3 IV Fluids and Infusion Management

Purpose and selection of IV fluids

IV fluid therapy may have different purposes, and the plan should reflect the patient’s assessed needs. Use the oral or enteral route when it can meet those needs, and reassess whether IV therapy is still required.

Resuscitation treats urgent circulatory volume loss. An isotonic crystalloid is commonly used initially, according to the clinical context and local protocol. After fluid is given, reassess the patient’s response rather than assuming the ordered volume is automatically sufficient or appropriate to continue.

Maintenance provides routine fluid needs when oral intake is inadequate. Replacement addresses existing or ongoing losses; maintenance alone is not necessarily enough when losses continue. The amount and nature of losses, existing deficits, other intake, examination, and laboratory results should guide the plan.

Reassessment checks whether the plan remains appropriate. Selection and review should take account of the patient’s condition, losses, other fluid intake, medications, examination, and laboratory results. IV fluids should be prescribed, administered, and monitored by trained clinicians, following the patient-specific prescription and local policy.

Calculate infusion rates

Calculate the pump setting from the prescribed volume and time:

For an order of $1{,}000\ \text{mL}$ over $8\ \text{hr}$, the calculation is $1{,}000 \div 8 = 125\ \text{mL/hr}$.

For gravity administration, include the tubing’s drop factor and express time in minutes:

Check the Drop factor printed on the actual administration set. Round a gravity rate to a whole drop per minute.

For $1{,}000\ \text{mL}$ over $8\ \text{hr}$ with tubing labeled $15\ \text{gtt/mL}$, convert the time to $480\ \text{min}$:

For $750\ \text{mL}$ over $6\ \text{hr}$ with a set labeled $60\ \text{gtt/mL}$, convert the time to $360\ \text{min}$:

Monitor fluid balance and respond to changes

A Fluid balance calculation compares recorded intake and output over a period. For example, intake of $1{,}250\ \text{mL}$ and output of $900\ \text{mL}$ give a net balance of $+350\ \text{mL}$:

Include fluid intake from all sources when assessing balance. Interpret the figures as part of the whole clinical picture, not in isolation. Relevant observations include trends in weight, vital signs, urine output, edema, respiratory status, and laboratory results.

Patients receiving IV fluids need regular clinical and fluid-balance review, with more frequent monitoring when indicated. New breathlessness and increasing peripheral edema during an infusion may indicate Fluid overload. Promptly assess the patient and escalate according to local policy; reassess both the patient and the infusion plan. Do not independently change a prescribed rate unless authorized by protocol or a prescriber.