Indications: Thoracic surgeries, upper abdominal surgeries
Patient Position: Sitting or lateral decubitus position
The spinous processes of T4 through T9 are sufficiently angulated to make the midline approach more difficult. A paramedian approach to the epidural space is preferred in this area of the thoracic spine. The needle (skin) insertion point is 1-1.5 cm lateral to the spinous process. Needle insertion above the spinous process is adjacent to the inferior vertebral body. For example, the spinous process of T7 lies opposite the vertebral body of T8. Use minimal medial angulation, otherwise, the needle may cross the midline, and you will encounter a false loss of resistance in the contralateral paravertebral gutter. Greater cephaloid angulation is needed than in the lumbar region. Paresthesia is extremely rare.
- Identify the desired interspace and mark a dot 1-2 cm lateral to the caudal border of the superior spinous process.
- Create a skin wheal with local anesthetic. Use 25 gauge needle and 1% lidocaine.
- Insert the tuohy needle and touch the pedicle of the vertebrae with needle tip (average depth of 4 cm in adult).
- Walk the tuohy needle off the lamina in a cephalad and medial direction.
- Usually 1 cm beyond the depth of pedicle, the ligamentum flavum is encountered. (average 4.5 cm beneath the skin)
- Detect loss of resistance with air or saline. Needle angle should be between 15 to 30 degrees from midline.
- Thread the catheter 3 cm into the epidural space.
- Administer 2 ml test dose of 1.5% lidocaine with epinephrine 1:200,000.
- If test dose is “negative,” then bolus with 3-5 ml of 0.0625% bupivicaine.
- Ask the patient to sit upright. Clean the skin. Prep with benzoin and apply StatLock or steristrips. Cover with transparent dressing and apply labels.
- Begin continuous infusion of 0.0625% bupivicaine with 10 mcg/ml hydromorphone at rate of 4-8 ml/hour. Add a patient-controlled dose of 2 ml every 20 minutes. Determine the 1-hour dose limit.
- Higher concentration or larger volumes may cause hypotension and bradycardia.
- If patient has a lower sensory level, the rate may need to be increased.
- If sensory level is adequate, but patient has pain, the concentration of local anesthetic may need to be increased.
- Beware of blockade of cardioaccelerator fibers above T4.