Small-Volume Field Blocks
Comfortable injecting without distorting the face you are treating
Most injectors avoid blocks for one reason: they distort the face. You anaesthetise the lip, and now the lip you are about to build is swollen, blanched and asymmetric. So the profession compromises with topical cream and hope.
The compromise is unnecessary. A properly executed block uses 0.2 to 0.5 ml placed at a foramen — a volume small enough that it changes nothing you can see, and sufficient because you are anaesthetising a nerve trunk rather than infiltrating a territory.
The clinical payoff is not just comfort. A comfortable patient stays still, allows you to use a larger, safer cannula gauge, and lets you take the time that low-pressure injecting requires.
The patients who say they "don't need anaesthetic" are usually the ones who move at the exact moment you don't want them to. Comfort is not a courtesy. It's a safety measure.
PHARMACOLOGY AND SAFE MAXIMUMS
Ceilings you will never approach if you block properly.
| Agent | Onset | Duration | Maximum dose |
|---|---|---|---|
| Lidocaine 1–2% plain | 2–5 min | 30–60 min | 3 mg/kg |
| Lidocaine with adrenaline 1:80,000–1:200,000 | 2–5 min | 90–180 min | 7 mg/kg |
| Articaine 4% with adrenaline | 1–3 min | 60–120 min | 7 mg/kg |
| Bupivacaine 0.5% | 5–10 min | 4–8 hours | 2 mg/kg |
- A 1% solution contains 10 mg per ml. A 2% solution contains 20 mg per ml. Do the arithmetic before, not during.
- For a 70 kg adult, plain lidocaine 2% has a ceiling of roughly 10 ml. Field blocks use a fraction of that, which is why toxicity is essentially a non-issue if you stay small.
- Adrenaline is your friend for haemostasis in the lip and perioral region, but it blanches — wait, or accept that you cannot judge colour for twenty minutes.
- Buffering with sodium bicarbonate (1 part 8.4% to 9 parts lidocaine) reduces the sting substantially and speeds onset.
- Warming the solution to body temperature reduces pain almost as much as buffering.
- Know the signs of local anaesthetic systemic toxicity: perioral tingling, metallic taste, tinnitus, agitation, then seizure and cardiac arrhythmia. Lipid emulsion should be available where higher volumes are used.
THE SMALL-VOLUME PRINCIPLE
Anaesthetise the nerve, not the face you are about to shape.
0.2–0.5 ml at a foramen anaesthetises a territory. 2 ml infiltrated into that territory ruins it. Precision replaces volume. If you need more than half a millilitre at a nerve, your landmark is wrong.
- Use a 30G needle and a 1 ml syringe — a large syringe encourages large volumes.
- Inject slowly. Speed, not volume, causes most of the pain.
- Always aspirate before depositing at a foramen; these are vascular bundles, not isolated nerves.
- Wait a full five minutes. Injectors who conclude that blocks "do not work" usually waited ninety seconds.
- Test with a blunt probe before you start, not with the filler needle.
- Block one side, treat that side, then block the other. This preserves a comparator and halves the distortion at any moment.
INFRAORBITAL BLOCK
Mid-pupillary line, below the rim, slowly.
The workhorse of midface and upper lip work. Anaesthetises the lower eyelid, lateral nose, medial cheek, upper lip and the anterior superior teeth.
Landmark
- The infraorbital foramen sits approximately 5–10 mm below the infraorbital rim, on a vertical line dropped from the medial limbus of the pupil in forward gaze.
- That same vertical line also passes through the supraorbital notch and the mental foramen — one line, three foramina.
- Palpate it. In most patients you can feel a slight depression, and pressure reproduces a tingle in the upper lip.
Technique
- Place a finger on the infraorbital rim as a physical guard — this prevents any upward travel toward the orbit.
- Insert transcutaneously about 1 cm inferolateral to the palpated foramen and advance toward it at a shallow angle.
- Do not enter the foramen. Deposit adjacent to it. Intraforaminal injection risks nerve injury and prolonged paraesthesia.
- Aspirate. Deposit 0.3–0.5 ml slowly.
- Massage gently for thirty seconds to disperse and reduce the visible bleb.
MENTAL BLOCK
How to numb a lip without inflating it first.
Anaesthetises the lower lip, chin and the mucosa of the lower lip. Essential for comfortable lower lip work and for chin projection.
- Landmark: the mental foramen lies below the second premolar, roughly midway between the alveolar crest and the inferior mandibular border, on the same mid-pupillary vertical line. In edentulous patients it migrates superiorly, sometimes to the crest itself.
- Direction matters: the mental nerve exits posterosuperiorly. Approach from below and in front, angling upward and backward, so you deposit into rather than away from the neurovascular bundle's path.
