Actual Impaired Fluid Volume Clinical Trial
Official title:
Fluid Responsiveness in the Postoperative Patient: a Prospective Study
The aim of this study is to determine the prevalence of Fluid Responsiveness (FR) (SV increases by at least 15% after Volume Expansion, VE) in postoperative patients admitted on a surgical ward after elective abdominal, thoracic and esophageal surgery
Perioperative care
Preoperative Period
As per usual practice, the patient's staff surgeon will provide directives for preoperative
fasting and fluid intake. These patients are encouraged to drink up to two hours before
hospital admission, and also receive preoperative carbohydrate drinks the night before (100
grams), and the morning of surgery (50 grams) when indicated. Additionally, routine use of
mechanical bowel preparation is avoided, and is prescribed only in selected cases. The
patient's weight will be obtained upon arrival in the operating room.
Anesthetic and analgesic management
Anesthetic management and choice of postoperative analgesia will be as per usual care, at
the discretion of the staff anesthesiologist in-charge of the case. An arterial line or
central venous line may be inserted, and Goal Directed Fluid Therapy (GDFT) employed if
deemed necessary.
Post-anesthesia Care Unit (PACU)
On arrival to the PACU, basic hemodynamic parameters, including heart rate (HR), blood
pressure (BP), oxygen saturation, respiratory rate, temperature, and central venous pressure
(CVP), if available, will be recorded according to standardized PACU protocol. A research
assistant will then collect initial PACU values for these hemodynamic variables. Surgical
time, estimated surgical blood loss, urine output, and intraoperative fluid and blood
product administration will also be recorded. PACU care will be dictated by the treating
staff anesthesiologists. Patients will be discharged from PACU according to standard
institutional criteria.
Surgical floor
Postoperative care management, including the commencement of oral diet and fluid management,
will be at the discretion of the surgical team. If required, VE (volume of the solution to
be infused and type of the intravenous solution) will be decided case by case by the
surgical team. The patient's weight will be obtained daily until hospital discharge.
Patients will typically be discharged if afebrile, able to tolerate oral diet, pain is
controlled (numeric rating scale (NRS) < 4), and they are able to ambulate.
Assessment of FR
A research assistant working in the department of Anesthesia will assess FR on two
occasions:
1. When any VE is ordered by the treating team, either in PACU or on the surgical floor
upon standard evaluation of hemodynamic parameters, urine output, surgical losses, and
laboratory test abnormalities. FR will be assessed by measuring SV and Cardiac Output
(CO) obtained by the ccNexfin system before 1 and 5 minute after VE. A patient will be
considered a fluid responder if SV increases by at least 15% 1 minute after VE. A
cut-off of 15% has been chosen as it represents the minimal clinical significant
difference between two CO measurements obtained by thermodilution.
2. Upon arrival to the PACU, and every day before breakfast during the hospital stay. FR
will be assessed by measuring SV and CO obtained by the ccNexfin system before and
after 1 minute following 250 ml of Lactated Ringer's given as fluid challenge. A
patient will be considered a fluid responder if SV increases by at least 15% after the
fluid challenge.
Prediction of FR
A fluid challenge of 250 ml of Lactated Ringer's will be used to predict FR before the
administration of any VE ordered by the treating team, either in PACU or on the surgical
floor upon standard evaluation of hemodynamic parameters, urine output, surgical losses, and
laboratory test abnormalities. A patient will be considered a fluid responder if SV
increases by at least 15% 1 min after the end of a fluid challenge The utilization of fluid
challenges has been shown to have high-accuracy (Receiver Operating Characteristic (ROC)
curve of > 0.9) to predict FR in spontaneously breathing patients47. Furthermore,
administration of fluid challenges to predict FR has already been described in several
trials, including those with sick patient populations48 (ICU patients, patients undergoing
major surgery, and patients with Ejection Fraction (EF) <40%).
Measurement of FR
1. Assessment of FR when VE is deemed necessary by the treating physician in PACU or on
the surgical floor Prior to administration of a non-emergent fluid bolus (VE) ordered
by the treating physician, nurses will additionally page the research assistant who
will measure ccNexfin CO-Trek parameters as described earlier, and then administer a
fluid challenge and measure FR. For simplicity, a single pager number will be used, and
it will be affixed to the front of the chart of patients included in the study. A copy
of the study protocol will also be given to nurses in the PACU and on the surgical
floors for perusal.
