Respiratory Management of Neuromuscular Disorders John R. Bach, MD
ICD-10 Codes G71.0 G12.9 G12.21 Z99.01 M62.81 G12.0
Muscular dystrophy G71.0 Spinal muscular atrophy Amyotrophic lateral sclerosis Dependence on respirator Generalized muscle weakness Infantile spinal muscular atrophy type 1
CPT Codes E0482 E0466 E0465
Mechanical insufflation-exsufflation Noninvasive mechanical ventilation Invasive mechanical ventilation
Definition The three respiratory muscle groups are: the inspiratory muscles, expiratory (predominantly abdominal and upper chest wall) muscles for coughing, and the bulbar-innervated muscles (BIMs). While the inspiratory and expiratory muscles can be completely supported by physical aids such as continuous noninvasive ventilatory support (CNVS) and mechanical insufflation-exsufflation (MIE) and patients have used these and avoided tracheostomy tubes for over 60 years and counting, there are no effective noninvasive measures to assist BIM function.1,2 However, even complete paralysis of BIM function does not preclude noninvasive management of chronic ventilatory muscle failure. Respiratory, or inspiratory and expiratory muscle aids, are devices and techniques that involve the manual or mechanical application of forces to the body, or intermittent pressure changes to the airway, to assist inspiratory 868
and expiratory muscle function. The devices that act on the body include body ventilators that create pressure changes around the thorax and abdomen. Negative pressure applied to the airway during expiration assists coughing just as positive pressure applied to the airway during inhalation (intermittent positive pressure ventilation or noninvasive ventilatory support [NVS]) assists or supports the inspiratory muscles. Continuous positive airway pressure does not assist ventilation and is not useful for patients with ventilatory impairment on the basis of neuromuscular disorders (NMDs). Respiratory muscle aids can greatly diminish the need to resort to invasive airway tubes, permit long-term survival, and permit the extubation and tracheostomy tube decannulation of ventilator-dependent (“unweanable”) patients. Physical medicine respiratory muscle aids including NVS and MIE can prolong survival for patients with little or no vital capacity (VC) or any ability to cough. Most aspects of this medical discipline were developed by physiatrists.3
Symptoms While patients with diminished ventilatory reserve who are able to walk complain of exertional dyspnea, wheelchair users’ symptoms may be minimal except during intercurrent respiratory infections when they may complain of anxiety, inability to fall asleep, and possibly dyspnea. Morning headaches, fatigue, sleep disturbances, and hypersomnolence result from nocturnal hypoventilation which is due to decreased ability to recruit accessory respiratory muscles, depressed respiratory drive, and cough during sleep.4
Physical Examination Signs of inspiratory muscle impairment and hypoventilation can include tachypnea, paradoxic breathing, hypophonia, nasal flaring, accessory respiratory muscle use, cyanosis, flushing or pallor, anxiety, and airway secretion congestion. Lethargy, obtundation, and confusion signal CO2 narcosis. Often there are no signs other than tachypnea despite symptoms of hypoventilation.
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Functional Limitations With diminished respiratory reserve, walking becomes limited by dyspnea; however, wheelchair users’ function is typically not limited by hypoventilation until CO2 levels rise to the point of obtundation.
Diagnostic Studies Respiratory muscle dysfunction and hypoventilation are diagnosed by CO2 monitoring (capnograph or transcutaneous), oximetry, spirometry, and assessment of cough peak flows (CPF). End-tidal CO2 is typically 2 to 6 mm Hg less than arterial PCO2. The VC is measured in sitting and supine positions and their difference should not be greater than 7%. Since hypoventilation begins and is more severe during sleep, the supine VC is the more important. Orthopnea is common when the VC is less than 25% of normal or the VC in supine position is at least 20% less than when sitting. Patients wearing thoracolumbar bracing should have the VC measured both with the brace on and off, since a good fitting brace can increase VC whereas one that restricts abdominal movement can decrease it. Patients are taught glossopharygneal breathing (GPB) and its progress, as well as progress in the use of active (air stacking) and passive (insufflation) methods of lung volume recruitment (LVR), measured spirometrically. Patients air stack by receiving consecutively delivered volumes of air via manual resuscitator or volume-preset ventilator that are held by the glottis to the greatest volume possible. The maximum retained volume is measured spirometrically and termed the “maximum insufflation capacity” (MIC). 5 The maximum passively insufflated volume is termed the “lung insufflation capacity.”6 Likewise, GPB can often provide volumes of air to or beyond those achieved by air stacking with a manual resuscitator and is also measured spirometrically. A nasal interface or oronasal interface can be used for air stacking when the lips are too weak for air stacking via a mouthpiece. The MIC minus the VC is a direct measure of glottis integrity and, therefore, an objective, quantifiable, reproducible measure of BIM.5 CPF are measured using a peak flow meter. CPF below 160 L/m are generally ineffective.7 The attainment of (unassisted) CPF over 120 L/m is a strong indicator for successful tracheostomy tube decannulation, irrespective of remaining pulmonary function.8 Patients with VCs less than 1500 mL should have assisted CPF measured from a deep air stacked volume of air with an abdominal thrust delivered simultaneously with glottic opening (manually assisted cough);5 this assisted CPF is also measured by peak flow meter. The assisted minus unassisted CPF is also solely dependent on glottis function and an indicator of BIM integrity.5 For the stable patient without intrinsic pulmonary disease, arterial blood gas sampling is unnecessary and often less accurate, since 25% of patients hyperventilate due to anxiety and pain during the procedure.9 For symptomatic patients with normal VC, an unclear pattern of nocturnal oxyhemoglobin desaturation, and no apparent hypercapnia, a polysomnogram is warranted.
