Diaphragm in health and disease
Dr Randeep Guleria
M.D.,D.M.
Professor and Head
Department of Pulmonary Medicine and Sleep Disorders
All India Institute of Medical Sciences
New-Delhi
Muscles of respiration
Diaphragm
Intercostals and accessory muscles
Abdominal muscles
• Diaphragm – main inspiratory muscle
• External intercostals and accessory muscle also
inspiratory muscles
• Abdominal muscles – rectus, transverse
abdominis, external and internal oblique
– expiratory muscles
– Augment passive recoil of lung
•Respiratory muscles are crucial for ventilation
•Yet often neglected in day to practice
• May contribute to dyspnoea and respiratory failure
•Respiratory muscle assessment important
–Unexplained dyspnoea may be due to respiratory muscle
weakness
–Generalized neuromuscular diseases have respiratory muscle
weakness – often missed
–NIV helpful if respiratory muscle weakness detected early
–Respiratory muscle weakness may compound other diseases :
malnutrition, steroid, drugs, thyroid disorders, heart failure etc.
Respiratory muscle strength
Assessment
• Clinical
• Laboratory – unique, multiple ways
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Volume displacement
Pressure generation
Electrophysiological
Radiology
Clinical Assessment
– Generalized neuromuscular disorder
Breathlessness, tachypnoea
– Breathlessness – in supine position
– Nocturnal hypoventilation
– Recurrent aspiration
– Paradoxical abdominal movement
– Features present when diaphragm strength
decreased to ¼th of normal
– Significant diaphragm weakness may be
overlooked in early stage
Lung function
Inspiratory muscle weakness
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Decreased VC, TLC, Normal RV
DLCO normal when corrected for volume.
Normal VC makes respiratory muscle weakness unlikely.
In diaphragm weakness – VC falls on supine position
Usually > 25%
Useful for monitoring of progression of weakness
Test is volitional
May be non specific & non diagnostic
Mouth Pressures
• Widely used test for global inspiratory and
expiratory muscle strength
• Static MIP and MEP at mouth measured
• Non invasive tests with established normal value
• MIP measured from near RV, RV to FRC
• MEP measured from TLC
• High MIP (>80 cm H2O) rules out significant
inspiratory muscle weakness
• Volitional test – 3 equal maximum efforts made
Mouth piece
scale
Mercury Column
JAPI 1992;40: 108-110
Indian values
• 689 healthy school and college students
studied
• Regression equation derived
• Normal values for north Indian subjects
also derived
Guleria R, Jindal SK Normal maximal expiratory pressures
in healthy teenagers JAPI 1992;40:108-110
Pande JN et al Respiratory pressures in normal Indian subjects
IJCD 1998 40(4): 251-56
Issues with mouth pressure
• Simple
• At times patient is not able to perform the
test
• Glottis may close
• Buccal pressure may contribute to overall
pressures
• Negative predictive value
• Direct transdiphrgmatic pressure values
more reliable
• Relatively invasive
• Oesphageal and gastric balloons needed
• Difficult in routine practice
• Useful in patients suspected have
respiratory muscle and as a research tool
Sniff pressures
• Sniff Pdi – narrower normal range – better than
MIP
• About 1/6th patient with low MIP have normal
sniff Pdi
• Sniff Poes can be used instead of sniff Pdi
• Single oesophageal catheter needed
• Sniff Poes closely correlates with sniff Pdi
• Sniff Poes and sniff Pdi most accurate and
reproducible volitional tests for global inspiratory
muscle strength
sniff oesophageal pressures
in a patient
Sniff oesphageal pressure issues
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More accurate
Invasive
Difficult to do in routine practice
Patients cooperation needed
Nasal Pressures
• Sniff pressure at nose measured – SNIP
• In normal individuals- pressure in oesophagus
and nose show a close relationship
• Poes = SNIP
• In COPD - SNIP may under estimate
esophageal pressure
• Simple bedside test
• Normal valve established (men > 70 cm H2O.
women > 60 cm H2O)
Initial approach
Utility of SNIP
• SNIP and MIP measured in normal, patients with
obstructive lung disease (COPD) and with restrictive
lung disease (ILD)
• Very good correlation in normal and patient with
restrictive lung disease
• Mild insignificant decrease in COPD
• Simple easy to do and reproducible
• More patient acceptability
•
Arora N, Guleria R et al. Am J Respir Crit Care Med 2001;163: 156
Thorax 2007;62
Transplantation Proceedings 2005;37:664
Imaging
Useful technique
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CXR – P/A, lateral view
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Qualitative estimates
Decreased lung volume in B/L palsy
Unilateral palsy easy to differentiate
Fluoroscopy – upward movement of diaphragm
Short sharp sniff – paradoxical movement
Video fluoroscopy may provide dynamic information
• Ultrasound
– Used at sites where there is little air between
the probe and the muscle
– Easier to visualize the right dome
– Craniocaudal movement of the posterior
dome measured
– Thickness of the diaphragm can also be
measured
• 1.7 to 3.3 mm at FRC in untrained subjects
• Diaphragm thicker in subjects with greater
inspiratory muscle strength
• Unilateral palsy associated with thin costal
diaphragm
• Increase echogenicity be reported in
patients with Duchenne muscular
dystrophy
Utility in COPD
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Evaluated 22 COPD and 21 normal subjects
Simple test, poor echo’s in 2 cases
Paradoxical movement in 2 patients with COPD
Significant correlation between diaphragm movement and SVC,
FVC and FEV1 seen
• Correlation between MIP also seen – not significant
• Fair predictor of lung function and inspiratory muscle pressure
• Useful to assess effect of intervention programs – rehabilitation,
exercise etc.
