Anesth Analg 1999;89:150
© 1999 International Anesthesia Research Society
REGIONAL ANESTHESIA AND PAIN MANAGEMENT
An Unusual Case of Subcutaneous Emphysema
Sylvia Y. Dolinski, MD,
Eric Meek, MD, and
Leanne Groban, MD
Department of Anesthesiology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
Address correspondence and reprint requests to Dr. Dolinski, Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1009. Address e-mail to dolinski{at}wfubmc.edu
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Introduction
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When subcutaneous air is found in the soft tissues of the neck, the process is usually pathologic (1). It can occur with barotrauma, in the presence of gas-forming organisms, or secondary to trauma to the subcutaneous tissues. Rarely, it occurs after epidural catheter placement (2–8). We describe a case in which the use of air during the loss-of-resistance technique for thoracic epidural catheter placement resulted in supraclavicular fossa emphysema.
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Case Report
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A 45-yr-old woman with interstitial infiltrates on chest roentgenogram presented for a right thoracoscopic lung biopsy. Her medical history was significant for a left lung resection. Her chest radiograph demonstrated bilateral opacities, right greater than left, with old surgical clips in the left lower lobe.
On the day of surgery, a left radial arterial catheter and a 16-gauge IV catheter were placed. In the seated position, the patient's upper back was prepared and draped sterilely for thoracic epidural placement. After the subcutaneous administration of 1% lidocaine at the T6-7 interspace, several midline attempts were made to locate the epidural space with an 18-gauge Hustead needle using the loss-of-resistance technique with an air-filled plastic syringe. A total of 20–30 mL of air were injected using the plastic syringe until good loss of resistance was detected. A 20-gauge Braun Perifix catheter (B. Braun Medical, Inc., Bethlehem, PA) was easily inserted, and no blood, cerebrospinal fluid, or air was aspirated before the injection of the 3-mL test dose of 1.5% lidocaine with 1:200,000 epinephrine. The thoracoscopy was uneventful, and the patient was left with a right chest tube. Her postoperative chest radiograph revealed decreased lung volumes bilaterally, residual bilateral interstitial infiltrates, and a right chest tube with a tiny apical pneumothorax. Old left lung surgical clips were noted. There was no evidence of pneumomediastinum. A large amount of subcutaneous emphysema was noted in the left supraclavicular soft tissues (Figure 1). Physical examination revealed crepitus over the left supraclavicular fossa and over the upper thoracic vertebrae. By the fourth postoperative day, the subcutaneous air had completely reabsorbed, and the patient was discharged from the hospital 2 days later.
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Figure 1. Left, Anteroposterior view of immediate postoperative chest radiograph. Note left supraclavicular air (see arrow). Right, Lateral view of postoperative chest radiograph. White arrows indicate thoracic subcutaneous air.
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Discussion
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Air in the neck occurs in three situations: 1) development from altered pressure gradients between alveoli and interstitial spaces, leading to alveolar rupture and subsequent tracking of air along the bronchovascular sheaths and pretracheal fascia; 2) presence of gas-forming microorganisms; and 3) direct insufflation from traumatic invasion of the skin barrier (1,9). In our patient, there was no evidence of a pneumomediastinum or subcutaneous emphysema originating from the right side. Ventilator-associated barotrauma is rather common (15%–40% of patients receiving mechanical ventilation), but subcutaneous neck emphysema unassociated with intrathoracic barotrauma is very uncommon (1). In addition, the patient had a chest tube decompressing the right chest after thoracic surgery. She had neither a retropharyngeal abscess, dental process, nor mediastinitis to cause the supraclavicular subcutaneous emphysema. Direct introduction of air into the neck soft tissues can occur from nose blowing, traumatic intubations, or placement of central lines. None of these common mechanisms for neck air explain the presence of subcutaneous air in our patient. However, our patient underwent an epidural placement with the loss-of-resistance technique with air and she had "crackles" in the skin from the site of the epidural to the left supraclavicular fossa.
Air (20–30 mL) was injected without obtaining the "true" loss of resistance normally experienced with penetration of the ligamentum flavum. When a substantial amount of air is injected during the loss-of-resistance technique, it is likely that some is injected subcutaneously, which can migrate cephalad. This pseudo-loss of resistance has been described as occurring with needle entry into the paraspinal muscles or into cysts that form when the interspinous ligament degenerates in the lumbar region (10). Whether such cysts also form in the thoracic region of the interspinous ligament is unknown.
Alternatively, the epidural space may have unknowingly been entered multiple times during the loss-of-resistance technique with air. This epidural air may escape via the thoracic intervertebral foramina into the deep fascial plane of the back before migrating to the cervical fascial planes and the subcutaneous tissues of the neck. It was first described by Laman and McLeskey (2) during placement of a lumbar labor epidural. There have been several subsequent reports of subcutaneous emphysema in association with epidural analgesia (3–8).
Air injected into the epidural space can impede even distribution of local anesthetic and result in a patchy block (11). Moreover, excessive amounts of air can migrate into the neck region, causing extrinsic neck compression and airway compromise. This could be problematic if nitrous oxide is used during combined general and regional anesthesia techniques. Despite these shortcomings, we prefer to use air to identify the epidural space in the thoracic region. We recommend using a 5-mL glass syringe rather than a 20-mL plastic syringe, thereby avoiding the temptation to inject large amounts of air. Using a saline-filled syringe does not always allow one to readily identify entrance into the subarachnoid space, which can be a buffer before one enters the spinal cord.
In summary, we described a case of epidural emphysema developed secondary to epidural catheter placement with subsequent migration of air into the supraclavicular fossa.
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References
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Accepted for publication April 2, 1999.
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Introduction
Case Report
