**4. Lung expansion therapy**

Lung expansion therapy often results in increasing VC, increasing CPF, maintaining or increasing pulmonary compliance, decreasing atelectasis and facilitating introduction of NIV. Various devices and techniques have been developed to prolong survival without tracheotomy through maintaining pulmonary compliance, and augmenting inspiratory and expiratory muscle function. For example, researchers have found that Duchenne muscular dystrophy patients requiring up to continuous ventilator dependence as NIV, can avoid

Respiratory Muscle Aids in the Management of Neuromuscular

Fig. 1. Patient demonstrating air stacking using a manual resuscitator.

Historically, negative pressure body ventilators have been used to apply pressure to the body for ventilatory support, but this is less effective than NIV as they can cause obstructive apneas and are decreasingly efficacious with increasing age and decreasing pulmonary compliance (Bach et al, 1989). In figure 2, the intermittent abdominal pressure ventilator (IAPV) or "Exsufflation Belt" is a body ventilator that can augment tidal volumes from 300 to 1,200 mL. The intermittent inflation of the elastic air sac worn in a corset or belt under the patient's clothing moves the diaphragm upward to assist in expiration. With bladder deflation, passive inspiration occurs with the diaphragm and abdominal contents returning to resting position with gravity. For effective use the trunk must be 30 degrees or more from the horizontal. Patients with inspiratory capacity or ability to glossopharyngeal breathe can add volumes of air to those mechanically taken in. Patients with less than one hour of breathing tolerance usually prefer it to NIV during daytime hours (Bach & Alba, 1991).

Inspiratory muscles can be assisted using NIV. There are no contraindications to long term use of NIV other than uncontrollable seizures. Multiple interfaces can be used and they can be introduced to the patients in a clinic or home setting. They include 15 mm angled mouth pieces, lipseals, and nasal and oral-nasal interfaces. Open NIV systems include mouthpiece *or* nasal NIV which rely on central nervous system reflexes to prevent insufflation air leakage during sleeping (Bach &Alba, 1990; Bach et al., 1955). A closed system, such as by using a lipseal-nasal prong system, can avoid excessive leakage by delivering air via mouth *and* nose during sleep (Figure 3). In addition to minimizing insufflation leakage, they maximize skin comfort. Using nocturnal NIV improves daytime O2 and CO2. Supplemental O2 and sedatives should be avoided to maintain maximal nocturnal NIV effectiveness.

**4.2 Inspiratory muscle assistance** 

Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy 239

hospitalizations, pulmonary morbidity and mortality for decades and tracheotomy indefinitely when properly managed with respiratory muscle aids (Gomez-Merino & Bach, 2002). Forty percent of ALS patients can survive for almost a year on average and up to 8 years without a tracheostomy tube despite continuous ventilator dependence supplied via NIV (Bach et al., 2004).

#### **4.1 Maintaining pulmonary compliance**

Maintaining pulmonary (chest wall and lung) compliance, constantly and consistently maintaining normal alveolar ventilation, and maximizing cough peak flows are essential to preventing episodes of ARF, avoiding hospitalizations and prolonging survival without tracheotomy. Particularly for children, maintaining chest wall/lung compliance promotes more normal lung and chest wall growth. Regular lung and chest wall mobilization is done by air stacking, receiving deep insufflations, or using nocturnal NIV for small children who cannot cooperate with air stacking (Bach et al., 2000). With increasing respiratory muscle weakness, the patient cannot expand the lungs to the predicted inspiratory capacity. This results in chest wall contractures and lung restriction (decreased pulmonary compliance).

Regular mobilization through deep insufflations, air stacking or NIV can result in an increase in VC and CPF. The degree to which the MIC exceeds the VC (MIC-VC) indicates glottis/bulbar innervated muscle integrity and correlates with the ability to use NIV rather than require tracheotomy. The Lung Insufflation Capacity (LIC) is the maximum passive insufflation volume using the assistance of a device (Bach & Kang, 2000).

