Autonomic nervous system
Dr. S. Parthasarathy
MD, DA, DNB, Dip Diab.MD ,DCA, Dip
software based statistics,
PhD (physiology)
Definition
• The autonomic nervous system (ANS) controls the body's
involuntary (i.e.,outside of consciousness) activities.
• Autonomic
• the most primitive and among the most essential of the
body's systems
• Primitive – all mammals
• Essential – most important systems
History
• Almost a century ago, in 1898 the autonomic nervous system
was actually described first by Langley.
•
It was called at that time as the visceral, vegetative or
involuntary nervous system
• by meditation and yoga the HR, BP, visceral sensation, etc,
which are controlled by the ANS can be modulated.
Nervous system in simple terms
Two systems
• Sympathetic
• Parasympathetic
• Nerves are traditionally classified by the chemical transmitters
that they contain.
• Nerves containing acetylcholine are called cholinergic,
• containing norepinephrine are called adrenergic.
Structure
• Autonomic sensory receptors
• Sensory neuron
• Integrating centres ( hypothalamus, cord,
brainstem)
• Motor -----• Effector
Motor Structure
• ANS is Reflex arc
• Preganglionic –( CNS ) –axons –
• synapse in ganglia --• postganglionic neurons --• effector organs
Sympathetic
Parasympathetic
ACh
Somatic .. ??
Path – sympathetics
• The 22 paired ganglia lie along either side of the vertebral column.
•
The preganglionic fibers leave the cord in the anterior nerve roots, join
the spinal nerve trunks, and enter the ganglion at their respective level
through the white (myelinated) ramus.
•
Leaving the ganglion, postsynaptic fibers reenter the spinal nerve
through the gray (unmyelinated) ramus
• innervate the pilomotor and sudomotor (sweat gland) effectors and
blood vessels of the skeletal muscle and skin
• Sympathetic postganglionic fibers innervate the trunk and limbs via the
spinal nerves.
Structure again !!
Amplification
in SNS
PNS
• The parasympathetic nervous system arises from cranial
nerves III, VII, IX, and X, as well as from sacral segments.
• EW- ciliary ,
• lacrimatory –sphenopalatine,
• dorsal nucleus – otic ganglion ……..
• Mainly vagus ---• The second to fourth sacral segments contribute the
nervi erigentes, or the pelvic splanchnic nerves.
• They synapse in terminal ganglia associated with the
rectum and genitourinary organs.
Parasympathetic
Sludge – muscarinic effects
•
•
•
•
•
•
Salivation:
Lacrimation:
Urination: of urethra,
Defecation:
Gastrointestinal upset:
Emesis:
Nicotinic effects
•
•
•
•
•
Monday
Tuesday
Wednesday
Thursday
Friday
Mydriasis (pupillary dilation)
Tachycardia
Weakness
Hypertension
Fasciculations
• SNS and PNS are Usually antagonistic – but
• Blood pressure
• We don’t give PNS antagonists
To increase BP
The enteric nervous system
• network of neurons and their supporting cells found
within the walls of the gastrointestinal tract, including
neurons within the pancreas and gallbladder.
• contains as many nerve cells as the spinal cord does.
• derived from neuroblasts of the neural crest that migrate
to the gastrointestinal tract along the vagus nerve
• Local autonomy
Progress
Adrenergic agonists
Dopamine
Phenyleph
Dopamine
Clonidine
Dobutamine
Isoprenaline
Oxymetazoline
Noradrenaline
Terbutalin
norad
Adrenaline
Alpha
Alpha 1
Ephedrine
Beta
Alpha 2
Beta 1
Beta 2
Ephedrine
Beta 3
Noninvasive Tests for
Assessing the Autonomic
Nervous System
Parasympathetic
• HR response to a Valsalva maneuver
• Deep inhalation prior
• The seated subject blows into a mouthpiece (while
maintaining a pressure of 40 mm Hg) for 15 seconds. The
Valsalva ratio is the ratio of the longest R-R interval (which
comes shortly after release) to the shortest R-R interval
(which occurs during the maneuver)
• Ratio of >1.21 is normal
• Two times, beware of retina, COPD, age ??
