Understanding Cefepime and its Properties
Cefepime is a broad-spectrum, fourth-generation cephalosporin antibiotic used to treat a variety of bacterial infections, including those involving the urinary tract, skin, and lungs [1.3.6]. It works by inhibiting bacterial cell wall synthesis, leading to bacterial death. Like other beta-lactam antibiotics, its effectiveness is optimized when the drug concentration remains above the minimum inhibitory concentration (MIC) for 60-70% of the dosing interval [1.2.5]. This is often achieved through intermittent or even extended infusions [1.2.2].
When considering intravenous (IV) administration, two key properties of a drug are its pH and osmolality, as these determine its compatibility with peripheral veins [1.2.3].
- pH: The reconstituted solution of cefepime has a pH ranging from 4 to 6 [1.3.3]. The Infusion Nurses Society (INS) has historically recommended a pH range of 5 to 9 for peripheral administration to minimize the risk of chemical phlebitis (vein inflammation) [1.2.3]. Cefepime's pH can fall just outside this lower limit.
- Irritant vs. Vesicant: Cefepime is classified as an irritant, not a vesicant [1.4.1, 1.4.2]. An irritant can cause discomfort, pain, and inflammation along the vein, while a vesicant can cause severe tissue damage and blistering if it leaks outside the vein (extravasation) [1.4.4]. Because it is an irritant, careful monitoring during infusion is essential [1.4.2]. Phlebitis is a known local reaction, occurring in about 1.3% of patients receiving it intravenously [1.8.1].
What is a Midline Catheter?
A midline catheter is a type of peripheral IV access, but it's longer than a standard peripheral IV (PIV). It is typically 8 to 20 cm long and inserted into a vein in the upper arm, like the basilic, cephalic, or brachial vein [1.5.1, 1.7.4]. The tip of the catheter terminates in the axillary vein, near the armpit, and does not enter the central circulation (the large veins leading to the heart) [1.2.1].
This distinction is crucial. Because they are not central lines, midlines are not suitable for continuous vesicant therapy, total parenteral nutrition (TPN), or solutions with an osmolality greater than 900 mOsm/L [1.2.3, 1.6.1]. They are generally preferred for therapies expected to last between 5 and 14 days, bridging the gap between short-term PIVs and long-term central lines like PICCs [1.5.1, 1.2.4].
Comparison of IV Access Devices
| Feature | Peripheral IV (PIV) | Midline Catheter | PICC / Central Line |
|---|---|---|---|
| Length | < 3 inches | 3-8 inches (8-20 cm) [1.5.1] | > 8 inches (20+ cm) |
| Tip Location | Peripheral vein in hand/arm | Axillary vein (peripheral) [1.2.1] | Superior Vena Cava (central) [1.7.3] |
| Dwell Time | 3-5 days | Up to 30 days (often 5-14) [1.2.1] | Months to a year |
| Suitable Drugs | Non-irritating, isotonic | Medications suitable for peripheral infusion [1.5.2] | Vesicants, irritants, TPN, high osmolality solutions [1.6.1] |
| Cefepime Use | Short-term, intermittent | Acceptable with caution for intermittent use [1.4.2] | Preferred for long-term or continuous infusion |
Can Cefepime Be Administered Through a Midline?
The short answer is yes, but with careful consideration. Since midlines are essentially long peripheral catheters, the same general rules apply: only drugs and solutions safe for any peripheral catheter should be infused [1.5.2].
Guidelines suggest that medications with a pH outside the 5-9 range should be used with caution [1.2.3]. Cefepime's pH can be as low as 4, and it is classified as an irritant, which increases the risk of phlebitis [1.3.3, 1.4.1]. However, many institutional policies and clinical practices allow for the administration of cefepime through a midline, especially for intermittent therapy of a limited duration (<14 days) [1.4.2].
The decision often comes down to a risk-benefit analysis for the individual patient, considering factors like the quality of their vascular access, the expected duration of therapy, and the concentration of the medication.
Best Practices for Administration
To minimize complications when administering cefepime through a midline, clinicians should adhere to the following best practices:
- Verify Institutional Policy: Always confirm your facility's specific guidelines on administering irritant medications through midlines.
- Use a Large Vein: Midlines are placed in the larger veins of the upper arm, which provides better hemodilution compared to smaller veins used for PIVs [1.7.4].
- Ensure Proper Dilution: Infusing a well-diluted solution of cefepime can reduce its irritating effects.
- Administer Slowly: Administer the infusion over the recommended time, typically 30 minutes or longer for extended infusions [1.2.2]. Avoid rapid IV push administration which can increase adverse event risk [1.8.3].
- Use a 10 mL Syringe: Never flush a midline with a syringe smaller than 10 mL to avoid excessive pressure that could rupture the catheter [1.7.3].
- Assess the Site Regularly: Monitor the insertion site before, during, and after infusion for signs of phlebitis (pain, redness, swelling, palpable cord) or infiltration/extravasation (swelling, coolness, pain) [1.5.1].
- Educate the Patient: Instruct the patient to report any pain, discomfort, or swelling at the site immediately [1.7.3].
Potential Complications
The primary complication associated with administering an irritant like cefepime through a midline is chemical phlebitis, an inflammation of the vein's inner lining [1.5.1]. Signs include redness, warmth, pain, and a palpable venous cord. Phlebitis is a documented adverse reaction to cefepime [1.8.2, 1.8.5]. Other risks include infiltration (the leakage of non-vesicant fluid into surrounding tissue) and catheter-related thrombosis (blood clots), though the risk of thrombosis with midlines may be lower than with PICCs in some studies [1.5.1].
Conclusion
Administering cefepime through a midline catheter is a common and generally acceptable practice in many clinical settings, provided that proper precautions are taken. As an irritant with a pH that can be slightly acidic, the key to safe administration lies in following evidence-based best practices [1.4.1, 1.3.3]. This includes ensuring proper dilution, using a slow infusion rate, performing regular site assessments, and adhering to institutional protocols. While a midline is a robust form of peripheral access, it is not a central line, and its limitations must be respected to ensure patient safety and optimal therapeutic outcomes [1.6.1].
For more information on infusion standards, you can refer to the Infusion Nurses Society (INS) Standards of Practice.
