Decreased oxygen requirement of body tissues & organs
In dog O2 requirement decreased to 50% at 30◦c & 65% at 25◦c.
Metabolic rate of isolated slices of heart was reduced by 90% at 10◦c.
Potassium arrested heart at 37◦c utilizes
4 times glycogen and produces 3 times lactic acid as by heart at 17◦c.
However O2 consumption varies for different organs at a particular temperature.
Conclusion ;- vital organs (liver, brain, heart) can survive at low temperature for considerable period when deprived of all or a portion of blood supply.
Level of hypothermia;
In Small lab. animals recovery rate was 80%-100% just above freezing point with cardiac & respiratory arrest for 1 hr.
Dog survived cooling to 1.5◦c on pump oxygenator
For induction of quick hypothermia shivering is to be controlled by deep anesthesia or light anesthesia with tranquilization.
Moderate hypothermia in dog produced rectilinear decrease in anesthetic dose (MAC) for cyclopropane , diethyl ether, fluroxene, halothane, & methoxyflourane.
Reduces concentration of anesthetic required to produce apnea.
Methods of producing whole body hypothermia
1) Surface cooling.
2) Body cavity cooling.
Surface cooling :- animal directly imersed in ice cold water or kept in cold matress. It needs hyperventilation to keep blood pH (7.2-7.4) on alkaline side to prevent cardiac arrhythmias & fibrillation.
Below 28◦c no anesthetic only ventilation required.
Cooling stopped when approx. ⅔ of desired temp. fall is accomplished
Body cavity cooling :- pouring cold saline water into open thoracic cavity.
Extracorporeal method :- running blood from a cannulated artery via a heat exchanger with tap water as a cooling medium with the help of a pump.
Used to lower brain temp. below that of general body temp. by cannulating carotid artery to 14◦c while body temp. remains at 31-32◦c.
Best control over body temp. & quick rewarming.
Interference with blood coagulation.
Surgery of heart, great vessels, brain & spinal cord.
Treatment of shock, stroke, cerebral & spinal contusion preventing brain damage from severe hypoxic episode.
Removal of heartworms & repair of cardiac anomalies in dog.
Limitations of hypothermic anesthesia
1) cardiac crisis ;-
Fall of B.P may be drastic due to decreased cardiac output & H.R and increased peripheral resistance.
In dog cardiac crisis occur b/w 23 & 15◦c characterised by intense bradycardia , ventricular extra- systoles & ventricular fibrillation .
Hypercapnia , Acidemia,& myocardial hypoxia also lead to ventricular fibrillation , Prevented by adequate ventilation or by some cardioplegic solutions.
7) Prolonged hypothermia can lead to CV colapse, depletion of cerebral energy stores.
8) Damage to liver , kidney & adrenal glands in dog at 25◦c for hours.
Induction of hypothermia in dog
Phenothiazine tranquilizer given I/V as preanaesthetic
Thiobarbiturate (G.A); Endotracheal catheter is inserted
Inhalant anesthetic for maintenance
Slow I/V drip of RL / Dextrose 5% & muscle relaxant given
Controlled respiration is started
Animal positioned in sink /bathtub/container with head above water
Electronic thermometer is placed in esophagus @ heart level & rectum
Electrodes of ECG machine attached to feet – constant monitoring required
Ice water used for rapid cooling
Dog is removed from bath before reaching of desired temp.
After removed, place in inactive heating pad during operative period
Rewarming started at start of surgical wound closure
First – placing pads/blankets with circulating warm water or air
Supplement – warm water bottles and bags
Warm s/c or i/v fluids approx. 98-99ºF
Water filled balloons or latex gloves used instead of bottles
Towels or blankets warmed in dryer and wrapped around patient to trap heat
Rewarm water bottle frequently
Electric heating pad should not be used
Severe thermal skin burn may occur
Skin sloughing can be serious complications
Principle :- electric stimulation of brain activate opiate or non-opiate pain controlling pathway or both thus producing analgesia.
Clinical trials in vety practice first performed by
Sir Frederic Hobday in England in 1932.
Used in situations requiring prolonged anesthesia.
Electrodes operating at A.C (35-50 mAmp & 40V) or D.C or in combination are applied to head.