Polysomnography is unnecessary for symptomatic patients with decreased VC because it is programmed to interpret every apnea and hypopnea as resulting from central or obstructive events rather than from inspiratory muscle weakness. While all clearly symptomatic patients with diminished lung volumes require a trial of NVS to ease symptoms, if symptoms are questionable, nocturnal continuous capnography and oximetry can be useful and most practically done in the home. A questionably symptomatic patient with decreased VC, multiple nocturnal oxyhemoglobin desaturations below 95%, and elevated CO2 should be encouraged to try sleep NVS to see if it makes them feel better.
Treatment The Intervention Objectives The intervention goals are to promote normal lung and chest-wall growth for children and to maintain lung and chest-wall compliance, to maintain normal alveolar ventilation to prolong survival, and to maximize CPF to avert episodes of pneumonia and respiratory failure, particularly during intercurrent upper respiratory tract infections. Unweanable intubated and cannulated patients can also be extubated and decannulated to CNVS. All goals can be facilitated by evaluating, training, and equipping patients in the outpatient and home setting.
Goal One: Maintain Pulmonary Compliance, Lung Growth, and Chest-Wall Mobility Pulmonary compliance is diminished, and chest-wall contractures and lung restriction occur when the lungs cannot be expanded to predicted inspiratory capacity because of inspiratory muscle dysfunction. As the VC decreases, the largest breath one can take only expands an increasingly smaller fraction of lung volume. Like limb articulations, regular mobilization is required. This LVR can be achieved passively by providing deep insufflations, actively by air stacking, or for those unable to cooperate for active LVR, by nocturnal NVS.8 The primary objectives of lung expansion therapy are to increase VC and voice volume, to maximize CPF, to maintain pulmonary compliance, diminish atelectasis, and to master NVS since anyone who can air stack via a mouthpiece can use mouthpiece NVS anytime during the day as well as for successful extubation/decannulation even if not ventilator weaned. Impaired glottis closure precludes active LVR and indicates need for passive LRV by delivering pressures of 40 to 70 cm H2O to the lungs via a pressure-preset ventilator or by using a manual resuscitator with the exhalation valve blocked. In 282 evaluations of VC, MIC, and LIC, the mean values were 1131 ± 744 mL, 1712 ± 926 mL, and 2069 ± 867 mL, respectively.6 Before patients’ VCs decrease to 70% or 80% of predicted normal,10 they are instructed to air stack 10 to 15 times 2 or 3 times daily, usually using a manual resuscitator. Because of the importance of air stacking, NVS is
PART 3 Rehabilitation
preferentially provided via ventilator volume rather than pressure-preset. Infants cannot air stack or cooperate with passive insufflation therapy. All small children with paradoxic breathing require nocturnal NVS to prevent pectus excavatum and promote lung growth as well as for inspiratory muscle assistance.11 Children can become cooperative with passive LVR by 14 to 30 months of age.
