diaphragm in health and disease dr randeep guleria m.d.,d.m. professor and head
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Diaphragm in health and disease
Dr Randeep GuleriaM.D.,D.M.
Professor and HeadDepartment of Pulmonary Medicine and Sleep Disorders
All India Institute of Medical SciencesNew-Delhi
Muscles of respiration
DiaphragmIntercostals and accessory musclesAbdominal 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 • 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– 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
Mercury Column
Mouth piece
scale
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;40:108-110Pande 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
• 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
• CXR – P/A, lateral view– 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
• 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.– 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
• Oesophageal and gastric balloons placed
• Phrenic nerve studied– Electric– Magnetic
• Oesophageal pressure, gastric pressure and Pdi measured
Non volitional tests
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
Vacum cleaner
Pressure meter
Two way non rebreathing valve
Mouth piece
Constant negative Pressure Device
Guleria R, Watson SC, Polkey MI, Moxham J, Green M. Thorax 1997;52: 29
30% of MIP as starting pressure Pressure decreased by 10cm H20 every 3 minutes
EtC02 During Negative Presure Run
05
1015202530354045
30% 40% 50% 60% 70% 80%
NEGATIVE PRESSURE RUN % OF MIP
EtC
02 (
mm
Hg
)
14.0 15.0 16.0 17.0 18.0 19.0 20.0 21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 32.0 33.0
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
88
Pdi
Interpolated twitch
P oes
P mouth
P gas
Twitch inbetween
NEGATIVE PRESSURE RUN, PRESSURE -30 cm H20
Magnetic stimulations
cm of H20
Time
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
30%Baseline 40% 50% 60% 70% 80% 0 20 40 60 0 20 40 60
Potentiated
minutesNegtive Pressure Run
Twitch inbetween
Interpolated twitches
Unpotentiated
Potentiated
CM OF H20
after run% of MIP
NEGATIVE PRESSURE RUN TWITCH Pdi
85.0 90.0 95.0 100.0 105.0 110.0 115.0 120.0 125.0 130.080.9
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
22.0
Kg
Interpolated twitch Resting twitch
Time
Magnetic stimulation
QUADRICEPS RUN, 30% OF MVC
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
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