**Author details**

**4.3. The importance of fluid balance**

48 Essentials of Accident and Emergency Medicine

avoiding the dangers of fluid overload [85].

between fluid overload and AKI [93].

**5. Conclusion**

**Conflict of interest**

The author declares no competing interest.

Fluid accumulation in the acute setting is a frequent event. While everything is geared toward early and aggressive fluid resuscitation, as it should be, less emphasis is given toward the risks associated with fluid accumulation and overload. As fluid overload is shown to contribute to poorer outcomes in different acute populations [81–84], it becomes imperative to achieve the right balance between overcoming hypovolemia and organ hypoperfusion and

A common quantitative definition of fluid overload in the literature is a percentage fluid accumulation of >10%, determined by dividing the cumulative fluid balance in liter by the patient's baseline body weight and multiplying by 100% [86, 87]. This is, however, on the assumption that the patient is volume depleted on admission to the acute unit, which is not necessarily the case as some patients have already been accumulating fluid by then. The negative effects of the excess fluid have been shown in various organ systems. In a large RCT, higher cumulative fluid balance was associated with longer mechanical ventilation duration and length of ICU stay and without reducing the incidence of shock and the need for renal replacement therapy [88]. In managing intra-abdominal hypertension and abdominal compartment syndrome, poorer outcomes have been attributed to fluid overload [89, 90], a phenomenon linked to capillary leak and tissue edema. While fluid is often aggressively given to prevent AKI, the association between fluid overload and poorer renal outcomes has been evident [86, 91, 92], prompting questions on the cause-effect relationship

A comprehensive fluid strategy will require a close monitoring of the fluid balance. In this context, a mindset of fluids as drugs will promote careful considerations of the indications

In conclusion, fluid therapy in the acute setting is a challenging and complex task for the clinicians. Two areas that are beyond the scope of the chapter—the specific needs of the different subpopulations of acute patients and the different access to resources at different locations of practice—further add to the complexity. Emerging evidence on various facets of fluid therapy has helped to offer some consistency in approach in what has been a very diverse practice. The underpinning principle should be fluids are drugs that must be chosen and prescribed

and the doses of the fluids, recognizing that more is not always better.

correctly, as wrong choice and doses lead to adverse effects.

Nor'azim Mohd Yunos

Address all correspondence to: nor.azim@monash.edu

Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Johor Bahru, Malaysia