- Volume: 0.3–0.5 ml adjacent to the foramen.
- Caution: the mental nerve is the most commonly injured nerve in perioral aesthetic practice. Never inject against resistance and never deposit if the patient reports an electric shock — withdraw 2 mm first.
SUPRAORBITAL AND SUPRATROCHLEAR BLOCKS
Small volumes near a very unforgiving vascular neighbourhood.
- Supraorbital: palpate the supraorbital notch on the mid-pupillary line at the superior orbital rim. Insert just lateral and inferior to it, aspirate, deposit 0.2–0.3 ml. Anaesthetises the forehead and the anterior scalp.
- Supratrochlear: approximately 1 cm medial to the supraorbital notch. Deposit 0.2 ml. Covers the glabella and medial forehead.
- Vascular caution: these are the vessels implicated in filler-induced blindness. Aspirate meticulously and use minimal pressure, and see when things go wrong.
- Expect periorbital oedema — warn the patient that a little upper-lid puffiness for a few hours is normal.
INTRAORAL VERSUS TRANSCUTANEOUS
One is more comfortable. The other is more controlled.
| Factor | Intraoral | Transcutaneous |
|---|---|---|
| Pain of the block itself | Lower — mucosa is more forgiving with topical prep | Higher |
| Visible distortion of the treatment area | Minimal — the bleb sits in the sulcus | Possible if volume is not controlled |
| Infection risk | Higher — oral flora; use chlorhexidine rinse first | Lower with proper skin prep |
| Best for | Lips, perioral, chin | Midface, forehead, temple |
For lip filler, the intraoral route through the buccal sulcus is generally superior: less distortion of the vermilion, less bruising in the treatment field, and a more comfortable needle passage. Rinse with chlorhexidine for thirty seconds first, and dry the mucosa before topical gel.
ENTRY-POINT BLEBS FOR CANNULA WORK
The port is the only genuinely painful moment. Treat that.
For most cannula work you do not need a nerve block at all. You need the entry point to be painless, because that is where the pain is.
- Raise a tiny intradermal bleb of 0.05–0.1 ml of lidocaine at the planned entry point with a 30G needle.
- Wait sixty seconds, then make the pilot hole with a needle one gauge larger than the cannula.
- Do not infiltrate along the intended cannula track — this obscures the plane, makes tissue feedback unreliable, and removes the resistance cues you depend on.
- Lidocaine-containing filler takes effect within the first pass. Deposit a small amount, pause, then continue — the second pass is nearly painless.
- Vibration, ice, and firm counter-pressure remain the most underrated analgesics in the room.
COMPLICATIONS OF THE BLOCK ITSELF
Bruising, blanching, and the block that outlasts the appointment.
- Haematoma — the infraorbital and mental regions bleed readily. Pressure for two minutes after every block.
- Nerve injury — usually transient paraesthesia from intraneural injection. Prevented by never injecting into a foramen and never injecting against resistance or through an electric-shock sensation.
- Intravascular injection — tinnitus, metallic taste, agitation. Stop, monitor, support.
- Vasovagal syncope — far more common than toxicity. Treat every patient supine or reclined.
- Allergy — true amide allergy is rare; most reported "allergy" is preservative sensitivity or a vasovagal event. Take an accurate history rather than accepting the label.
- Prolonged numbness — reassure, review, and document. Refer if not resolving by eight weeks.
Final Word
Comfort is not a courtesy. It is a technical enabler. The patient who is not braced against the needle lets you work slowly, in the right plane, with the right instrument, and that is the combination that produces both better results and fewer emergencies.
Half a millilitre in the right place buys you an hour of unhurried, unflinching, safer injecting.
Questions Injectors Actually Ask
Short answers. The long ones are above.
- How do you anaesthetise the lips without distorting them for filler?
- Use a small-volume mental or intraoral block placed away from the vermilion, typically well under a millilitre per side, so anaesthesia is achieved neurologically rather than by infiltrating the tissue you are about to shape.
- Where is the infraorbital nerve block placed?
- At the infraorbital foramen, roughly in the mid-pupillary line a short distance below the orbital rim, approached either intraorally through the buccal sulcus or transcutaneously, always aspirating and depositing slowly and away from the rim.
- What is the maximum safe dose of lidocaine for facial blocks?
- Conventional maximums are approximately 3 mg/kg for plain lidocaine and 7 mg/kg with adrenaline, but facial field blocks should sit far below these ceilings — a few tenths of a millilitre per site is usually sufficient.
- Do you need a block for cannula entry points?
- A tiny intradermal bleb at each entry point is enough. It anaesthetises the only genuinely painful moment of cannula work — the port — without adding volume to the treatment field.