• The purpose of this guideline is to provide anaesthetic trainees (and consultants) with evidence based spinal anaesthetic dosing regimens for different surgical operations.

• Ideally, we should aim to utilize the lowest spinal dose possible, thereby minimizing adverse events and facilitating timely recovery. However, low doses may compromise surgical anaesthesia when operating times are longer than normal.

• The dosing regimens aim to strike a balance between these competing interests, hence providing a safe and reliable approach.

• As with all recommendations, clinical judgement should guide their application. Airway assessment, clinical state of patient, expected duration of surgery and surgeon experience will all impact the final dose.

• Keep in mind that bupivacaine is a long acting anaesthetic and even small doses can inhibit the ability to ambulate and void for a prolonged period [1].

• Combining fentanyl with bupivacaine prolongs surgical anaesthesia, prolongs post-operative analgesia, and does not increase the incidence of urinary retention [2].

• Addition of fentanyl facilitates a reduction in bupivacaine dose without any change in failure rate or duration of post-operative analgesia [3].

References

1. Kamphius. Recovery of storage and emptying functions  of the urinary bladder after spinal anesthesia with lidocaine and with bupivacaine in men. Anesthesiology 1998;88(2):310-6.

2. Popping et al. Opioids added to local anaesthetics for single-shot intrathecal anesthesia  in patients  undergoing minorsurgery: A meta-analysis of randomized trials. Pain 2012;153:784-793.

3. Popping et al. Combination of a reduced dose of an intrathecal local anaesthetic with a smalldose of an opioid: A meta-analysis of randomized  trials. Pain 2013;154:1383-1390.