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