Practical procedures and patient investigation

Introduction

Surgery is the field of medicine that uses operative or instrumental techniques to treat or investigate pathologic conditions. Most surgical procedures are invasive in nature in that they involve physically cutting into a patient to repair or remove tissues or organs, to restore physiologic function or improve appearance. The key to surgical success is to do “the right operation to the right patient at the right time”. In this chapter, we will focus on the practical aspects of the common interventional procedures that all clinicians may be expected to perform in their daily work or in an emergency.

General principles of practical procedures

Consent

Before embarking on any surgical procedure or intervention, consideration must be given to the benefit to the patient versus the risks of the technique. Patients should be involved in the decisions about their treatment and supported to make these decisions through clear verbal communication and written information where appropriate. In patients who lack capacity, efforts should be made to consult with those who are close to the patient or advocating for them. Written consent should be obtained in all but the most minor procedures (e.g., venepuncture) and a record of the intervention documented in the clinical notes.

Preparation

When preparing to undertake a practical procedure, consider the following:

A.
Environment: Can it be done at the bedside/treatment room, or does it need to be performed in a clean operating theatre?
B.
Assistance: Do you need an assistant? This is advisable for all but the most basic procedures.
C.
Equipment: Ensure you have all the equipment you require within easy reach before you start. This will include any local anaesthesia, sutures and wound dressings that will be required.
D.
Safety: Be aware of the risk of iatrogenic injury to the patient, operator or assistant. These risks are minimised by following simple rules: needles should not be resheathed, and all disposable sharp instruments discarded by the operator should be placed into a sharps bin to minimise the risk of needle-stick injury. Soiled drapes and gowns should be checked for sharps and disposed of appropriately at the end of the procedure.

Aseptic technique: All invasive procedures carry a risk of infection. To minimise this risk, the skin should be cleansed with an antiseptic solution before all procedures, and sterile instruments should be used. For some procedures, such as central venous catheterisation, bladder catheterisation, insertion of chest drains and lumbar puncture, a full aseptic technique must be employed. Infection rates can be reduced through combining several interventions or “bundles”. Table 10.1 outlines the 2019 NICE guidance for reducing surgical site infection.

Table 10.1

Surgical site infection: Prevention and treatment

Adapted from NICE guidance 2019. www.nice.org.uk/guidance/ng125

Intervention	Comment
Preoperative showering	On day of surgery if possible
Nasal decolonisation and chlorhexidine body wash	If high risk of Staphylococcus aureus infection
Hair removal	On day of surgery with electric clippers, if required
Antibiotic prophylaxis	In all cases except clean surgery with no implant
Skin preparation	Alcohol-based chlorhexidine is first choice
Diathermy	Do not use for skin incision
Maintain patient homoeostasis	Temperature, oxygen, perfusion
Closure sutures	Antimicrobial triclosan sutures may reduce infection. Do not use clips in caesarean section.
Wound dressing	Apply at end of procedure
Postoperative shower	After 48 hours

Local anaesthetics

Most surgical procedures are performed under local anaesthetic (LA) to minimise patient pain and discomfort. LAs act through reversible inhibition of sodium channels, preventing axonal nerve conduction. There are various preparations of LAs that can be topically applied to areas such as the urethra, eye, nose, throat and bronchial tree to provide analgesia. In children, the topical application of LAs to the skin 1 hour prior to venepuncture is recommended. In minor surgical procedures, LAs are frequently administered by local infiltration. Care must be taken to avoid inadvertent intravascular injection as this can cause significant neurologic and cardiac dysfunction through central sodium channel blockade. The first sign of toxicity is often numbness or tingling of the tongue or around the mouth, followed by light-headedness and tinnitus. At higher blood concentrations, there is loss of consciousness, convulsions and apnoea, which may culminate in cardiovascular collapse. In this situation, full cardiopulmonary resuscitation should be initiated. The administration of an intravenous lipid emulsion (Intralipid) can counteract the toxic systemic effects of the LAs.

The most common LAs used for infiltration are lidocaine and bupivacaine. Lidocaine has a rapid onset of action with a good analgesic effect for up to 2 hours. Bupivacaine has a slower onset but a more prolonged analgesic window of up to 8 hours. It is important to note that LAs are available in various concentrations, and careful calculation is required prior to infiltration to ensure that LA levels do not exceed safe limits. For example, the maximum safe dose of lidocaine is 4 mg/kg. Solutions of LA mixed with a 1:200,000 concentration of adrenaline (epinephrine) are also available. Adrenaline acts as a vasoconstrictor, which minimises bleeding and reduces redistribution of the anaesthetic agent, increasing its efficacy and duration of action. The maximum dose of lidocaine increases to 7 mg/kg when adrenaline is added. LA agents with adrenaline should not be used in anatomic areas supplied by an end-artery, for example, the fingers and toes, penis, ear pinna and nose, because of the risk of vasoconstriction that can result in ischaemia and necrosis (gangrene).

