NEUROMUSCULAR & DISEASE OF
CHESTWALL
PATHOPHYSIOLOGY AND PULMONARY
FUNCTION TESTING
Pulmonary function testing in patients
with neuromuscular weakness typically
reveals a restrictive ventilatory defect
even if the lungs are normal.
Diffusing capacity is usually normal or
near normal, representing normal lungs
with preserved gas exchange function.
Clinically significant weakness of the
diaphragm presents with orthopnea and
can be identified by a decrease in VC
going from the upright to the supine
position. Supplemental oxygen (O2) can be
dangerous for patients with
The normal decrease is 7% to 10%. A neuromuscular dysfunction and
10% to 20% decrease suggests preexisting hypercapnia, as it can result
diaphragm weakness or unilateral in acute worsening of hypercapnia.
paralysis but can also be seen in obesity
and or abdominal wall disorders. A 25% Effective cough has three phases:
decrease has a 79% sensitivity and 90% inflation, compression, and expulsion.
specificity for diaphragm weakness. Inflation requires adequate inspiratory
muscle strength to pull in enough
Whereas a decreased maximal volume in the lungs to generate
inspiratory pressure (PImax) is generally appropriate cough pressure.
specific for diaphragm weakness, a
decreased maximal expiratory pressure During expulsion, the glottis opens and
(PEmax) is not specific to any single air moves down the pressure gradient
muscle group. through the narrowed tracheobronchial
tree at high velocities, thus clearing the
Gas exchange, which can be evaluated airways.
by arterial blood gas (ABG) analysis, is
often normal in early neuromuscular
pulmonary dysfunction. CLINICAL SIGN AND SYMPTOMS
-The first symptoms usually start by affecting
sleep. This leads to nocturnal
hypoventilation and interrupted sleep.
, The risk of aspiration is especially high
in patients with bulbar weakness
-The patients will often recognize a change in the
(weakness of the mouth and throat) In
quality of sleep, frequent awakenings,
these patients, The inability to clear the
morning headaches, daytime sleepiness, and
airway can increase the work of
fatigue. As the disease process progresses,
breathing, resulting in muscle fatigue,
patients may complain of orthopnea and
hypoventilation, and respiratory failure.
show signs of cor pulmonale (remodeling of
the right ventricle, usually in response to
Malnutrition is a major risk in patients
pulmonary hypertension, which causes
with neuromuscular weakness,
symptoms including dyspnea, fatigue,
especially with bulbar dysfunction.
anorexia, chest pain, edema, and syncope).
Once identified, Malnutrition should
-They also may experience a decline in voice
prompt consideration of dietary
volume or quality. Muscle weakness can
supplements, or if consistent with the
progress to the point that adequate
patients’ goals of care a feeding tube.
ventilation is no longer maintained, and
hypercapnia occurs.
Patients with neuromuscular weakness are
especially vulnerable to sleep disordered
Step 1: Lung Hyperinflation, Re-expansion of
breathing, including:
Atelectasis
- Sleep hypoventilation
Step 2: Cough-Assist and Secretion Clearance
- Obstructive sleep apnea (OSA)
Modalities
Step 3: Ventilatory Support Devices
Monitoring and assessing patients with
neuromuscular respiratory weaknesses.
There are multiple important
physiologic processes to monitor in
patient with neuromuscular respiratory
weakness, including oxygenation,
ventilation lung expansion cough
adequacy, aspiration risk, and nutrition
and sleep quality.
, Modern home ventilators (both invasive expiratory pressures, respiratory rate,
and noninvasive) have sophisticated tidal volume, and minute ventilation.
technology that records many
ventilatory and physiologic parameters
and allow remote access to these data Routine ventilatory function testing includes:
through ''device download'' functions.
