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828
Amyotrophic Lateral Sclerosis: Predictors for Prolongation of
Life by Noninvasive Respiratory Aids
John Robert Bach, AID
ABSTRACT. Bach JR. Amyotrophic lateral sclerosis: predictors for prolongation of life by noninvasive respiratory aids. Arch Phys Med Rehabil 1995;76:828-32.
• The purpose of this study was to determine which pulmonary function variables best predicted the potential
for prolonging survival of individuals with amyotrophic lateral sclerosis (ALS) by the use of physical medicine
respiratory muscle aid alternatives to tracheostomy for ventilatory support and airway suctioning. The records
of 27 such ALS ventilator users with less than 15 minutes of ventilator-free breathing time for a mean _+ standard
deviation of 23.7 _+ 20.3 months (range, 1 to 65) were reviewed. All patients underwent measurements of vital
capacity (VC), m a x i m u m insufflation capacity (MIC), MIC VC difference, forced expiratory volumes, and peak
cough expiratory flows (PCEF) every 1 to 6 months, depending on rate of disease progression, until requiring
24-hour ventilatory support. The ability to generate assisted PCEF in excess of 3L/sec and the ability to hold an
insufflation deeper than the VC were associated with the capacity to prolong survival by methods other than
tracheostomy, whereas the extent of decrease in VC and autonomous breathing ability were not. Because the
PCEF and MIC VC difference correlate with bulbar muscle function, it can be concluded that the ability to use
24-hour ventilatory support by noninvasive means is a function of residual bulbar muscle strength and is independent of VC or the extent of need for ventilatory support. Properly equipped and trained, some ALS patients can
use noninvasive respiratory muscle aids to delay or eliminate the need for tracheostomy.
© 1995 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and
Rehabilitation
Survival can be prolonged for most individuals with
amyotrophic lateral sclerosis (ALS) by providing intermittent positive pressure ventilation (IPPV) via an indwelling
tracheostomy tube and performing transtracheal suctioning
of airway secretions. However, many clinicians have ethical
reservations about offering ventilator use to these individuals, especially via tracheostomy, and in some states, fewer
than 10% of ALS patients are offered or agree to undergo
tracheostomy. J Nevertheless, like ventilator users with other
severe neuromuscular disorders, 2'3 the great majority of ALS
ventilator users indicate that they are contented with the
decision to use a ventilator and would do it again.l'4
Many individuals who require 24-hour-a-day ventilatory
support are maintained without resort to an indwelling tracheostomy tube by continuous use of noninvasive respiratory
m u s c l e aids. 5-9 The most important noninvasive inspiratory
aids are IPPV delivered to the airway via appropriate interfaces 5-7 and the intermittent abdominal pressure ventilator
(IAPV). 8'9 IPPV is delivered from a portable volume-triggered ventilator, via a simple mouthpiece for daytime ventilatory support, a mouthpiece retained in the mouth with a
lipseal retention system a for nocturnal support, or via a nasal
interface (commercially available continuous positive airway
pressure [CPAP] mask or custom-molded mask F°) for daytime or nocturnal support. Occasionally an interface covering
both mouth and nose is used for nocturnal support, m The
From the Department of Physical Medicine and Rehabilitation, UMD-New Jersey
Medical School, Newark, NJ.
Submitted for publication December 19, 1994. Accepted in revised form April 23,
1995.
No commercial party having a direct financial interest in the results of the research
supporting this article has or will confer a benefit upon the authors or upon any
organization with which the authors are associated.
Reprint requests to John R. Bach, MD, 17 Woodbine Terrace, Sparta, NJ 07871.
© 1995 by the American Congress of Rehabilitation Medicine and the American
Academy of Physical Medicine and Rehabilitation
0003-9993/95/7609-335653.00/0
Arch Phys Med Rehabil Vol 76, September 1995
IAPV acts on the abdomen to move the diaphragm to assist
alveolar ventilation. Because it is convenient, optimizes appearance, and is effective with the individual erect, it is most
useful for daytime support, especially for ventilator-assisted
individuals with little or no vital capacity (VC) or ventilatorfree breathing time. 8
The expiratory muscle aids include the use of deep breaths
or insufflations followed by manually assisted coughing, mechanically assisted coughing with the use of mechanical insufflation-exsufflation, or simultaneous use of both. The assisted coughing methods can eliminate airway secretions and
obviate the need for transtracheal suctioning when the peak
cough expiratory flows (PCEF) generated by them exceed
3L/sec. 1
As early as 1970 the use of tracheostomy IPPV was delayed 4 years and 3 months for one ALS ventilator user by
24-hour-a-day noninvasive IPPV and use of an Exsufflation
Belt.b ~2 There have been no similar subsequent reports for
ALS patients. We now report 27 ALS ventilator users who
succeeded in using ventilatory support by noninvasive methods for a mean ___standard deviation of 23.7 + 20.3 months.