Basic equipment

Minor surgery pack

In most practical procedures, you will need a minor surgery pack and an appropriate suture. Most surgery packs contain the following: plastic gallipot (for skin preparation/saline), 2× paper wound drapes, 5 small swabs, scissors, a pair of toothed and nontoothed forceps, a needle holder and an artery clip (mosquito). The pack may contain a scalpel blade handle/blade and sterile gloves, or these may come packaged separately.

Suture needles

Suture needles can be straight or curved. Straight and large curved needles are usually handheld, whereas smaller curved needles are designed for use with a needle holder. The thread is “swaged” inside the needle to eliminate drag. Needles can be cutting (usually reverse-cutting) or round-bodied. Round-bodied needles push tissue aside rather than cut through and are preferred when stitching blood vessels and bowel. Cutting needles are generally used to pass through tough tissues, e.g., skin. For abdominal wall fascial closure, blunt needles are available, which reduce the risk of needle-stick injuries.

Suture materials

Suture material can be nonabsorbable or fully absorbable. Nonabsorbable sutures can be classified into three groups:

1.
Natural braided sutures (e.g., silk, linen). These have good handling qualities and knot easily and securely. Their disadvantage is increased tissue reaction and suture line sepsis caused by the capillary action of the braided material drawing microorganisms into the suture track. Such materials also lose tensile strength quickly with time or when wet. These sutures are used less frequently.
2.
Synthetic braided materials, such as polyester (e.g., Ethibond). These cause less tissue reaction than natural materials. They have good handling qualities and knot easily and securely.
3.
Synthetic monofilament materials (e.g., nylon, polypropylene). These have less drag through the tissues and cause little tissue reaction. They are free from the capillary effect of braided sutures and cause less suture track sepsis. However, thicker grades handle less well than braided sutures because of increased “memory” (i.e., they retain the configuration in which they were packaged). Knots in monofilament sutures are less secure than those in braided or natural sutures, and most surgeons use a minimum of six throws when knotting monofilament sutures.

Absorbable sutures are generally made from synthetic materials. They cause relatively little tissue reaction, retain their tensile strength and are digested slowly through the action of tissue fluid enzymes. They can be multifilament, such as Vicryl (polyglactin), or monofilament, such as Monocryl (poliglecaprone) and PDS (polydioxonone). These synthetic sutures are commonly used for intraabdominal procedures and subcuticular wound closure. Interrupted sutures with each knot buried are used for small wounds, whereas in longer wounds a continuous subcuticular suture is employed.

Sutures come in various sizes, which determine their tensile strength and handing properties. The size describes the diameter of the suture, as defined by the United States Pharmacopeia (USP) system. The larger the number, the smaller the suture. For example, you would use a small 6/0 suture for a facial laceration compared with a 1/0 suture for closing the abdominal wall fascia.

Diathermy

Since 1926, surgeons have been using electrosurgical devices to cut and coagulate tissues to minimise blood loss. Diathermy or Electrosurgical Units (ESU) convert the normal low frequency, 60-Hz electric current that normally powers homes to a high radiofrequency (>500 Hz) alternating current (AC). When applied to tissues, this current causes a rapid rise in intracellular temperature, leading to vapourisation and protein coagulation. Fundamentally, diathermy requires the creation of an electric circuit between two ESU electrodes and the patient. Monopolar diathermy is where the current passes from the ESU to the tip of the diathermy instrument, through the patient to a separate diathermy electrode plate placed on the patient’s skin then back to the ESU. In bipolar diathermy, energy flows from the ESU to the tips of the diathermy forceps, which each contain an electrode. The circuit is completed by grasping tissue between the instrument tips. The advantage of monopolar diathermy is that it can be used easily over wide areas to mobilise various tissues and organs whilst providing rapid haemostasis, but it is associated with a higher incidence of iatrogenic thermal injury. Bipolar instruments apply highly focused energy to small areas of tissue, increasing the time required to achieve haemostasis but minimising the risk of thermal injury ( Fig. 10.1 ).

