We report the case of a cervical abscess complicating a continuous interscalene block placed under ultrasound guidance and requiring surgical drainage. The case illustrates the importance of adhering to strict asepsis during all aspects of regional anesthesia including skin preparation and catheter insertion, infection control during ultrasound guidance, and the importance of postoperative monitoring.
The patient gave written consent to publish this case report.
A 65-year-old 62-kg ASA physical status II woman, with a medical history of penicillin allergy and Arnold neuralgia treated with amitriptyline, was admitted for elective shoulder rotator cuff repair.
In the preoperative area, a continuous interscalene nerve block was performed before induction of general anesthesia. The staff involved in catheter placement wore caps and facemasks. The puncture site was first identified by the anesthesiologist using the ultrasound probe without aseptic conditions and marked with a pen. All needle and material necessary for catheter placement were opened and prepared by the anesthesiologist in a sterile manner. After hand disinfection with chlorhexidine gluconate in alcohol (Hopirub®, Solution Hydro-Alcoolic, University Hospital of Genève, Genève, Switzerland), the anesthesiologist put on sterile gloves but no sterile gown. The skin was widely disinfected 3 times with alcoholic povidone iodine (Betaseptic®, Mundipharma Medical Company, Basel, Switzerland), and the site was draped with sterile covering. The block was performed with the aid of a nerve stimulator (Stimuplex®, Braun, Melsungen, Germany) connected to the stimulation needle (initial setting: 2 Hz, 0.1 ms, and 1 mA) and with ultrasonography (SonoSite®, Bothell, WA).
A linear high-frequency (6-13 MHz) ultrasound probe was covered by adapted single-use sterile and telescopic protection maintained with tape, and sterile gel (Bichsel®, Genève, Suisse) was used. The skin puncture site was infiltrated with 3 to 5 mL of 1% lidocaine. After visualization of the C5-C6-C7 roots in the interscalene space, an insulated 18-gauge short-beveled 50-mm needle (SilverStim®, Vygon, Ecouen, France) was inserted next to C7 under continuous out-of-plane ultrasound guidance and sentinel neurostimulation. A biceps muscle contraction was observed at 0.4 mA. The catheter was inserted through the needle and advanced (1 cm) beyond the needle tip. The needle was removed, and the catheter was fixed 6 cm to the skin and was stabilized with a crescent posterior pad (epidural crescent, Statlock®, Crawley, United Kingdom), secured with steri-strip (Steri-Strip TM, 3M Health Care, Neuss, Germany) and covered with a transparent adhesive dressing (Opsite Flexigrid®, Smith&Nephew, Paris, France). Ten milliliters of 0.5% ropivacaine and 10 mL of 1% lidocaine were injected in divided doses through the catheter and a micropore flat bacterial filter. The spread of the local anesthetic around the cervical roots was visualized using ultrasonography.
After catheter placement, and before incision, IV cefuroxime 1.5 g was administered. The surgical procedure was completed in 59 minutes without any problem.
Postoperative analgesia was started in the recovery room and continued in the ward. This patient was participating in a study evaluating different modes of administration of 0.2% ropivacaine: continuous infusion (4 mL/h) versus automated bolus (4 mL each hour), associated with patient-controlled analgesia 5 mL bolus with a lockout of 60 minutes. For that purpose, the catheter was connected to 2 GemStar pumps (pain controlled analgesia infusion pump; Advance Care Pharmacy, Escondido, CA), one providing the random and blinded continuous infusion versus automatic bolus and the other providing patient-controlled analgesia. Acute pain service nurses monitored the following once a day: pain level (visual analog scale), temperature, appearance of the puncture site and adhesive dressing, adverse effects related to regional block, and medication, and they were the only persons allowed to change the setting of the pumps or the dressing. Bags of 200 mL of 0.2% ropivacaine, prepared in a sterile manner by our pharmacy, were set in each pump and could be changed by the acute pain or the ward nurses when needed. The first 3 days (D1, D2, and D3) were uneventful, with no fever, clean dressing, and no sign of infection at the puncture site. The analgesic block was not fully effective, and the patient required several doses of opioids (morphine and then hydromorphone because of nausea).
The catheter was removed at D3, and its tip was not sent for bacterial culture. There were no local signs of infection, but her temperature did intermittently peak at 39°C. At D5, the patient complained of pain at the shoulder and neck at which time her temperature was 39°C. The puncture site was painful, indurated, appeared inflamed but without purulent discharge. (Fig. 1). There was no leukocytosis, and her C-reactive protein was 49 g/L. Figure 2 shows the ultrasound performed at D6 with a hypoechogenic image, poorly defined, measuring 3.1-cm long axis and 5-mm thick, consistent with right cervical fluid collection. Antibiotic treatment with moxifloxacin tablet 400 mg (1 × 24 hours) was started on D6. At D8, after clinical worsening, a computed tomography scan was performed showing multiple right laterocervical abscesses within the scalene and the sternocleidomastoid muscles and a subacromial collection in contact with the right subscapularis muscle (Fig. 3).