The purpose of this study was to determine which factors
predicted the successful use of these noninvasive alternatives
to IPPV via an indwelling tracheostomy.
P A T I E N T S AND M E T H O D S
All of the referrals to the author from 1981 to the present
were studied. The presence of ALS was documented in all
cases by clinical and electrodiagnostic evaluation. All patients underwent regular measurements of VC (maximum
observed value in 4 to 7 attempts), maximum insufflation
capacity (MIC; the deepest insufflation provided by air stacking delivered air volumes from a manual resuscitator or portable volume ventilator and held with a closed glottis), ~3c
forced expiratory volume in 1 second divided by forced
ALS SURVIVAL WITH RESPIRATORY AIDS, Bach
829
to them. These patients either died suddenly or underwent
tracheostomy in local hospitals without attempting to use
noninvasive aids to manage their respiratory failure. Some
patients had not been provided with an oximeter early
enough to capture the acute event, and in failing to maintain
normal Sao2 by using noninvasive aids, presented with pneumonia and severe oxygenation impairment that necessitated
oxygen therapy. Oxygen therapy generally precludes effective nocturnal use of noninvasive IPPV. ~7 Data collection
was inadequate for these patients to be included in this study.
Another 23 patients learned how to use noninvasive aids,
but because their use did not reverse their first episode of
respiratory failure, they underwent tracheostomy ("unsucexpiratory volume (FEV1/FVC) as a percentage of predicted cessful group"). All of these patients developed respiratory
normal, and PCEF a every 1 to 6 months depending on rate failure suddenly, in many cases without hypercapnia obof disease progression. Oxyhemoglobin saturation (Sa02) ~ served during waking hours (by capnography) in the 1 to 3
and end-tidal Pc02 (ETCO2)f monitoring were performed with preceding months, and often during an otherwise benign
the patient in both sitting and supine positions during each upper respiratory tract infection during which they could not
clinic visit once the VC was determined to be decreasing. successfully clear airway secretions. During these episodes
Nocturnal Sa02 monitoring was performed every 6 months most patients could maintain normal or low Paco2 levels
when the VC was below 60% of predicted normal, or when when using noninvasive IPPV. However, because most had
symptoms characteristic of hypoventilation were noted, until been found to be aspirating food and saliva during barium
the onset of ventilator use, then less frequently thereafter. 5 swallow evaluations, and were unable to fully abduct their
These indications for nocturnal monitoring were used be- vocal cords or firmly close their glotti, their PCEF were low
cause hypercapnia has been described to develop when the and none were able to sufficiently clear their airways of
VC decreases below 4 0 % 14 t o 5 5 % 15 of predicted normal.
aspirated food, saliva, and airway secretions. As a result,
It has been found that most patients who have VCs (mea- oxyhemoglobin desaturation and dyspnea could not be resured in the supine position) less than 30% of predicted versed by assisted coughing, and tracheostomy became necnormal require nocturnal ventilatory support. 5 Therefore, essary.
when the VC was first noted below 40% of predicted normal
Successful noninvasive aid users eventually required traor when Sao2 or ETCO2was found to be abnormal, the patients cheostomy, or died, or they continue to use 24-hour noninvawere familiarized with the use of volume ventilators and sire support. Those who underwent tracheostomy did so
instructed to periodically deliver maximum tolerated in- when, because of inadequate generation of expiratory flows
sufflations to themselves via a mouthpiece, or occasionally, to eliminate airway secretions by assisted coughing, or invia a nosepiece. Early on, manual resuscitators were used ability to prevent excessive ventilator insufflation air leakage
for this purpose to temporarily increase dynamic pulmonary out of the nose or mouth because of severe soft palate, lip,
compliance 16 and, most importantly, to assure the clinician and buccal muscle paralysis, Sao2 could not be maintained
that the patient would be able to use mouthpiece IPPV, nasal within the normal range and the patients became dyspneic
IPPV, or both for ventilatory support in the event of acute despite noninvasive ventilatory support. At this point, parespiratory deterioration. When unassisted PCEF were found tients appeared to continuously aspirate their saliva and had
to be less than 5L/sec, the patients were also instructed in decreased upper airway patency because of vocal cord paralthe use of manually and mechanically assisted coughing j3 ysis.
