Peri operative Shivering

1. 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 Peri operative Shivering

2. Shivering of patients

3. Shivering is an involuntary, oscillatory muscular activity that augments metabolic heat production. Vigorous shivering increases metabolic heat production up to 600% above basal level Definition

4. 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, waxing-and-waning pattern

5. a tonic stiffening and appeared to be largely a direct, non–temperature-dependent effect of isoflurane anesthesia.

6. 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, Temperature-regulating system

8. C fibres – spinal cord modulation – Nucleus Raphe Magnus and Locus ceruleus ----- preoptic anterior hypothalamus Spinal cord possible recurrent inhibition of renshaw cells Motor activity

9. 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 How to cool a man !!

11. This is normal but in anaesthesia ??

12. Regional 0.6 * C More with GA Other than behavioural changes

13. Does the vasoconstriction cause ischemia ?? Does the vasoconstriction decrease blood flow to the peripheries ?? NO Dormant blood vessels in the forearm Questions ??

14. Perioperative hypothermia • Phase I: 1st hour • Internal redistribution: from center to peripheral • Phase II: 2-4 hours • Heat loss: skin, viscera • Phase III: • Steady-state RA

15. Cold --- SNS stimulation ---- brown fat --- mitochondrial oxidation ---- uncoupling --- heat production Infants Propofolfentanyl abolishes NST Nonshiveringthermogenesis

16. Uninhibited spinal reflexes, postoperative pain, pyrogen release, adrenal suppression, respiratory alkalosis Normothermic shivering --- Why??

17. 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 . What is the incidence ??

18. 0 – no – shivering even in palpation of masseter 1 – shivering neck and thorax 2. – grossly seen includes upper extremities 3 – through out the body Bedside shivering assessment scale

19. 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 Why should we worry ??

20. Shivering increases intraocular and intracranial pressures. Disturbing to mother Reduced in elderly and frail patients

21. 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

22. OCCCCCO- pneumonic Oxygen, carbon dioxide ,comfort, clotting, catecholamines, cardiac, , cranial, ocular Problems of shivering

23. Management

24. prevention

25. 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 Prevention

26. 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. active warming

27. biogenic monoamines, Cholinomimetics, cations, endogenous peptides N-methyl-D- aspartate (NMDA) receptor antagonists Pharmacotherapy

28. Pharmacological intervention does not raise body temperature, but resets the shivering threshold to a lower level, thereby decreasing rigors and its episodes What do the drugs do ??

29. Physostigmine a nonselective centrally acting cholinesterase inhibitor is a potent antishivering drug Availability ??

30. 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 Opioids

31. morphine (2.5 mg), fentanyl (25 mic g), alfentanil (250 mic. g), Pethidine ( 25 mg) Dosage of opiods

32. 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 Neuraxialopiods

33. Pre induction IV pethidine -- minimal role in a few studies Various studies

34. 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-desmethyltramadol, reduce neuronal firing rate and hyperpolarize neurons in a concentration-dependent manner. Opioids

35. 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. Butorphanol

36. It is a nonsedativebenzoxacine analgesic 0.15 mg/kg IV As effective as clonidine But less effects on hemodynamics nefopam

37. Excess of Ca2+ into the posterior hypothalamus leads to a decrease in body temperature Magnesium may be considered as physiologic calcium channel blocker Cations

38. Magsulf – NMDA antagonism Orphenadrine is both antimuscarinic and has noncompetitive NMDA receptor antagonist properties NMDA

39. Ketamine, which is a competitive NMDA-receptor antagonist, also inhibits postanaesthetic shivering. 0.25 mg / kg of IV ketamine as prophylaxis Ketamine

40. 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 Methylphenidate

41. 5 HT antagonism 10 mg IV Effective as 150 mic gm of clonidine Vasodilation also occurs Ketanserin

42. Differential recovery of brain and spinal cord Hence doxapram effective against shivering Coming out of anaesthesia

43. 4 mg of IV ondansetron Buspirone 60 mg prior 75 mic. gm Clonidine -- best option Prophylaxis

44. Definition Pathway BSAS Prophylaxis ( hypo and drugs ) Treatment --- opiods, 5 HT, cholinomimetics,NMDA , analeptics,analgesics (Clo and nefo) Summary

45. More than 20 references Anybody can shiver when this is the situation Thank you all