In patients with inability to close the glottis, insufflation can be achieved passively through the use of a Cough AssistTM, pressure cycling ventilator with pressures 40 to 70 cm H2O, or using a manual resuscitator with the exhalation valve blocked to air stack (Figure 1). Patients are instructed to air stack at least 10 to 15 times, 2 to 3 times a day once the VC is found to have decreased below 80% of predicted normal. For NIV users, volume cycling is preferable to pressure cycling as it enables air stacking and this allows for increased volume of voice (Bach et al., 2008). In patients with primarily ventilatory impairment, CPAP is not useful since it does not aid inspiratory or expiratory muscles.

In addition, patients who are able to air stack are also able to use NIV. If at any point the patient is intubated, he or she can more easily be extubated directly to NIV regardless of ventilator free breathing ability (VFBA). Proper instruction is essential as the extubation of inexperienced patients without VFBA to NIV can at times result in panic, ventilator dyssynchrony, asphyxia or even reintubation.

In patients, such as infants, who can not cooperate with active insufflation therapy, that is, who are unable to air stack, oral-nasal interfaces are used for deep passive insufflations. Infants with spinal muscular atrophy (SMA) of any type or any neuromuscular disease with paradoxical chest wall movement require nocturnal NIV to promote normal chest wall/lung growth, prevent pectus excavatum, as well as possibly for ventilatory assistance (Bach et al., 2002). Often by 14 to 30 months children can become cooperative with deep insufflation therapy.

Fig. 1. Patient demonstrating air stacking using a manual resuscitator.

### **4.2 Inspiratory muscle assistance**

238 Neuromuscular Disorders

hospitalizations, pulmonary morbidity and mortality for decades and tracheotomy indefinitely when properly managed with respiratory muscle aids (Gomez-Merino & Bach, 2002). Forty percent of ALS patients can survive for almost a year on average and up to 8 years without a tracheostomy tube despite continuous ventilator dependence supplied via

Maintaining pulmonary (chest wall and lung) compliance, constantly and consistently maintaining normal alveolar ventilation, and maximizing cough peak flows are essential to preventing episodes of ARF, avoiding hospitalizations and prolonging survival without tracheotomy. Particularly for children, maintaining chest wall/lung compliance promotes more normal lung and chest wall growth. Regular lung and chest wall mobilization is done by air stacking, receiving deep insufflations, or using nocturnal NIV for small children who cannot cooperate with air stacking (Bach et al., 2000). With increasing respiratory muscle weakness, the patient cannot expand the lungs to the predicted inspiratory capacity. This results in chest wall contractures and lung restriction (decreased pulmonary

Regular mobilization through deep insufflations, air stacking or NIV can result in an increase in VC and CPF. The degree to which the MIC exceeds the VC (MIC-VC) indicates glottis/bulbar innervated muscle integrity and correlates with the ability to use NIV rather than require tracheotomy. The Lung Insufflation Capacity (LIC) is the maximum passive

In patients with inability to close the glottis, insufflation can be achieved passively through the use of a Cough AssistTM, pressure cycling ventilator with pressures 40 to 70 cm H2O, or using a manual resuscitator with the exhalation valve blocked to air stack (Figure 1). Patients are instructed to air stack at least 10 to 15 times, 2 to 3 times a day once the VC is found to have decreased below 80% of predicted normal. For NIV users, volume cycling is preferable to pressure cycling as it enables air stacking and this allows for increased volume of voice (Bach et al., 2008). In patients with primarily ventilatory impairment, CPAP is not

In addition, patients who are able to air stack are also able to use NIV. If at any point the patient is intubated, he or she can more easily be extubated directly to NIV regardless of ventilator free breathing ability (VFBA). Proper instruction is essential as the extubation of inexperienced patients without VFBA to NIV can at times result in panic, ventilator

In patients, such as infants, who can not cooperate with active insufflation therapy, that is, who are unable to air stack, oral-nasal interfaces are used for deep passive insufflations. Infants with spinal muscular atrophy (SMA) of any type or any neuromuscular disease with paradoxical chest wall movement require nocturnal NIV to promote normal chest wall/lung growth, prevent pectus excavatum, as well as possibly for ventilatory assistance (Bach et al., 2002). Often by 14 to 30 months children can become cooperative with deep insufflation

insufflation volume using the assistance of a device (Bach & Kang, 2000).

useful since it does not aid inspiratory or expiratory muscles.

dyssynchrony, asphyxia or even reintubation.