and were instructed to increase maximal assisted PCEF with
Pulmonary function parameters were longitudinally compractice. They were provided with an oximeter and in- pared between the noninvasive aid users and the unsuccessstructed to always maintain Sao2 greater than 94% (oximetry ful group. The duration of 24-hour dependence on noninvabiofeedback) by using noninvasive IPPV, up to 24 hours a sive aids was calculated from the point at which the
day if necessary, and by using assisted coughing methods ventilator user could tolerate ventilator-free breathing for 15
when needed. The choice of noninvasive inspiratory aids, to minutes or less. The t test was used to compare the means
a degree, was left to the patient. These methods became of the ages of the chronological milestones and other respiracritical at the first signs of respiratory tract infection, airway tory parameters of the two groups. A p -< .05 was considered
congestion, or respiratory distress for any reason.
significant.
Twenty-seven patients succeeded in using these noninvaRESULTS
sive aids to maintain normal Sao2 and avert or reverse acute
respiratory failure without supplemental oxygen administraThe rate of clinical disease progression was similar for
tion or intubation. They all developed 24-hour dependence both ALS groups (table 1). The 27 successful noninvasive
on noninvasive aids as their VCs diminished ("noninvasive aid users used noninvasive aids up to 16 hours a day for 4
users").
+ 6 months and 24 hours a day with less than 15 minutes
Approximately 50 patients either did not learn how to use of free breathing time for 19.7 _+ 20.3 months (range, 1 to
noninvasive aid.s, often because of irregular clinic visits, or 65). This was 20.2 _+ 23.4 months (range, 1 to 65) before
experienced acute respiratory failure before having access tracheostomy for 14 patients, 24.1 _ 15.6 months (range, 4
Abbreviations
ALS: amyotrophic lateral sclerosis
CPAP: continuous positive airway pressure
FEV1/FVC: forced expiratory volume in 1 second divided
by forced expiratory volume
IPPV: intermittent positive pressure ventilation
MIC: maximum insufflation capacity
PCEF: peak cough expiratory flows
SaQ: oxyhemoglobin saturation
VC: vital capacity
Arch Phys Med Rehabil Vol 76, September 1995
830
ALS SURVIVAL WITH RESPIRATORY AIDS, Bach
Table 1: Phenotypic Comparison of ALS Patient Groups
Number of patients
Age at onset of ALS
Age at diagnosis
Time from onset
Loss of ambulation
Time from diagnosis
Time from onset
Successful
Group
Unsuccessful
Group
27
49.5 ___ 13.2
(22-66)
51.3 ± 13.0
(22.7-69.5)
1.8 ± 4.3
(0.1-19.5)
52.1 _ 13.0
(25.6-70.1)
1.9 _+ 2.4
(0-10)
2.6 _ 3.1
23
52.4 __+ 15.0
(26-85.1)
53.6 ± 15.1
(28.1-85.2)
1.2 ± 1.3
(0-6.1)
55.3 _+ 14.1
(28-76.9)
1.6 ± 2.0
(0-8.4)
2.8 ± 2.7
(0.1-14.6)
Age at onset of ventilatory aid
Time from onset
Time from diagnosis
Noninvasive aid use*
Part of day
24 hours a day
Total ventilatory support
Deceased
54.3 __. 11.1
(28.4-70.3)
4.9 ± 5.7
(0.5-24.0)
3.0 ± 3.0
(0.3-13)
1.9 + 1.6
(0.1-5.4)
0.3 ± 1.1
(0.1-1.8)
1.6 __. 1.1
(0.1-5.1)
3.9 + 5.2
(0.1-26.5)
16
(0.2___14.6)
56.8 ± 13.7
(31.7-85.2)
4.5 ± 4.8
(0.1-25.3)
3.4 ± 4.6
(0-25)
0
4.6 ± 3.2
(0.5-15.9)
21
All figures are in years __+ standard deviation except where indicated.
