Adequate Operating Theatre (OT) Temperature

Adults

"As a general principle, the comfort of operating room personnel must be reconciled with patient care, and for adult patients, ambient room temperature should be maintained between 68°F (20°C) and 75°F (24°C)." — Morgan & Mikhail's Clinical Anesthesiology, 7e

Paediatrics / Neonates

• Larger body surface area-to-weight ratio
• Thinner skin and low fat content
• Limited ability for nonshivering thermogenesis (especially premature infants)

• General paediatric surgery: OT should be kept warmer than for adults; the exact temperature is adjusted upward.
• Burns / major surgery in children: OT temperature is commonly maintained at 80°F–100°F (27°C–38°C), depending on age and severity.
• Neonates: The pre-induction area and OT should be kept above-normal levels; patients should be covered with warm blankets during transport.

"Children have greater surface-area-to-body-weight ratios, resulting in more rapid heat loss." — Miller's Anesthesia, 10e

Complications of Failing to Maintain OT Temperature

1. Cardiovascular Complications

• Cardiac depression and reduced cardiac output
• Myocardial ischemia
• Dysrhythmias / arrhythmias
• Peripheral vasoconstriction
• Impaired tissue oxygen delivery
• Blunted response to catecholamines
• Hypotension
• When core temp falls below 32°C: significant drops in BP and cardiac output occur
• ECG shows J-point elevation (Osborn wave) — pathognomonic of hypothermia

2. Coagulation / Bleeding

• Hypothermia induces coagulopathy by attenuating hemostatic enzyme function and causing platelet sequestration
• Increased risk of bleeding and need for blood transfusion (relative risk: 1.33)
• Greater intraoperative blood loss

3. Wound and Infectious Complications

• Impaired granulocyte chemotaxis and phagocytosis
• Reduced macrophage function and antibody production
• Decreased tissue oxygen tension
• Abnormal collagen deposition and poor wound healing
• Increased surgical site infection risk (impaired wound healing relative risk: 3.25)

4. Respiratory Complications

• Respiratory depression
• Increased pulmonary vascular resistance (important in neonates)
• Abolition of hypoxic pulmonary vasoconstriction (in burns)
• Acute lung injury (in burns)

5. Neurological / Anesthetic Complications

• Delayed awakening from anaesthesia
• Increased susceptibility to anaesthetic agents and neuromuscular blockers
• Impaired drug clearance postoperatively

6. Metabolic / Endocrine Complications

• Exaggerated increase in oxygen consumption
• Exacerbated catabolic response (especially in burns)
• Postoperative shivering — increases O₂ consumption by up to 500%, increases demand on cardiopulmonary system, can dislodge grafts

7. Prolonged Hospitalisation

• Hypothermia is associated with prolonged hospitalization and prolonged postanesthetic recovery

Relative Risk of Complications from Hypothermia (Table from Schwartz's Principles of Surgery, 11e)

How to Prevent Hypothermia in the OT

• Raise ambient OT temperature appropriately
• Forced-air warming blankets (convective heating)
• Thermal water/warming mattresses
• Warmed IV fluids and blood products
• Warmed irrigation solutions
• Wrapping head and extremities with plastic or thermal insulation
• Minimising skin surface exposure
• Pre-warming patients in the pre-induction area

Sources: Morgan & Mikhail's Clinical Anesthesiology 7e | Miller's Anesthesia 10e | Schwartz's Principles of Surgery 11e | Sabiston Textbook of Surgery