Fluid Management in the Post Anesthesia Care Unit

Fluid therapy is a cornerstone in patient therapy perioperatively. Many studies have addressed the amount of fluid administered (restrictive vs liberal strategies). Other studies focused on the type of fluids (colloid vs crystalloids), and in the last twenty years a more common subject of research was- the correct evaluation of the dynamic fluid status of patients.Bolus driven fluid therapy has been investigated in many goal-directed hemodynamic therapy (GDHT) trials and has become a widely used approach in intraoperative fluid management.

While there are numerous studies on the intraoperative outcome of GDHT, research on the immediate postoperative outcome of GDHT therapy use is scarce.

In this study the investigators aim to evaluate the efficacy of bolus-based fluid management guided by common clinical parameters in postoperative period in post-anesthesia care unit.

In this randomized clinical trial all patients will be randomized to one of the following groups:

The control group will receive standard care which includes fluid maintenance program as dictated by the operating room anesthesiologist and as needed boluses through the PACU stay.

The GDT group will not receive any maintenance fluid. Fluid boluses will be given according to the flowchart attached.

Measurements of hemodynamic variables including heart rate and automatic non-invasive blood pressure measurements as well pulse oximetry as routine procedures will be recorded and stored by Metavision system (iMDsoft company) at regular intervals, all according to standard clinical practice.

Blood gases measurement will be performed upon admission and at discharge. Urine output will be measured and recorded every hour.

Methods Prior to surgery the patient will be assessed in the pre-anesthesia clinic, study protocol will be explained, questions answered and informed consent form will be signed by one of the investigating physicians. In case of an urgent case with no pre-anesthetic clinic visit, the process will take place in the entrance to the surgery room. Following surgery, patients will be assessed for eligibility and randomized to one of the study arms.

The control group will receive standard care which includes fluid maintenance program as dictated by the operating room anesthesiologist and as needed boluses through the PACU stay.

Study Arm:

The GDT group will not receive any maintenance fluid. Fluid boluses will be given according to the flowchart attached.

Baseline MAP and HR will be measured in the pre-anesthetic clinic or if not available will be recorded according to community medical record.

Blood products will be administered according to departmental guidelines and clinician decision unrelated to participation in the study.

Patients will be extubated, either in the operating room or postoperatively, when they fulfilled standard clinical criteria (adequate protective reflexes, adequate oxygenation, and stable hemodynamics), according to clinical indication unrelated to the participation in the study.

Measurements of hemodynamic variables including heart rate and automatic non-invasive blood pressure measurements as well pulse oximetry as routine procedures will be recorded and stored by Metavision system (iMDsoft company) at regular intervals, all according to standard clinical practice.

Blood gases measurement will be performed upon admission and at discharge. Urine output will be measured and recorded every hour.

Other laboratory exams will be taken based on the physician discretion unrelated to the participation in the study.

Data Collection:

For each participating patient the following data will be collected and recorded:

1. Demographic data
2. Medical history including regular medications
3. Hemodynamic data including heart rate, automatic non-invasive blood pressure measurements, temperature as well pulse oximetry as routine procedures will be recorded and stored by Metavision system
4. Anesthetic data including anesthetic method, anesthetic drugs, total fluid intake, anesthetic complications.
5. Laboratory values
6. Length of stay in PACU
7. Length of stay in hospital
8. Post-operative pulmonary complications
9. Acute kidney injury

Eligibility Criteria:
Inclusion Criteria:

* Patient undergoing general surgery, vascular surgery or urological surgery and who are expected to stay in the PACU for more than 8 hours.
* Above 18 years old
* Not requiring dialysis treatment
* Not requiring advanced monitoring (arterial waveform analysis or cardiac output monitoring)
* Eligible for signing an informed consent prior to surgery

Exclusion Criteria:

* - Pregnancy
* Inability to obtain an informed consent
* Massive transfusion in OR (more than 5 blood products)
* Colloids infusion needed
* The requirement for greater than 0.1mcg/kg/min of noradrenaline at arrival to PACU