What is the recommended approach to Goal Directed Fluid Therapy (GDFT) in patients undergoing major surgery or who are critically ill?

Goal Directed Fluid Therapy (GDFT) in Major Surgery and Critical Illness

Goal Directed Fluid Therapy should be implemented for high-risk patients undergoing major surgery and critically ill patients, using minimally invasive cardiac output monitoring to optimize stroke volume and oxygen delivery while maintaining a near-zero fluid balance approach. 1

Definition and Purpose of GDFT

• GDFT is the process of using cardiac output monitoring to guide the administration of fluids and vasopressors, with the aim of optimizing intravascular volume, cardiac output, and tissue perfusion while avoiding salt and water overload 1
• The primary goal is to maintain central euvolemia by utilizing changes in stroke volume measured by minimally invasive cardiac output monitors to optimize patients on their individual Frank-Starling curve 1
• GDFT targets adequate cardiac output and end-organ perfusion, which has shown significant benefits in reducing morbidity and mortality in major surgery 1

Patient Selection for GDFT

• GDFT is strongly recommended for high-risk patients and those undergoing surgery with large intravascular fluid loss (blood loss and protein/fluid shift) 1
• For low-risk patients undergoing low-risk surgery, GDFT has shown less benefit, and a simpler "zero-balance" approach might be sufficient 2
• All emergency laparotomy patients should be considered high-risk and may benefit from GDFT 1
• Patients with comorbidities and reduced cardiac function may benefit most from GDFT 1

Implementation of GDFT

Monitoring Tools

• Minimally invasive cardiac output monitors such as esophageal Doppler, arterial waveform analysis, or thoracic bioimpedance/bioreactance should be used to guide fluid therapy 1
• Dynamic variables using arterial waveform analysis such as stroke volume variation (SVV) or pulse pressure variation (PPV) can help predict fluid responsiveness in ventilated patients 1, 3
• Measurement of stroke volume is preferable to using central venous pressure, which is a poor predictor of fluid responsiveness 1

Fluid Challenge Technique

• Administer fluid challenges (typically 200-250 ml of colloid) over a short period of time to test if a patient has preload reserve 4, 3
• Assess response by measuring changes in stroke volume - a positive response is defined as an increase in stroke volume ≥10-15% from pre-challenge values 3
• Repeat fluid challenges until the patient no longer shows significant improvement in stroke volume (increase <10%) or until other signs of shock are resolved 3

Fluid Selection

• Balanced crystalloids (e.g., Ringer's lactate) should be preferred over 0.9% saline for maintenance fluid to avoid hyperchloremic acidosis 1, 4
• Crystalloids should be administered at a rate of 1-4 ml/kg/h as maintenance fluid during surgery 1, 4
• In critical illness, synthetic colloids should be avoided due to increased risk of kidney dysfunction 1
• Albumin is not recommended for routine use in critical illness, though it may be considered in specific circumstances 1

Evidence for GDFT Efficacy

• A meta-analysis of 32 RCTs including about 3000 patients demonstrated significant benefits of GDFT in reducing morbidity and mortality during major surgery 1
• GDFT has been shown to decrease major postoperative complications by up to 52% compared to conventional fluid management in high-risk surgical patients 5
• In cardiac surgery patients, GDFT was associated with reduction in the incidence of acute kidney injury (6.5% vs 19.9%) and shorter hospital stays 6
• Recent studies within enhanced recovery protocols have shown mixed results, with some showing no difference in outcomes between GDFT and conventional care 1

Special Considerations

Liver Surgery

• During hepatic transection, low central venous pressure (below 5 cm H2O) with close monitoring is recommended to reduce blood loss 1
• Stroke volume variation (SVV) monitoring may be preferable to CVP recording in laparoscopic liver surgery, showing reduced conversion rates and blood loss 1
• GDFT may be particularly beneficial after liver resection to restore tissue perfusion following a low central venous pressure state 1

Emergency Surgery

• All emergency laparotomy patients should be considered high-risk and may benefit from GDFT 1
• Balanced crystalloids should be used in preference to 0.9% normal saline for resuscitation and to maintain intravascular volume in emergency surgery 1

Colorectal Surgery

• Within enhanced recovery protocols for colorectal surgery, GDFT may not be necessary for all patients and should be reserved for high-risk patients 1
• A perioperative near-zero fluid balance approach is preferred, with fluid excess leading to weight gain more than 2.5 kg being avoided 1

Pitfalls and Caveats

• Excessive fluid administration can lead to bowel edema, increased interstitial lung water, and complications 1, 2
• Persistent hypovolemia can lead to hypoperfusion of vital organs and the bowel, also causing complications 5, 7
• Arterial hypotension should be treated with vasopressors when administering intravenous fluid boluses fails to improve stroke volume significantly (>10%) 1
• Inotropes should be considered in patients with reduced contractility (cardiac index < 2.5 L/min) to achieve adequate oxygen delivery 1
• Postoperative intravenous fluids should be minimized to maintain normovolemia and avoid fluid excess, with early transition to enteral route 1, 2