Auto dysfunction

1. Autonomic Dysfunction:
Bedside Tests
Akhila Mathews

2. Autonomic Nervous system
• An automatic system to maintain homeostasis.
• Controls involuntary functions like blood pressure, heart
rate,pupillary,glandular,bowel-bladder,sexual function.
• Three functional components:sympathetic,parasympathetic,enteral
systems

3. Divisions of ANS
• Parasympathetic: rest and digest
Energy conservation restoration system
• Sympathetic: Flight and fight responses
Energy expenditure system

4. Central control of ANS
• Hypothalamus and extra hypothalamic structures
• paraventricular nucleus of hypothalamus
• sympathetic outflow include locus cerulus and rostral and caudal
medulla,serotonin containg neurons of pons and medullary raphe
nucleui
• parasympathetic outflow include amydala,dorsal nucleus of vagus
nucleus ambigus,periaqueductal grey materand parbrachial grey
mater
• Limbic cortex influence both set of autonomic outflow

5. Peripheral ANS
• Craniosacral: parasympathetic
• Thoraco lumbar:sympathetic

9. • Dysautonomia:autonomic nervous system doesnot work properly
.reflexes are intact but may be excessive or inappropriate
• Autonomic failure:autonomic nervous system is damaged and
doesnot work at all.
• Etiology of autonomic failure:
primary neurodegenerative disease(multiple system atrophy,pure
autonomic failure,parkinsons disease,huntingtons disease or dementia)
seconary to systemic diseases that affect peripheral
nerves(diabetes,amylodosis,paraneoplastic syndrome,b12 defeciency)

10. Features of autonomic failure
• Orthostatic hypotension
Decrease in SBP>/=20mmhg
Decrease in DBP>/=10mmhg
Within 3 mins of standing
Causes:autonomic disorders,low blood volume,vasodilation(drugs
ang alcohol)
•Postprandial hypotension:fall in SBP>20mmhg at 2hr after a
meal.average drop is 50mmhg and starts at 15 min after meal

11. •supine hypertension
•resting tachycardia
•exercise intolerance
•reverse dipping and non dipping:
healthy individuals have nightly drop in bp
In autonomic dysfunctionthere will be increased bp with increased
sympathetic tone at night

12. Autonomic symptoms
• Syncope
• Weakness or light headedness
• Constipation
• Urinary incontinence or retention
• Dimished or increased sweating
• Exercise intolerance,fatigue
• Palpitation ,tachycardia
• Nausea ,vomiting
• Anorexia,bloating or fullness after eating
• Dry eye,dry mouth

13. Autonomic function tests
• Heart rate variation with deep breathing
• Valsalva response
• Orthostatic bp recording
• Tilt table test
• Sudomotor function test
• Thermoregulatory sweat test

14. Patient preparation
• To be discontinued before
48hrs:anticholinergics<sympathomimetics<parasympathomimetics,min
eralocorticcoids,diuretics.
24 hrs: sympatholytics
12hrs:alcohol ,analgesics
at the morning:
confinig clothing,corset,supportive stocking
3hrs:coffee,nicotine,food

15. Heart rate response to deep breathing
Physiological basis:
•Respiratory sinus arrhythmia: HR increases with inspiration and
decreases with expiration.
• Most sensitive test for cardiovagal function
• Reduced heart variability is one of the earliest manifestation of
autonomic dysfunction

16. Technique
Supine position
Three ecg leads
six cycles/ min(each cycle5sec inspiration and 5 sec expiration) for 5min
Machine records the heart rate
The maximun and minimum HR recorded in each cycletheir average
difference and E:I ratio is calculated its that ratio between longest rR-R
interval and shortest R-R interval
HR difference of >/=15 is normal while </=10 is abnormal
E:I RATIO normal is >/=1.21

19. Valsalva manuevere
• Asses intergrity of baroreflex
It is forced expiration against closed glottis
• Supine position
• Finometer attached to finger
• Instructed to breathe into a bugle with closed nose and maintain post
expiratory pressure of 40mmhg for 15sec
• Evaluates sympathetic adrenergic function using BP responses and
parasympathetic function using HR responses

22. Postural challenge test
• It can be done by orthostatic bp recording in standing up position
actively or head up tilt test.
Physiological basis
• standing up puts hydrostatic stress on venous return causing venous
pooling hence bp drops and baroreflex gets activated
• HR increases in 10-20 sec and decreases later by25-35 sec

23. Head up tilt test
• Before tilt patient lies supine and relaxes for 5min
• Safety strap and finometer connected
• On tilt 70 degree over 2-3 sec
• Routine tilt period is 10 min
• HR nad BP will be recorded( at 0.5,1,2,3,5,7,10 min)

29. Quantitative sudomotor axon reflex testing
• It measures post ganglionic small nerve fibre functions where nerve
conduction studies are normal
• The use of multiple recording sites help in evaluating the distribution
of sweating abnormality

30. Technique
• For multicompartment capsules are applied on the forearn,proximal
leg,distal leg,foot
• Ach is iontophoresed in one compartment activating a local axon
reflex stimulating the sweat glands under this compartment
• Sweat output is collected and measured in microlitres/cm2

33. Thermoregulatory sweat test
• Qualitative measure of sweat production in response to elevation of
body temperatureunder controlled conditions
• An indicator powder is placed on anterior surface of body which
changes colour with sweat production during temperature elevation.

35. •thank you