Summary of Key Points for OSCEs
Indications and Contraindications
| Indications | Contraindications |
| Wound closure | Patient refusal |
| Fixing drains in place, e.g. chest drains, drains sited intraoperatively | Foreign matter in the wound, including glass, dirt, etc. |
| Repair of deep structures, e.g. tendons | Infected wound |
| Large wound whose ends cannot be suitably apposed without significant tension |
There are some situations where alternative wound closure methods would be more appropriate. For example, glue may be used on facial wounds or for children; Steri-Strips may provide a useful and less painful alternative.
Certain wounds may need specialist referral (e.g. to a plastics centre), and simple closure methods are inappropriate.
Types of Suture
Choosing the appropriate suture material is important. Suture material can be broadly classified as absorbable or non-absorbable.
| Type of material | Absorbable | Non-absorbable |
| Properties | Dissolve | Remain in situ until removed |
| Examples | Monocryl Vicryl Polydiaxonone (PDS) | Nylon Silk Prolene |
| Removal required? | No | Yes, timing depends on site |
| Suitable sites | Lips, mouth, tongue, viscera | Limbs, face, neck, abdominal/chest wall |
Suture needles come in a variety of shapes, including circular, semi-circular, three-eighths of a circle, five-eighths of a circle, straight, compound curved, half curved, etc. You do not need a detailed knowledge of these differences for the exam, but it is likely that you will get a curved needle to use and be asked to demonstrate that you can close a wound without actually touching the needle with your hands, i.e. using only forceps and a needle holder.
Sutures also come in different sizes: the larger the number, the smaller the suture. Hence, a 5/0 suture is larger than a 6/0 suture. The following table provides some guidance, but there may be local protocols in your hospital or medical school.
| Site | Suture and size | Time to removal |
| Scalp | Non-absorbable 3/0 | 7 days |
| Face | Non-absorbable 5/0–6/0 | 4–5 days |
| Chest wall | Non-absorbable 3/0 | 10 days |
| Limbs and hands | Non-absorbable 4/0–5/0 | 10 days |
| Lips/tongue/mouth | Absorbable 6/0 | n/a |
Choice of Local Anaesthetic
Lidocaine is the first choice of local anaesthetic agent as it has a reasonably quick onset and relatively short duration of action. The alternative is bupivacaine (Marcaine), which has a longer onset of action but is more dangerous in terms of toxicity.
Some local anaesthetic preparations contain adrenaline (epinephrine). The aim of this is to cause local vasoconstriction, hence limiting blood flow to the area and resulting in a reduced absorption of the local anaesthetic. This prolongs the action of the local anaesthetic agent. However, when applying the solution to the extremities or to areas that do not have a notable collateral circulation, you must not use a solution containing adrenaline as vasoconstriction may cause necrosis of distal tissues.
The maximum safe dose of local anaesthetic depends on a patient’s body weight. For lidocaine it is 3 mg/kg, and with adrenaline it is 5 mg/kg as its absorption is less. For bupivacaine it is 2 mg/kg. One may give as much local anaesthetic as required as long as it does not exceed these maximum doses.
If a larger volume is required to cover a wider area, a greater volume of a more dilute concentration is sufficient to achieve the same effect. If no dilute preparations are available, dilute your local anaesthetic with saline to the desired volume.
Local anaesthetic does not work as effectively in infected tissue.
Suturing Technique
The following should be considered:
- Local anaesthetic infiltration, from around the perimeter of the wound inwards, including corners and angles
- Position of the suture needle in the needle holder
- Half and half suture technique
- Tying the suture knot
This station is written to demonstrate one method of suturing. There are, however, other techniques that, for example, do not start in the middle of the wound and that advocate tying the knot differently. There are still other methods that allow you to use your hands to handle the suture needle. It is important that you check with your own medical school syllabus or clinical skills centre what techniques they suggest and follow them, as this will be what you face in your exam.
Figure 67.1 One technique to suture a simple skin wound
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