Day Case Spinal Anaesthesia
Take home messages
- Spinal anaesthesia, when timed and dosed appropriately, is game-changing for day case surgery
- The two key agents to be aware of are 2-chloroprocaine and prilocaine
- The key is identifying the right patient, right procedure and timing it effectively
Hop onto the table
Imagine this - you slip in a cheeky spinal with a couple of millilitres of heavy prilocaine with the patient lying on their side and they lie there for 10 minutes, numbing everything down the right (and correct) side, but not the other, before they literally hop into theatre and onto the operating table. Four hours later, they're walking home.
You're not going to do this. Please don't try this.
Of course you're not going to let your patient try and ambulate immediately after injecting a spinal, but you can do all the rest - you can have their operative side numb and ready to go, leaving them awake and fully functional on the other side and able to walk home later that day.
This is the beauty of day case spinal anaesthesia.
The benefits of day case spinal anaesthesia
- Reduced postoperative nausea and vomiting
- Reduced postoperative delirium
- Reduced postoperative pain
- Avoids airway management and its associated risks
- Allows day case surgery in patients who would otherwise require inpatient admission (high BMI, OSA) with general anaesthesia
- Reduced opioid requirement
- Shorter hospital stay
- Earlier mobility
- Faster return to normal eating
- Some patients prefer to be awake and more in control during the procedure*
- Cheaper
*By having the opportunity to engage with the anaesthetic and surgical teams, ask questions and in some cases observe what the surgeon is doing, many patients find improved satisfaciton and psychological benefit from being awake.
The patient also doesn't have to be fully awake - sedation is still an option in patients for whom it is of an acceptable risk profile.
So what do we need?
We need the soon-to-be-sliced portion of the patient to be completely numb and motionless for at least the duration of the surgery, but ideally not a whole lot more.
We also want as little of the rest of the patient to be anaesthetised, including their airway and respiratory system.
For this we need the right patient, for the right operation and the right local anaesthetic.
We'll go in reverse order.
The right local anaesthetic
Whatever we're slipping into the intrathecal space needs to be as many of the following as possible:
- Rapid onset
- Short acting so the patient can function at home
- Predictable offset (so you're not having to convert to GA at the last minute)
- Minimal cardiovascular side effects
We used to use lidocaine for this, and it worked well, but it caused high rates of transient neurologic symptoms (TNS), and by high rates we mean like one in seven.
Hence it has been largely confined to the history books.
The two main players these days are 2-chloroprocaine and prilocaine.
The right operation
Clearly open heart surgery isn't going to be on the cards here, but many operations are:
- General procedures - hernias, haemorrhoids, perianal abscess, EUA
- Urological procedures - circumcision, meatoplasty, cystoscopy, stenting, TURP
- Gynaecological surgery - vulval surgery, vaginal repair
- Orthopaedics - arthroscopies, ACL repairs, Total knee and hip replacements
Clearly this depends massively on the surgeon and how quick they are - as a general rule the procedure should be taking less than 90 minutes.
The right patient
One of the key benefits of day case spinal anaesthesia is that it allows patients who would require inpatient admission after general anaesthesia to have their procedure done as a day case, such as:
- High BMI
- Obstructive sleep apnoea
- Chronic lung disease
Some patients with severe co-morbities, BMI >50 or inadequate support at home will not be suitable for day surgery under any circumstances, however as long as you feel the patient is going to be able to:
- mobilise as normal
- control their pain at home
- have someone supporting them for the next 24 hours
Then they can usually be at least considered for day case surgery, and spinal anaesthesia in the absence of any contraindications.
The day case duo
2-chloroprocaine
Available since 2017.
- 1% solution
- Ester local anaesthetic
- Dose 40-50mg (intermediate potency)
- Lasts around 40 minutes (very short acting duration of action)
- Suitable for knee arthroscopy and foot surgery
- Metabolised by pseudocholinesterase
Prilocaine
Available since 2010.
Usually provided as hyperbaric or 'heavy' formulation which kicks in much quicker than the 'plain' version.