NIV (Bach et al., 2004).

compliance).

therapy.

**4.1 Maintaining pulmonary compliance** 

Historically, negative pressure body ventilators have been used to apply pressure to the body for ventilatory support, but this is less effective than NIV as they can cause obstructive apneas and are decreasingly efficacious with increasing age and decreasing pulmonary compliance (Bach et al, 1989). In figure 2, the intermittent abdominal pressure ventilator (IAPV) or "Exsufflation Belt" is a body ventilator that can augment tidal volumes from 300 to 1,200 mL. The intermittent inflation of the elastic air sac worn in a corset or belt under the patient's clothing moves the diaphragm upward to assist in expiration. With bladder deflation, passive inspiration occurs with the diaphragm and abdominal contents returning to resting position with gravity. For effective use the trunk must be 30 degrees or more from the horizontal. Patients with inspiratory capacity or ability to glossopharyngeal breathe can add volumes of air to those mechanically taken in. Patients with less than one hour of breathing tolerance usually prefer it to NIV during daytime hours (Bach & Alba, 1991).

Inspiratory muscles can be assisted using NIV. There are no contraindications to long term use of NIV other than uncontrollable seizures. Multiple interfaces can be used and they can be introduced to the patients in a clinic or home setting. They include 15 mm angled mouth pieces, lipseals, and nasal and oral-nasal interfaces. Open NIV systems include mouthpiece *or* nasal NIV which rely on central nervous system reflexes to prevent insufflation air leakage during sleeping (Bach &Alba, 1990; Bach et al., 1955). A closed system, such as by using a lipseal-nasal prong system, can avoid excessive leakage by delivering air via mouth *and* nose during sleep (Figure 3). In addition to minimizing insufflation leakage, they maximize skin comfort. Using nocturnal NIV improves daytime O2 and CO2. Supplemental O2 and sedatives should be avoided to maintain maximal nocturnal NIV effectiveness.

Respiratory Muscle Aids in the Management of Neuromuscular

or full breath support, as demonstrated in Figure 4.

Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy 241

In patients with some neck movement and lip function, the 15 mm angled mouthpiece interface is the most useful, and is able to be used by some patients all day (Ishikawa, 2005). Often times patients can keep the mouthpiece near the mouth with a metal clamp attached to the wheelchair or affixed onto the motorized wheelchair controls, most commonly the sip and puff, chin or tongue controls. The patient can grab the mouthpiece for supplemental air

The volume ventilator is set for large tidal volumes, commonly 800 to 1500 mL. Therefore, the patient can control the volume of air obtained and can use air stacking to cough, increase speech volumes, and maintain pulmonary compliance. To use mouthpiece NIV a patient must be able to move the soft palate posteriocranially to seal off the nasopharynx, open the glottis and vocal cords, and maintain hypopharynx and airway patency. These movements quickly become reflexive. They must and usually can be quickly relearned by patients who

Fig. 4. A 66 year old woman with multiple sclerosis and continuous ventilator dependence using a 15 mm angled mouth piece for daytime support for 27 years despite having only 30

mL of vital capacity.

have been ventilated via tracheostomy and have lost them (Bach et al., 1993).

Fig. 2. High level spinal cord injured patient with no measurable vital capacity or ventilatorfree breathing ability using an intermittent abdominal pressure ventilator for daytime ventilatory assistance (Exsufflation BeltTM, Philips-Respironics International Inc., Murrysville, PA) and using a lipseal for nocturnal support for 15 years.

Fig. 3. Duchenne muscular dystrophy patient using an interface that includes nasal prongs with lip covering to provide a closed system of ventilatory support during sleep, here seen using it during surgery with general anesthesia.

Fig. 2. High level spinal cord injured patient with no measurable vital capacity or ventilatorfree breathing ability using an intermittent abdominal pressure ventilator for daytime ventilatory assistance (Exsufflation BeltTM, Philips-Respironics International Inc.,

Fig. 3. Duchenne muscular dystrophy patient using an interface that includes nasal prongs with lip covering to provide a closed system of ventilatory support during sleep, here seen

using it during surgery with general anesthesia.

