PERI OPERATIVE SHIVERING
Dr. S. Parthasarathy
MD., DA., DNB, MD (Acu),
Dip. Diab. DCA, Dip. Software statistics
PhD (physio)
Mahatma Gandhi medical college and
research institute , puducherry, India

Shivering of patients
DEFINITION

Shivering is an involuntary, oscillatory muscular
activity that augments metabolic heat
production.

Vigorous shivering increases metabolic heat
production up to 600% above basal level
HOW IS IT??

Thermoregulatory


The fundamental tremor
frequency on the
electromyogram in
humans is typically near
200 Hz.
This basal frequency is
modulated by a slow, 4–
8 cycles/ min, waxingand-waning pattern

a tonic stiffening and appeared to be largely a
direct, non–temperature-dependent effect of
isoflurane anesthesia.
TEMPERATURE-REGULATING SYSTEM
Thermosensors
Skin ( C ) to hypothalamus
 Integration area
Spinal cord
Modulate: NRM( serotonin),NE(LC)
Integration inputs: - PO AH
 Efferent pathway
Central descending shivering pathway: PH
Multiple inputs>common efferent signal
Spinal α motor neurons,

6

C fibres – spinal cord modulation – Nucleus
Raphe Magnus and Locus ceruleus ----preoptic anterior hypothalamus


Spinal cord possible recurrent inhibition of
renshaw cells

Motor activity
HOW TO COOL A MAN !!

Pickering wrote in 1956: “The most effective
system for cooling a man is to subject him to
anaesthesia”.

mid of 1960’s -- first case of malignant
hyperthermia
THIS IS NORMAL BUT IN ANAESTHESIA ??
OTHER THAN BEHAVIOURAL CHANGES
Regional
 0.6 * C
 More with GA

QUESTIONS ??

Does the vasoconstriction cause ischemia ??

Does the vasoconstriction decrease blood flow
to the peripheries ??

NO

Dormant blood vessels in the forearm
PERIOPERATIVE HYPOTHERMIA

37.5
37
Phase I: 1st hour

36.5
36
35.5

35
Phase II: 2-4 hours

34.5

Temp
34
33.5
Heat loss: skin, viscera
Phase III:

33
Internal redistribution:
from center to
peripheral
Steady-state
R
A
32.5
0
1
2
3
4
5
14
NONSHIVERING THERMOGENESIS

Cold --- SNS stimulation ---- brown fat --mitochondrial oxidation ---- uncoupling --- heat
production

Infants

Propofol fentanyl abolishes NST
NORMOTHERMIC SHIVERING --- WHY??
Uninhibited spinal reflexes,
 postoperative pain,
 pyrogen release,
 adrenal suppression,
 respiratory alkalosis

WHAT IS THE INCIDENCE ??

Shivering occurs in approximately 40% of
unwarmed patients who are recovering from
GA and in about 50% of patients with a core
temperature of 35.5 C and in 90% of patients
with a core temperature of 34.5 C .
BEDSIDE SHIVERING ASSESSMENT SCALE
0 – no – shivering even in palpation of
masseter
 1 – shivering neck and thorax
 2. – grossly seen includes upper extremities
 3 – through out the body

WHY SHOULD WE WORRY ??

Shivering can double or even triple oxygen
consumption and carbon dioxide production
Marked increase in plasma catecholamine
 Level
 Three times more likely to have adverse
myocardial outcomes


Shivering increases intraocular and intracranial
pressures.

Disturbing to mother

Reduced in elderly and frail patients
PROBLEMS OF SHIVERING
Uncomfortable, and some even find the
accompanying cold sensation worse than
surgical pain.
 Increased surgical bleeding , wound infection
 may aggravate postoperative pain simply by
stretching surgical incisions.

PROBLEMS OF SHIVERING
OCCCCCO- pneumonic
Oxygen, carbon dioxide ,comfort, clotting,
catecholamines, cardiac, , cranial, ocular
Management
prevention
PREVENTION

Cutaneous heat loss can be decreased by
covering the skin (e.g. with surgical drapes,
blankets or plastic bags).

Single covering can decrease heat loss by 30 %

Maintain above 36 as far as possible
ACTIVE WARMING

most cases some form of active warming is
required to prevent hypothermia

Forced air warming or a combination of forced
air warming along with fluid warming is
required to maintain normal intra operative
and postoperative core temperatures.
PHARMACOTHERAPY
biogenic monoamines,
 Cholino mimetics,
 cations, endogenous peptides
 N-methyl-D- aspartate (NMDA) receptor
antagonists

WHAT DO THE DRUGS DO ??
Pharmacological intervention does not raise
body temperature,
 but resets the shivering threshold to a lower
 level, thereby decreasing rigors and its
episodes

Physostigmine a nonselective centrally acting
cholinesterase inhibitor is a potent
antishivering drug
 Availability ??

OPIOIDS

Fentanyl,alfentanyl morphine has got
antishivering properties
But pethidine
 Twice more effective


The antishivering activity of meperidine may be
partially mediated by k- opiod receptors
DOSAGE OF OPIODS
morphine (2.5 mg),
 fentanyl (25 mic g),
 alfentanil (250 mic. g),
 Pethidine ( 25 mg)

NEURAXIAL OPIODS

Epidurally administered sufentanil in patients
produces
a
dose-dependent
decrease
in
shivering response and body temperature.

Epidural fentanyl also reduced the shivering
threshold when added to lidocaine for epidural
VARIOUS STUDIES


Pre induction IV pethidine -- minimal role in
a few studies
OPIOIDS

The effects of nefopam and tramadol at the level
of the pons may partially explain their antishivering
effect.

In the rat locus coeruleus, tramadol and its main
metabolite,
O-desmethyl
tramadol,
reduce
neuronal firing rate and hyperpolarize neurons in a
concentration-dependent manner.
BUTORPHANOL
Butorphanol had an edge over tramadol in
controlling shivering with lower chances
 of recurrence,
 Both were superior to clonidine for this purpose
with an early onset of action.

NEFOPAM
It is a nonsedative benzoxacine analgesic
 0.15 mg/kg IV
 As effective as clonidine
 But less effects on hemodynamics

CATIONS

Excess of Ca2+ into the posterior hypothalamus
leads to a decrease in body temperature

Magnesium may be considered as physiologic
calcium channel blocker
NMDA

Magsulf – NMDA antagonism

Orphenadrine is both antimuscarinic and has
noncompetitive NMDA receptor antagonist
properties
KETAMINE
Ketamine,
 which is a competitive NMDA-receptor
antagonist, also inhibits postanaesthetic
shivering.
 0.25 mg / kg of IV ketamine as prophylaxis

METHYLPHENIDATE
Methylphenidate is an analeptic agent that
binds presynaptic sites on dopamine, nor
epinephrine and 5-HT transport complexes,
which in turn blocks reuptake of the respective
neurotransmitters
 10 – 20 mg IV dose

KETANSERIN
5 HT antagonism
 10 mg IV
 Effective as 150 mic gm of clonidine
 Vasodilation also occurs

COMING OUT OF ANAESTHESIA

Differential recovery of brain and spinal cord

Hence doxapram effective against shivering
PROPHYLAXIS
4 mg of IV ondansetron
Buspirone 60 mg prior
75 mic. gm Clonidine -- best option
SUMMARY
Definition
Pathway
BSAS
Prophylaxis ( hypo and drugs )
Treatment --- opiods, 5 HT,
cholinomimetics,NMDA , analeptics,analgesics
(Clo and nefo)
THANK YOU ALL
More than 20 references
 Anybody can shiver when this is the situation
