Key Points
- 1.
The costs of healthcare are escalating. Goal-directed fluid therapy (GDT) and multimodal pain relief are ways to control cost while improving quality.
- 2.
GDT is an integral part of enhanced recovery programs (ERPs), as is multimodal pain management.
- 3.
The traditional, liberal approach to perioperative fluid management has no sound evidence base and causes perioperative fluid and salt overload. “Zero fluid balance” is recommended using a goal-directed approach. ERPs emphasize avoidance of salt and water overload.
- 4.
GDT involves cardiovascular monitoring such as minimally invasive cardiac output and application of an algorithm or guidelines specific to fluid and hemodynamic management.
- 5.
GDT and ERPs increase quality by decreasing variability in practice with evidence-based management. Decreased cost results from less perioperative morbidity and streamlined care delivery.
- 6.
Various monitors may be used for GDT, ranging from invasive (e.g., pulmonary artery catheter) to noninvasive (e.g., finger cuff cardiac output). The choice of monitor is based on the clinical situation and individual or institutional preference. The most common monitors used are esophageal Doppler and arterial pulse-wave analysis systems.
- 7.
ERPs are multidisciplinary, multifactorial care pathways. They incorporate optimal preoperative preparation, careful intraoperative management of fluid status and temperature, antibiotic administration, minimally invasive surgery, multimodal pain relief, postoperative nausea and vomiting control, and early mobilization.
- 8.
Multimodal perioperative pain relief using opiate-sparing techniques facilitates early mobilization and patient comfort and decreases opiate-related complications. Effective multimodal pain management is essential for ERPs.
With recent advances in expensive diagnostic and treatment modalities, the costs of healthcare have skyrocketed. The need to care for increasing numbers of patients undergoing procedures while controlling cost has pushed healthcare systems to devise increasingly efficient ways to deliver care. The “throughput” of patients is often stymied by prolonged hospital stays and readmission after procedures. Inefficient systems, inconsistent care, and perioperative complications cause delays, poor patient and provider satisfaction, and high cost.
Goal-directed fluid therapy (GDT), enhanced recovery programs (ERPs), and the perioperative surgical home (PSH) are three related approaches to patient care that have emerged to provide optimal outcomes for patients undergoing surgery. GDT refers to fluid and hemodynamic management targeting optimal cardiovascular performance using monitoring beyond standard noninvasive monitors. ERPs are designed to incorporate patient management processes, such as preoperative optimization, multimodal pain management, and early mobilization after surgery, so as to facilitate recovery. PSH is a construct consisting of a coordinated, multidisciplinary team using best-evidence guidelines and protocols to guide patients through the entire perioperative experience as seamlessly as possible. Fig. 19.1 shows GDT as a component of ERPs and both under the PSH umbrella. GDT and multimodal pain relief are two approaches that facilitate early ambulation, patient comfort, and enhanced recovery. These approaches are particularly important in patients with cardiovascular illness.
Goal-Directed Fluid Therapy
Traditional, liberal fluid management, which entailed a cookbook-type approach, is now outmoded. This involved calculation of maintenance fluid requirement based on body weight, calculation of a deficit based on the period during which the patient has not had any fluid (e.g., nothing by mouth [NPO]), presumed effects of a bowel prep, and estimation of third-space losses based on the invasiveness of the surgery. Typically, for major abdominal surgery, 6, 8, 10, or even 12 mL/kg per hour of crystalloid would be administered to replace insensible losses and loss to the third space. The concept of a “third space” has been called into question. What has been referred to as fluid loss to the third space likely represents translocation of administered fluid out of the vascular space, resulting in intracellular and extracellular edema.
Excess salt and fluid in the perioperative period is potentially harmful. Fluid and salt excess can lead to airway edema, increased lung water, tissue edema, and cardiac failure. Relative fluid restriction results in shorter hospital lengths of stay, improved wound healing, fewer surgical infections, and fewer cardiovascular and pulmonary complications. It is sometimes argued that excess perioperative fluid and salt are acceptable because, with time, the patient will mobilize the fluid. However, the potential airway problems, prolonged ventilation, increased complication rate, and extra time in recovery associated with excess fluid and salt administration are neither necessary nor acceptable. Avoidance of fluid and salt overload in major surgery is now a standard component of ERPs ( Fig. 19.2 ).
Overaggressive fluid restriction can have negative consequences as well, with hypovolemia leading to hypotension, tachycardia, organ ischemia, and vital organ failure. Morbidity rates are higher in the setting of either hypovolemia or hypervolemia ( Fig. 19.3 ). Targeting no perioperative change in body weight, fluid restriction protocols do allow modest fluid administration with a background rate (e.g., 1–4 mL/kg per hour) and fluid boluses to maintain hemodynamic stability. Likewise, blood products are used as needed to maintain adequate hemoglobin concentration and coagulation.
A goal-directed, protocol-based approach to fluid and hemodynamic management has grown out of accumulating evidence that optimizing hemodynamic status improves outcome and that accurate assessment of volume and hemodynamic status using only standard, noninvasive monitors is often impossible. Tachycardia, hypotension, and oliguria can result from either hypovolemia or hypervolemia (i.e., heart failure). GDT adoption has also resulted from recognition that decreasing variability of practice using a best-evidence approach improves outcome. Decreasing process variability is essential to creating high-performance systems.
Some perioperative GDT grows out of current approaches to critically ill patients. Early, aggressive fluid and hemodynamic management of septic patients is an integral factor leading to dramatic improvements in mortality rate. This work, published in 2001, revolutionized the initial management of patients with sepsis, such that the vast majority of tertiary care centers now have a sepsis protocol that incorporates an early, goal-directed approach.