Goal Two: Maintain Alveolar Ventilation Respiratory orthopnea, symptoms of hypoventilation,12 or paradoxic breathing in children indicate need for nocturnal NVS.11 Since, in general, only patients improperly treated with supplemental O2 develop CO2 narcosis,13 and since respiratory failure is most often caused by ineffective cough flows and airway secretion management, any patient finding that NVS use is more burdensome than beneficial on symptoms we advise to discontinue it until the next reevaluation. Because negative pressure body ventilators cause obstructive apneas, are less effective than NVS, and become even less effective with age and decreasing pulmonary compliance, they are no longer recommended for ongoing ventilatory assistance.14 One useful body ventilator, however, is the intermittent abdominal pressure ventilator (IAPV) (BachBelt, ResMed, Dima Italia, Bologna, Italy). The IAPV involves the intermittent inflation of an elastic air sac that is contained in a corset or belt worn beneath the patient’s outer clothing. The sac is cyclically inflated, often to 2500 mL or more, by a positive pressure ventilator. This moves the diaphragm upward to exsufflate the lungs. With bladder deflation, gravity causes the abdominal contents and diaphragm to return to the resting position and inspiration occurs. A trunk angle of 30 degrees or more from the horizontal is required for effectiveness. A patient can add to the IAPV delivered volume by breathing or using glossopharyngeal breathing along with it. The IAPV augments tidal volumes by 300 to as high as 1200 mL and is often preferred to mouthpiece NVS by patients with little autonomous breathing ability during daytime hours.15 Noninvasive ventilatory support can be delivered via lipseals, nasal, and oronasal interfaces during sleep or via mouthpiece or nasal interface during daytime hours. Mouthpiece and nasal NVS are open systems that require the user to rely on central nervous system reflexes to prevent excessive insufflation leakage during sleep;4,16 thus, supplemental oxygen and sedatives can render it ineffective. NVS can be introduced in the clinic or home setting. There are numerous commercially available vented and non-vented interfaces to use. For the delivery of mouthpiece or nasal NVS to permit air stacking, an active ventilator circuit—that is, one with an exhalation valve—should be used along with a non-vented interface or a vented interface with the ports sealed. Several nasal interfaces should be tried for sleep and if nasal NVS is used aroundthe-clock, the nasal interfaces should be alternated every 12 hours to avoid prolonged skin pressure. Excessive insufflation leakage or air out of the mouth can be avoided if necessary by switching from an open to a closed system by
using a nasal prongs-lipseal system. Such interfaces deliver air via mouth and nose during sleep and require minimal strap pressure. This optimizes skin comfort and minimizes air (insufflation) leakage. The most useful method for daytime NVS is via a 15 mm angled mouthpiece. Although some prefer to keep the mouthpiece in the mouth all day, most have it fixed adjacent to the mouth by a flexible metal support arm (gooseneck clamp) that is attached to their wheelchair.17–19 The mouthpiece can also be fixed onto motorized wheelchair controls (e.g., sip and puff, chin, and tongue controls) (Fig. 151.1). Large volumes of 800 to 1500 mL are delivered to adolescents and adults so that the patient can take as much of the air as desired for each breath to vary tidal volumes, speech volume, and cough flows as well as to air stack. Neck movement and lip function are needed to use mouthpiece NVS; otherwise, a nasal prongs system or IAPV is used for daytime support.15 Nasal NVS is also most practical for nocturnal and daytime use by infants since they are obligate nose breathers. Other than perhaps for uncontrollable seizures and inability to cooperate, there are no contraindications to the use of NVS long term.
Goal Three: Augment Cough Flows In a study of manually assisted coughing (air stacking and abdominal thrust) for 364 patients, whereas mean VC was 997 mL, mean MIC was 1648 mL, and although CPFs were 135 L/m, mean assisted CPF were 235 L/m. This can be the difference between developing pneumonia or coughing effectively to prevent it.20 The inability to generate 160 L/m of assisted CPF despite having a VC or MIC greater than 1 L indicates upper-airway obstruction, which can be due to severe BIM dysfunction or other lesion that should be identified by laryngoscopy to correct reversible lesions. Mechanically assisted coughing is the use of MIE along with an exsufflation-timed abdominal thrust when this has been demonstrated to further increase exsufflation flows (MIE-EF). MIE insufflation and exsufflation pressures of
FIG. 151.1 A 64-year-old woman who depended on continuous noninvasive ventilatory support (CNVS) since 1953 and CNVS via 15 mm angled mouthpiece for 34 years with the mouthpiece fixed adjacent to the chin control of her motorized wheelchair.
