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Blanket Technology Clinical Review

Evaluation of an alternative to forced air warming for temperature management in major spine surgery.
J. John, F. Kader, M. Ockendon
Robert Jones Agnes Hunt Orthopaedic Hospital NHS Trus


Maintaining patient temperature above 96.8 degrees is crucial to reduce infection in surgical patients [1]. A forced- air warming device (FAW) is routinely used to maintain temperature for spine surgery. Several studies have raised concerns about the potential for FAW devices to be a source of infection due to its effect on laminar flow and direct bacterial contamination of the machine’s hose [2]. Resistive heating mattresses are an alternative that is difficult to use in prone spine surgery as the patient lies on two cushioned supports. We conducted a prospective trial of a new warming blanket (Siren) and compared it to a similar cohort of patients who had a standard approach using FAW.


Fifty consecutive patients undergoing various spine surgeries were studied. Precautions were taken to minimize exposure and heat loss during induction. Once turned prone on to cushions the patient's exposed body areas outside the surgical field were covered with warm cloth blankets over which a blanket with our technology cut in two was placed, over the thorax and lower limbs. Our wrap is a unique six-layer laminate passive stand-alone warming blanket that is used to keep and maintain a patient in a normothermic state. Tympanic temperature was checked hourly and on arrival in recovery. The data obtained was compared to a similar consecutive cohort of patients using a FAW device. The primary outcome measure was the percentage of patients with a temperature above 96.8 degrees on arrival in recovery.


The control group had 40 lumbar and ten anterior cervical surgeries with an average procedure time of 163 minutes (67-270 min). 90% of the procedures took longer than two hours. The treatment group was similar with 43 lumbar

surgeries, six anterior cervical surgeries and one anterior lumbar surgery. The average procedure time was 191 minutes (85-410min). In the control group, 3/50 patients had temperatures below 96.8 degrees, however, five patients were recorded as being hyperpyrexial (above 99.5 degrees) in recovery. In the treatment group, temperature was measured as below 96.8 degrees on arrival in recovery in 4/50 patients. No patients had temperatures above 99.5 degrees.


1. Global guidelines for the prevention of surgical site infection WHO 2016 116

2. Forced-air patient warming blankets disrupt unidirectional airflow A. J. Legg, A. J. Hamer Bone Joint J 2013;95-B:407–10.

Surgical origins. 
Built to preserve life in high trauma scenarios.

Siren Survival Wraps were born as a Class 1 Medical Device, used in a clinical setting to stabilize patient body temperature during major surgery. 

We have taken our core product and fitted it for use in field environments, with rugged, airtight flat bag, built to store easily in bulk, field medical supply, and for easy distribution to effected persons. 

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