The Effect of Unintended Perioperative Hypothermia on Brain Function

In the realm of surgical care, maintaining optimal patient conditions is paramount to ensuring successful outcomes. One critical yet often overlooked factor
is perioperative hypothermia – a condition where a patient’s core body temperature drops below 36°C (96.8°F) during the preoperative, intraoperative,
or postoperative phases. While hypothermia is sometimes intentionally induced for therapeutic purposes, unintended perioperative hypothermia can have significant consequences, particularly on brain function. Understanding the effects of perioperative hypothermia on brain function is crucial for optimizing patient
care and outcomes.

How Hypothermia Impacts Brain Function

The brain is highly sensitive to changes in temperature, relying on a stable environment to perform its complex tasks. When unintended perioperative hypothermia sets in, several mechanisms can influence neurological outcomes:

• Reduced Cerebral Metabolism. A drop in body temperature slows metabolic processes, including those in the brain. While controlled hypothermia can be neuroprotective in specific scenarios (e.g., cardiac surgery), unintended hypothermia may disrupt the delicate balance of oxygen and glucose delivery to brain cells. This can lead to impaired cognitive function post-surgery.
• Altered Cerebral Blood Flow. Hypothermia affects blood viscosity and vascular tone, potentially reducing cerebral blood flow. Inadequate perfusion can starve brain tissue of oxygen, increasing the risk of ischemic injury. Studies have shown that even unintended  mild hypothermia can alter autoregulation, the brain’s ability to maintain consistent blood flow despite changes in systemic pressure.
• Neurotransmitter Dysregulation. Temperature changes can interfere with the release and uptake of neurotransmitters like dopamine, serotonin, and acetylcholine. This disruption may contribute to postoperative cognitive dysfunction (POCD), a condition characterized by memory issues, confusion, and reduced attention span.
• Cognitive Dysfunction. Postoperative cognitive dysfunction (POCD) is a concern in patients experiencing unintended perioperative hypothermia. Studies suggest that even mild hypothermia can lead to impaired memory, attention deficits, and delayed cognitive recovery. The elderly and those undergoing prolonged surgeries are particularly vulnerable.
• Increased Risk of Delirium. Perioperative hypothermia has been linked to a higher incidence of postoperative delirium, a state of acute confusion that can delay recovery. The combination of hypothermia-induced metabolic stress and anesthesia’s lingering effects may overwhelm the brain’s compensatory mechanisms, especially in vulnerable populations.
• Blood-Brain Barrier Disruption. Studies indicate that hypothermia may weaken the integrity of the blood-brain barrier (BBB), making the brain more susceptible to inflammatory responses and potential neurotoxic damage. This increases the risk of postoperative delirium and other neurological complications.

Who’s at Risk?

Certain patients are more susceptible to the neurological effects of perioperative hypothermia. These include:

Patients who experienced intraoperative hypothermia had a higher incidence of POCD compared to those kept normothermic. Even mild hypothermia (34–36°C) could impair cognitive recovery, suggesting that temperature management is a critical variable in surgical care.

Mitigating the Risks

Preventing unintended perioperative hypothermia is both achievable and essential for protecting brain function. Here are some evidence-based strategies:

• Prewarming: Applying warming blankets and mattresses before surgery can stabilize core temperature and reduce intraoperative heat loss.
• Intraoperative Warming: Using warmed IV fluids (e.g. Ampir-01 and Ampirmini blood and IV fluid warmers), patient warming systems (e.g. RAMONAK-03 patient warming systems), and temperature-controlled operating rooms helps maintain normothermia during procedures.
• Monitoring: Continuous core temperature monitoring allows surgical teams to detect and address hypothermia promptly.
• Anesthetic Adjustments: Understanding the thermoregulatory effects of different anesthetic agents can help in tailoring approaches to minimize hypothermic risks.
• Postoperative Care: Ensuring patients are warmed and monitored in recovery wards can prevent prolonged hypothermic states that might affect neurological recovery.

Why It Matters for Patient Outcomes

The brain’s role in recovery cannot be overstated – cognition, memory, and emotional regulation all influence a patient’s ability to heal and return to normal life. By minimizing unintended perioperative hypothermia, healthcare providers can reduce the risk of neurological complications, shorten hospital stays, and improve overall quality of life post-surgery. For hospitals and surgical centers, prioritizing temperature management also aligns with patient safety goals and can enhance institutional reputation.

Unintended perioperative hypothermia is more than a minor inconvenience; it’s a modifiable risk factor with profound implications for brain function. The medical community must prioritize proactive temperature management to safeguard patients’ neurological health. By integrating prewarming, intraoperative monitoring, and postoperative care, we can mitigate the risks and ensure better outcomes for those undergoing surgery.

For healthcare providers and patients alike, understanding the link between hypothermia and brain function is a step toward safer, more effective surgical experiences. Let’s keep the focus on keeping patients warm - and their minds sharp.