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50 to 60 cm H2O via a mouthpiece or oronasal interface are used unless these pressures cause stridor, in which case flows as low as 40 cm H2O may maximize MIE-EF. MIE is also effective via translaryngeal and tracheostomy tubes at pressures of 60 to 70 cm H2O. When delivered via invasive airway tubes their cuff, if present, should be inflated. Most MIE devices on the market can be manually or automatically cycled. Manual cycling facilitates caregiver-patient coordination of inspiration and expiration with insufflation and exsufflation, but it requires hands to deliver an abdominal thrust, to hold the interface on the patient, and to operate machine cycling. The pressure preset ventilator can also be used to permit the user to trigger every MIE. One treatment consists of about five MIE cycles followed by a short period of normal breathing or ventilator use to avoid hyperventilation. Insufflation and exsufflation times are adjusted to provide maximum observable chest expansion, then full lung emptying. In general, 2 to 3 seconds are required. Treatment continues until no further secretions are expulsed and secretion-related oxyhemoglobin desaturations are reversed. Use can be required as often as every 20 minutes around the clock during upper respiratory tract infections. The use of MIE via the upper airway can be effective for children as young as 11 months of age who can occasionally facilitate its efficacy by not crying or closing the glottis. Between 2.5 and 5 years of age, most children fully cooperate with it. Before that the insufflations and exsufflations are timed to the child’s own breathing cycle or triggered by the child to maintain normal O2 sat to avert pneumonia and respiratory failure. Triggering can greatly facilitate effective use by infants. While conventional airway suctioning misses the left main stem bronchus about 90% of the time,21 MIE effectively expulses debris from both left and right airways without the discomfort or airway trauma. Patients prefer it to suctioning.22 Deep suctioning, whether via tube or upper airway, becomes unnecessary for most patients. VC, pulmonary flow rates, and oxyhemoglobin saturation (O2 sat) when abnormal can improve immediately with clearing of airway secretions by MIE.23 An increase in VC of 15% to 42% was noted immediately following treatment in 67 patients with “obstructive dyspnea,” and a 55% increase in VC was noted following MIE for patients with NMDs.24 We have observed 15% to 400% (200 to 800 mL) improvements in VC and normalization of O2 sat for patients during chest infections.25
MIE takes the place of the inspiratory and expiratory muscles. However, ventilator users with intact bulbar muscles can usually air stack to volumes of 3 L or more, and, unless very scoliotic or obese, can achieve effective assisted CPF of over 300 L/m and may not need MIE. Thus, the patients who need it the most have moderately to severely impaired BIM function that limits assisted CPF to less than 300 L/m. This is typical of spinal muscular atrophy, Duchenne muscular dystrophy (DMD), and other myopathies.20 Remarkably, MIE is effective even for patients with no inspiratory, expiratory, or BIM function at all. Our 20+ year-old patients with SMA type 1 who have 0 mL of VC and absolutely no BIM function for over 15 years can achieve over 350 L/m of MIE-EF and, therefore, very effective expulsion of airway debris using MIE. A type of pressure-preset ventilator permits measurements of MIE-EF. Flows generally over 150 L/m are effective. Whereas MIE is effective for these patients with SMA type 1 and all other severe NMDs who have no BIM at all, it eventually becomes ineffective for patients with ALS, whose BIM dysfunction is from upper motor neuron disease or central nervous system disease that causes stridor due to reflex hypertonicity of the larynx and upper airways.26 For these patients, MIE-EF may not exceed 100 L/m at the point at which they require tracheotomy for continued survival. Patients with respiratory muscle weakness complicated by scoliosis with inability to capture the asymmetric diaphragm by abdominal thrusting can also greatly benefit from MIE.
Glossopharyngeal Breathing Both inspiratory and, indirectly, expiratory muscle function can be assisted by GPB.28 This is the glottis pistoning boluses of air into the lungs. One GPB breath usually consists of 6 to 9 gulps of 40 to 200 mL each (Fig. 151.2). During the training period, its efficiency can be monitored by spirometrically measuring the milliliters of air per piston action, actions per breath, and breaths per minute. A training manual27 and numerous videos are available,28 the most analytical of which was produced in 1999.29 Approximately 60% of ventilator users with no autonomous ability to breathe but with good bulbar muscle function can use GPB for ventilator-free breathing up to all day.30,31 This includes patients with no VC at all.30,31
1600 1200 800
400 0 60
FIG. 151.2 Graph of glossopharyngeal breathing volumes for a patient with no measurable vital capacity for 52 years and intact bulbarinnervated musculature. He could glossopharyngeal breathe all day with normal minute ventilation and tidal volumes, rate 12 per minute. (With permission from the March of Dimes.)