Surgical drainage was performed. Methicillin-sensitive Staphylococcus aureus was identified in the tissue specimens acquired during surgical incision and drainage. Moxifloxacin was replaced by co-trimoxazole tablet 160 mg per 12 hours for 10 days.
The infection resolved, and the patient was discharged on D15.
We report the case of a cervical abscess complicating a continuous interscalene block placed under ultrasound guidance, requiring surgical drainage. This is the first serious infection associated with a perineural catheter (PNC) in our institution in the last 15 years (400 catheters per year approximately).
S aureus was identified in our patient because it is often reported in infections and abscesses related to PNC, whereas S epidermidis is the microorganism most frequently colonizing the skin surface and catheters.
Several risk factors are thought to be associated with the rate of infections related to PNCs.1 These include the duration of continuous infusion (>48 hours), the absence of antibiotic prophylaxis, patient location in the intensive care unit, axillary or femoral catheter location, and frequent changing of dressings. Unproven risk factors are male gender, diabetes mellitus, absence of catheter tunneling, mobility of head and neck, and not using gloves, masks, hats, and gowns. The catheter was not tunneled and was removed after 3 days, as is our usual practice for patients without other risk factors. The dressing was changed once on the second postoperative day using aseptic technique by the acute pain clinic nurse.
Although there are no specific asepsis guidelines for the prevention of PNC-related infection, the current recommendations are based on the literature governing prevention of epidural or intravascular catheter-related infections. These recommendations2 emphasize the importance of asepsis during procedures and include hand washing with aqueous alcoholic solution and use of surgical cap and mask, sterile gloves, gowns, and drapes. Routine use of alcohol-based chlorhexidine is recommended for skin disinfection before all neuraxial and peripheral regional techniques due to its rapid and prolonged effect. The alcohol content of chlorhexidine facilitates penetration into hair follicles and the stratum corneum, with more potent bactericidal activity against S aureus.3
In our case, the anesthesiologist did not wear a gown during the nerve block and alcoholic povidone iodine (Betaseptic) rather than chlorhexidine was used for skin preparation. Also, there was no record of the time during which the skin preparation was allowed to dry before the interscalene block was started.
We do believe that correct measures to control infection related to ultrasound use in regional anesthesia were implemented: use of single-dose sterile gel, telescopic cover for the probe, and correct disinfection procedures with the ultrasound device between patients.4
Injected or infused local anesthetic solution is another potential contamination source during peripheral nerve blockade. In our hospital, ropivacaine and other local anesthetic solutions come from industry (ropivacaine, AstraZeneca®, Astra Zeneca UK, Luton, UK; bupivacaine, Synthetica®, Sintetica SA, Mendrisio, Switzerland).
We cannot exclude the possibility that the mode of administration of the local anesthetic solution had a role in the development of the infection. Intermittent bolus administration may create a pocket of liquid next to the nerve creating a milieu for bacterial proliferation. However, we were unable to find data in the literature describing infections related to this mode of administration.
Finally, we cannot exclude a defect in the adhesiveness of the transparent dressing (Opsite Flexigrid) between D1 and D3.
This case of abscess complicating an interscalene catheter emphasizes the importance of adhering to strict asepsis during puncture and catheter insertion and in all subsequent manipulations.
1. Capdevila X, Jaber S, Pesonen P, Borgeat A, Eledjam JJ. Acute neck cellulitis and mediastinitis complicating a continuous interscalene block. Anesth Analg. 2008;107:1419–21
2. American Society of Anesthesiologists Task Force on infectious complications associated with neuraxial techniques. . Practice advisory for the prevention, diagnosis, and management of infectious complications associated with neuraxial techniques: a report by the American Society of Anesthesiologists Task Force on infectious complications associated with neuraxial techniques. Anesthesiology. 2010;112:530–45
3. Hebl JR. The importance and implications of aseptic techniques during regional anesthesia. Reg Anesth Pain Med. 2006;31:311–23
4. Jochum D. Recommandations formalisées d’experts Hygiène relative à l’utilisation des ultrasons. Infection control in ultrasound guided regional anaesthesia. Ann Fr Anesth Reanim. 2012;31:219–21