To the Editor:
Central venous pressure (CVP) measurement continues to be used as an indicator of resuscitation in polytrauma patients. In a patient with left lung contusion and hemopneumothorax requiring tube thoracostomy, a double-lumen (7F, 16 cm, Biosensors International, Singapore) central venous catheter (CVC) was inserted into the left subclavian vein with nonpulsatile free backflow in both lumens. It was secured with the tip 15 cm into the skin. The chest radiograph (CXR) confirmed satisfactory CVC tip positioning at the junction of the left brachiocephalic vein and superior vena cava (SVC). The proximal port (10 cm) was used for perioperative continuous CVP monitoring, and the distal port (15 cm) for fluid therapy. After approximately 20 hours of CVC insertion, it was also noticed during aspiration and flushing that backflow of venous blood ceased from the distal lumen despite a patent forward flow. The proximal port continued to have free backflow and a normal CVP waveform morphology (4 cm H2O). On transducing the distal port, a waveform resembling airway pressure (Fig. 1 on page 1248) (Video 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A76, showing airway pressure waveform during inspiration followed by normal CVP waveform during expiration) was seen during the inspiratory phase of ventilation (peak pressure 31 cm H2O). During expiration, a pulsatile tracing resembling CVP waveform morphology was seen with a pressure reading of 6 cm H2O, corresponding to the positive end-expiratory pressure applied by the ventilator. Repeat CXR showed the CVC tip within the cardiac silhouette with no apparent deviation in its course. There was no percutaneous migration of CVC because it was still firmly secured at the 15-cm mark. Postoperatively, 600 to 700 mL of isotonic saline had been infused from the distal lumen of the CVC at 50 mL · h−1. The overnight thoracostomy output was 400 mL of blood-stained fluid. The patient remained hemodynamically stable with no decrease in hemoglobin oxygen saturation. A possible diagnosis of postoperative extravascular-mediastinal migration of the CVC tip was made and the catheter removed. The patient's trachea was later successfully extubated after 12 hours, and the patient recovered uneventfully.
Extravascular CVC migration remains a rare but significant clinical problem with potentially lethal complications.1 Left-sided CVC migration is more frequent because of the angulation between the left brachiocephalic vein and the SVC, bringing the CVC tip close to the venous wall.2,3 Consequently, the CVC tip grazes the venous wall with head and neck movements and cardiorespiratory motion.2,4 The tip of CVC should be within the SVC and above the pericardial reflection to reduce the risk of vessel perforation.1 Even though CVC migration can occur within hours to days,5 the diagnosis is often delayed and is usually suspected after some cardiorespiratory complications.1–5
In our case, migration of the catheter tip was initially suspected by absence of blood aspiration from the distal lumen. The proximal lumen possibly remained intravascular, thus showing a good CVP waveform with free venous aspirate.
Careful interpretation of anteroposterior and lateral radiographs and computed tomographic scans can also assist in localizing CVC tip misplacements. Free aspiration of blood, an appropriate pressure trace, and CXR remain the routine methods of confirming CVC malposition. Contrast studies remain the “gold standard” for all assessments.6
Ashish Bangaari, MD
Department of Anaesthesiology
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