OUTCOMES:
Duchenne Muscular Dystrophy (DMD)

 

BACKGROUND

 

Duchenne muscular dystrophy (DMD) is the classic neuromuscular disease type 3. Despite being relatively severe and rapidly progressive, nearly all properly managed people never require a tracheostomy tube. In addition, the majority of people with DMD can:

  • Avoid episodes of serious breathing problems (i.e. respiratory failure),

  • Avoid frequent hospitalizations, and

  • Avoid invasive airway tubes passed through the neck and into the windpipe (i.e. invasive airway tubes).

 

The principles of management of people with DMD are essentially identical to those for managing all other myopathies and neurological disorders of muscle flaccidity.

 

Hypoventilation

\ˈhī-(ˌ)pō-ˌvent-əl-ˈā-shən\

Deficient ventilation of the lungs that results in reduction in the oxygen content (PaO2) and/or increase in the carbon dioxide content (PaCO2) of the blood.

 

People living with DMD will require nocturnal/sleep noninvasive ventilatory support (NVS) to relieve symptoms of hypoventilation during sleep once vital capacity (VC) decreases below 700 mL. They will gradually extend nocturnal/sleep NVS into daytime hours. Eventually, they will use continuous NVS (CNVS) without ever developing respiratory failure or being hospitalized or intubated.

 

Symptoms of hypoventilation:

  • Morning headaches

  • Daytime sleepiness

  • Daytime fatigue

 

Typically, people living with DMD (or other myopathies/disorders of muscle flaccidity) can depend on CNVS for improved survival up to 20-30 years or more (cardiac function permitting) without any need to consider tracheotomy.

 

Although no person with DMD should ever need a tracheostomy tube for being too weak to breathe or for failing extubation, we have had two DMD patients, who were CNVS-dependent, receive emergency tracheotomy for failing intubation during intercurrent episodes of pneumonia. The first patient died two months later. The second patient underwent tracheotomy after severe bronchiectasis during an episode of acute respiratory failure after being CNVS-dependent for 15 years. People living with DMD patients may only require tracheotomy when their condition is complicated by:

  • Long-term cardiovascular instability

  • Severe intrinsic lung disease (e.g. severe bronchiectasis)

  • Severe cognitive impairment

  • Multi-organ failure

  • Inadequate home care.

 

 

OUTCOMES OF CONVENTIONAL MANAGEMENT

 

Gatin reported results for eight DMD patients who used tracheostomy mechanical ventilation (TMV) (DMD1):

  • Two DMD patients died within 36 days following tracheotomy - one from accidental decannulation and the other from massive tracheal hemorrhage.

  • The remaining six DMD patients survived at least 38 months.

  • No patient required more than 16 hours per day of TMV.

  • In total, the patients experienced a total of four pneumonias, two near respiratory arrests (from tracheobronchial mucus plugging), and occurrences of tracheal stenosis, granulation, and pseudopolyp formation (consequences from having the tracheostomy tube).

 

Baydur et al. reported results for seven DMD patients who used continuous TMV (CTMV) for 6.1 ± 5.5 years (range of 3 to 18.2 years) starting from the average age of 22.3±6.5 to 28.5±8.1 years (starting range of 17 to 36; ending range of 20.5 to 42.3 years) (DMD2):

  • Two DMD patients died from pneumonia.

  • The remaining five DMD patients had pneumonia or recurrent pneumonias.


Soudon reported results for 20+ DMD patients who used CTMV (DMD3). The patients had an average survival of 3.6 years.

 

Eagle et al. reported results for 200 DMD patients who were either untreated or used TMV/CTMV (DMD4). The untreated patients had an average survival of 19.5 years (cardiomyopathy was the cause of death for 7.4%). The patients who used TMV/CTMV had an average survival of 24.8 years (cardiomyopathy was the cause of death for 36.8%).

 

Bach et al. reported results for seven DMD patients who used CTMV for a mean of 7.1 years starting from the average age of 21.1±3.8 to 28.1±4.5 years (JBCV7). Two of the seven patients were still alive at time of publication. Complications were not reported.

 

The DMD patients of Baydur and Bach, who survived long enough after episodes of acute respiratory failure to be referred to rehabilitation centers and who used TMV/CTMV, had an improved average survival of 6.2 and 7.1 years, respectively.

 

Ishikawa et al. reported that (YICV7):

  • Prior to 1984:

    • 56 DMD patients who were untreated died mostly from respiratory failure at 18.6 ± 2.9 years of age (YICV7). This is consistent with numerous other reports of DMD patients who were untreated.

  • From 1984 to 1991:

    • 21 consecutive DMD patients who went into respiratory failure underwent tracheotomy. They survived to 28.1 ± 8.3 years of age with three still alive at time of publication.

  • From 1991 to 2011:

    • 88 consecutive DMD patients used NVS and avoided tracheotomy. By 2010, they had 50% survival to 39.6 years of age (p<0.001; Kaplan-Meier analysis).

Thus, DMD patients who used NVS/CNVS had improved survival by at least 10 years compared to TMV/CTMV.

 

POLYSOMNOGRAPHY AND WHY YOU DO NOT NEED ONE:

 

Often, asymptomatic patients with DMD are sent for unnecessary polysomnography (see Most Common Mistakes). Polysomnography interprets abnormalities as resulting from:

1. Central events (i.e. absence of central nervous stimulation arising from the brain)

2. Obstructive events (i.e. throat collapse).

 

After polysomnography, patients are inappropriately treated with:

 

As a consequence, they will develop:

  • Carbon dioxide narcosis followed by acute respiratory failure

  • Acute respiratory failure during an otherwise benign upper respiratory tract infection followed by pneumonia.

