Background
Vacuum mattress (VM) for surgical patient positionning is very litle known althoug it has been avaliable in market for several years. In our hospital we have also used this mattress for time-consumming interventions such as modified radical neck dissection (MRND), with the intention of avoiding complications of patients due to prolonged decubitus. 
Objectives
This study aims to analyze the incidence of acute kidney injury (AKI) and pressure ulcers (PU) that develop after modified radical neck dissection (MRND) performed due to thyroid cáncer and the usefulness of a vacuum mattress on the operation table in the reduction of these rates.
Methods
Observational retrospective cohort study on the appearance of AKI or PU, among patients undergoing MRND, with or without associated thyroidectomy during the period 2010-2018. Patients with previous kidney desease were excluded. Pressure ulcer rate, creatine kinase (CK) and AKI values in the postoperative period, in these patients have been compared. The appearance of PU has been determined through observations recorded by surgeons, anesthetists and nurses in evolution and hospital discharge reports. AKI is defined as a postoperatively glomerular filtration (GF) value under 60ml/min/1.73m2. GF has been calculated by MDRD-4 criterion. A bivariate analysis was performed, calculating the chi-square statistic of Pearson for  qualitative variables, and t of Student or Mann-Whitney for numerical ones, according to whether the hypothesis of normality was fulfilled or not. 
Results
109 patients, submitted to MRND were included. 41 men (37.6%) and 68 women (62.4%); with an average age of 49.73+/-16.42 years. In 44 patients the vacuum mattress was used (Intervention group), while 65 were operated without this device (Control group). Postoperative CK values were higher in the CG with median values of 2470 mcg/L vs 434 mcg/L in the IG . The level of significance was <0.001. The percentage of PU was also lower in the IG (4.5% vs 15.4%), although without reaching statistical significance. In the CG postoperative AKI incidence was 3 cases of 65 patients (4,6%)  while there was none AKI in the IG in the 44 patient operated with vacuum mattress. Nevertheless  there was not statistical significance for this result either.
Conclusions
The use of vacuum mattress for positioning surgical patients supposes an increase in safety regarding the decrease of pressure ulcers and a lower incidence of acute kidney injury due to rhabdomyolysis.

Decrease of decubitus complication by vacuum mattress in time consumming surgical operations