Peripheral IV Access in the Field
Intravenous access is a fundamental paramedic skill that enables fluid resuscitation, medication administration, and blood sampling. Establishing IV access in the field presents unique challenges compared to the hospital setting: poor lighting, patient movement during transport, vasoconstriction in shock states, and the pressure of time-critical situations. Mastering this skill requires understanding anatomy, proper technique, and the ability to adapt when first attempts fail.
The most common sites for peripheral IV insertion are the veins of the forearm (cephalic and basilic veins), the hand (dorsal venous arch), and the antecubital fossa (median cubital vein). The antecubital fossa provides the largest, most accessible veins and is ideal for rapid fluid resuscitation, but it limits arm movement and is more likely to infiltrate with patient movement. Forearm veins offer a good balance of size and stability. Hand veins are a last resort for peripheral access due to their small size and fragility.
IV Insertion Technique
Successful IV insertion follows a systematic approach. Apply a tourniquet 4 to 6 inches above the intended insertion site. Ask the patient to make a fist to engorge the veins. Select an appropriate gauge catheter (18-gauge for trauma and fluid resuscitation, 20-gauge for general use, 22-gauge for elderly or pediatric patients with fragile veins). Clean the site with alcohol or chlorhexidine. Anchor the vein by applying traction below the insertion point. Insert the catheter at a 15 to 30 degree angle, bevel up, and advance until you see a flash of blood in the chamber. Advance the catheter over the needle, remove the tourniquet, connect the IV tubing, and secure the catheter with a transparent dressing.
Fluid Selection and Administration
The two most common IV fluids in EMS are normal saline (0.9% sodium chloride) and lactated Ringer's solution. Both are isotonic crystalloid solutions appropriate for volume resuscitation. Normal saline contains 154 mEq/L each of sodium and chloride. Lactated Ringer's is more physiologically balanced and contains sodium, chloride, potassium, calcium, and lactate. Some protocols prefer lactated Ringer's for trauma patients because large-volume normal saline can cause hyperchloremic metabolic acidosis.
Flow rate depends on the clinical situation. For hypovolemic shock, wide-open fluid boluses (typically 1 to 2 liters for adults, 20 mL/kg for pediatrics) are appropriate. For maintenance fluids, use a drip rate that keeps the line patent (typically 30 to 60 mL/hr). To calculate drip rates: drops per minute equals volume (mL) times the drip set factor (10, 15, or 60 drops/mL) divided by time in minutes.
Complications and Troubleshooting
Common IV complications include infiltration (fluid leaking into surrounding tissue, causing swelling and coolness at the site), phlebitis (inflammation of the vein, causing redness and pain along the vein), hematoma (blood collecting under the skin from a missed or blown vein), and air embolism (air entering the bloodstream, prevented by proper priming of tubing). If infiltration occurs, discontinue the IV, apply a warm compress, and establish a new IV at a different site, ideally above the infiltrated area or on the opposite extremity.