Turn head to contralateral side, avoid excessive turning as it changes the relationship of the vein and artery and can collapse the vein.

If you experience difficulty in cannulating the vein or it keeps collapsing:

Turn head to contralateral side.

Place a rolled up towel or bag of fluids between the scapula to extend the spine.

It you have difficulty locating the vein, ask an assistant to pull caudally on the ipsilateral arm.

If you are unable to get beneath the clavicle consider starting more laterally and bending your needle upward slightly.

If arterial puncture occurs, withdraw the needle and apply firm pressure both above and below the clavicle.

If a chest drain is already in situ (e.g. following chest trauma) place the CVC on the same side.

The patient should be supine with a pillow under the buttocks to elevate the groin. The thigh should be abducted and externally rotated.

It can be difficult to feel the arterial pulsation especially in obese patients. Get an assistant to retract the abdomen if this is a problem and recheck the landmarks.

The spinal cord terminates at L1–2 in the adult, L3 in children.

Below this level the lumbar and sacral nerves form the cauda equina.

The meninges (dura, arachnoid and pia mater) surround the spinal cord from the foramen magnum to S2 level.

Dural cuffs extend laterally as far as intervertebral foraminae.

There is a potential space between the dura and arachnoid mater – the subdural space; inadvertent injection into this space is a recognized complication of spinal and epidural injections.

The epidural (extradural) space lies between the walls of the spinal canal and the spinal dural mater. It is a potential, low pressure space filled with fat, areolar tissue and the internal vertebral venous plexus.

The ligamentum flavum links the vertebral laminae and is at its thickest in the lumbar region.

Wide variety of elective and emergency surgery below the level of the umbilicus (T10).

Sitting or lateral position with spine flexed.

Line between iliac crests (Tuffier’s line) passes across L4 and is used to locate L3–4 space, which is most commonly used.

Midline and paramedian approaches can be used.

Paramedian – 1–2 cm lateral to upper border of spinous process, insert needle perpendicular to skin and advance to contact bone (lamina), then withdraw and re-angle 15 degrees medially and 30 degrees cephalad to pass over lamina and enter interlaminar space.

Sterilize skin using 0.5% chlorhexidine spray and allow it to dry.

Drape and use 1% lidocaine to skin if patient awake.

Insert introducer needle at 90 degrees to skin in midline.

Spinal needle passes through introducer into supraspinous and interspinous ligaments then the tougher ligamentum flavum and through the dura (see Figure 29.1).

If bone is contacted withdraw and redirect needle, cephalad in first instance.

Following dural puncture cerebrospinal fluid (CSF) should flow freely.

Bupivacaine 0.5% heavy or plain. Plain produces a less reliable block and approximately 0.5 ml more volume is required for a similar level block.

Ropivacaine not licenced for intrathecal use.

Opioids commonly added are diamorphine 0.25–0.5 mg or fentanyl 10–25 mcg.

Position of patient and comfort of operator are key to success, do not be tempted to rush or compromise.

Accurate identification of L3/4 space is difficult, 70% of clinicians are higher than they think.

If a second space is attempted go down as level of termination of the conus is variable.

Sitting position allows easier identification of the midline and gives higher CSF pressure so improves flow.

Lateral position allows possibility of sedation.

Anaesthesia in abdominal and lower limb surgery.

Acute pain relief post-operatively in thoracic, abdominal or lower limb surgery, labour, trauma and for miscellaneous reasons (e.g. pancreatitis, ischaemic pain).

Chronic pain states.

Position as for spinal.

Identify the appropriate vertebral space (use landmarks of Tuffier’s line indicating spinous process of L4 or tip of scapula is level with T7 and count spaces to correct level).

Midline/paramedian approaches can be used (as for spinal).

Prepare trolley (see Figure 29.2) and flush the catheter and filter with saline to ensure free passage.

Clean, drape and infiltrate 1% lidocaine as for spinal. You can use slightly more lidocaine and use the injecting needle to seek the space and infiltrate local into the interspinous ligaments.

Insert the Tuohy needle in the direction indicated, the higher the level the more cephalad the angle is likely to be. When resistance becomes more obvious remove the trocar.

Attach the loss of resistance syringe filled with saline (or air) and carefully advance into ligamentum flavum, constantly checking for loss of resistance as the needle is advanced through the ligament.

On loss of resistance immobilize the Tuohy and check no blood or CSF flows from the Tuohy needle.

Note the depth and insert the catheter generously.

Remove the Tuohy over the catheter and pull back to leave 4–5 cm in the space.

Check for absence of blood or CSF and look for a meniscal drop.

Fix the catheter to the skin with a sterile see-through dressing to allow site inspection.

Fix catheter well up back and over shoulder.

Opioids commonly added are diamorphine 2.5–5 mg or fentanyl 50–100 mcg.

Many factors affect spread of epidural solutions; therefore, an understanding of these allow manipulation of the block.

Drug mass is critical and more important than volume, for a given mass a larger volume will spread more.

Epidural space increases in volume in a caudal direction so larger volumes are required to achieve the same dermatomal cover the lower the epidural is sited.

Smaller volumes may be needed in age >40, pregnancy and morbid obesity.

Position can be used to manipulate the block, sitting will reduce upward spread.