Perioperative Normothermia – a lesson in how attention to detail matters

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; 334:1209-1215 • 200 patients • elective colorectal surgery • Interventions started at induction • hypothermia vs normothermia Normothermia • Target temps: 36.5 ° C • Fluids via warmer activated • Forced air @ 40°C Hypothermia • Target temps: 34.5 ° C • Fluids via warmer in-activated • Forced air @ ambient temperature

7. Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization Kurz A - N Engl J Med 1996; 334:1209-1215 • 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; 358:876-880 • 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; 94:421-426 • 103 patients • All patients with • Forced air @ 40°C intra-op • Warmed fluids • Treatment group • Warming pad beneath • 40°C - 2 hrs before and throughout OR • Control group • Warming pad beneath • Turned off • Core temp adm: treatment 36.5 control 36.5 • Core temp at start: treatment 36.4 control 36.0 • Core temp at study end: treatment 36.3 control 36.2

10. Randomized clinical trial of perioperative systemic warming in major elective abdominal surgery Wong PF. Br J Surg 2007; 94:421-426 • 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 air @ 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