In 2002, Gan and colleagues studied 100 patients undergoing major elective surgery, randomly assigning them to receive either “standard” therapy or GDT based on esophageal Doppler parameters. The GDT group experienced shorter hospital stays (5 ± 3 days vs. 7 ± 3 days), less nausea and vomiting, and earlier return of bowel function. Numerous studies of a wide variety of surgical populations using various GDT algorithms and monitors followed, with the vast majority showing benefit. Large meta-analyses have subsequently confirmed the benefits of using thoughtful, informed fluid administration, often with the use of algorithms with sound bases in physiology.
Goal-Directed Fluid Therapy and Cost Reduction
With its decreased morbidity and hospital length of stay, GDT reduces cost. Perioperative complications, in addition to being distressing to patients and healthcare delivery teams, dramatically increase healthcare costs. This increased cost results from increased utilization of expensive resources (e.g., intensive care unit and hospital beds, diagnostic tests, medical and surgical therapies) and lost opportunity as fewer patients can be cared for in the system. A single complication in a major surgery patient can cost many thousands of dollars, and by decreasing the incidence of such complications, GDT dramatically reduces cost. The mortality rate, hospital length of stay, and direct costs for patients with at least one complication versus those with no complications are shown in Table 19.1 .
| No Complications | ≥1 Complication | P Value | |
|---|---|---|---|
| Mortality rate | 1.4% | 12.4% | <.001 |
| Hospital LOS (days) | 8.1 ± 7.1 days | 20.5 ± 20.1 days | <.001 |
| Direct costs (mean) | $17,408 ± $15,612 | $47,284 ± $49,170 | <.001 |
Monitoring for Goal-Directed Fluid Therapy
Various monitors have been used successfully in GDT, ranging from invasive (e.g., pulmonary artery catheter) to noninvasive (e.g., finger plethysmographic waveform). The data provided supplements standard monitoring (i.e., heart rate and blood pressure) with parameters tracking overall cardiac performance such as cardiac output and stroke volume (SV), or indexes of potential fluid responsiveness such as stroke volume variation (SVV), pulse pressure variation (PPV, arterial pulse-wave analysis systems), and corrected flow time (FTc, esophageal Doppler). Continuous monitoring of central venous oxygenation also has been used to assess adequacy of circulation. Assessment of tissue perfusion by means of gastric tonometry has been used in GDT, and attempts at evaluating tissue oxygenation (e.g., near-infrared spectroscopy) have been made as well.
Each monitoring system has strengths and weaknesses, and monitoring should be tailored to individual situations and institutional preference. Although the accuracy of minimally invasive cardiac output monitors such as arterial waveform systems and esophageal Doppler has been questioned, the ability of the systems to assess and trend cardiovascular performance appears to be adequate for perioperative GDT. In critically ill or unstable patients, invasive monitors such as pulmonary artery catheters and transesophageal echocardiography should be considered. Monitors used for GDT are presented in Table 19.2 .
| Invasiveness | Technology | Device | Parameters for GDT | Strengths | Weaknesses |
|---|---|---|---|---|---|
| Invasive | Thermodilution, CO, pulmonary artery and central pressure | Pulmonary artery catheter | CO | Clinical gold standard CO measurement; vast amount of potentially useful data, including RV function | Invasive, requires central venous access |
| Transpulmonary thermodilution | PiCCO (Pulsion Medical Systems) central arterial catheter | Pulmonary artery and central venous pressure | Vast amount of potentially useful data, including thoracic blood volume and extravascular lung water | Invasive; requires central arterial access | |
| Fiberoptic oximetry | Precep Catheter (Edwards Lifesciences) | Mixed venous and venous oxygen saturation | Assessment of global oxygen balance and extraction ratio | No direct information about cardiac performance or fluid responsiveness | |
| Minimally invasive | Doppler flow measurement, descending aorta | CardioQ (Deltex Medical) | CO | Most common monitor successfully used for GDT | Requires skill (placement) |
| Corrected flow time (preload, afterload), peak velocity | Newer systems incorporate arterial pressure wave | Inaccurate in aortic crossclamping, aortic aneurysm, aortic regurgitation | |||
| Pressure wave pulsatility | Vigileo/FloTrac (Edwards Lifesciences) | CO, SVV (fluid responsiveness) | Easy to use SVV is a powerful parameter combined with CO | Inaccurate in aortic crossclamping, aortic regurgitation, cirrhosis, and sepsis | |
| Noninvasive | Finger cuff | Clearsight (Edwards Lifesciences) | CO, SVV (fluid responsiveness) | Noninvasive | Potential accuracy issues; relatively unstudied in GDT |
| Finger plethysmography | Pulse oximetry (Masimo) | Waveform variation, pleth variability index | Noninvasive | Potential accuracy issues; relatively unstudied in GDT; no CO data | |
| Thoracic electrical impedance, bioreactance, velocimetry | NICOM (Cheetah Medical), ICON (Cardiotronics) | CO | Noninvasive | Potential accuracy issues; relatively unstudied in GDT |
The most studied monitor for GDT is esophageal Doppler (CardioQ Deltex Medical). This system consists of a small probe placed in the esophagus that insonates the descending thoracic aorta. Estimation of the cross-sectional area of the aorta is made based on patient characteristics (e.g., age, height, gender, and weight) and the area under the velocity time is calculated, with the terms velocity time integral (VTI) and stroke distance (SD) used interchangeably. SD is multiplied by the aortic cross-sectional area to obtain SV:
SV=SD×Aortic cross-sectional area
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