HR response to standing
• HR is measured as the subject moves from a resting supine
position to standing.
• A normal tachycardic response is maximal around the 15th beat
after rising.
•
A relative bradycardia follows that is most marked around the
30th beat after standing.
• The response to standing is expressed as a 30 : 15 ratio and is the
ratio of the longest R-R interval around the 30th beat to the
shortest R-R interval around the 15th beat
• Ratio of >1.04
HR response to deep breathing
• The subject takes six deep breaths in 1 minute.
• The maximum and minimum heart rates during each cycle
are measured, and the mean of the differences (maximum
HR - minimum HR) during three successive breathing cycles
is taken as the maximum-minimum HR Mean difference >15
beats/min.
Sympathetic function
tests
• The subject moves from resting supine to
standing, and standing SBP is subtracted from
supine SBP
• Difference <10 mm Hg
BP response to sustained handgrip
• The subject maintains a handgrip of 30% of the
maximum handgrip squeeze for up to 5 minutes.
• BP is measured every minute
• Release BP – initial BP = >16 mm Hg
• Silastic imprint test
• Sympathetic cholinergic sweat function
• Tilt table test
British Journal of Anaesthesia 104 (5):
587–95 (2010)
• Autonomic nervous system state: the effect of general
anaesthesia and bilateral tonsillectomy after unilateral
infiltration of lidocaine.
• Local and nociceptive blunting depresses autonomic
activity.
• perioperative factors such as anxiety, pain and surgical
trauma are known to cause an imbalance of the
autonomous
nervous
system,
haemodynamic and metabolic changes
with
resulting
Which all can cause autonomic changes ??
•
•
•
•
•
•
Laryngoscopy
Intubation
Incision
CVP catheters and guide wires
Lap ports , extra ocular muscles
Mesentery ,anus, D &C,
General anaesthesia
•
•
•
•
•
•
Anticholinergics
Pupil drops
IV anaesthetics blunt baroreceptor reflexes
Ketamine -- increases SNS
Alpha 2 agonists
Minimal blunt baroreceptor reflexes with agents
…. But desflurane increases SNS
• But light plane ?? !!
• Anticholinesterases
Think in --resection and anastamosis
• “over-reversal” of muscle relaxants, the gut (in
which cholinesterase is inhibited) has a tendency to
become hyperreactive.
Regional anaesthesia
• Sympathetic block
• Gastric hyperperistalsis and nausea and
vomiting
• Spinal and postop urinary retention
Anaesthetic concern
• a spinal or epidural anesthetic covering the midthoracic levels
yields a contracted, small intestine that may afford superior
surgical conditions in combination with the profound muscle
relaxation of a spinal anesthetic.
• The sphincters are relaxed, and peristalsis is normally active.
• Think of hysterectomy
Do we need to test
these things ??
YES
• Mostly associated complications nephropathy
neuropathy cause problems than this
• More morbidity or mortality
• Gastroparesis , hypotension, arrest etc..
ANS
• The clinical importance of visceral afferent
fibers is more closely associated with chronic
pain management.
• why sweat in cardiac and renal diseases ??
•
•
CRPS
What is new ??
• many potential genetic contributors to autonomic-related
disease states (e.g., essential hypertension, lipid and glucose
metabolism, and postural tachycardia syndrome have been
identified
•
no single genetic mutation has completely explained any of
the examined autonomic dysfunctions.
•
It is almost certainly true that abnormalities in autonomic
function are polygenic in origin and also involve significant
environmental input.
What is rule of two's ??
•
•
•
•
•
•
•
Afferent and efferent
Sympathetic and parasympathetic
Thoraco lumbar
Cranio sacral
Cholinergic and adrenergic
Fight or flight
Rest or digest
We know
•
•
•
•
General medicine
Paediatric medicine
Metabolic medicine
Dermatological medicine etc…
• Anaesthesia is autonomic medicine
•Thank you all