16.2 Vascular Access, Enteral Tubes, Drains & Extravasation Management
Key Takeaways
Flow through a catheter rises with the fourth power of its radius and falls with its length, so a short 14 to 16 G peripheral line outruns the lumen of a long central venous catheter.
Vasopressor extravasation is treated with phentolamine 5 to 10 mg diluted in 10 mL of normal saline, injected subcutaneously around the site, ideally within 12 hours.
Hemodialysis catheter lumens are locked with concentrated heparin or citrate, and the lock must be withdrawn and discarded before the lumen is used for anything else.
Arterial lines are for monitoring and blood sampling only; injecting a drug into one can cause limb ischemia.
Medications given through enteral tubes are given one at a time with 15 to 30 mL water flushes, and extended-release, enteric-coated or hazardous products are not crushed.
16.2 Vascular Access, Enteral Tubes, Drains & Extravasation Management
Note
Exam scope: 2025 outline subtopics 1B4 (Lines, Tubes, and Drains) and 2C1 (Medication Preparation and Delivery). Intraosseous access and the cardiac arrest access hierarchy are covered in Section 1.3; infusion pumps and patient devices are covered in Section 16.3.
Peripheral Catheters and Flow Physics
The Hagen-Poiseuille relationship explains why access choice matters in hemorrhage: flow is proportional to the fourth power of the radius and inversely proportional to catheter length. Halving the radius cuts flow sixteen-fold.
Practical consequences:
- A short 14 or 16 G peripheral catheter gives faster flow than the 16 G distal lumen of a 20-cm triple-lumen central line.
- For massive transfusion, use large-bore peripheral lines, a rapid infusion catheter, or an introducer sheath (8.5 to 9 Fr) connected to a rapid infuser.
- A pressure bag cannot make up for a 22 G catheter.
- Viscous fluids such as packed red cells flow more slowly than crystalloid through the same catheter.
Peripheral Administration of Vasopressors and Irritant Drugs
The Surviving Sepsis Campaign suggests starting vasopressors peripherally rather than delaying them until a central line is placed. Institutional protocols usually require:
- A catheter of 20 G or larger in a large vein at or above the antecubital fossa, often placed with ultrasound and checked for blood return.
- Limits on concentration and duration, with a plan to place central access if therapy continues.
- Site checks every 1 to 2 hours by nursing staff, with stop-and-treat instructions for extravasation.
Observational data show that extravasation is uncommon and rarely causes lasting tissue injury when such protocols are followed.
Common Vesicants and Irritants in the ED
| Drug or solution | Concern |
|---|---|
| Norepinephrine, epinephrine, dopamine, phenylephrine, vasopressin | Vasoconstriction causing ischemic necrosis |
| Calcium chloride (more than gluconate) | Hyperosmolar, causes tissue calcification and necrosis |
| Dextrose 50%, hypertonic saline above 3%, sodium bicarbonate 8.4% | Hyperosmolar injury |
| Potassium chloride in high concentration | Pain, phlebitis and necrosis; concentration limits apply peripherally |
| Phenytoin | pH around 12; "purple glove syndrome" |
| Promethazine | Severe tissue injury and gangrene; FDA's 2023 labeling prefers deep IM injection, and IV use requires dilution and infusion |
| Acyclovir, vancomycin, radiocontrast | Irritants causing phlebitis or injury at high concentration |
| Anthracyclines, vinca alkaloids | Chemotherapy vesicants |
Parenteral nutrition above about 900 mOsm/L needs central access (ASPEN), and 23.4% saline is given only centrally.
Extravasation Management
General steps: stop the infusion, leave the catheter in place and aspirate what you can, mark the borders, elevate the limb, then remove the catheter and give the specific antidote. Photograph the site, document it, and arrange follow-up for any blistering or necrosis.
| Extravasated agent | Antidote | Thermal therapy |
|---|---|---|
| Vasopressors | Phentolamine 5 to 10 mg in 10 mL normal saline, injected subcutaneously in small aliquots around the site, ideally within 12 hours. Children: 0.1 to 0.2 mg/kg (maximum 10 mg). Topical nitroglycerin or subcutaneous terbutaline are alternatives during shortages | Avoid cold, which adds vasoconstriction |
| Hyperosmolar solutions, calcium, contrast, dextrose | Hyaluronidase, commonly 150 units as several small subcutaneous injections around the site | Warm compresses to help dispersion |
| Vinca alkaloids (vincristine, vinblastine) | Hyaluronidase | Warm compresses |
| Anthracyclines (doxorubicin, daunorubicin) | Dexrazoxane IV within 6 hours, in the opposite limb: 1,000 mg/m2 on days 1 and 2, then 500 mg/m2 on day 3 | Cold compresses, removed 15 minutes before dexrazoxane |
Tip
Warm compresses disperse drugs that are safer spread out (vinca alkaloids, hyperosmolar solutions). Cold compresses keep drugs that are dangerous in tissue localized (anthracyclines). Do not combine topical dimethyl sulfoxide with dexrazoxane.
Central Venous, Dialysis, Port and Arterial Lines
Multi-Lumen Central Venous Catheters
A typical 7 Fr triple-lumen catheter has a larger distal lumen (about 16 G) and two smaller lumens (about 18 G). Pharmacist checks include:
- A dedicated lumen for vasopressors. A bolus pushed through the vasopressor lumen flushes the drug in the dead space into the patient as an unintended pressor bolus.
