Expert Q&A: top tips to prevent perioperative hypothermia
Pre-warming surgical patients is already best practice in many hospitals but there’s still work to do to reduce the risk of perioperative hypothermia – and pre-op nurses are central to success, says Professor Jed Duff.
In this Q&A, Professor Duff explains why surgical pre-warming is critical and offers his top tips for practical protocols in the pre-operative phase.
Q: Why is it important to pre-warm surgical patients?
A: The body's natural defences to cold are impacted by anaesthetic – the patient can’t shiver or vasoconstrict to keep warm. In fact, the opposite happens – there’s vasodilation, and cold blood from the peripheries mixes with the warm blood in the core. This causes a dramatic temperature drop at the moment we give the anaesthetic.
So our goal is to prevent that dramatic temperature drop. Pre-warming aims to increase the temperature of the blood in the peripheries so it’s similar to the core.
The Australian College of Perioperative Nurses (ACORN) recommends the use of active warming interventions to maintain a steady temperature before surgery, and NICE guidance suggest patients should be “comfortably warm”, i.e. between 36.5°C and 37.5°C1,2.
Q: Is pre-warming a consistently used practice, or is there still work to do to ensure it’s used as a matter of course?
A: Pre-warming is accepted as an evidence-based intervention. However, practical barriers like workflow constraints, surgical scheduling and the hectic nature of the pre-operative area can make it difficult to implement. So there’s still work to do for pre-warming to be universally implemented. But these barriers can be overcome with some practical protocols.
Q: What role do perioperative nurses play in pre-warming protocols?
A: Nurses are central in the pre-operative space and pre-warming is really nurse-driven. The ability to prevent perioperative hypothermia is in their hands.
The pre-operative holding area is very busy and often chaotic, and nurses have anxious patients, multiple tasks and a host of paperwork to deal with, so it can seem like a challenge to add another thing for the nurses to do. But by preventing perioperative hypothermia, they're preventing a lot of adverse complications that the patient may experience because of the hypothermia.
“Perioperative hypothermia is not a benign event, and the ability to prevent it is led by nurses.”
-Professor Jed Duff
Q: So what are the potential consequences if patients aren’t adequately pre-warmed?
A: It’s important to note that perioperative hypothermia is not a benign event, and is linked to really serious adverse surgical events.
The big one is surgical site infection (SSI) – and perioperative hypothermia significantly increases the risk of SSI. Immune system function starts to deteriorate so cells that would normally respond to pathogens may not respond as quickly. Poor tissue oxygenation and less blood supply due to vasoconstriction can also lead to wound breakdown, which also leaves the patient vulnerable to infection.
Perioperative hypothermia also significantly increases the risk of surgical bleeding and the need for a blood transfusion because cold adversely affects the clotting cascade. Other consequences include increased risk of cardiac events, delayed recovery from anaesthetic, and patient discomfort, which is not a trivial thing –memories of being cold affect a patient's overall perception of their hospital experience.
You can see how those consequences all add up to extra healthcare resources and costs.
Q: Should all patients be pre-warmed or should pre-warming be based on risk of hypothermia ?
A: My rule of thumb is to pre-warm everyone unless there's a contraindication – and there are very few contraindications.
In the past, the advice was to pre-warm patients who were having major surgery or surgery lasting longer than 30 minutes. However, in my experience, even patients having short surgeries become hypothermic. During longer surgeries, we have time for active warming to heat the patient back up, but we don’t have time for that in a shorter surgery before we take them to recovery. So the patient would have been hypothermic the entire time.
The only contraindications for pre-warming would be emergency surgery cases or patients who are febrile – and if someone’s febrile they wouldn’t be having elective surgery anyway. The other group is patients who have some inability to thermoregulate, such as patients with head or brain injuries.
Q: How do you use active warming devices like the BARRIER® EasyWarm® blanket help avoid hypothermia?
A: Active warming is the gold standard to avoid perioperative hypothermia and single-use, self-warming blankets are a really effective method for active warming. When I say active warming, it has to transfer heat to the patient. Ordinary blankets and silver reflective blankets offer only passive warming.
The, self-warming blanket has other potential benefits. It's easy to use, portable and practical because it’s good for use in small spaces like the pre-op area, and it can be used at all stages of the perioperative journey.
Q: What has been your experience of patients who get too cold during the surgical process?
A: As nurses, we don't see what could happen to these patients downstream, with increased risk of SSI, wound breakdown and post-operative bleeding, but every perioperative nurse will have experience of a patient in recovery who is freezing cold and won't wake up. Being cold slows down recovery so they can be in the recovery unit for the whole day, and we’re trying to get them warmed up, so it’s resource intensive. We only have a certain number of recovery nurses so patients like that can impact our ability to care for other patients.
Q: What are your top tips for practical pre-warming protocols?
A: A key tip is to get on to pre-warming as soon as possible. The pre-operative area is unpredictable – a surgery gets cancelled and suddenly your patient gets called to surgery sooner. So put the pre-warming blankets on the chairs at the beginning of the day as part of your prep so they’re ready to go when the patients arrive. Though we usually aim for at least 20–30 minutes of pre-warming, there’s no such thing as too much pre-warming so get the heated blanket on as soon as the patient is settled.
Second, educate your patients so they will be on your side and co-operate with pre-warming. Explain that the blanket is a therapy that helps to reduce their risks of infections and improve their recovery. Ask them, and their family if they’re there, to ensure the patient stays warm and doesn’t throw the blanket off.
Third, perioperative warming needs to have a team approach. Unfortunately, pre-warming isn't the silver bullet. It's got to be used in conjunction with other measures throughout the perioperative journey. I’ve seen people provide great pre-warming and then they take the blanket off, the orderly comes to pick the patient up for theatre and puts them in a cold bed and they're left without any warm blanket until they get to theatre. All the good work from the pre-op nurses is lost. So we need to see end-to-end warming from the pre-operative stage, through surgery and on to the post-operative stage of the patient’s surgical journey.
References:
- Australian College of Perioperative Nurses Ltd (ACORN). The New ACORN Standards: Volume 3 – 2023 Standards for Safe and Quality Care in the Perioperative Environment (SSQCPE) for Organisations. Adelaide: ACORN 2023.
- National Institute of Health and Care Excellence (NICE). Clinical Guideline. Hypothermia: prevention and management in adults having surgery, 23 April 2008 (updated 14 December 2016). Available at: https://www.nice.org.uk/guidance/cg65/resources/hypothermia-prevention-and-management-in-adults-having-surgery-pdf-975569636293 Accessed July 2025.
