WHITE PAPER

The Role of Advanced Hemodynamic Monitoring in
Enhanced Recovery Afer Surgery (ERAS) Initiatives
Using continuous hemodynamic monitoring as a tool to help maintain patient fluid balance and reduce
postoperative complications.

INTRODUCTION
Patients undergoing major surgery are faced with an inherent risk of morbidity and mortality (See Table 1).These risks canincrease depending on a patient’s cardiovascular and hemodynamic condition and are known to contribute to a variety of
postoperative complications and increased lengths of stay (LOS) in the hospital.1,2 Specifc factors that influence a patient’s
LOS during postoperative rehabilitation include the need for analgesia, intravenous fluids, and lack of mobility.3 To minimize
recovery time and reduce postoperative complications for a variety of high- to moderate-risk surgical patients, hospitals
and surgical teams around the world have adopted a comprehensive set of perioperative practice guidelines known as
Enhanced Recovery Afer Surgery (ERAS).
TABLE 1. POSTOPERATIVE COMPLICATION RATE2

ERAS guidelines consist of 22 preoperative, intraoperative, andpostoperative protocols, which have been shown to lead to a

SURGERY

MORBIDITY RATE

Esophagectomy

55%

Pelvic exenteration

45%

mobilization, and earlier resumption of normal activities. 4,5,6 These

Pancreatectomy

35%

practice guidelines represent a fundamental shif in perioperative

Colectomy

29%

care for numerous types of surgical interventions including

Gastrectomy

29%

colorectal surgery, vascular surgery, thoracic surgery, radical

Liver resection

27%

cystectomy, and orthopedic cases.7,8,9,10,11

reduction in complications and hospital LOS, improvements in
cardiopulmonary function, earlier return of bowel function, enhanced

One critical element of all ERAS programs is a protocol known
as perioperative goal-directed therapy (PGDT), which helps ensure adequate hydration and maintain euvolemia, while
avoiding hypervolemia or hypovolemia that can contribute to postoperative complications (See Figure 1).12,13 To achieve
optimal fluid balance for the surgical patient, PGDT relies on continuous monitoring of a variety of hemodynamic targets,
which can all be derived from minimally invasive cardiac output (CO) monitoring technologies.
PERIOPERATIVE GOAL-DIRECTED THERAPYPGDT is an integral element of ERAS and has beenshown in multiple single-center studies, quality
improvement studies, and published meta analyses
to signifcantly improve patient outcomes.14,15,16,17
By improving cardiovascular function andbalancing fluid intake, PGDT helps clinicians
maintain adequate oxygen supply perioperatively.
As part of ERAS guidelines, PGDT helps decreasenausea, vomiting, and the incidence of ileus, orOne critical element of all ERAS
programs is a protocol known asperioperative goal-directed therapy(PGDT), which helps avoid hypervolemia
or hypovolemia that can contribute topostoperative complications.12,13

intestinal obstruction, while allowing patients to take solid food earlier, become more alert, and start walking sooner afer
surgery, ultimately reducing hospital LOS. 12,13

Complications

FIGURE 1. COMPLICATIONS ASSOCIATED WITH SUBOPTIMAL PERIOPERATIVE FLUID MANAGEMENT13

Hypovolemic

OPTIMAL

Hypervolemic

Low blood pressure

Pulmonary edema

Low cardiac output

Organ dysfunction

Arrhythmia

Prolonged mechanical ventilation

Hypoperfusion

Hemodilution and Coagulopathy

Infection

Adverse outcome

Organ dysfunction
Organ failure
Adverse outcome

Volume Status
Intraoperative fluid management protocols are designed to maintain a patient’s preoperative euvolemia, or properly
hydrated state by avoiding excess salt and water as well as hypovolemia conditions known to increase postoperativecomplication rates.18,19,20,21 Once optimal intravascular volume is established, intravenous fluid administration is controlled
and increased only if clinically indicated.
Intravascular hypovolemia can lead to complications stemming from hypoperfusion of vital organs and the bowel. However,administering too much fluid can lead to bowel edema and increased interstitial lung water, resulting in complications
and delayed return of gastrointestinal function.18,20,22 As a result, intravascular volume is one of the key determinants ofcardiac output (CO) and oxygen delivery to the tissues. Determining the correct amount of fluid required is simplifed withthe focus on easily accessible, flow-based hemodynamic parameters.

To achieve optimal fluid balance,clinicians must monitor a varietyof hemodynamic targets, including
cardiac index (CI), stroke volume(SV), stroke volume variation (SVV),
and pulse pressure variation (PPV).