Narayanan R, Guleria R, Gupta AK, Pande JN. Chest 2000;118: 201
Malnutrition and diaphragmatic
strength
• 24 under nourished (BMI < 18.5) and 26 well
nourished (BMI> 18.5) individual evaluated.
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Anthropometry
MIP, SNIP, Sniff esophageal pressure
US assessment – movement & thickness done
Correlation between strength and nutritional status
observed
– Mild to moderate malnutrition had little effect on
strength & thickness of diaphragm
Malav IC, Guleria R, Gupta AK, Pande JN, Sharma SK, Misra A. Chest 2006;130: 248S.
European J of Endocrinology 2002;147:299-303
Combination of tests increases diagnostic precision. Having multiple rests
of respiratory muscle function available both increases diagnostic precision
and makes possible in a range of clinical circumstances
Indian J Chest Dis. Allied Sci. 2009 Apr-Jun; 51 (2) : 83-5
Non volitional tests
• Oesophageal and gastric balloons placed
• Phrenic nerve studied
– Electric
– Magnetic
• Oesophageal pressure, gastric pressure
and Pdi measured
Electric Stimulation
• Phrenic nerve stimulation done in neck at FRC
• Twitch Pdi measured
• Uncomfortable - repeated stimulation needed for
precise electrode placement.
• Patient unable to relax – twitch potentiation
• Unilateral and bilateral electric stimulation done
• Normal twitch Pdi – 8.8 to 33 cm H2O
Magnetic stimulation
• Magnetic coil used
• Pulsed magnetic field causes current to flow in
nervous tissue within the field
• Circular coil used over cervical phrenic nerve
roots
• Magnetic Pdi slightly greater than electric Pdi
• Painless & reproducible procedure
• Figure of 8 coil used for hemidiaphragm
assessment
Am J Respir Crit Care Med 1999; 160(2):513-22.
Fatigue and endurance
• Ventilatory endurance tests
– Maximum sustainable ventilation
• 70 – 80% MVV for 8 minutes
• 20% MVV, increase by 10% every 3 minutes
• Threshold loading- weighted plungers/ valves
• Repeated MIP
– 18 repeated MIP maneuvers – each effort for 10
seconds with a 5 second rest
• Resistive loading
Constant negative Pressure Device
Two way non rebreathing valve
Pressure meter
Mouth piece
Vacum cleaner
30% of MIP as starting pressure
Pressure decreased by 10cm H20 every 3 minutes
Guleria R, Watson SC, Polkey MI, Moxham J, Green M. Thorax 1997;52: 29
EtC02 (mmHg)
EtC02 During Negative Presure Run
45
40
35
30
25
20
15
10
5
0
30%
40%
50%
60%
70%
NEGATIVE PRESSURE RUN % OF MIP
80%
NEGATIVE PRESSURE RUN, PRESSURE -30 cm H20
cm of H20
88
80
Twitch inbetween
Interpolated twitch
70
60
Pdi
50
40
30
P gas
20
10
0
-10
-20
P mouth
-30
-40
P oes
-50
-60
14.0
15.0
16.0
17.0
18.0
19.0
20.0
21.0
22.0
23.0
Time
Magnetic stimulations
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
3
CM OF H20
NEGATIVE PRESSURE RUN TWITCH Pdi
45.00
Twitch inbetween
Potentiated
Potentiated
40.00
Unpotentiated
35.00
30.00
25.00
Interpolated twitches
20.00
15.00
10.00
5.00
0.00
Baseline
30%
40%
50%
Negtive Pressure Run
60%
70%
80%
% of MIP
0 20
40 60
minutes
0
20 40
after run
60
Kg
QUADRICEPS RUN, 30% OF MVC
22.0
Interpolated twitch
20.0
Resting twitch
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
-2.0
-4.0
-6.0
-8.0
80.9
85.0
90.0
95.0
100.0
105.0
Time
Magnetic stimulation
110.0
115.0
120.0
125.0
130.
Conclusion
• Respiratory muscle function is an important but
neglected area in pulmonary medicine
• Simple multiple assessment tests possible
• Number of conditions affect respiratory muscles
• Early diagnosis of respiratory muscle
dysfunction helps in prompt and proper
intervention
• Respiratory muscle endurance and fatigue
continues to be a fascinating area
Thank You