Intravenous Infusion

Core Concepts

The pieces of an infusion system

An infusion setup has a consistent anatomy. The bag holds the solution and carries the label checked against the order. The primary tubing connects bag to catheter; it includes a drip chamber (where falling fluid is counted) and a clamp that adjusts flow. The drop factor — printed on the tubing packaging — tells how many drops (gtt) make one milliliter for that tubing. Macrodrip tubing delivers larger drops (fewer per mL); microdrip delivers smaller drops (more per mL, for slow, precise rates). The rate-control device is either the clamp (a gravity infusion, counted in drops per minute) or an infusion pump, which delivers a set number of milliliters per hour and alarms when something is wrong. The catheter is the final connection into the vein.

The flow-rate formula

The core calculation for a gravity infusion is:

gtt/min = (volume in mL × drop factor in gtt/mL) ÷ time in minutes

For a pump, the simpler relationship applies:

mL/hr = volume in mL ÷ time in hours

Every term has a defined meaning: volume is the ordered amount, time is the infusion duration, and drop factor is a property of the chosen tubing. These formulas are teaching tools — the real skill is checking that the answer makes sense (a rate that would empty the bag in ten minutes is a red flag, not a solution).

Gravity versus pump

Gravity infusions rely on counting drops and adjusting the clamp; they are simple and portable but drift over time, so they are checked frequently. Pumps deliver a precise rate and alarm on occlusion and air — but a pump is a machine, and the person still needs site and response monitoring. The equipment controls the rate; the nurse controls the verification.

Monitoring the infusion and the person

Monitoring is a checklist that repeats throughout the infusion:

• The site: look and feel for redness, swelling, coolness, pain, or leaking at the catheter — early signs that must be reported.
• The rate: verify the bag is running on time; investigate before adjusting if too much or too little has infused.
• The person: watch for new symptoms — shortness of breath, swelling elsewhere, fever, or feeling unwell — and report them promptly.
• The system: check tubing for kinks, the drip chamber's fill, connections for leaks, and pump alarms; know the hang-time and tubing-change intervals set by facility policy.

Changing, flushing, and discontinuing

Infusions end in an orderly way: verify the order, clamp the tubing, remove the catheter cleanly, hold pressure until bleeding stops, and inspect and document the site. Some catheters are flushed to keep them patent between uses — the flush solution and technique follow facility policy. Continuous documentation of the infusion, site assessments, and interventions is how complications get caught early and care is communicated.

The complication map

Four complications dominate IV practice. Infiltration: fluid leaks into surrounding tissue — the site swells, feels cool, the flow slows. Extravasation: a vesicant (tissue-damaging) medication leaks out — more serious than infiltration, handled per specific policy. Phlebitis: inflammation of the vein — red, warm, tender, often with a palpable cord. Fluid overload: too much fluid too fast — shortness of breath and swelling are reportable signs. None is treated from memory; each triggers the same first response: stop per policy, assess, report, document.

Common Confusions