Perioperative fluid management: Progress despite lingering controversies

INTRAOPERATIVE MONITORING TO OPTIMIZE FLUID THERAPY

Another important issue is the emergence of minimally invasive technologies for monitoring hemodynamic measures intraoperatively. The aim is to enable more precise tailoring of fluid therapy to meet patient needs on a case-by-case basis.

One of the simplest of these techniques is esophageal Doppler monitoring to measure descending aortic blood flow using Doppler ultrasonography. The technique is used to titrate repeated boluses of fluid based on continuous estimations of stroke volume and surrogate markers of preload indices. Typical protocols for esophageal Doppler monitoring call for administration of colloid to maintain a descending thoracic corrected flow time of no more than 0.35 seconds and stroke volume increments of 10%.

Phan et al recently published a meta-analysis to assess the effect of intraoperative esophageal Doppler monitoring in guiding fluid therapy to optimize intravascular volume status.⁹ The analysis, which included nine randomized controlled trials in a total of 920 patients, found statistically significant reductions in the rate of complications and in length of hospital stay with the use of esophageal Doppler monitoring; there was no difference in mortality. Use of Doppler monitoring was associated with an increase (+671 mL) in the volume of colloid administered and a decrease (–156 mL) in the volume of crystalloid.

Timing of fluid administration can be critical

One of the trials in the above meta-analysis illustrated that the timing of fluid administration might be more critical than the volume of fluid given. Noblett et al placed an esophageal Doppler probe in each of a series of 108 patients undergoing colorectal resection;¹⁰ the control group received perioperative fluid at the anesthesiologist’s discretion, whereas the intervention group received additional colloid boluses based on Doppler assessment. While the overall volume of colloid given was comparable between the two groups, the intervention group received nearly 100% of the total volume during the first quarter of surgery. The intervention group had significantly fewer postoperative complications than the control group as well as a 2-day reduction in average length of stay. Circulating levels of interleukin-6 and cytokines also were significantly lower in the intervention group, which suggests that the intervention blunted the inflammatory response to surgery.

Fluid management must be individualized

Intraoperative fluid needs are highly variable and patient-specific. Parker et al tested an approach in which they universally administered 500 mL of a gelatin colloid solution prior to hip fracture surgery and compared it with a conventional intravenous saline crystalloid solution; neither approach used invasive intraoperative monitoring.¹¹ They found no significant difference in length of stay, 30-day mortality, or postoperative complications between the two study arms. They concluded that more invasive investigation of patients before or during surgery may have been able to identify a subgroup in whom the colloid therapy or more precise fluid control would have been beneficial.

THE ROAD AHEAD

Fluid management remains suboptimal

Despite being a fundamental component of surgical and perioperative care, fluid management remains suboptimal in clinical practice. I can speak most directly to the practice of fluid management in the United Kingdom (UK), but the same types of shortcomings apply broadly to the United States as well.

In 1999, the UK’s National Confidential Enquiry into Patient Outcome and Death examined perioperative death in the UK, concluding that patients were dying as a result of too much or too little perioperative fluid administration.¹² Their report cited staff inexperience as an important contributor to the problem, as junior physicians order and deliver the majority of postoperative fluid regimens.

This cautionary report from 10 years ago appears not to have produced substantial improvements in practice, at least according to a recent study by Walsh et al.¹³ These researchers prospectively audited postoperative fluid management practices in 106 consecutive patients undergoing laparotomy in a UK general surgical unit over a 6-month period in 2003. They found no correlation between available fluid balance data and the quantities of fluids prescribed, suggesting that physicians routinely ignore such data when prescribing. Fifty-four percent of the patients developed at least one fluid-related complication. Patients routinely received significantly greater amounts of fluid and sodium than were physiologically needed, and multivariate analysis showed that mean daily fluid load predicted development of fluid-related complications.

Guidance from a new British consensus document

Where can clinicians turn for a good synthesis of current evidence to guide better perioperative fluid management? I would recommend the newly released British Consensus Guidelines on Intravenous Fluid Therapy for Adult Surgical Patients,¹⁴ which are available on the Evidence Based Peri-Operative Medicine Web site (https://www.ebpom.org). These guidelines were developed by a multidisciplinary team of clinicians to improve perioperative fluid prescribing. They cover principles of preoperative, intraoperative, and postoperative fluid management, as well as fluid therapy in acute kidney injury. They pre­sent 28 recommendations in all, at least 12 of which are based on high-level (grade 1a or 1b) evidence.

DISCUSSION

Question from the audience: What is the relationship between perioperative fluid management, gut edema from perioperative fluid use, and postoperative ileus?

Dr. Hamilton: There’s no easy answer. Excessive administration of sodium and fluid does predispose to gut and tissue fluid edema. Many of the enhanced surgery recovery programs require no preoperative fasting. There’s no bowel prep. The enteral route is used primarily as quickly as possible. In the UK, we no longer use nasogastric tubes for many of those programs. But there’s no doubt that tissue edema still occurs with excess fluid therapy.

The premise for individualizing fluid therapy is that less is not more but that more is not the right approach either. The stroke volume approaches or the corrected flow time approaches have been related to return of gastrointestinal function and return of flatus, which is a function of gastrointestinal recovery.

Question from the audience: Can you comment on the perioperative use of the Swan-Ganz catheter for fluid management?

Dr. Hamilton: I don’t use it intraoperatively, and not many hospitals in the UK use it apart from liver resection surgery. Having said that, Swan-Ganz catheters were the predominant monitor for 30% to 40% of the original studies of hemodynamic optimization. I cannot give you intraoperative data to support the use of Swan-Ganz catheters for monitoring, but if you lift evidence from the other methods of monitoring hemodynamics, if you’re optimizing flow in a bolus and dynamic fashion, then you should see the kinds of improvements in outcomes that are associated with the other modalities.

The drawback with the Swan-Ganz catheter, obviously, is the morbidity associated with its insertion and its interpretation. But if you’re confident in doing those things, I think it’s a perfectly good monitor.