Hypothermia and cholecystectomy

• Flores-Maldonado et al. 2001• 290 consecutive patients• 30-day follow-up• Patients that received blood transfusion

were excluded• 35.4º±0.4ºC vs 36.2º±0.2ºC• 11.5% vs 2% SSI

Complications and treatment of mild hypothermia

Anesthesiology 2001; 95:531-43

• Myocardial Ischemia Frank et al. JAMA 1997;277:1127-34 High risk patients assigned to 1.3ºC core hypothermia were three times as likely to experienced adverse cardiac outcome

• Cold-induced hypertension is associated with a threefold increase in plasma norepinephrine concentrations

Complications and treatment of mild hypothermia

• Coagulopathy• Platelet dysfunction (reduction in the

release of thromboxane A2• Clotting factor enzyme• Fibrinolytic activity-TEG

Complications and treatment of mild hypothermia

Hypothermia and SSI

• Vasoconstriction Decreases the partial pressure of oxygen in tissues which impairs the oxidative killing by neutrophils Reduces the deposition of collagen

• Impairs immunity Chemo taxis and phagocytosis of granulocytes motility of macrophages Production of antibody Reduces the production of super oxide radicals

Hopf et al, Arch Surg 1997

• Subcutaneous oxygen tension at surrogate wound inversely correlated with the risk of SSI

• S/C O2 40-50mmHg had a SSI of 43%• S/C O2 above 90 mmHg had no SSI

Complications and treatment of mild hypothermia

• Pharmacokinetics and Pharmacodynamics Reduces clearance during hypothermia

• Prolongs PACU stay

Minimizing hypothermia

• Anesthetics profoundly inhibits central thermoregulation decreasing the vasoconstriction threshold by 2-4ºC

• The second major factor is the magnitude of the core-to-peripheral temperature gradient

• Minimizing the core-to-peripheral temperature gradient and preoperative vasodilatation, is the basis to reduce heat redistribution

• Degree of adiposity, concurrent medication

Minimizing hypothermia

• Prewarming: Decreases core-to-peripheral temperature gradient Eventually provokes vasodilatation

• Pharmacologic vasodilatation

Laparatomy

P has e 2 IntraOp T emperature P rog res s ion in C ontrol & P reWarmed P opulations

35.4

35.6

35.8

36

36.2

36.4

InitialIntraOP

15m 30m 45m 1h 75m 90m 2h 2.5h 3h 4h 5h

Tem

per

atu

re (

oC

)

P rewarmed (26.7% finis hed hypothermic ) C ontrol (50% finis hed hypothermic )

Active cutaneous warming systems

• Forced-air systems• Circulating-water mattresses• Resistive heating systems (ICU,trauma)

Carbon-fiber patient cover• Circulating-water garments

Water has a conductivity of heat 26 times higher than air

• Infrared radiation(neonats, pediatric Sx)

Fluid warming

• One liter of crystalloid or 1 unit of refrigerated blood decreases core temperature by 0.25ºC

Core temperature monitoring

• Pulmonary artery• Nasopharynx• Tympanic membrane

Aural thermocouples probe Infrared thermometer

• Distal Oesophagus• Rectal temperature during neuraxial

anesthesia

Getting a Reading is as Easy as 1,2,3

Patient temperature readings are

gathered quickly and displayed clearly

What is the Technique?