The mortality and postoperative complications of high risk surgeries vary in the different series. The management of this group of patients in intensive care unit (ICU) is fundamental to improve these outcomes. The objective of this study will be to evaluate whether the use of bedside ultrasound has an impact on the management of this group of patients with a consequent reduction in the incidence of acute renal failure in ICU and, secondarily, the incidence of associated complications. All adult patients (≥ 18 years old) admitted to ICU at Hospital das Clinicas of UFMG in the immediate postoperative period of major surgery with indication of ICU monitoring will be included and randomly randomized to the control or intervention group. The control group will be conducted by the intensive care physicians in charge without the US, while the second group will be conducted based in US findings. The US protocol will consist of a pulmonary US in four windows in each hemithorax , qualitative assessment of contractility and variation of inferior vena cava diameter. The primary outcome will be the development of acute renal failure as measured by the KDIGO score. Secondary outcomes will be length of ICU and hospital stay, ICU and 28 days mortality, length spent in mechanical ventilation, accumulated water balance, noradrenaline and dobutamine dose. Serum and urinary biomarkers will also be evaluated. Key words: ultrasound, high-risk surgery, intensive care

This is a single-center randomized clinical trial to be performed at the Adult Intensive Care Unit (ICU) of the Clinical Hospital of the Federal University of Minas Gerais, Belo Horizonte. The ICU is a clinical-surgical unit that has 18 beds with admission of approximately 100 patients per month, being 70% surgical patients and 30% clinical patients. Postoperative patients who meet the inclusion criteria reported below will be randomized to guide therapy according to ultrasound findings at the bedside versus a group that will not perform this method. Serum and urine samples will be collected in three times: admission (T0), after 12 hours (T1) and after 24 hours (T2) to analysed urine and serum biomarkers.

Inclusion Criteria:

• Age equal or superior to 18 years.

• Major surgeries requiring ICU admission associated with one of the following criteria:

  • Use of vasoactive drugs
  • Use of inotropic drugs
  • Mean blood pressure less than 65 mmHg or SBP <90 mmHg.
  • Hyperlactatemia> 2 mmol / L
  • Heart rate> 90 bpm.
  • Invasive mechanical ventilation required for at least 6 hours at the time of inclusion.
  • Hypoxia: satO2 <92% in ambient air.
  • Length of surgery greater than 4 hours.
  • Request for transfusion of blood products in a surgical block
  • Oliguria during procedure, defined as diuresis <0.5 ml/kg/h.

Exclusion Criteria:

Patients who do not agree to the terms of the

• Dying patients with impending death in the first 24 hours
• Patients in a previous renal replacement therapy program