PART 3 Rehabilitation
Severe oropharyngeal muscle weakness, however, can limit or eliminate the usefulness of GPB. Thus, about 70% of high level patients with spinal cord injury,32,33 but only about 25% of CNVS users with DMD who have no ventilator-free breathing ability, can use GPB for it.34 Furthermore, GPB is rarely useful in the presence of an indwelling tracheostomy tube. Patients dependent on continuous tracheostomy mechanical ventilation (CTMV) fear sudden ventilator failure or accidental ventilator disconnection.30,31,35 GPB eliminates this. Indeed, the safety and versatility afforded by GPB are key reasons for tube decannulation or avoidance of tracheostomy in favor of NVS and MIE.
Oximetry Monitoring and Feedback Protocol For a hypercapnic patient with oxyhemoglobin desaturation due to chronic alveolar hypoventilation or the patient being weaned from CTMV, introduction to and use of mouthpiece or nasal NVS is facilitated by oximetry feedback. An O2 sat alarm set at 94% signals the patient to return O2 sat to normal—that is, 95% or greater—by taking deeper breaths.20 When it is no longer possible to achieve this by unassisted breathing, it is done by mouthpiece or nasal NVS. With advancing disease and muscle weakness, the patient requires increasing periods of daytime NVS to maintain normal O2 sat and intact central ventilatory drive. Continuous O2 sat feedback is especially important during respiratory tract infections. The cough of infants and small children who can never sit is inadequate to prevent chest cold-triggered pneumonia and ARF. MIE needs to be used for any dip in O2 sat below 95%. When using NVS continuously, such dips are usually due to bronchial mucus plugging rather than hypoventilation, and if the mucus is not quickly cleared, atelectasis and pneumonia can ensue. Thus, patients are simply instructed and equipped to use NVS and MIE to maintain normal SpO2 to avert pneumonia and respiratory failure. For adults with infrequent chest colds, rapid access to MIE may be all that is necessary.
Technology No new technology is available for the treatment or rehabilitation of these patients.
Surgery No surgery is indicated in these patients.
Long-Term Outcomes We currently have 55 patients with typical to severe SMA type 1 using NVS. They began sleep NVS at 0.4 ± 0.5 years of age, used it for less than CNVS for 3.8 ± 6.3 years, and 27 are now CNVS dependent with little or no autonomous ability to breathe for 12.0 ± 3.5 years to a current age of 13.9 ± 3.4 years of age. Seven became CNVS dependent without being hospitalized and 15 are still CNVS dependent, 7 died, and 4 underwent tracheotomy, although 3 of the 4 were in other states, at 4.8 ± 3.7 years of age. Others have also reported CNVS dependence for patients with SMA type 1 (Figs. 151.1–151.3).37
FIG. 151.3 A 24-year-old male with spinal muscular atrophy type 1 who is continuously dependent on nasal noninvasive positive pressure ventilation support.
Of 116 of our patients with DMD who began sleep nasal NVS at 20.3 ± 2.8 years of age and used it for less than CNVS for 2 ± 2.1 years, 114 became CNVS dependent at 22.5 ± 5.9 years of age thus far for a mean 11.0 ± 5.9 years to a mean 33.6 ± 6.1 years of age; 38 became CNVS dependent without developing ARF or being hospitalized; 95 continue to use CNVS, 1 underwent tracheotomy, and 21 died from cardiac/sudden and apparently non-respiratory causes. Eight CTMV users were decannulated to CNVS and 65 intubated and ventilator “unweanable” DMD patients with intercurrent pneumonias were extubated successfully back to CNVS and MIE without resort to tracheotomy. Eleven of our DMD patients have now lived to over age 40, up to 53, using CNVS for 22 to 28 years. Twenty-one other centers have also reported prolongation of life for DMD by CNVS.37 In one of them, 21 consecutive DMD patients whose ventilatory insufficiency was managed by tracheostomy died at a mean 28.1 years of age as opposed to 88 consecutive CNVS users for whom 50% survival was to age 39.6 without tracheostomy tubes.17 None of over 250 CNVS dependent patients with DMD in a multicenter study have undergone tracheotomy.37 Of 246 ALS patients, 179 began sleep NVS at 55.9 ± 5.6 years of age, used it for less than CNVS for 1.2 ± 1.3 years, then 115 went on to be CNVS dependent for 1.2 ± 3.4 (0.1 to 10.2) years before their O2 sat baseline decreased below 95% due to upper motor neuron upper airway collapse and they required tracheotomy for further survival. Another center reported that 25% of ALS patients survived for almost 1 year using NVS before needing a tracheotomy or dying.37
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Table 151.1 Extubation Criteria for Ventilator “Unweanable” Patients • Oxyhemoglobin saturation (O2 sat) ≥95% in ambient air with CO2 < 40 mm Hg for at least 12 h on up to full ventilatory support, normal HCO3− • Peak inspiratory pressures less than 35 cm H2O on up to full ventilatory support settings • Afebrile and normal white blood cell count • Fully alert and cooperative, receiving little or no sedative medications • Air leakage via upper airway documenting patency upon cuff deflation • Chest radiograph abnormalities cleared or clearing