* Noninvasive aids used part of day, ie, up to 16 hours per day; and 24
hours a day with little or no ventilator-free breathing time.
5 nasal IPPV users, and most nasal IPPV users had two or
more nasal interfaces, mostly commercially available CPAP
masks. They alternated mask use to avoid excessive pressure
on skin surfaces in contact with any particular interface.
Four of the nasal IPPV users were also eventually switched
to lipseal IPPV because of the gradual deterioration in mean
nocturnal Sao2 as the soft palate became incompetent to
seal off the nose, thereby permitting excessive ventilator air
delivery (insufflation) leakage out of the nose.
Pulmonary parameter comparisons between the 27 successful noninvasive aid users and the 23 unsuccessful or
tracheostomy-only ventilator users are listed in table 2. Because it is most likely that the majority of patients who did
not use noninvasive aids when experiencing acute respiratory failure would have failed to use them successfully anyway because as a group they were less cooperative, had
predominantly bulbar-onset ALS, severe bulbar muscle
Table 2: Comparison of ALS Patient Groups'
Pulmonary Parameters
Within 3 months of initial
ventilator use
VC sitting (mL)*
VC supine (mL)t
MIC (mL)
to 50) for 7 patients who died without being intubated, and
30.2 + 20.0 (range, 1 to 51) months for 6 patients still using
noninvasive aids.
These patients received ventilatory support by all means
for a total of 3.9 +_ 5.2 years (range, 1 month to 26.5 years).
This was 3.0 ___ 2.7 years (range, 3 months to 10 years) for
the 16 who died and 5.5 _ 8.0 years (range, 1 month to
26.5 years) for the 11 ventilator users still using support.
Only 7 of these ventilator users underwent tracheostomy
before gastrostomy. Despite relatively high VCs just before
undergoing tracheostomy, all ventilator-free breathing time
was lost within days to weeks and VC decreased precipitously once patients in the tracheostomy-only group had undergone tracheostomy for IPPV.
The results of the nocturnal oximetry studies performed
once the successful group required 24-hour aid without significant free breathing time were as follows: the 22 nasal
IPPV users had mean Sao2 of 94%, with 5 having desaturation below 90% between 5% and 10% of the time and no
prolonged desaturation below 85%; the 3 mouthpiece with
lipseal a IPPV users had mean Sao2 of 95%; and the 2 exsufflation belt users had mean nocturnal Sao2 of 95% early
on, diminishing ultimately to below 90% after months of
nocturnal use.
For daytime aid, 4 patients used Exsufflation Belts, b 10
used mouthpiece IPPV, and 13 whose lip and oral muscle
function was inadequate to hold a mouthpiece used nasal
IPPV. Two of the patients used exsufflation belts 24 hours
a day. Custom molded nasal interfaces were constructed for
Arch Phys Med RehabilVol 76, September 1995
PCEF (L/sec)
At the time of initial use
noninvasive ventilatory
support methods
VC sitting (mL)
VC supine (mL)
MIC (mL)
PCEF (L/sec)
At the point of requiring
24-hour noninvasive
ventilatory support
VC sitting (mL)
VC supine (mL)
MIC (mL)
PCEF (L/sec)
At tracheostomy$
VC sitting (mL)
VC supine (mL)
MIC (mL)
PCEF (L/sec)
Successful
Group
(27 Patients)
Unsuccessful
Group
(23 Patients)
732 _+ 232
(300-1,440)
672 _+ 230
(290-820)
1,415 ___ 380
(990-1,945)
4.6 _ 1.1
(3.1-6.3)
934 _ 321
(540-1,670)
844 ± 309
(360-1,480)
1,052 _+ 476
(560-1,700)
2,5 ___ 1.3
(0-5.1)
p
value
.02
.047
.007
<.0005
720 _ 231
(300-1,440)
668 _+ 228
(300-820)
1,404 ± 372
(990-1,945)
4.6 _ 1.1
(1.8-6.3)
580 _+ 195
(300-850)
545 ___ 190
(300-720)
1,010 ± 205
(630-1,450)
4.1 ± 1.0
(1.6-5.8)
160 __+ 165
(0-470)
143 _+ 161
(0-440)
460 ___ 241
(0-655)
< 1 (0-2.6)
650 ± 427
(120-970)
607 ± 411
(120-960)
703 _+ 187
(180-980)
< 1 (0-2.5)
* Vital capacity measured with the subject in the sitting position.
t Vital capacity measured with the subject supine.