- Y-site compatibility. Phenytoin precipitates with dextrose, ceftriaxone must never be mixed with calcium-containing solutions in neonates, and propofol's lipid emulsion limits co-infusion.
- Line infection prevention. Use chlorhexidine-alcohol skin preparation and full barrier precautions at insertion, scrub the hub before every access, and remove lines that are no longer needed.
Hemodialysis Catheters
Dialysis catheter lumens are locked between treatments with concentrated heparin (often 1,000 to 5,000 units/mL) or citrate, filling the lumen volume printed on the hub. Using the line without first withdrawing and discarding the lock gives the patient an unplanned heparin bolus that can reach thousands of units. These lines are reserved for dialysis except in emergencies, and only after the lock is removed.
Implanted Ports and PICCs
Implanted ports are accessed with a non-coring (Huber) needle under sterile technique and flushed according to policy. PICCs can be used for most medications once the tip position is confirmed, but small lumens limit rapid infusion.
Arterial Lines
Arterial catheters are for continuous pressure monitoring and blood sampling. Never inject medications into them. Accidental intra-arterial injection of drugs such as promethazine, benzodiazepines or barbiturates can cause severe vasospasm and limb ischemia. Clear line labeling and distinct tubing prevent mix-ups.
Medication Administration Through Enteral Tubes
- Do not crush extended-release, enteric-coated, sublingual or buccal products, or hazardous drugs. Use the ISMP "Do Not Crush" list and switch to an immediate-release or liquid product with adjusted dosing.
- Give each medication separately and flush with 15 to 30 mL of water before, between and after doses. Dilute hypertonic or sorbitol-containing liquids, which cause diarrhea.
- Check tube position. Jejunal tubes bypass the stomach, which matters for drugs that need gastric acid or act in the stomach.
- Drug-feed interactions:
- Phenytoin absorption falls with continuous feeds. Hold feeds 1 to 2 hours before and after each dose where policy supports it, and follow levels.
- Fluoroquinolones and tetracyclines chelate with divalent cations in feeds; separate them or choose another route.
- Levothyroxine and warfarin also need consistent timing relative to feeds.
- Carbamazepine suspension binds to PVC tubing, so dilute it and flush well.
- Clogged tubes: start with warm water. If that fails, use non-enteric-coated pancreatic enzyme with sodium bicarbonate dissolved in water. Avoid cola and acidic juices.
Chest Tubes and Other Drains
- Pleural infection: intrapleural alteplase 10 mg plus dornase alfa 5 mg twice daily for 3 days (MIST2, 2011) improved drainage and reduced referral for surgery compared with either agent alone or placebo.
- Procedural analgesia: local anesthetic infiltration within maximum doses (Section 9.4), supplemented by procedural sedation (Section 17.6).
- External ventricular drains:
- For ventriculitis that responds poorly to IV therapy, IDSA (2017) allows intraventricular antibiotics, such as preservative-free vancomycin (5 to 20 mg) or gentamicin (4 to 8 mg) in adults, with the drain clamped for 15 to 60 minutes.
- Intraventricular alteplase 1 mg every 8 hours for intraventricular hemorrhage (CLEAR III, 2016) lowered mortality but did not improve the primary functional outcome.
- Only preservative-free products in small volumes may be given intrathecally or intraventricularly.
- Urinary catheters: remove them as soon as possible to prevent catheter-associated infection, and do not treat asymptomatic bacteriuria in catheterized patients (Section 17.2).
A norepinephrine infusion running through a 20 G forearm IV has infiltrated. The skin around the site is pale, cool and firm. The infusion has been stopped and moved to a new line. Which treatment should be prepared for the extravasation site?
Topical dimethyl sulfoxide applied every 8 hours for 7 days
Hyaluronidase 150 units SC with ice packs for 24 hours
Dexrazoxane 1,000 mg/m2 IV in the opposite arm
Phentolamine 5 to 10 mg in 10 mL normal saline injected SC around the site
A patient on hemodialysis arrives in septic shock with no peripheral access. The team plans to give the first antibiotic dose through the patient's tunneled dialysis catheter. What must happen before any medication is given through that lumen?
Flush the existing lock into the patient with 10 mL of normal saline
Withdraw and discard the heparin or citrate lock volume from the lumen
Instill alteplase 2 mg into the lumen to clear any thrombus
Give protamine 50 mg IV to neutralize the heparin lock first
A patient receiving continuous enteral feeds through a nasogastric tube has a low phenytoin concentration despite adherence to phenytoin suspension 100 mg every 8 hours. Which intervention best addresses the likely cause?
Mix the phenytoin dose directly into the enteral feeding bag
Switch the patient to fosphenytoin given through the nasogastric tube
Crush extended-release phenytoin capsules instead of using the suspension
Hold feeds around each dose, flush with water, and recheck the level
A trauma patient in hemorrhagic shock needs rapid blood product infusion. Which existing access will allow the fastest flow by gravity?
A 20 G forearm catheter connected to a fluid warmer
A 22 G hand IV with a pressure bag inflated to 300 mmHg
A 16 G, 30-mm peripheral catheter in the antecubital vein
The 16 G distal lumen of a 20-cm triple-lumen central venous catheter
Sections you finish are checked off in the contents.