Hypothermia and SSI

Claude Laflamme MD, FRCPC Director Cardio-vascular anesthesia

Assistant Professor U of Toronto

Surgical site infection (SSI)

• 30,000,000 operations/year in USA

• 2% = 600,000 have SSI

• Increases in mortality

• Increases readmission rates

• Increases LOS by an average of 7 days

• Increases cost to more than $30,000

Patient and operation characteristics that may influence

the SSI rates

Age

Nutritional status

Diabetes

Smoking

Obesity

Steroid use

Prolonged pre-op LOS

Patient Operation Post-op care

Antiseptic technique

Surgical technique

Wound classification

Length of surgery

Antimicrobial prophylaxis

Hair removal, BG,

Normothermia,

Blood transfusion

Wound care

Discharge

Complications of mild hypothermia

• Increases duration of hospitalization

• Increases intra-operative blood loss

• Increases adverse cardiac event

• Increases patient shivering in PACU

• Increases SSI rates

Perioperative hypothermia

• GA alters central thermoregulation

• Thermoregulatory responses are triggered after 2-3ºC of hypothermia (±34ºC)

• Core temperature decreases by 1ºC within 30 minutes of induction

• Heat production decreases by 5%/ºC in the absence of shivering

• Enhanced heat loss

Normothermia for colorectal surgery

• A Kurz, NEJM 1996; 334:1209-15• 200 patients, double-blind study• Followed for 2 weeks• 34.7±0.6 Celsius VS 36.6±0.5 Celsius• SSI 18.8% VS 5.8% (p=0.009)• Sutures were removed one day later (p=0.002)• Hospital LOS prolonged by 2.6 days (p=0.01)

Normothermia for colorectal surgery

• 1.9ºC core hypothermia triples the incidence of surgical wound infection after colon resection

• Hypothermia increases by 20% the duration of hospitalization

Normothermia for colorectal surgery

• A Kurz, NEJM 1996; 334:1209-15• Intraoperative vasoconstriction was present

in 74% vs 6% of patients and persisted throughout the 6 hr recovery period

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

What do I do now?

Realistic options

• Get the department of Anesthesiology on board

• Listen to their concerns about SSI

• Provide support to address their concerns

• Choose your battles

• Emphasize on the critical role they play on SSI

Patient and operation characteristics that may influence

the SSI rates

Age

Nutritional status

Diabetes

Smoking

Obesity

Steroid use

Prolonged pre-op LOS

Patient Operation Post-op care

Antiseptic technique

Surgical technique

Wound classification

Length of surgery

Antimicrobial prophylaxis

Hair removal, BG,

Normothermia,

Blood transfusion

Wound care

Discharge

The Anesthesiologist’s RoleAnesthesiology 2006; 105:413-21

• Hypothermia

• Hyperoxia

• Fluid Management

• Hyperglycemia

• Blood transfusion

• Antimicrobial Prophylaxis

CSI: Hypothermia

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

Impairs neutrophilsfunction

Vasoconstriction

Tissue hypoxia

Hypothermia

• 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

Hypothermia

• Animal study

• Hypothermia increased levels of interleukin 10 and decreased levels of interleukin 2

• This profile is similar to other proinfectious state as burn and hemorrhagic choc.

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

Cutaneous warming

• Passive insulation reduces heat loss by approximately 30%

• Active cutaneous heating: efficacy will be proportional to the skin surface warmed Circulating water, Forced air, Radiant warmers

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)

Core temperature monitoring

• Pulmonary artery

• Nasopharynx

• Tympanic membrane Aural thermocouples probe Infrared thermometer

• Distal Oesophagus

• Rectal temperature during neuraxial anesthesia

Fluid warming

• If more than 2 liters/hr

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

Sugery Date

ProcedureProcedure

Yes NoIs Temperature >= 36 o on leaving OR

Yes NoIs Temperature >= 36 o on Arrival in PACU

OR TempTemperature

PACU TemoTemperature

Safer Healthcare Now! Campaign

Sunnybrook and Women's CollegeHealth Sciences CentreData Collection Record

SSI BUNDLE

Normothermia

OR

D D M M M Y Y Y YSugery Date Copy

BRADMA

Infection rates in colorectal

Infection No Infection Total

Hypothermic N=13

46.4%

N=15

53.6%

N=28

Normothermic N=2

12.5%

N=14

87.5%

N=16

Total N=15 N=29 N=44

P=0.022

Quarterly Incidence of InfectionsAmong Isolated ACB’s 2004-2005

0

5

10

15

20

1stQuarter2004

2ndQuarter3004

3rdQuarted

2004

4thQuarter2004

1stQuarter2005

2ndQuarter2005

3rdQuarter2005

4thQuarter2005

SS

I R

ate

(%

)

Quiz

• Is prewarming useful?

• Is postoperative rewarming efficient?

• Do you believe that an open cholecystectomy carries approximately the same risk of hypothermia than a laparascopic cholecystectomy?

• What is the future of normothermia in your OR?

Quiz

• What is the definition of intraoperative hypothermia?

• Is intravenous fluid warming helpful?

• How do you mesure the temperature to reflect core temperature reliably?