At tracheostomy for 14 patients in successful group.
<.0005
<.0005
<.0005
--
ALS SURVIVAL WITH RESPIRATORY AIDS, Bach
831
PCEFs greater than 3L/sec while avoiding excessive aspiration of saliva and food. Thus, tracheal intubation was unnecessary either for ventilatory support or for airway secretion
clearance in this group despite, in many cases, total absence
of respiratory muscle function. The low incidence of need
for gastrostomy tube placement also signified better bulbar
muscle function in this group.
In the unsuccessful group, tracheostomy was performed
during episodes of acute respiratory distress triggered by
aspiration of food, upper airway secretions, or both, which
resulted in oxyhemoglobin desaturation that could not be
reversed by the use of noninvasive respiratory muscle aids.
During episodes of bronchial congestion, mucus plugging
causes sudden severe oxyhemoglobin desaturations and respiratory distress, and VC and assisted PCEF decrease precipitously. When assisted PCEF decreases below about 3L/
sec, indicating poor inspiratory volumes and glottic control,
airway debris cannot be cleared noninvasively, Sao2 cannot
be normalized, and tracheal intubation is necessary for survival. Poor glottic control prevents both the retention of
adequate insufflation volumes for an effective cough and the
upper airway patency needed to permit explosive decompression.
DISCUSSION
For those patients who underwent tracheostomy, there was
This study demonstrated that individuals with ALS who an additional post-tracheostomy loss in VC and a rapid loss
could generate PCEF exceeding 3L/sec and who had a high of ventilator-free breathing time that may be explained by
MIC or high M][C VC difference could use noninvasive exacerbation of weakness due to acute illness, 23 inspiratory
physical medicine aids as alternatives to tracheostomy for muscle deconditioning from the tendency to use tracheoslong-term, 24-hour-a-day ventilatory support and airway se- tomy IPPV for unnecessarily long periods of time, and the
cretion management. Thus, the ability to hold a deep insuf- fact that tracheostomy IPPV users tend to complain of air
flation and to generate adequate PCEF can decrease the risk hunger unless they are hyperventilated.24 This decreases tolof pulmonary complications and eliminate the need for tra- erance for free breathing time, which may, in turn, lead to
cheostomy despite the patient retaining little or no measur- respiratory muscle deconditioning.
able VC and no ventilator-free breathing time] 8'19 This is
By normalizing alveolar ventilation and eliminating airnot surprising because noninvasive methods of ventilatory way secretions, the use of noninvasive respiratory muscle
support can prov;tde normal alveolar ventilation for anyone aids eases the patient's and family's feelings of helplessness
with global alveolar hypoventilation irrespective of the ex- when shortness of breath or airway congestion occurs in the
tent of inspiratory muscle dysfunction; however, irreversible home. Use of noninvasive aids can also test the family's
airway obstruction because of failure to effectively mobilize resolve and the patient's home support before resort to traairway secretions invariably leads to oxyhemoglobin desatu- cheostomy needs to be considered for some, and it can help
ration and, eventually, pulmonary infiltration. Airway secre- maintain the patient in the communityY
tions are normally eliminated by coughing.
We have recently had considerable success in some paA normal cough involves taking a deep breath to about tients with less than 3L/sec of unassisted or manually as2.3L,2° closing the glottis, and using expiratory muscles to sisted PCEF by using mechanical insufflation-exsufflationto
create sufficient thoracoabdominal pressures to generate 6 clear airway secretions to renormalize Sat2. ~8This technique
to 16L/sec of PCEF, depending on sex, height, and age, 2°'2~ bypasses the need for glottic control to retain a deep insufon glottic opening. The effectiveness of airway mucus clear- flation because the deep insufflation is delivered via an oralance is largely &~pendent on the magnitude of the PCEF. 22 nasal mask just before an instantaneous decrease in pressure
Bulbar muscle function is vital both for closing the glottis of approximately 80cmHzO to generate expiratory flow. It
to permit adequate generation of precough pressures and for remains to be seen whether this method will enable many
optimizing airway patency by vocal cord abduction during ALS patients with PCEF below 3L/sec to maintain adequate
the explosive decompression that actually generates the vocal cord abduction and upper airway patency, thus permitflows. No specific tests, however, have been developed to ting the use of this technique to effectively eliminate airway
quantitate bulbar muscle function and, in particular, the rela- secretions on a long-term basis.