Murrysville, PA) and using a lipseal for nocturnal support for 15 years.

In patients with some neck movement and lip function, the 15 mm angled mouthpiece interface is the most useful, and is able to be used by some patients all day (Ishikawa, 2005). Often times patients can keep the mouthpiece near the mouth with a metal clamp attached to the wheelchair or affixed onto the motorized wheelchair controls, most commonly the sip and puff, chin or tongue controls. The patient can grab the mouthpiece for supplemental air or full breath support, as demonstrated in Figure 4.

The volume ventilator is set for large tidal volumes, commonly 800 to 1500 mL. Therefore, the patient can control the volume of air obtained and can use air stacking to cough, increase speech volumes, and maintain pulmonary compliance. To use mouthpiece NIV a patient must be able to move the soft palate posteriocranially to seal off the nasopharynx, open the glottis and vocal cords, and maintain hypopharynx and airway patency. These movements quickly become reflexive. They must and usually can be quickly relearned by patients who have been ventilated via tracheostomy and have lost them (Bach et al., 1993).

Fig. 4. A 66 year old woman with multiple sclerosis and continuous ventilator dependence using a 15 mm angled mouth piece for daytime support for 27 years despite having only 30 mL of vital capacity.

Respiratory Muscle Aids in the Management of Neuromuscular

Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy 243

Fig. 5.A. Manually assisted coughing with abdominal thrust applied concomittant with glottic opening following air stacking with flows to be measured by peak flow meter.

Fig. 5.B. Assisted cough peak flow measured by peak flow meter.

For those who are unable to grab or maintain a tight seal on a mouthpiece for daytime NIV, such as infants, nasal NIV using small nasal prong systems can be ideal and can be used continuously as a viable alternative to tracheostomy (Bach & Alba, 1990). To prevent oral insufflation leakage during nasal NIV, patients learn to close the mouth or seal the oropharynx with the soft palate and tongue. Humidifying the air is essential for nocturnal mouthpiece/lipseal ventilation but infrequently for nocturnal nasal NIV. Suboptimal humidification results in dry, irritated mucous membranes and increased airflow resistance to up to 8 cm H2O (Richards et al., 1996). The air can be warmed to body temperature and humidified using a hot water bath humidifier to decrease irritation of nasal membranes (Richards et al., 1996).

Complications from NIV are few. At times abdominal distension can occur sporadically. The air usually passes as flatus when the patient is mobilized in the morning. If severe, it can increase ventilator dependence and result in necessary placement of a gastrostomy or nasogastric tube to burp out the air or a rectal tube to decompress the colon. In 1000 NIV users there was noted to be one case of pneumothorax despite aggressive lung mobilization and expansion three times daily with NIV support for most and, indeed for over 50 years in many cases (Suri et al., 2008). Often mistakenly noted to be a complication or limiting aspect of NIV, secretion management remains the most important aspect of noninvasive management.

#### **4.3 Cough Augmentation: Expiratory muscle assistance**

Cough Augmentation is essential in maintaining the health of patients with a poor cough due to weak expiratory muscles. Essential techniques include manually assisted coughing, mechanically assisted coughing (MAC), glossopharyngeal breathing, and oximetry monitoring to guide in airway clearance when using these techniques. Routine suctioning through the upper airway or indwelling airway tubes misses the left main stem bronchus 90 percent of the time (Fishburn et al., 1990). Manually assisted coughing is the application of an abdominal thrust timed to glottis opening after filling the lungs maximally with air, usually through air stacking, Figure 5A and Figure 5B.

The air stacking is important for patients with less than 1500 mL VC. With air stacking, manually assisted coughing has produced air flows of 4.3 ± 1.7 L/sec compared to 2.5 ± 2.0 L/sec unassisted (Kang & Bach, 2000). In our population of 364 NMD patient able to air stack the mean VC in the sitting position was 996.9 mL, while the mean MIC by air stacking was 1647.6 mL. Upper airway obstruction, often due to severe bulbar-innervated muscle dysfunction, is indicated by the inability to generate 160 L/m of assisted CPF with a VC or MIC greater than 1 L. With CPF this low, the airway should be evaluated by laryngoscopy and reversible lesions corrected surgically.

