategically planned. Even though the patient may be able to effect only a series of a few weak coughs, it is essential that these attempts be maximized (i.e., the patient, optimally rested and medicated [e.g., bronchodilators, analgesia, reduced sedation and narcotics], is physically positioned to optimize length-tension relationship of the diaphragm and abdominal muscles; is positioned vertically to optimize inspiratory lung volumes and expiratory flows and avoid aspiration; and is provided thoracic and abdominal support during expiration to maximize intrathoracic and intraabdominal pressures) (see Chapter 22). These supportive measures will ensure that the benefits of the normal physiological cough mechanism, which is the single best secretion clearance technique, are maximized (i.e., the most productive cough with the least energy expenditure).⁸ Forced chest wall compression or forced expiratory maneuvers are contraindicated because of airway closure and impairment of gas exchange.⁹

Impaired mobility, inability to cough effectively, decreased airway diameter, and bronchospasm contribute to impaired mucociliary transport and secretion accumulation. In addition, impaired glottic closure and increased risk of reflux in this patient population expose the airway to risk of aspiration. Prophylactically, multiple body positions and frequent position changes will minimize the risk of secretion accumulation and stasis. If mechanically ventilated, these patients are suctioned as indicated. If pulmonary secretions become a significant problem despite these preventative measures, postural drainage positions are selected to achieve the optimal effect (i.e., secretion mobilization and optimal gas exchange). Given the treatment response, manual techniques, of which manual vibration would have the greatest physiological justification, may yield some benefit.

Patients with chronic neuromuscular dysfunction and residual musculoskeletal deformity pose an additional challenge to the cardiovascular and pulmonary physical therapist in that cardiovascular and pulmonary function is less predictable because of altered lung mechanics and possibly cardiac dynamics. Thus, clinical decision making is more experiential in these patients, and they require close monitoring.

Principles of Physical Therapy Management

The patient who is obese can be treated aggressively provided there are no contraindications and he or she is being fully monitored. Treatments must be intense, to the limits of the patient’s tolerance, provided this is not contraindicated. An aggressive approach is essential given that the obese patient is at greater risk of deteriorating between treatments than a nonobese patient. Recumbency is tolerated poorly by an individual who is obese. Positional decrements in PaO₂ and SaO₂ can induce dysrhythmias. The weight of the abdominal viscera limits diaphragmatic descent and elevates the resting position of the diaphragm, impeding its mechanical efficiency. Furthermore, these patients are likely to become distressed if positioned prone because of restriction of chest wall mobility. Half-prone positions in which the abdominal contents are displaced forward, however, may be well tolerated.

These patients need to be aggressively mobilized; both whole-body exercise stress and range-of-motion exercises between mobilization sessions are required. Active and active-assisted upper-extremity range-of-motion exercises are associated with increased hemodynamic stress; thus the patient must be monitored closely. Lower-extremity exercise, such as pedaling and hip and knee flexion and extension exercises may help position and improve the excursion of the diaphragm. Lower-extremity movement will augment venous return. Depending on the patient and the work of the heart, the effect of lower-extremity movement will require monitoring to ensure that myocardial work is not increased excessively.

The patient should be encouraged to sit out of bed as much as possible when tolerated. The erect upright position is optimal to augment ventilation and reduce the work of the mechanical ventilator and the risk of barotrauma. The upright position coupled with leaning forward displaces the abdominal contents forward, thereby reducing intraabdominal pressure and facilitating diaphragmatic descent. The posterior lung fields, particularly of the bases, are at risk for dynamic airway closure and atelectasis. Numerous positions and position changes ensure that the dependent alveoli remain open. The time spent in the supine position should be minimized. In fact, greater emphasis should be placed on nursing these patients in the upright position (i.e., the position of least risk and its variants). In addition to its pulmonary benefits, the upright position can reduce compression of the heart and mediastinal structures, and there is a potential decrease in stroke volume and cardiac output. The weight of the chest wall, in addition to the weight of internal fat deposits in and around the cardiovascular and pulmonary unit, can compromise cardiac output and contribute to dysrhythmias. Thus during all body position changes the patient should be monitored hemodynamically to ensure the position is being tolerated well. People who are obese often slump after being positioned in the upright position. It is crucial that the position of these patients be checked frequently and corrected. The slumped position can be counterproductive in that the benefits of the upright position are significantly reduced and can lead to deterioration.

Although patients who are obese do not tolerate the prone position well, the semiprone position can be beneficial by simulating the benefits of the upright lean-forward position on the displacement of the abdominal viscera.¹⁰ This position also simulates the prone abdomen-free position, which is associated with even greater benefit than the prone abdomen-restricted position. The benefits of the prone position for the obese individual include increased lung compliance and enhanced gas exchange and oxygenation. The full prone abdomen-restricted position is contraindicated in the obese individual with cardiovascular and pulmonary failure, however, because this position can compromise diaphragmatic descent and contribute to further cardiovascular and pulmonary distress and failure and possibly cardiac arrest.

Mucociliary transport is slowed and ineffective in individuals who are obese with cardiovascular and pulmonary failure. Frequent body positioning will facilitate mucociliary transport and lymphatic drainage. The postural drainage positions can be effective in mobilizing secretions should accumulation become a problem. Manual techniques are not likely to add much benefit, particularly in the person who is morbidly obese. Suctioning is essential to clear pulmonary secretions from the central airways.

A person who is obese is at risk for postextubation atelectasis. Thus, aggressive mobilization, numerous positions, and frequent position changes must be continued.

The spontaneously breathing patient who is obese may have a weak ineffective cough, which will be even less effective after a period of intubation and mechanical ventilation. These patients are taught deep breathing and coughing maneuvers comparable with those described for the patient with neuromuscular disease. Body positioning to facilitate coughing and supported coughing must be instituted to maximize cough effectiveness. These maneuvers should be carried out in conjunction with hourly extreme position shifts.

People who are morbidly obese have a high incidence of upper airway obstruction and sleep apnea secondary to floppy compliant pharyngeal tissue. Thus the quality of their sleep and rest is suboptimal, and they are apt to desaturate while sleeping. These patients are also at high risk for esophageal reflux and aspiration. The optimal resting position is with the head of the bed up.

Individuals who are obese must be positioned upright and mobilized particularly aggressively because of their cardiovascular and pulmonary risks. Positioning and mobilizing can be facilitated with hinged beds, heavy-duty lifts, and reinforced stretcher chairs and walking frames. These items are essential to ensure that the patients are physiologically perturbed as much as possible and to minimize biomechanical injury to staff. The physical therapist has to ensure that the optimal devices are selected such that the individual is actively involved as much as possible and optimal but not excessive support is provided. The care of the individual who is morbidity obese is a particular challenge in the ICU and places increased demand on coordinated teamwork in the unit.