Extubation of Unweanable Patients Specific extubation criteria and a new extubation protocol were developed for the “unweanable” patients with neuromuscular respiratory muscle failure (Table 151.1). Once meeting criteria, any oro- or nasogastric tube present is removed to facilitate post-extubation nasal NVS. The patient is then extubated directly to NVS or CNVS on assist/control at volumes two to four times those of normal tidal volumes and physiological back-up rates in ambient air. The NVS is delivered via nasal, oronasal, and/or mouthpiece interfaces. Post-extubation, patients wean if they can by using nasal NVS for decreasing periods of time or by taking fewer and fewer breaths via an accessible 15 mm angled mouthpiece (Fig. 151.1), as tolerated. Although mouthpiece NVS is preferred, nasal NVS is used for those who cannot secure the mouthpiece between their teeth. Patients are taught active LVR (air stacking) via mouthpiece or non-vented nasal interface along with volume preset ventilation delivered via active ventilator circuits.5,38 Oximetry feedback is used to maintain O2 sat greater than 95% with adequate use of NVS and MIE.2 The therapists, nurses, and family and personal care attendants provide MIE via mouthpieces or oronasal interfaces up to every 20 to 30 minutes until O2 sat no longer dips below 95% and the patient feels clear of secretions. When post-extubation oral intake is considered unsafe, open gastrostomies, radiographically inserted gastrostomies, or percutaneous endoscopic gastrostomies via oronasal interfaces that permit continued CNVS (without intubation) are performed.39 Data were reported on the extubations of 157 consecutive “unweanable” patients to CNVS: 25 with SMA, 20 with DMD, 16 with ALS, 51 with other NMDs, 17 with spinal cord injury, and 11 with polio. Eighty-three who refused tracheostomies were transferred from other hospitals. None could not pass spontaneous breathing trials before or after extubation. Once meeting criteria, besides being extubated to CNVS, their care providers are taught and instructed to provide MIE at 50 to 60 cm H2O pressures to maintain normal O2 sat for at least the first 36 hours post-extubation in the critical care unit.
One hundred fifty-five of the 157 extubations were successful, including 149 (95%) on the first try. Six of eight were successful on the second or third attempt, so only two bulbar ALS patients with severe stridor underwent tracheotomy.40 In 2015 we reported the successful extubation of 97 of 98 more such patients including 26 with SMA type 1 and described the importance of using MIE via the translaryngeal tube to normalize O2 sat to prepare the patient for successful extubation. The only patient who underwent tracheotomy did so because of cardiovascular instability.38
Decannulation of Unweanable Patients In 1990 and 1991 the decannulation of 50 high-level traumatic spinal cord injured patients to NVS was reported. 30,35 Because of their usually intact bulbar musculature, such patients are usually excellent candidates for decannulation and noninvasive management (Table 151.2). In 1996 we reported the decannulation of 50 unweanable patients with NMD. 7 In 2015 we reported the successful decannulation of 61 ventilator unweanable CTMV dependent patients with NMDs or SCI to CNVS and MIE, 51 of whom in the outpatient setting. 8 Their VCs increased significantly after decannulation, even though 34 of the 61 had been ventilated via tracheostomy tubes for 18.1 ± 21.1 months. None underwent re-tracheotomy over an 8-year follow-up. Thirty-two were CNVS dependent following decannulation, but 26 weaned from continuous ventilatory support. The principles of decannulating are essentially the same as those for extubation. Any ventilator dependent patient whose BIM is sufficient to avoid a continuous decrease in O2 sat below 95% is a candidate for decannulation to NVS. Patients who had been using CTMV without ventilator-free breathing ability but who had VCs of 250 mL or greater invariably weaned from CNVS following decannulation. Many weaned to nocturnal-only NVS within 3 weeks of decannulation. Tube removal also facilitated speech and swallowing.40 In one study, all patients who had depended on CTMV and CNVS for at least 1 month or more preferred the latter for convenience, speech, swallowing, cosmesis, comfort, safety, and preferred it overall.41
Potential Treatment Complications Abdominal distention tends to occur sporadically in NVS users. The air usually passes as flatus once the patient is mobilized in the morning. When severe, however, it can increase ventilator dependence and necessitate burping the air out by opening a gastrostomy or nasogastric tube when present. Otherwise, switching from volume to pressure-preset ventilation for sleep can decrease or eliminate the distention. A number of our patients have undergone gastrostomy placement for burping out the air rather than tracheotomy. Use of NVS by patients with severe aerophagia and abdominal distention even prior to its use, however, can severely exacerbate distention and necessitate tracheotomy.