These avoidable conditions may necessitate intubation.

 

Once intubated in intensive/critical care units, patients are told that they must undergo tracheotomy. After tracheotomy, patients are typically sent to long-term acute care centers (LTACs) for about a month. After the LTAC, if they are not weaned from ventilatory support, patients are sent either to nursing home ventilator units or to home with 16-24 hours per day of nursing care at a cost of $300,000 to $400,000 per year for the rest of their lives (up to 30 years) (JBCV237).

 

Gastrostomy

\ga-ˈsträs-tə-mē\

The surgical opening through the abdomen into the stomach that allows for direct feeding into the stomach.

 

THE FACTS:

 

  • DMD patients who used NVS/CNVS had improved prognosis for survival by at least 10 years compared to TMV/CTMV.

  • Most DMD patients who undergo tracheotomy will also undergo gastrostomy because the tracheostomy tube makes it more difficult to swallow (16 of 25).

  • Of 25 DMD patients who used CTMV and had never been introduced to NVS/CNVS, 14 lost all ventilator-free breathing ability once they underwent tracheotomy (JBCV237).

 

In 1998, Bach et al. reported results for 654 patients with neuromuscular disease (76 with DMD) who used mechanical ventilation at home. The patients were ventilator-dependent for an average of 19.8 years (a total of 13,574 patient-years of ventilator support). Conditions included DMD, other myopathies, post-poliomyelitis, spinal cord injury, spinal muscular atrophy, scoliosis, amyotrophic lateral sclerosis (ALS), motor neuron disease, myelopathy, myasthenia gravis, obesity hypoventilation, and other conditions. Of 654 patients, 146 used CTMV and the other 508 used NVS/CNVS. Pneumonia and hospitalization rates were significantly lower for the patients who used NVS/CNVS compared to those with tracheostomy tubes (JBCV126).

 

(Note: Patients with gastrostomy tubes were eliminated from the analysis to remove patients with bulbar-innervated muscle dysfunction or BIMD.)

 

Typically, at "Centers for Noninvasive Respiratory Management," only ALS patients undergo tracheotomy. As a result, data on morbidity after tracheotomy is best derived from ALS patients (JBCV67). While ALS is a very different condition than DMD and other myopathies, excessive morbidity and mortality after tracheotomy also occurs in DMD from:

  • Hemorrhage

  • Fistulas between the trachea and esophagus

  • Airway mucus plugging

  • Chronic bronchitis

  • Tracheostomy tube cuff dysfunction

  • Ventilator-associated pneumonia (VAP)

  • Atelectasis

  • Dysphagia

  • Aspiration caused by the tube

  • Pneumothorax

  • Hemothorax

  • Tracheitis

  • Trachiectasis.

 

People living with DMD or any of these diagnoses who use NVS/CNVS live significantly longer and have fewer long-term complications compared to patients who have tracheostomy tubes and use TMV/CTMV (JBCV126).

 

 

OUTCOMES OF NONINVASIVE RESPIRATORY MANAGEMENT

 

At five "Centers for Noninvasive Respiratory Management," there are 243 DMD patients who are NVS-dependent (YICV7,DMD5,DMD6,JBCV235):

  • 202 patients used NVS for an average of 3.4 years and then CNVS for an average 10.1 years up to an average age of 32.8 years (maximum age of 53 years).

  • 118 of the 202 patients became CNVS-dependent without developing acute respiratory failure or being hospitalized or intubated.

  • The current average age is 34.0 ± 2.1 years. 167 patients are still alive.

  • The projected life expectancy is over 40 years of age (by Kaplan-Meier analysis).

 

  • 8 DMD patients who use CNVS are now 40 years of age and have been CNVS-dependent for up to 27 years.

 

  • Only 16% of DMD patients who use NVS/CNVS have required gastrostomy tubes.

  • About 16% of DMD patients who use NVS/CNVS have weak lips and use a nasal interface through the daytime. These patients alternate between a nasal prong interface for daytime NVS and other nasal interfaces for nocturnal/sleep NVS.

 

  • 35 DMD patients who use CNVS died at an average age of 33.9 years after 9.1 years of CNVS dependence. 32 died from complications of cardiomyopathy, two died from gastrointestinal complications, and only one from respiratory complications.

 

 

OUTCOMES OF DMD EXTUBATION

 

Extubation

\ˌek-ˌst(y)ü-ˈbā-shən\

Removal of an airway tube passed down the throat (i.e. endotracheal tube).

 

At five "Centers for Noninvasive Respiratory Management," the successful extubation of 43 consecutive DMD patients who were CNVS-dependent has been reported (64 successful extubations in 68 attempts)  (JBCV197,JBCV235). None of the extubated DMD patients ever underwent tracheotomy for extubation failure.

 

 

OUTCOMES OF DMD DECANNULATION

 

Decannulation

\dē-kan′yū-lā′shun\

Removal of an airway tube passed through the neck and into the windpipe (i.e. tracheostomy tube).

 

At "Centers for Noninvasive Respiratory Management," the successful decannulation of 12 DMD patients who used TMV/CTMV has been reported. Nine patients had gastrostomy tubes that were placed at the time of tracheotomy and removed during decannulation. Only 17% (18/108) of DMD patients who use CNVS require gastrostomy tubes (JBCV237,JBCV232).

 

(Note: Gastrostomy tubes may be required when there is severe bulbar-innervated muscle dysfunction or BIMD.)