- Measurement of sitting and supine VC
Allowing care providers to review - Inspiratory and Expiratory pressure
information such as the apnea- - CO2 levels (using end- tidal Co2 or ABG)
hypopnea index, inspiratory and Management of Respiratory Muscle Weakness
CHESTWALL
PATHOPHYSIOLOGY AND PULMONARY
FUNCTION TESTING
Pulmonary function testing in patients
with neuromuscular weakness typically
reveals a restrictive ventilatory defect
even if the lungs are normal.
Diffusing capacity is usually normal or
near normal, representing normal lungs
with preserved gas exchange function.
Clinically significant weakness of the
diaphragm presents with orthopnea and
can be identified by a decrease in VC
going from the upright to the supine
position. Supplemental oxygen (O2) can be
dangerous for patients with
The normal decrease is 7% to 10%. A neuromuscular dysfunction and
10% to 20% decrease suggests preexisting hypercapnia, as it can result
diaphragm weakness or unilateral in acute worsening of hypercapnia.
paralysis but can also be seen in obesity
and or abdominal wall disorders. A 25% Effective cough has three phases:
decrease has a 79% sensitivity and 90% inflation, compression, and expulsion.
specificity for diaphragm weakness. Inflation requires adequate inspiratory
muscle strength to pull in enough
Whereas a decreased maximal volume in the lungs to generate
inspiratory pressure (PImax) is generally appropriate cough pressure.
specific for diaphragm weakness, a
decreased maximal expiratory pressure During expulsion, the glottis opens and
(PEmax) is not specific to any single air moves down the pressure gradient
muscle group. through the narrowed tracheobronchial
tree at high velocities, thus clearing the
Gas exchange, which can be evaluated airways.
by arterial blood gas (ABG) analysis, is
often normal in early neuromuscular
pulmonary dysfunction. CLINICAL SIGN AND SYMPTOMS
-The first symptoms usually start by affecting
sleep. This leads to nocturnal
hypoventilation and interrupted sleep.
, The risk of aspiration is especially high
in patients with bulbar weakness
-The patients will often recognize a change in the
(weakness of the mouth and throat) In
quality of sleep, frequent awakenings,
these patients, The inability to clear the
morning headaches, daytime sleepiness, and
airway can increase the work of
fatigue. As the disease process progresses,
breathing, resulting in muscle fatigue,
patients may complain of orthopnea and
hypoventilation, and respiratory failure.
show signs of cor pulmonale (remodeling of
the right ventricle, usually in response to
Malnutrition is a major risk in patients
pulmonary hypertension, which causes
with neuromuscular weakness,
symptoms including dyspnea, fatigue,
especially with bulbar dysfunction.
anorexia, chest pain, edema, and syncope).
Once identified, Malnutrition should
-They also may experience a decline in voice
prompt consideration of dietary
volume or quality. Muscle weakness can
supplements, or if consistent with the
progress to the point that adequate
patients’ goals of care a feeding tube.
ventilation is no longer maintained, and
hypercapnia occurs.
Patients with neuromuscular weakness are
especially vulnerable to sleep disordered
Step 1: Lung Hyperinflation, Re-expansion of
breathing, including:
Atelectasis
- Sleep hypoventilation
Step 2: Cough-Assist and Secretion Clearance
- Obstructive sleep apnea (OSA)
Modalities
Step 3: Ventilatory Support Devices
Monitoring and assessing patients with
neuromuscular respiratory weaknesses.
There are multiple important
physiologic processes to monitor in
patient with neuromuscular respiratory
weakness, including oxygenation,
ventilation lung expansion cough
adequacy, aspiration risk, and nutrition
and sleep quality.
, Modern home ventilators (both invasive expiratory pressures, respiratory rate,
and noninvasive) have sophisticated tidal volume, and minute ventilation.
technology that records many
ventilatory and physiologic parameters
and allow remote access to these data Routine ventilatory function testing includes:
through ''device download'' functions.
- Measurement of sitting and supine VC
Allowing care providers to review - Inspiratory and Expiratory pressure
information such as the apnea- - CO2 levels (using end- tidal Co2 or ABG)
hypopnea index, inspiratory and Management of Respiratory Muscle Weakness