PART 3 Rehabilitation
Table 151.2 Management of Patients With Spinal Cord Injury Motor Level
Bulbar Function/Neck Functiona
neck function involves sufficient oral and neck muscular function to grab a mouthpiece adjacent to the mouth; bulbar function adequate for O2 sat baseline ≥95% in ambient air. EPR, Electrophrenic pacing; IAPV, intermittent abdominal pressure ventilator15; MPNVS, mouthpiece noninvasive ventilatory support; NNVS, nasal noninvasive ventilatory support; TMV, tracheostomy mechanical ventilation.
Despite aggressive LVR three times daily, often to over 80 cm H2O pressures, and use of up to CNVS for over 60 years in many cases, we have had only one case of pneumothorax for over 2000 NVS users.36 Although airway congestion is often described as a complication or limiting factor for NVS, it is often due to failure to administer MIE. Indeed, patients are more likely to die from complications of tracheostomy management due to failure to use NVS and MIE at pressures adequate to prevent pneumonia and ARF.
References 1. Bach JR. Update and perspectives on noninvasive respiratory muscle aids: part 1–the inspiratory muscle aids. Chest. 1994;105: 1230–1240. 2. Bach JR, Bianchi C, Aufiero E. Oximetry and indications for tracheotomy in amyotrophic lateral sclerosis. Chest. 2004;126: 1502–1507. 3. Bach JR, Tuccio MC. Respiratory physical medicine: physiatry’s neglected discipline. Am J Phy Med Rehabil. 2011;90(2):169–174. 4. Bach JR, Alba AS. Management of chronic alveolar hypoventilation by nasal ventilation. Chest. 1990;97:52–57. 5. Kang SW, Bach JR. Maximum insufflation capacity. Chest. 118:61–65. 6. Bach JR, Mahajan K, Lipa B, Saporito L, Komaroff E. Lung insufflation capacity in neuromuscular disease. Am J Phys Med Rehabil. 2008;87:720–725. 7. Bach JR, Saporito LR. Criteria for extubation and tracheostomy tube removal for patients with ventilatory failure. A different approach to weaning. Chest. 1996;110:1566–1571. 8. Bach JR, Saporito LR, Shah HR, Sinquee D. Decannulation of patients with severe respiratory muscle insufficiency: efficacy of mechanical insufflation-exsufflation. J Rehabil Med. 2014;46:1037–1041. 9. Currie DC, Munro C, Gaskell D, et al. Practice, problems and compliance with postural drainage: a survey of chronic sputum producers. Br J Dis Chest. 1986;80:249–253. 10. McKim DA, Katz SL, Barrowman N, Ni A, LeBlanc C. Lung volume recruitment slows pulmonary function decline in Duchenne muscular dystrophy. Arch Phys Med Rehabil. 2012;93:1117–1122. 11. Bach JR, Baird JS, Plosky D, et al. Spinal muscular atrophy type 1: management and outcomes. Pediatr Pulmonol. 2002;34:16–22. 12. Bach JR, Alba AS. Management of chronic alveolar hypoventilation by nasal ventilation. Chest. 1990;97(1):52–57. 13. Chiou M, Bach JR, Saporito LR, Albert O. Quantitation of oxygen induced hypercapnia in respiratory pump failure. Rev Port Pneumol. 2016;22(5):262–265. 14. Bach JR, Alba AS, Shin D. Management alternatives for post-polio respiratory insufficiency: assisted ventilation by nasal or oral-nasal interface. Am J Phys Med Rehabil. 1989;68:264–271. 15. Bach JR, Alba AS. Intermittent abdominal pressure ventilator in a regimen of noninvasive ventilatory support. Chest. 1991;99:630–636. 16. Bach JR, Robert D, Leger P, et al. Sleep fragmentation in kyphoscoliotic individuals with alveolar hypoventilation treated by nasal IPPV. Chest. 1995;107:1552–1558.
