How do I place an intrathecal catheter in an adult patient?

Intrathecal Catheter Placement in Adults

Intrathecal catheters should be advanced 3-5 cm into the subarachnoid space after dural puncture, with most practitioners inserting 2-4 cm to balance the risk of dislodgement against paraesthesia and nerve injury. 1, 2

Indications and Decision-Making

An intrathecal catheter may be inserted following inadvertent dural puncture during attempted epidural placement, with the decision based on weighing potential risks and benefits. 3 This approach has become increasingly popular over the past 30 years, particularly in obstetric anesthesia, as an alternative to re-siting an epidural at a different level. 3

Technical Insertion Steps

Catheter Advancement Depth

• Insert the catheter 3-5 cm into the subarachnoid space as recommended by the American Society of Anesthesiologists to optimize placement while minimizing complications. 1, 2
• Most published evidence supports advancing 2-4 cm into the subarachnoid space, though the ideal length is not definitively established. 1, 2
• **Shorter insertion depths (<2 cm) increase dislodgement risk**, while longer depths (>5 cm) increase the risk of paraesthesia and nerve root irritation. 1

Catheter Size Selection

• Avoid micro-catheters smaller than 24-gauge due to the risk of cauda equina syndrome, which led to FDA withdrawal of these devices in 1992. 2
• 17-gauge and 18-gauge epidural needles are most commonly used in obstetric practice for initial dural puncture. 2
• 19-gauge catheters are commonly employed in clinical practice, though some studies have examined 28-gauge catheters in obstetric populations without reports of permanent neurological deficits. 2

Aseptic Technique

• Maintain strict aseptic precautions during insertion since the dura has been breached and infection risk is present. 1
• Use sterile technique throughout the procedure, including sterile gloves, drapes, and skin preparation. 4
• All intrathecal medications must be preservative-free and administered through a filter connected to the catheter. 3

Critical Safety Measures

Labeling and Documentation

• Label the catheter clearly as "INTRATHECAL" immediately adjacent to the filter and on the front of any infusion pump to prevent catastrophic dosing errors. 3, 1
• This labeling is crucial because epidural doses given intrathecally can cause total spinal anesthesia, respiratory arrest, and death. 1
• Mark the catheter at skin level and document the insertion depth in the patient's record. 2

Communication Protocol

• Communicate catheter placement verbally to the patient, attending nurse, resident team, and all anaesthetists who may be involved in care. 3
• Place alerts on multidisciplinary handover boards and consider posting a notice on the patient's door. 3
• Document insertion clearly in written notes (electronic or paper) with integrated safety protocols. 3
• Highlight the intrathecal nature of the catheter at every staff handover to maintain vigilance for complications. 3

Catheter Position Verification

• Verify position by marking the catheter at skin level and securing it with appropriate fixation. 2
• Account for the dead space of the catheter and filter (typically 0.5-1 ml) when administering medications. 3
• Do not flush the catheter with saline after top-ups, as this may have unquantifiable effects on drug baricity and dosing. 3

Monitoring Requirements

Initial Monitoring

• Check maternal blood pressure every 5 minutes for 15 minutes following the first dose and after every subsequent bolus. 3
• Monitor non-invasive blood pressure, ECG, and oxygen saturations throughout the duration of intrathecal anesthesia. 3
• Assess sensory and motor block every hour during intrathecal catheter analgesia. 3

Ongoing Surveillance

• Continuously monitor fetal heart rate during intrathecal analgesia in obstetric patients. 3
• Check block height at least every 5 minutes until no further extension is observed during operative procedures. 3

Drug Administration Protocol

Personnel Restrictions

• Only anaesthetists should administer top-ups, connect, disconnect, or reconnect the catheter and tubing to minimize the risk of dosing errors. 3
• Any staff member may stop an infusion if safety concerns arise, but only anaesthetists should manipulate the system. 3

Dosing Considerations

• Use the same local anaesthetic solution throughout labour whether using intermittent boluses or continuous infusion. 3
• Limit each bolus to 2.5 mg bupivacaine (or equivalent) when topping up for caesarean delivery. 3
• Give top-ups incrementally with at least 3 minutes between each increment, assessing response before additional doses. 3
• Consider closed-loop infusion systems to minimize infection risk and drug errors from frequent disconnections. 3

Catheter Removal

• Remove intrathecal catheters at the earliest opportunity following delivery to reduce the risk of accidental overdose and infectious complications. 3
• Consider leaving the catheter in place for 24 hours postpartum to decrease the likelihood of post-dural puncture headache. 2
• Remove without extensive skin preparation, but culture the distal 2-3 cm if infection is suspected. 4

Infection Prevention

Risk Profile

• The rate of deep infections is approximately 1.4% (95% CI, 0.5-3.8), with superficial infections at 2.3% (95% CI, 0.8-6.1). 5
• Significant bacterial growth typically occurs only after more than 96 hours of catheter duration. 4
• Prophylactic antibiotics are not necessary if careful aseptic technique is maintained during insertion and care. 6

Infection Surveillance

• Assess daily for fever, worsening back pain, headache, erythema, tenderness, or drainage at the insertion site. 7
• Evaluate new radicular pain, motor weakness, or sensory changes promptly as they may indicate neural irritation. 7
• Watch for neck stiffness, photophobia, or confusion as red-flag symptoms of meningitis. 7

Common Pitfalls to Avoid

• Never insert the catheter more than 5 cm into the subarachnoid space, as this increases breakage risk during removal and paraesthesia risk. 1, 7
• Do not use micro-catheters (<24-gauge) due to cauda equina syndrome risk. 2
• Avoid inadequate labeling, which is the primary cause of catastrophic dosing errors. 1
• Do not allow non-anaesthetist staff to administer medications through the catheter. 3
• Never flush with saline after drug administration, as this affects drug distribution unpredictably. 3

Institutional Requirements

• Use intrathecal catheters only within institutions with established protocols for their management. 1
• Develop clear written guidelines covering labour analgesia protocols, operative delivery management, breakthrough pain algorithms, and complication management. 3
• These guidelines should highlight key risks, monitoring protocols, and safety measures specific to intrathecal catheter use. 3