1. Perioperative Normothermia – a lesson in how attention to detail matters
Addison K. May, MD, FACS, FCCM
Professor of Surgery and Anesthesiology
Division of Trauma and Surgical Critical Care

2. Objectives:
identify complications associated with perioperative hypothermia
identify measures associated with intraoperative normothermia
review standardized processes introduced for the trauma/EGS services to maintain normothermia

3. What is normothermia?
Definition: a condition of normal body temperature
37°C (36.5–37.5°C) or 98.6°F (98–100°F) core temperature
Peripheral tissues may fall significantly below and before core temperature falls
Mild hypothermia: 32–35°C or 90–95°F
shivering
hypertension
tachycardia
tachypnea
vasoconstriction
cold diuresis
mental confusion
hyperglycemia
hepatic dysfunction

4. Why should we maintain normothermia?
The World Health Organization standard: maintain patient core temperature > 36°C throughout the perioperative period
Perioperative hypothermia:
Increases susceptibility to infections
Decreased perfusion, decreased antibiotic penetration, altered phagocytic function
Increases blood loss
Temperature induced coagulopathy, altered platelet function
Decreases wound healing
Increases cardiac morbidity
Vasoconstriction, shivering, cardiac dysthymias
Randomized studies demonstrate improved outcome with normothermia

5. What factors contribute to perioperative hypothermia?
anesthetic-induced impairment of thermoregulation
altered distribution of body heat
exposure
body surface
body cavities
application of fluids to body surface
low ambient room temperatures
delivery of and exposure to hypothermic fluids

6. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization
Kurz A - N Engl J Med 1996; 334:
200 patients
elective colorectal surgery
Interventions started at induction
hypothermia vs normothermia
Normothermia
Target temps: 36.5 ° C
Fluids via warmer activated
Forced 40°C
Hypothermia
Target temps: 34.5 ° C
Fluids via warmer in-activated
Forced ambient temperature

7. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization
Kurz A - N Engl J Med 1996; 334:
Active warming resulted in significant
reduction of infections, hospital length of stay
improved wound healing and resolution of ileus
Postoperative Findings in the Two Study Groups
Multivariate Analysis of Risk Factors for
Surgical-Wound Infection

8. Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomized controlled trial
Melling AC . Lancet 2001; 358:
Warming vs standard
Warming
Systemic warming: forced air 30 min prior to OR
Local warming: radiant heat dressing
Standard
No intervention
421 patients
clean (breast, varicose vein, or hernia) surgery
Intervention prior to OR
The effects of warming therapies compared with standard treatment

9. Randomized clinical trial of perioperative systemic warming in major elective abdominal surgery
Wong PF. Br J Surg 2007; 94:
103 patients
All patients with
Forced 40°C intra-op
Warmed fluids
Treatment group
Warming pad beneath
40°C - 2 hrs before and throughout OR
Control group
Turned off
Core temp adm: treatment control 36.5
Core temp at start: treatment control 36.0
Core temp at study end: treatment control 36.2

10. Randomized clinical trial of perioperative systemic warming in major elective abdominal surgery
Wong PF. Br J Surg 2007; 94:
Addition of warming blanket before and through surgery improved outcomes
Treatment group
fewer complications: 32 vs 54% (p=0.027)
less blood loss: 200 vs 400 ml (p=0.011)

11. How is VUMCs performance for normothermia?
Trauma/EGS cases for August 2008
240 of 255 cases with temp values
All cases:
55% of cases - lowest temp < 360C
20% never get above 360C
Elective cases:
59% of elective cases - lowest temp < 360C
41% of elective cases - 1st temp < 36°C
Colorectal cases for August 2008
111 of 131 cases with temp values
41% of colorectal cases 1st temp < 360C
52% of cases have either the first or last temp recorded < 360C

12. Trauma/EGS normothermia initiative
Purpose/description:
To improve maintenance of normothermia for the Trauma/EGS patient population
Target goals:
> 90% patients with first and post-op temperature > 36°C.
> 80% patients with minimum temperature > 36°C

13. Trauma/EGS Perioperative Process
Pre-operative:
Bear Paws:
All elective cases should have Bear Paws placed on the patient in holding room and forced warm air turned on to maintain temperature greater than 36.5°C at all times
Intra-operative:
Ambient room temperature:
non-trauma cases: Room temperature should be set to 24°C (75°F)
Room temperature to be recorded in VPIMS
Adjust room temperature during case if core temp > 36.5°C
Peri-induction and intra-operative management:
Bear Paws (if elective) / Bear Hugger applied, forced 40°C prior to induction & prep
Upper & lower forced air warming devices should be applied as allowed by the case
Intraoperative fluids and irrigation should be warmed to 37°C
 Post-operative management:
Patients immediately covered with either warm blankets and/or forced air device depending on pt core temperature at completion of case

14. Trauma/EGS: % patients with temperature value < 36°C
Percentage of patients with hypothermia
VPIMS reported data: Min temp = lowest recorded intra-op temp, first temp = 1st after induction

15. Colorectal: % patients with temperature value < 36°C
Percentage of patients with hypothermia
VPIMS reported data: first temp = 1st after induction

16. My take home points:
Strict attention to normothermia improves patient outcomes
Attention to detail throughout the perioperative period required to achieve high level compliance with normothermia
Ability to measure and monitor compliance is important in achieving our goals
To maintain normothermia in the majority of patients, likely need
Pre-op active warming to maintain > 36.5°C
Intra-op maintenance of ambient temp, active warming, and warm fluids