The investigators wish to undertake a randomized controlled non-inferiority trial to evaluate the ability of a simple and low-cost method (Hibler´s method of wrapping the patient in multiple insulating layers) to prevent intraoperative heat-loss in children undergoing neurosurgery under anesthesia in Malawi. The control group will be heated actively with the use of warm-air blankets. The aim of this study is to evaluate whether Hibler´s method can provide a cheap and technically simple way of adequately preserving the patients´ core temperature in the operating theatre in a resource-poor setting.

Hypothermia in the perioperative setting is receiving increasing attention in anaesthetic and surgical care. The paediatric age group is arguably at increased risk and thus deserves more intensive focus.

The investigators wish to undertake a randomized controlled non-inferiority study in which two different modalities for preventing inadvertent intraoperative hypothermia are compared. The trial will be carried out in a paediatric neurosurgical population in a South-East African regional tertiary care hospital.

The primary objective is to determine whether a low cost and simple method can be as effective and safe as a more expensive and technically demanding method. The goal is to recruit 40 patients in each of the two study arms. Patients younger than 12 years of age presenting for scheduled neurosurgery will be approached and given information about the study. If informed consent (and assent, where applicable) is obtained, participants will be randomized to one of the two different techniques; either passive heat preservation using what has become known as Hibler´s method (interventional group) or active warming with warm-air blankets (control group). Throughout the study period core temperature will be measured continuously, both for purposes of data accuracy and to maintain safety standards.

Primary study outcomes focus on the comparative ability of the methods in maintaining acceptable core temperatures. The trial will also examine a number of secondary end-points such as prevalence of shivering, conscious level, analgesia requirements, oxygenation and overall cost.

Upon completion of the study the investigators will seek to publish the findings in a relevant medical journal. Presenting the results in abstract form or as a poster in an appropriate medical congress may also be desirable.

Inclusion criteria:

I. Age under 12 years. II. Ensured bed in HDU for postoperative management. III. Undergoing general anaesthesia with endotracheal intubation for planned cranial procedures; e.g. craniotomies, ventriculo-peritoneal shunt placements, endoscopic third ventriculostomies and similar procedures with a predominantly cranial access.

IV. Informed parental/guardian consent given

Exclusion criteria:

I. Pts. aged 12 years or older. II. Pts. with a temperature upon arrival at the anaesthetic suite lower than 36,0 °C III. Pts. with a temperature upon arrival at the anaesthetic suite greater than 37,5°C IV. Pts. judged to be unsuited for the standardized anaesthetic technique chosen (due to known allergy, known or suspected difficult airway requiring other anaesthetic interventions, cardiovascular conditions incompatible with the standard anaesthetic agents or due to any other condition where the chosen technique is deemed unsafe)