Mechanical insufflation-exsufflation (CoughAssistTM) augments or substitutes for inspiratory and expiratory muscles. Both mechanical and manually assisted cough techniques provide effective exsufflation flows in the left and right airways, allowing for their use in place of deep suctioning. Patients prefer MAC compared with suctioning for comfort and effectiveness, in addition to finding it less tiring (Gastang et al., 2000).

For those who are unable to grab or maintain a tight seal on a mouthpiece for daytime NIV, such as infants, nasal NIV using small nasal prong systems can be ideal and can be used continuously as a viable alternative to tracheostomy (Bach & Alba, 1990). To prevent oral insufflation leakage during nasal NIV, patients learn to close the mouth or seal the oropharynx with the soft palate and tongue. Humidifying the air is essential for nocturnal mouthpiece/lipseal ventilation but infrequently for nocturnal nasal NIV. Suboptimal humidification results in dry, irritated mucous membranes and increased airflow resistance to up to 8 cm H2O (Richards et al., 1996). The air can be warmed to body temperature and humidified using a hot water bath humidifier to decrease irritation of nasal membranes

Complications from NIV are few. At times abdominal distension can occur sporadically. The air usually passes as flatus when the patient is mobilized in the morning. If severe, it can increase ventilator dependence and result in necessary placement of a gastrostomy or nasogastric tube to burp out the air or a rectal tube to decompress the colon. In 1000 NIV users there was noted to be one case of pneumothorax despite aggressive lung mobilization and expansion three times daily with NIV support for most and, indeed for over 50 years in many cases (Suri et al., 2008). Often mistakenly noted to be a complication or limiting aspect of NIV, secretion management remains the most important aspect of

Cough Augmentation is essential in maintaining the health of patients with a poor cough due to weak expiratory muscles. Essential techniques include manually assisted coughing, mechanically assisted coughing (MAC), glossopharyngeal breathing, and oximetry monitoring to guide in airway clearance when using these techniques. Routine suctioning through the upper airway or indwelling airway tubes misses the left main stem bronchus 90 percent of the time (Fishburn et al., 1990). Manually assisted coughing is the application of an abdominal thrust timed to glottis opening after filling the lungs maximally with air,

The air stacking is important for patients with less than 1500 mL VC. With air stacking, manually assisted coughing has produced air flows of 4.3 ± 1.7 L/sec compared to 2.5 ± 2.0 L/sec unassisted (Kang & Bach, 2000). In our population of 364 NMD patient able to air stack the mean VC in the sitting position was 996.9 mL, while the mean MIC by air stacking was 1647.6 mL. Upper airway obstruction, often due to severe bulbar-innervated muscle dysfunction, is indicated by the inability to generate 160 L/m of assisted CPF with a VC or MIC greater than 1 L. With CPF this low, the airway should be evaluated by laryngoscopy

Mechanical insufflation-exsufflation (CoughAssistTM) augments or substitutes for inspiratory and expiratory muscles. Both mechanical and manually assisted cough techniques provide effective exsufflation flows in the left and right airways, allowing for their use in place of deep suctioning. Patients prefer MAC compared with suctioning for

comfort and effectiveness, in addition to finding it less tiring (Gastang et al., 2000).

(Richards et al., 1996).

noninvasive management.

**4.3 Cough Augmentation: Expiratory muscle assistance** 

usually through air stacking, Figure 5A and Figure 5B.

and reversible lesions corrected surgically.

Fig. 5.A. Manually assisted coughing with abdominal thrust applied concomittant with glottic opening following air stacking with flows to be measured by peak flow meter.

Fig. 5.B. Assisted cough peak flow measured by peak flow meter.

Respiratory Muscle Aids in the Management of Neuromuscular

having 0 mL of vital capacity for 52 years (Bach et al., 1987).

solely with GPB (Bach et al. 2007).

**4.3.3 Oximetry monitoring** 

minute as seen in Figure 6.

Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy 245

Dail & Affeldt, 1954). The patient's developing proficiency can be monitored using spirometry to measure the milliliter of air per gulp, gulps per breath and the breaths per

Fig. 6. Glossopharyngeal breathing used for 6 liters of minute ventilation in "gulps" of 60 to 90 mL or 6 to 8 gulps per breath, 12 breaths per minute, for autonomous respiration despite

Normal minute ventilation and normal alveolar ventilation can be maintained by glossopharyngeal breathing for individuals with little to no measurable vital capacity. Autonomous breathing is possible from minutes to up to all day by using it. It has been noted that 60% of ventilator users with no autonomous ability to breathe and sufficient bulbar muscle function can use GPB for ventilator-free breathing (Bach et al., 1987; Bach & Alba, 1990). This technique is ideal in the event of ventilator failure or disconnection during the day or night (Bach et al., 1987; Bach, 1991). The versatility and safety afforded by GPB are safeguards that make noninvasive management safer than support via tracheostomy. Although severe oropharyngeal muscle weakness can limit the effectiveness of GPB, 13 Duchenne muscular dystrophy patients with no breathing tolerance could be maintained

Oximetry monitoring, through the use of a pulse oximeter, is essential in managing patients with NMD using respiratory muscle aids. A SpO2 alarm set at 94% alerts the patient to take deeper breaths to maintain SpO2 consistently over 94% all day (Gomez-Marino & Bach, 2002), and when tiring, to take ventilator assisted breaths usually via a mouthpiece. Thus, SpO2 feedback provides a method to monitor a hypercapnic patient with desaturation due to chronic alveolar hypoventilation and during transition from tracheostomy ventilation. If the patient is unable to independently maintain a sufficient level of at least SpO2 of 94%, mouthpiece or nasal NIV should be initiated for increasing periods to maintain normal SpO2 which helps to reset central ventilatory drive. Thereby, oximetry feedback facilitates the introduction and indicates the extent of daytime need for mouthpiece and/or nasal NIV. In addition, oximetry monitoring is especially useful during episodes of respiratory tract infection as an indicator to use MAC to prevent cold triggered pneumonias and acute respiratory failure, usually due to mucus plugging in the NIV patient population. Proper

#### **4.3.1 Mechanically assisted coughing**

Mechanically assisted coughing (MAC) combines mechanical insufflation-exsufflation with an exsufflation-timed abdominal thrust to increase CPF. The CoughAssistTM can be manually or automatically cycled with the deep insufflations followed immediately by deep exsufflations, ideally with pressures of 40 to 60 alternating with -40 to -60 cm H2O. Interfaces for MAC include oral-nasal masks, a simple mouthpiece, or translaryngeal or tracheostomy tubes. With use via a tracheostomy tube, the cuff, if present, should be inflated. Manual cycling allows caregiver-patient coordination during inspiration and expiration with the insufflation and exsufflation.

Treatments can be as frequent as up to every 30 minutes during respiratory infections and post-extubation. One treatment set includes about five cycles of MAC followed by a short period of normal breathing or ventilator use to avoid hyperventilation. When patients cannot cooperate with MAC, the timing of the insufflation and exsufflation is adjusted to the patient's breathing to provide maximum chest expansion and rapid lung emptying, in general 2 to 4 seconds for adults but much more quickly for small children. Treatments continue until no further secretions are able to be removed and oxyhemoglobin desaturation due to mucus plugging is reversed. The abdominal thrust is also important for infants. By 2.5 to 5 years of age, children become accustomed to coughing simultaneously with the insufflation-exsufflation.

With the elimination of airway secretions and mucus using MAC, vital capacity, abnormal pulmonary flow rates and oxyhemoglobin saturation can improve immediately (Bach et al., 1993). Fifteen percent to 42 percent increase in VC was noted immediately following MAC for 67 patients with "obstructive dyspnea" and a 55 percent increase in VC was noted in patients with neuromuscular conditions (Barach, 1954). In ventilator assisted neuromuscular disease patients with chest infections, a 15 to 400 percent (200 to 800 mL) increase was noted following secretion removal with MAC (Bach, 1993).