The need for VE will be evaluated by the anesthetist in charge in PACU, or by the
surgical team on the surgical ward. Hemodynamic variables triggering fluid
administration will be decided based on standard evaluation of hemodynamic parameters,
urine output, surgical losses, and laboratory test abnormalities. The type and amount
of intravenous solution to be used will be decided by the anesthetist in charge or by
the surgical team.
Before VE, hemodynamic variables including HR and BP will be measured by the research
assistant. CVP will me measured in PACU if patients receive a central venous catheter.
Then, the ccNexfin system will be applied in a standardized fashion according to
manufacturer recommendations: an appropriately sized finger cuff will be selected and
placed around the patient's middle finger. The wrist unit and heart reference sensor
(HRS) will then be placed around the patient's wrist and ring finger respectively. The
system will be zeroed, and the sensor end of the HRS will be placed at the level of the
patient's heart, which allows for compensation for hydrostatic pressure differences
between the finger and the heart. The ccNexfin will then calculate and display the
values for an initial post-operative CO, Cardiac Index (CI), and SV. One and 5 minutes
after the end of the VE, the same hemodynamic parameters will be measured. Should any
further bolus of fluid be administered, FR and basic hemodynamic variables will be
measured as above, upon administration of VE as ordered by the treating team.
2. Prediction of FR before the administration of any VE ordered by the treating team
A fluid challenge of 250 ml of Lactated Ringer's solution (Baxter, Lactated Ringer's
Injection, USP, 1000 mL VIAFLEX Plastic Container) will be administered over 5 minutes
by the research assistant before VE. One and 5 minutes following the end of the fluid
challenge, basic hemodynamic values (as described above), as well as CO, CI, and SV
obtained from the ccNexfin system, will again be recorded. An increase of SV by at
least 15% 1 minute after the end of the fluid challenge will be considered clinically
significant. Upon termination of a fluid challenge, the decision on weather to proceed
with VE will be taken by the treating physician based only on standard signs and
measures of hypovolemia and not on any of the ccNexfin SV and CO measurements obtained
during the fluid challenge. The proportion of patients identified as fluid responsive
after VE will be compared with the proportion of patients responding to the fluid
challenge.
The research assistant will be available to measure FR from 6.30 AM to 7.30 PM every
day during patient hospitalization. For patient safety, the research assistant must
arrive at the bedside within ten minutes of being paged, in order to measure FR before
VE. Intravenous fluids will be administered without measuring CO and administering a
fluid challenge if:
1. the research assistant will not be able to arrive at the bedside within ten
minutes;
2. the treating physician considers immediate administration of intravenous fluids
necessary.
CO measurements will not be taken before administering blood products. Blood product
administration (erythrocytes, platelets, fresh frozen plasma, or cryoprecipitate) will
also be at the discretion of the staff anesthetist (in PACU) or at the discretion of
the surgical team (surgical ward).
3. Daily assessment of FR
After surgery in PACU, and daily (before breakfast) for the duration of the patient's
hospital stay a research assistant will administer a fluid challenge. As described above,
CO, CI, and SV will be measured by the research assistant using the ccNexfin system, to
assess for FR. A fluid challenge of 250 ml of Lactated Ringer's solution (Baxter, Lactated
Ringer's Injection, USP, 1000 mL VIAFLEX Plastic Container) will then be administered over 5
minutes. One and 5 minutes following fluid challenge completion, basic hemodynamic values
(as described above), as well as CO, CI, and SV obtained from the ccNexfin system, will
again be recorded. An increase of SV by at least 15% 1 minute after the end of the fluid
challenge will be considered clinically significant.
Daily assessment of FR, regardless of whether patients will receive intravenous fluids, will
determine if FR is associated with an increased risk of complications and/or prolonged
hospital stay.
All ccNexfin values obtained before and after VE and any fluid challenge will be blinded to
the treating anesthetist, the surgical team and the nursing team.
;
Intervention Model: Single Group Assignment, Masking: Double Blind (Subject, Caregiver, Outcomes Assessor), Primary Purpose: Screening
| Status | Clinical Trial | Phase | |
|---|---|---|---|
| Recruiting |
NCT02071524 -
Evaluation of the Effects of Fluid Therapy on Respiratory Mechanics
|
N/A | |
| Completed |
NCT02717533 -
Blood Volume Analysis and Renal Outcomes in Hemodialysis
|
N/A |