17. Ishikawa Y, Miura T, Ishikawa Y, et al. Duchenne muscular dystrophy: survival by cardio-respiratory interventions. Neuromuscul Disord. 2011;21:47–51. 18. Bach JR, Alba AS, Saporito LR. Intermittent positive pressure ventilation via the mouth as an alternative to tracheostomy for 257 ventilator users. Chest. 1993;103:174–182. 19. Bach JR, Gonçalves MR, Hon AJ, et al. Changing trends in the management of end-stage respiratory muscle failure in neuromuscular disease: current recommendations of an international consensus. Am J Phys Med Rehabil. 2013;92(3):267–277. 20. Gomez-Merino E, Bach JR. Duchenne muscular dystrophy: prolongation of life by noninvasive respiratory muscle aids. Am J Phys Med Rehabil. 2002;81:411–415. 21. Fishburn MJ, Marino RJ, Ditunno JF Jr. Atelectasis and pneumonia in acute spinal cord injury. Arch Phys Med Rehabil. 1990;71:197–200. 22. Garstang SV, Kirshblum SC, Wood KE. Patient preference for inexsufflation for secretion management with spinal cord injury. J Spinal Cord Med. 2000;23:80–85. 23. Bach JR, Smith WH, Michaels J, et al. Airway secretion clearance by mechanical exsufflation for post-poliomyelitis ventilator assisted individuals. Arch Phys Med Rehabil. 1993;74:170–177. 24. Barach AL, Beck GJ. Exsufflation with negative pressure: physiologic and clinical studies in poliomyelitis, bronchial asthma, pulmonary emphysema and bronchiectasis. Arch Intern Med. 1954;93:825–841. 25. Bach JR. Mechanical insufflation-exsufflation: comparison of peak expiratory flows with manually assisted and unassisted coughing techniques. Chest. 1993;104:1553–1562. 26. Andersen T, Sandnes A, Brekka AK, et al. Laryngeal response patterns influence the efficacy of mechanical assisted cough in amyotrophic lateral sclerosis. Thorax. 2017;72(3):221–229. 27. Dail C, Rodgers M, Guess V, et al. Glossopharyngeal Breathing. Downey, CA: Rancho Los Amigos Department of Physical Therapy; 1979. 28. Dail CW, Affeldt JE. Glossopharyngeal breathing [video]. Los Angeles: Department of Visual Education, College of Medical Evangelists; 1954. 29. Webber B, Higgens J. Glossopharyngeal breathing: What, when and how? [Video]. Holbrook, Horsham: West Sussex, England: Aslan Studios Ltd; 1999. 30. Bach JR. New approaches in the rehabilitation of the traumatic high level quadriplegic. Am J Phys Med Rehabil. 1991;70:13–20. 31. Bach JR, Alba AS, Bodofsky E, et al. Glossopharyngeal breathing and noninvasive aids in the management of post-polio respiratory insufficiency. Birth Defects. 1987;23:99–113. 32. Bach JR, Alba AS. Noninvasive options for ventilatory support of the traumatic high level quadriplegic. Chest. 1990;98(3):613–619. 33. Bach JR. New approaches in the rehabilitation of the traumatic high level quadriplegic. Am J Phys Med Rehabil. 1991;70(1):13–20. 34. Bach JR, Bianchi C, Vidigal-Lopes M, et al. Lung inflation by glossopharyngeal breathing and “air stacking” in Duchenne muscular dystrophy. Am J Phys Med Rehabil. 2007;86:295–300. 35. Bach JR, Alba AS. Noninvasive options for ventilatory support of the traumatic high level quadriplegic. Chest. 1990;98:613–619. 36. Suri P, Burns SP, Bach JR. Pneumothorax associated with mechanical insufflation-exsufflation and related factors. Am J Phys Med Rehabil. 2008;87(11):951–955.
CHAPTER 151 Respiratory Management of Neuromuscular Disorders
37. Gonçalves MR, Bach JR, Ishikawa Y, Saporito, Winck JC. Continuous noninvasive ventilatory support outcomes for neuromuscular disease: a multicenter collaboration and literature review. Port J Pulmono. (in press). 38. Bach JR, Sinquee D, Saporito LR, Botticello AL. Efficacy of mechanical insufflation-exsufflation in extubating unweanable subjects with restrictive pulmonary disorders. Respir Care. 2015;60(4):477–483. 39. Sharma A, Bach JR, Swan KG. Gastrostomy under local anesthesia for patients with neuromuscular disorders. Am Surg. 2010;76(4):369–371.
40. Bach JR, Gonçalves MR, Hamdani I, Winck JC. Extubation of unweanable patients with neuromuscular weakness: a new management paradigm. Chest. 2010;137:1033–1039. 41. Bach JR. A comparison of long-term ventilatory support alternatives from the perspective of the patient and care giver. Chest. 104:1702–1706.