MAINTAINING FLUID BALANCE WITH ACCURATEHEMODYNAMIC MONITORING
Clinicians have studied both restrictive and liberal fluid
regimens as a means to guide PGDT, fnding that it isimportant to evaluate patients on the basis of being
in a state of “fluid balance.”20 To achieve this optimal
fluid balance, clinicians must monitor a variety ofhemodynamic targets, including cardiac index (CI), strokevolume (SV), stroke volume variation (SVV), and pulsepressure variation (PPV).

Routine hemodynamic measurements, such as heart rate and mean arterial pressure (MAP), remain relatively unchanged
despite reduced blood flow and are considered insensitive indicators of hypovolemia or changes in CI.23,24 As a result,conventional fluid management is based on clinical assessment, vital signs, central venous pressure (CVP) monitoring, ora combination of these. However, recent studies have shown that CVP is not able to predict fluid responsiveness nor canchanges in blood pressure be used to approximate changes in SV or CO.25,26

Many of the clinical parameters that help clinicians efectively manage patient fluids are considered dynamic due to theircontinuous updating and sensitivity to fluid volume changes in patients. These dynamic flow parameters, such as SV, SVV,
and PPV, are needed to accurately predict fluid responsiveness.27 More than two dozen randomized controlled studies
and meta-analyses support the advantages of hemodynamic optimization over standard fluid management to achieve
superior clinical outcomes.12,28,29,30
DEMONSTRATING THE CLINICAL EFFECTIVENESS OF PGDT
PGDT has proven to help improve outcomes for a variety of patient populations, including orthopedic cases, which ofen
carry a signifcant burden of complications and mortality when performed in elderly patients. One study examining theefectiveness of PGDT protocols when used with total hip replacement (THR) surgery patients found that PGDT patients
received a greater volume of fluids during the intraoperative period, exhibited higher urine output, achieved a morepositive fluid balance and ultimately experienced fewer postoperative complications.14 In this study, SV and CO weretracked continuously and oxygen delivery index (DO2I) was calculated by inputting the hemoglobin concentration and
SaO2 into standard equations.
PGDT based on pulse pressure variation (PPV) has also been shown to improve patient outcomes while utilizing less invasive,
pulse contour-based, arterial pressure monitoring devices to determine CO.31,32,33 These devices provide a wide variety ofdynamic parameters, are generally easier to use, and have exhibited the ability to adequately assess dynamic changes in
CO.34 PPV, which is inversely proportional to SV when attempting to maximize SV intraoperatively, has also been shown toaccurately reflect volume responsiveness in a number of diferent high-risk surgical groups, helping avoid unnecessary andpotentially harmful volume loading by reflecting the cyclic changes in preload induced by mechanical ventilation.35,36,37,38
A randomized, multi-center study of patients undergoing major abdominal surgery demonstrated that PGDT using PPV,
radial artery pulse contour CI, and MAP leads to a reduction in postoperative complications (See Figure 2).39 Afer an initialassessment, patients in the study were reassessed every 15 minutes intraoperatively to maintain hemodynamically stablevalues. Hemodynamic data were documented every 30 minutes, and ventilatory parameters every 60 minutes. Meanwhile,the treatment of patients in the control group was performed at the discretion of the care-giving anesthesiologist.
FIGURE 2. MULTI-CENTER COMPARISON OF COMPLICATIONS FOLLOWING MAJOR

Number of Complications

SURGERY BETWEEN PGDT AND NON-PGDT GROUPS39
80

I=

Non-PGDT Control Group(P=0.038)

PGDT Study Group60

40(P=0.023)

20

Ot
he
rs

Re
na
l

Re
sp
ira
to
ry

cu
lar
as

Ca
rd
io
v

Ab
do
m
in
al

tio
n
In
fe
c

To
ta
l

0

Control group (basic anesthesia monitoring without PPV and CI information; treatment at the discretionof the caregiver); Study group (basic anesthesia monitor including continuous PPV and CI information;
initial hemodynamic assessment/intervention based on PPV and CI treatment algorithms)

Study data showed that the number ofStudies show that applying ERAS practiceguidelines reduces postoperative complications
by up to 50% and hospital LOS by 2.5 days.28,44

patients experiencing a complication,such as renal failure, respiratory failure,
or wound infections was signifcantly
lower in the PGDT study group.
One study examining the efects of PGDT

based on an SVV-guided protocol (See Figure 3) showed that by maintaining an SVV of <12% helped reduce complicationsand LOS for moderate-risk patients following major surgery. 40 In the study, the PGDT group experienced earlier return of
GI function (3 vs. 4 days) and oral intake (4 vs. 5 days), decreased hospital stay (5 vs. 7.5 days), and signifcantly higher
recovery scores compared to the non-PGDT control group. Another study of patients undergoing major surgeries showedthat monitoring SV increases greater than 10% with 250 mL boluses reduced total LOS by 3.6 days (See Figure 4). 41
If large amounts of blood loss with severe hemodynamic instability are anticipated during the course of surgery, such as
vascular surgery or liver transplant, arterial pressure-based hemodynamic monitoring may be warranted.39 Research showsthat, for some high-risk patients, the use of central venous oxygen saturation (ScvO2) in the early postoperative period isan efective parameter to help guide fluid therapy. 42,43
FIGURE 3. GDT FLUID MANAGEMENT PROTOCOL40

GDT Group

Measure SV(ventilate 8 mL/kg)

SVV >12%FIGURE 4. STROKE VOLUME OPTIMIZATION PROTOCOL41

NO .......