tionship between bulbar function and risk of pulmonar-y comBecause the majority of patients who were in the group
plications.
that failed to use noninvasive aids in the prescribed manner
Although they required 24-hour ventilator use, the nonin- would have most likely been unsuccessful with them, we
vasive aid users retained MICs that were several hundred conclude that noninvasive respiratory muscle aids can promilliliters greater than their VCs. Their greater bulbar muscle long survival and delay need for tracheostomy for at least a
function and glottic control enabled them to have assisted significant minority of ALS patients. In particular, patients
involvement, and in some cases dementia, these 50 patients
are considered unsuccessful users.
There were significant differences between those who succeeded in using noninvasive aids for prolonged survival and
the 23 who were unsuccessful, in VC (both absolute VC and
VC as a percentage of predicted normal), MIC, and PCEF.
The FEV1/FVC as a percentage of predicted normal was
within normal limits before ventilator use for all patients
and was not measured subsequently. The "successful
group" had significantly lower VC but greater MIC and
PCEF within 3 months of becoming ventilator-dependent
and significantly lower VC at the time of switching from
noninvasive aids to tracheostomy IPPV. The unsuccessful
group had greater MIC at the time of tracheostomy, but the
MIC was only slightly greater than the VC, indicating inability to use the oropharyngeal muscles to hold an adequate
breath to permit an effective cough.
Twenty of the 27 noninvasive aid users remained in the
community setting. The remaining 7 were institutionalized
after undergoing tracheostomy. Twelve of 13 ventilator users
who used noninvasive aids and who never underwent tracheostomy were also never institutionalized.
Arch Phys Med Rehabil Vol 76, September 1995
832
ALS SURVIVAL WITH RESPIRATORY AIDS, Bach
who have adequate bulbar muscle function to permit assisted
PCEF to exceed 3L/sec can use noninvasive ventilatory support and airway secretion management alternatives to tracheostomy IPPV and suctioning. These patients can generally
clear aspirated food, saliva, or airway secretions sufficiently
to maintain virtually normal Saoz with the use of noninvasive
inspiratory and expiratory aids. Thus, aspiration of food or
saliva appears to be significant only when airway clearance
mechanisms, including assisted coughing, are inadequate to
maintain normal Sa02 despite effective ventilatory support.
Extent of ventilatory failure, even absence of measurable
VC, is not in itself an indication for tracheostomy. It is
instructive that there are no previous comparable studies of
this nature. These noninvasive physical medicine applications deserve more widespread application to spare patients
the hazards, cost, discomfort, and impairments of swallowing, taste, communication, and appearance associated
with tracheostomy. 26 Further information is available regarding the use of noninvasive respiratory muscle aids.5'6']°'J3'lS'19
References
1. Moss AH, Casey P, Stocking CB, Roos RP, Brooks BR, Siegler M.
Home ventilation for amyotrophic lateral sclerosis patients: outcomes,
costs, and patient, family, and physician attitudes. Neurology
1993; 43:438-43.
2. Bach JR, Campagnolo DI, Hoeman S. Life satisfaction of individuals
with Duchenne muscular dystrophy using long-term mechanical ventilatory support. Am J Phys Med Rehabil 1991 ;70:129-35.
3. Bach JR, Campagnolo D. Psychosocial adjustment of post-poliomyelitis
ventilator assisted individuals. Arch Phys Med Rehabil 1992;73:9349.
4. Oppenheimer EA, Baldwin-Myers A, Tanquary P. Ventilator use by
patients with amyotrophic lateral sclerosis. In: Make B, editor. Proceedings of the International Conference on Pulmonary Rehabilitation and
Home Ventilation. Denver: National Jewish Center, 1991:49.
5. Bach JR, Alba AS. Management of chronic alveolar hypoventilation
by nasal ventilation. Chest 1990;97:52-7.
6. Bach JR, Alba AS, Saporito LR. Intermittent positive pressure ventilation via the mouth as an alternative to tracheostomy for 257 ventilator
users. Chest 1993; 103:174-82.
7. Bach JR, Saporito LS. Indications and criteria for decannulation and
transition from invasive to noninvasive long-term ventilatory support.
Respir Care 1994;39:515-31.