Individual variations are adjusted.
Characterized by convulsions on induction , profuse salivation & hyperthermia.
Clotting time , ESR , Hb conc. , PCV , total WBC count or DLC do not differ much.
B.P rises sharply & then gradually falls to near normal level.
No effect on oxygen content of blood.
Glucose level rises.
Difficult to assess depth of anesthesia. Muscle relaxation may vary from adequate to poor and surgical pain may cause body movements in apparently unconscious animal.
Photo motor reflexes are probably best means to determine depth.
Quick recovery following removal of current by slight stimulus & animal resumes all normal activities.
Economy and immediate recovery
Brain lesions demonstrated.
Non-availability of suitable equipments and standardized technique in clinical application.
Acus – needle; Punctura – to prick
Current meaning – any type of stimulation (Acupressure, moxibustion, heat, cold, ultrasound, aquapuncture, electro stimulation, implantation and laser) at acupuncture points to produce analgesia or to cure certain diseases.
Used increasingly in man & animals for producing analgesia.
Used in conjunction with Western treatments- surgery or pharmacological therapy
Existed in India 7000 years ago
Huang Ti Nei Ching (Yellow emperors classic of internal medicine) – oldest document
Integral part of Traditional Chinese Medicine- used more than 2500 years to treat diseases and relieve pain
1921 – Ban in China
1960s – Maoists regime – reintroduction
Points are called ‘ Xue’ – means ‘cave’ or ‘hole’.
Eastern countries- specify points different names describing their location or function e.g. ‘wei shu’ means point associated with stomach & is used for gastric diseases but are confusing.
Western acupuncture practitioners – identify points by number and capital letter abbr. of the meridian to which they belong e.g. BL/UB, LI, ST, SP, GB, etc.
Acupoints differ in their physiological behavior, electrical response,& therapeutic role.
Reflect various organs on surface of body.
Small as a pin head.
Referred as areas of hypersensitivity & lowered electric resistance.
Located on imaginary horizontal lines k/as MERIDIANS which have internal connections with the organs from which they get their name.
12 organ meridians like LU, LI, ST, SP, H, SI, UB/BL, K, P, TW, GB, LIV & 2 non-organ meridians GOV(governor vessel) and COV(conception vessel) in large animals.
365 classic points located along the meridians.
Acc. to Chinese vital energy “chi” flow through these pathways.
Exact location of points is important – small deviations nullify the response (classic theory)
Acupuncture points are cutaneous areas with high conc. Of nerves ,mast cells, capillaries ,and venules & lower electrical resistance than surrounding areas
Located in small hollow or depression on skin surface
Are tender compared with surrounding area & response (discomfort) elicited with deep palpation
Subjective roughness or stickiness appreciated when brushed slightly with finger
Clinically used points in most species are believed to be 3 – 15 mm below skin surface
Each point has sp. functions and indications for use
Stimulation of site specific acupoints induces spatially restricted analgesia.
Each point has sp. functions and indications for use.
Stimulation of site specific acupoints induces spatially restricted analgesia
Yang organs (hollow organs of the body)
ST = Stomach
SI = Small intestine
LIV = Large intestine
GB = Gall bladder; bile ducts
BL= Urinary bladder; ureter & urethra
TH = Triple heater
Yin organs (solid organs of the body)
LIV = Liver
SP = Spleen / Pancreas
KI = Kidney
PC = Pericardium
Mechanism of action
Comprehensive mechanism theory (Pomeranx & Stux) :-
3 mechanisms to A/analgesia
1. A/ needles stimulate type 1 & 11 afferent nerves or A-∂ fibres
send impulses to AL-tract of spinal cord
Pain blocked presynaptically by release of enkephalin & dynorphin
Prevent pain messages from ascending in the spinothalamic tract
2 A/ stimulate mid-brain structures by activating cells in periaqueductal gray matter & raphae nucleus
send descending signals through DL-tract release of monoamines NE & serotonin in spinal cord
Nts. inhibit pain presynaptically & postsynaptically by reducing transmission of signals through spinothalamic tract
3. Stimulation of pituitary-hypothalamic complex
systemic release of β -endorphin into blood stream from pituitary gland accompanied by release of ACTH