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BACKGROUND

Intrathecal (IT) catheters, also known as continuous spinal anesthesia, are a reliable and effective neuraxial technique.1 Except in select cases, an intentional IT catheter is not recommended for labor analgesia due to the potential risks of high/total spinal anesthesia or devastating medication errors (Chapter 60, “High Spinal”).2 Here, the chapter focuses on the strategy and management of unintentional IT catheters in obstetric patients (Fig. 59-1).

FIGURE 59-1

Strategy and management of unintentional intrathecal catheter. IT, intrathecal; PCEA, patient-controlled epidural analgesia.

POTENTIAL INDICATIONS FOR IT CATHETER

Consider insert an IT catheter after an unintentional dural puncture with a large bore epidural needle in the following scenarios:

  • Difficult placement (multiple attempts, morbid obesity, marked scoliosis, history of back surgery potentially affecting the epidural space)

  • Inability to position

  • Near delivery

  • Non-reassuring fetal heart rate tracing

SAFETY PRECAUTIONS FOR IT CATHETERS

To ensure safety when working with an IT catheter, please pay attention to:

  • Label the IT catheter and inform the anesthesia team, the nurse, and the obstetrician.

  • Use the filter for the administration of medications.

  • Suggest using local anesthetic and opioid at low concentrations for IT catheter infusion.

  • Check sensory and motor blockage diligently and adjust the IT infusion rate accordingly.

IDENTIFICATION OF MISPLACED EPIDURAL CATHETERS

Failure to identify an IT catheter can lead to a dangerously high spinal level or total spinal. This can lead to hypotension and poor perfusion of the fetus or emergent intubation outside the operating room and possible maternal aspiration. The importance of careful aspiration of an epidural catheter and performing a test dose cannot be overemphasized (Chapter 40, “Test Dose”). When managing an epidural catheter, consider every bolus as a test dose.

On rare occasions, an epidural catheter can be freely aspirated after prolonged infusion. The differential for this can be elicited from a glucose test and a physical exam. If the glucose test is positive, this may be explained by the catheter being placed in Tarlov cyst. If the glucose test is negative, this may represent the local accumulation of epidural solution—further aspiration attempts are typically negative. In physical exam, the patient usually lacks dense motor block in low extremities.

The differential diagnosis of IT catheter is summarized in Table 59-1.

TABLE 59-1Characteristics of Intrathecal, Subdural, and Epidural Catheters

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