Although MAC can augment and even substitute for the inspiratory and expiratory muscles, if bulbar innervated muscles, which prevent airway collapse and protect against food and saliva aspiration, are inadequately functioning, tracheotomy becomes indicated. However, this is generally only observed in advanced bulbar ALS patients. Patients with intact bulbar muscle function can usually air stack to volumes of 3 L or more, and, unless very scoliotic or obese, a properly delivered abdominal thrust can result in assisted CPF of 6 to 9 L/s, which is sufficient to clear secretions and prevent pneumonia and ARF without requiring MAC. Those with moderately impaired bulbar muscle function, e.g., non-ALS neuromuscular disease patients like those with Duchenne muscular dystrophy, that limits assisted CPF to less than 300 L/m benefit the most from MAC (Gomez-Merino, 2002).

#### **4.3.2 Glossopharyngeal Breathing**

Glossopharyngeal Breathing (GPB) is a technique that involves "gulping" boluses of air into the lungs using the glottis to add to the inspiratory effort. Six to 9 gulps (40 mL to 200 mL) total a full breath. The technique can be taught, to assist inspiratory and indirectly expiratory muscle function in patients with good bulbar-innervated musculature (Bach et al., 1987), allowing for discontinuation of ventilator use from minutes up to a whole day. Initial training can be supplemented with a training manual and videos (Dail et al., 1979; Dail & Affeldt, 1954). The patient's developing proficiency can be monitored using spirometry to measure the milliliter of air per gulp, gulps per breath and the breaths per minute as seen in Figure 6.

Fig. 6. Glossopharyngeal breathing used for 6 liters of minute ventilation in "gulps" of 60 to 90 mL or 6 to 8 gulps per breath, 12 breaths per minute, for autonomous respiration despite having 0 mL of vital capacity for 52 years (Bach et al., 1987).

Normal minute ventilation and normal alveolar ventilation can be maintained by glossopharyngeal breathing for individuals with little to no measurable vital capacity. Autonomous breathing is possible from minutes to up to all day by using it. It has been noted that 60% of ventilator users with no autonomous ability to breathe and sufficient bulbar muscle function can use GPB for ventilator-free breathing (Bach et al., 1987; Bach & Alba, 1990). This technique is ideal in the event of ventilator failure or disconnection during the day or night (Bach et al., 1987; Bach, 1991). The versatility and safety afforded by GPB are safeguards that make noninvasive management safer than support via tracheostomy. Although severe oropharyngeal muscle weakness can limit the effectiveness of GPB, 13 Duchenne muscular dystrophy patients with no breathing tolerance could be maintained solely with GPB (Bach et al. 2007).

#### **4.3.3 Oximetry monitoring**

244 Neuromuscular Disorders

Mechanically assisted coughing (MAC) combines mechanical insufflation-exsufflation with an exsufflation-timed abdominal thrust to increase CPF. The CoughAssistTM can be manually or automatically cycled with the deep insufflations followed immediately by deep exsufflations, ideally with pressures of 40 to 60 alternating with -40 to -60 cm H2O. Interfaces for MAC include oral-nasal masks, a simple mouthpiece, or translaryngeal or tracheostomy tubes. With use via a tracheostomy tube, the cuff, if present, should be inflated. Manual cycling allows caregiver-patient coordination during inspiration and expiration with the

Treatments can be as frequent as up to every 30 minutes during respiratory infections and post-extubation. One treatment set includes about five cycles of MAC followed by a short period of normal breathing or ventilator use to avoid hyperventilation. When patients cannot cooperate with MAC, the timing of the insufflation and exsufflation is adjusted to the patient's breathing to provide maximum chest expansion and rapid lung emptying, in general 2 to 4 seconds for adults but much more quickly for small children. Treatments continue until no further secretions are able to be removed and oxyhemoglobin desaturation due to mucus plugging is reversed. The abdominal thrust is also important for infants. By 2.5 to 5 years of age, children become accustomed to coughing simultaneously with the