- 2% solution
- Amide local anaesthetic
- Dose 40-50mg (intermediate potency)
- Lasts around 90 minutes (intermediate duration of action)
- Discharge home from four hours after injection
- Saddle block possible with 10mg
There is a theoretical risk of methaemoglobinaemia due to the 0-toluidine metabolite of prilocaine, (which gets examined disproportionately frequently), making prilocaine somewhat contraindicated in:
- sickle cell disease
- known methaemoglobinaemia
For context you'd have to give around 500mg to a normal adult to induce any sort of meaningful methaemoglobinaemia.
What about good ol' heavy marcain?
A lot of people have tried with mixed success to use bupivacaine and levobupivacaine for short day surgery procedures, largely because there wasn't much other choice.
The problem is its long duration of action.
To counteract this, anaesthetists have tried giving seriously small doses (less than 10mg) to shorten its effects, often resulting in an inadequate block and a conversion to general anaesthesia which completely unravelled the whole point of the spinal in the first place.
Should I use opioids?
The classic 300mcg of diamorphine or 20mcg of fentanyl to buff your spinal and make it kick in a little quicker seems to be going out of fashion, especially in orthopaedic day surgery.
If you peek around the gold-laced curtain to the world of private practice you'll notice an array of patients undergoing highly effective 'opioid-free' spinals with often fabulous (and expensive) results.
- Intrathecal fentanyl may let you use a slightly lower dose of anaesthetic, and it might make it kick in a little sooner
- But it also makes three quarters of patients uncomfortably itchy
- There's increased urinary retention
- They vomit more
- It also doesn't get the patient home any quicker
What to give and how much
Saddle block
- 10-20mg of 2% heavy prilocaine
- Keep the patient sat up for 5-10 minutes
Up to T10
- 40-50mg 1% 2-chloroprocaine if less than 40min surgical time
- 40-60mg 2% heavy prilocaine if 40-90 minutes surgical time
Remember that includes all the prepping and draping!
Above T10
- 60mg 2% heavy prilocaine
- Lie patient down with some head down tilt
This is probably only really suitable for superficial upper abdominal wall surgery such as an epigastric hernia repair.
Analgesia
Even if they don't feel any pain yet, just do it for the following reasons:
- The patient then has some analgesia on board when the spinal wears off
- The patient feels more comfortable taking a second dose at home, rather than starting fresh
- It prevents having to 'catch up' with the pain
- Psychologically the patient doesn't feel that they've just been left to deal with the pain on their own
Clearly you don't want to smash them with a whole load of opiates in recovery when they're completely comfortable, but loading them up with the basic oral analgesics and a small dose of something longer acting is only going to help.
The reality
It can work really, really well - when the correct infrastructure is in place.
Knowledge is knowing that 2-chloroprocaine will give you 40 minutes of surgical anaesthesia.
— Anaestheasier (@Anaestheasier21) May 1, 2024
Wisdom is knowing the surgeon will spend 25 of those minutes getting ready.
Much of the time it isn't the spinal anaesthesia itself that ends up being the issue, its the logistics and communication (surprise surprise) surrounding it that becomes the limiting factor in facilitating day case spinal anaesthesia.
What could go wrong?
Complications of day case spinal anaesthesia include:
- Failed block requiring conversion to GA
- Delayed mobility if longer acting agent use
- Urinary retention
- Dural puncture headache
- Bradycardia and hypotension
- Nerve injury (approx 1:150 000 according to NAP3)
Remember that peripheral nerve injury from positioning under general anaesthesia is vastly more common at 1:350.
Useful Tweets and Resources
Here's our full-size post on spinal anaesthesia
Anaestheasier ltd.
You might want to follow the British Association of Day Surgery on Twitter/X
🔐Delivering day‐case spinal anaesthesia.
— 𝘈𝘯𝘢𝘦𝘴𝘵𝘩𝘦𝘴𝘪𝘢 (@Anaes_Journal) November 22, 2019
"The barriers hampering the feasibility of day‐case spinal anaesthesia ‘in all centres’ were a reference to the non‐technical aspects of this procedure."
🔗https://t.co/qNRhLurYLT pic.twitter.com/ZY2Zo1wPRg
Here's an awesome overview of spinal anaesthesia from the WFSA
References and Further Reading
Dusanka Zaric
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