►

Monitor SVV
and CO

YES

200-250 mL fluid over
5–10 minutes

YES

SV Increase >10%··•••250 mL Albumin bolusNO(may repeat to a max of 20 mL/kg)

NO

YES .............••NO

SVV <12%

Monitor SV for clinicalsigns of fluid loss

NO ···········~>20 mL/kg Albumin?

YES

SV Increase >10%........................ •Abbreviation: SV = Stroke Volume

YES ••••••••••••••►

Crystalloid 3:1 replacement(consider PRBCs, monitor ABGs)

The above SVV-based GDT protocol was used to manage patientsby maintaining an SVV <12%. Data from the study indicates thisintraoperative protocol, guided by arterial pressure-based cardiac
output monitoring, may impact postoperative outcomes andhospital LOS.

The above SV optimization protocol has been associated with reduced
postoperative complications and hospital LOS and is now ofcially
recommended by the National Institute for Clinical Excellence in the UK
and by the French Society of Anesthesiology & Intensive Care (SFAR).

One review of twenty-nine randomized controlled trials (4,805 patients) found that proactive hemodynamic intervention
in the perioperative period for cardiovascular management of moderate- to high-risk patients was associated with a
52% reduction in mortality in studies using a pulmonary artery catheter as well as those that employed cardiac index or
oxygen delivery as the end-point targets.30 The meta-analysis also found that preemptive hemodynamic intervention was
associated with a 57% reduction in overall rates of surgical complications.
ECONOMIC BENEFITS
Meta-analyses of published studies focusedon major abdominal surgery show that
applying ERAS practice guidelines reduces
postoperative complications by up to 50%
and hospital LOS by 2.5 days.28,44 One study
evaluating the economic impact of theclinical benefts of ERAS found that both
direct medical and indirect non-medical
costs were signifcantly lower in the ERAS
group. 45 A similar published cost analysis

Although ERAS protocols were initiallycreated for colorectal surgery, the concept
has been studied and adapted for use acrossa wide range of medical specialties including
gynecology, thoracic, vascular, pediatric,
and orthopedic surgery.

of ERAS for colorectal sugery showed thatthe full fnancial burden of setting up and maintaining an ERAS program was signifcantly ofset by the costs saved by
reducing postoperative resource utilization. 46 For the 50 patients managed using ERAS protocols, clinicians documented asignifcant reduction in total hospital stay, intravenous fluid use, complications, and duration of epidural use, representing
an overall cost-savings of roughly $345,000, or $6900 per patient—more than ofsetting the $102,000 cost associatedwith implementing the ERAS program.
According to a study conducted at the University of Virginia Medical Center, ERAS patients undergoing colorectal surgery
reduced their length of hospital stay to 4.5 days compared to 6.9 days for patients who didn’t experience ERAS protocols. 47
The hospital also cut its surgical complication rate from 30% to 15% and saved an average of $7,000 per patient, totaling$700,000 over six months. ERAS programs also allowed the hospital to accept more transfer patients with added bed
capacity resulting from shorter LOS. In addition, patient engagement and satisfaction increased signifcantly, and the
30-day readmission rate fell from 19% to 7%, suggesting the benefts of ERAS protocols extend beyond the hospital walls.
CONCLUSION
The implementation of PGDT protocols guided by continuous hemodynamic monitoring is associated with improved
postoperative outcomes and decreased LOS. ERAS guidelines were initially created for colorectal surgery but have since
been studied and adapted for use across a wide range of medical specialties, including gynecology, thoracic, vascular,
pediatric, and orthopedic surgery. The current evidence base shows that perioperative management, specifcally the useof PGDT guided by real-time, continuous hemodynamic monitoring, helps clinicians maintain a patient’s optimal fluidbalance. Clinical awareness of the impact of ERAS is continuing to grow with help from organizations and societies suchas the Enhanced Recovery Partnership (ERP), the Association of Surgeons of Great Britain and Ireland, the French Societyof Anesthesiology (SFAR), and the Enhanced Recovery Afer Surgery Society. 48,49,50,51

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