With the elimination of airway secretions and mucus using MAC, vital capacity, abnormal pulmonary flow rates and oxyhemoglobin saturation can improve immediately (Bach et al., 1993). Fifteen percent to 42 percent increase in VC was noted immediately following MAC for 67 patients with "obstructive dyspnea" and a 55 percent increase in VC was noted in patients with neuromuscular conditions (Barach, 1954). In ventilator assisted neuromuscular disease patients with chest infections, a 15 to 400 percent (200 to 800 mL) increase was noted

Although MAC can augment and even substitute for the inspiratory and expiratory muscles, if bulbar innervated muscles, which prevent airway collapse and protect against food and saliva aspiration, are inadequately functioning, tracheotomy becomes indicated. However, this is generally only observed in advanced bulbar ALS patients. Patients with intact bulbar muscle function can usually air stack to volumes of 3 L or more, and, unless very scoliotic or obese, a properly delivered abdominal thrust can result in assisted CPF of 6 to 9 L/s, which is sufficient to clear secretions and prevent pneumonia and ARF without requiring MAC. Those with moderately impaired bulbar muscle function, e.g., non-ALS neuromuscular disease patients like those with Duchenne muscular dystrophy, that limits assisted CPF to less than 300 L/m benefit the most from MAC (Gomez-Merino, 2002).

Glossopharyngeal Breathing (GPB) is a technique that involves "gulping" boluses of air into the lungs using the glottis to add to the inspiratory effort. Six to 9 gulps (40 mL to 200 mL) total a full breath. The technique can be taught, to assist inspiratory and indirectly expiratory muscle function in patients with good bulbar-innervated musculature (Bach et al., 1987), allowing for discontinuation of ventilator use from minutes up to a whole day. Initial training can be supplemented with a training manual and videos (Dail et al., 1979;

**4.3.1 Mechanically assisted coughing** 

insufflation and exsufflation.

insufflation-exsufflation.

following secretion removal with MAC (Bach, 1993).

**4.3.2 Glossopharyngeal Breathing** 

Oximetry monitoring, through the use of a pulse oximeter, is essential in managing patients with NMD using respiratory muscle aids. A SpO2 alarm set at 94% alerts the patient to take deeper breaths to maintain SpO2 consistently over 94% all day (Gomez-Marino & Bach, 2002), and when tiring, to take ventilator assisted breaths usually via a mouthpiece. Thus, SpO2 feedback provides a method to monitor a hypercapnic patient with desaturation due to chronic alveolar hypoventilation and during transition from tracheostomy ventilation. If the patient is unable to independently maintain a sufficient level of at least SpO2 of 94%, mouthpiece or nasal NIV should be initiated for increasing periods to maintain normal SpO2 which helps to reset central ventilatory drive. Thereby, oximetry feedback facilitates the introduction and indicates the extent of daytime need for mouthpiece and/or nasal NIV. In addition, oximetry monitoring is especially useful during episodes of respiratory tract infection as an indicator to use MAC to prevent cold triggered pneumonias and acute respiratory failure, usually due to mucus plugging in the NIV patient population. Proper

Respiratory Muscle Aids in the Management of Neuromuscular

dependence since 4 months of age.

vital capacity.

Respiratory Impairment to Prevent Respiratory Failure and Need for Tracheostomy 247

Fig. 7. Two brothers with spinal muscular atrophy type 1 and continuous ventilator

Fig. 8. The same brothers as in Figure 7, now 16 and 14 years of age and with no measurable

In our 176 ALS patients using nocturnal NIV, 42 percent (109 ALS patients) progressed to requiring continuous NIV due to progression of disease, developing severe bulbar innervated muscle impairment that would eventually lead to requiring tracheotomy. Significant aspiration, resulting in consistent baseline SpO2 desaturations to below 95%, due to the

weakness of bulbar innervated muscles is the sole indication for tracheotomy in NMD.

instruction of NIV and MAC, and rapid access to MAC during the onset of a chest cold may be all that is necessary to avert pneumonia, ARF and subsequent hospitalizations.

Especially in infants and small children, with often inadequate cough to prevent chest colds from triggering pneumonia and ARF, MAC should be used for any desaturation below 95 percent. In continuous NIV users, desaturations are usually due to bronchial mucus plugging, which can develop into atelectasis and pneumonia if the secretions are not quickly cleared.