8. Bach JR, Alba AS. Total ventilatory support by the intermittent abdominal pressure ventilator. Chest 1991;99:630-6.
9. Bach JR, Beltrame F. Alternative methods of ventilatory support. In:
Rothkopf MM, Askanazi J, editors. Intensive homecare. Baltimore:
Williams & Wilkins, 1992:173-97.
10. McDermott I, Bach JR, Parker C, Sortor S. Custom-fabricated interfaces for intermittent positive pressure ventilation. Int J Prosthodontics
1989;2:224-33.
11. Bach JR. Update and perspectives on noninvasive respiratory muscle
aids: part 2 - - t h e expiratory muscle aids. Chest 1994; 105:1538-44.
12. Alba A, Pilkington LA, Kaplan E, Baum J, Schultheiss M, Ruggieri
Arch Phys Med Rehabil Vol 76, September 1995
A, et al. Long-term pulmonary care in amyotrophic lateral sclerosis.
Respir Ther 1976;6:49-56, 102-5.
13. Bach JR. Pulmonary rehabilitation considerations for Duchenne muscular dystrophy: the prolongation of life by respiratory muscle aids. Crit
Rev Phys Rehabil Meal 1992;3:239-69.
14. Canny GJ, Szeinberg A, Koreska J, Levison H. Hypercapnia in relation
to pulmonary function in Duchenne muscular dystrophy. Pediatr Pulmonology 1989;6:169-71.
15. Braun NMT, Arora NS, Rochester DF. Respiratory muscle and pulmonary function in polymyositis and other proximal myopathies. Thorax
1983;38:616-23.
16. Miller WF. Rehabilitation of patients with chronic obstructive lung
disease. Med Clin North Am 1967;51:349-61.
17. Bach JR, Robert D, Leger P, Langevin B. Sleep fragmentation in kyphoscoliotic individuals with alveolar hypoventilation treated by nasal
IPPV. Chest 1995; 107:1552-8.
18. Bach JR. Mechanical insufflation-exsufflation: comparison of peak expiratory flows with manually assisted and unassisted coughing techniques. Chest 1993; 104:1553-62.
19. Bach JR, Smith WH, Michaels J, Saporito LS, Alba AS, Dayal R, et
al. Airway secretion clearance by mechanical exsufflation for postpoliomyelitis ventilator assisted individuals. Arch Phys Med Rehabil
1993; 74:170-7.
20. Leith DE. Cough. In: Brain JD, Proctor D, Reid L, editors. Lung biology
in health and disease: respiratory defense mechanisms, part 2. New
York: Marcel Dekker, 1977:545-92.
21. Leiner GC, Abramowitz S, Small MJ, Stenby VB, Lewis WA. Expiratory peak flow rate. Standard values for normal subjects. Am Rev
Respir Dis 1963;88:644.
22. King M, Brock G, Lundell C. Clearance of mucus by simulated cough.
J Appl Physiol 1985;58:1776-85.
23. Mier-Jedrzejowicz A, Brophy C, Green M. Respiratory muscle weakness during upper respiratory tract infections. Am Rev Respir Dis
1988; 138:5-7.
24. Haber II, Bach JR. Normalization of blood carbon dioxide levels by
transition from conventional ventilatory support to noninvasive inspiratory aids. Arch Phys Med Rehabil 1994;75:1145-50.
25. Bach JR, Intintola P, Alba AS, Holland I. The ventilator-assisted individual: cost analysis of institutionalization versus rehabilitation and inhome management. Chest 1992; 101:26-30.
26. Bach JR. A comparison of long-term ventilatory support alternatives
from the perspective of the patient and care giver. Chest
1993; 104:1702-6.
Suppliers
a. Puritan Bennett Inc., 1915 Clements Road, Unit 7, Picketing, Ontario
LIW 3V1.
b. Lifecare International Inc., 1401 West 122nd Ave., Westminster, CO
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c. Wright Spirometer Mark 14; Ferraris Development and Engineering Co.,
Ltd., 26 Lea Valley Trading Estate, Angel Road, Edmonton, London
N18 3JD.
d. Peak Flow Meter Model 710; Health Scan Products, Inc., 908 Pompton
Avenue, Cedar Grove, NJ 07009-1292.
e. Ohmeda model 3760; Ohmeda Inc., 1315 West Century Drive, Louisville, CO 80027.
f. Microspan 8090 Capnograph; Biochem International Inc., W238 N1650
Rockwood Drive, Waukesha, WI 53188-1199.