In addition to producing higher voltage RF output, ESUs can also produce current with different waveforms to give the surgeon more control over the energy’s effect on the tissues. In the “cutting” setting, a low voltage sine wave is produced that delivers energy continuously, causing tissue vapourisation. In the “coagulation” setting, the ESU produces an interrupted wave, with pulses of high voltage output (approximately 6% of the time) that promote coagulation. These waveforms can also be “blended” when required.

There are a wide range of monopolar instruments and bipolar devices adapted for use in open, laparoscopic and endoscopic procedures. More recently, energy devices utilising high frequency sound waves have also been developed, such as the CUSA device and Harmonic Scalpel ( Fig. 10.2 ).

Fig. 10.2, Modern surgical energy devices. The picture shows a standard monopolar diathermy pencil, and advanced bipolar device for open surgery use (Ligasure) and a laparoscopic USS haemostatic device (Harmonic Scalpel).

Common practical procedures

Closure of a skin wound

The way to achieve a good cosmetic scar is to ensure minimal handling of the skin tissue, with good skin edge approximation and the right amount of tension across the wound. If the sutures are tied too tightly, the skin may become ischaemic and the sutures can cut through. Too little tension and the wound will gape open. Interrupted sutures have an advantage over continuous sutures in that the removal of one or two appropriately sited stitches may allow adequate drainage if the wound becomes infected.

Preparation

You will require the following equipment: A minor surgery pack, skin preparation, a syringe and needle to inject LA, an appropriate suture and a wound dressing. Bipolar diathermy or Vicryl ties may be required for larger wounds.

Procedure

The area of skin to be closed should be widely exposed, with the patient and operating surgeon in a comfortable position. The area should be cleaned with either betadine or chlorhexidine skin preparation. LA should be infiltrated. All foreign material and necrotic tissues should be debrided. The wound should be irrigated copiously with saline if heavily contaminated/infected and consideration given to delayed primary closure or healing by secondary intention if appropriate. Careful haemostasis of bleeding subcutaneous vessels should be performed, either by clipping and tying the bleeding points with 2/0 Vicryl or using diathermy. If there is a deep layer of subcutaneous tissue, this can be closed using 2/0 Vicryl, reducing the space where tissue fluid can accumulate (dead space). If this space is large, then a suction drain can also be placed.

In most wounds, the skin is closed using the required number of single, interrupted sutures. Cutting needles should be used, and the size of suture is determined by the site of the wound. Table 10.2 shows the suture size and recommended time of suture removal for the common body areas. The sutures should be placed equidistant from one another, taking equal “bites” on either side of the wound. For abdominal wounds, 5-mm bites are taken on either side of the wound, whereas on the face, a 1- to 2-mm bite is preferred. The wound edge is picked up gently with toothed dissecting forceps, then the needle is introduced through the skin at an angle as close to vertical as possible and brought out on the other side at a similar angle. Similar principles apply when using a continuous suture. A subcuticular continuous suture is preferred by some surgeons that avoids the small pinpoint scars at the site of entry and exit of interrupted sutures, or the cross-hatching that results if sutures are tied too tightly or left in too long.

Table 10.2

Suture size and removal guide

Anatomic site	Suture size	Suture type	Removal time
Face	6/0	Monofilament, Nonabsorbable	3–5 days
Scalp	3/0	Monofilament, Nonabsorbable	7 days
Trunk	3/0	Monofilament, Absorbable/Nonabsorbable	7–10 days
Limbs	3/0, 4/0	Monofilament, Absorbable/Nonabsorbable	7–10 days
Hands/Feet	4/0, 5/0	Monofilament, Nonabsorbable	10–14 days

In some situations, such as pretibial lacerations where the skin is very thin, adhesive strips (Steristrips) can be used to approximate the skin edges. Other alternative methods to close the skin include skin staples, which are supplied in disposable cartridges for single patient use and are easily removed. Topical cyanoacrylate tissue adhesive glues are often used either alone or in combination with subcuticular sutures. They are most appropriate for small (<5 cm), noncontaminated, low-tension wounds.

Vascular procedures

The most common interventional procedures performed in patients are the sampling of peripheral venous/arterial blood and the establishment of venous access to allow the administration of fluid and medications. A good knowledge of normal venous anatomy is essential, particularly of the upper limb. This is displayed in Fig. 10.3 .

Fig. 10.3, The normal venous anatomy of the upper limb.

When considering the most appropriate type of venous access, you must first consider the indication for the access and the duration for which it is required. For example, a patient who requires long-term parenteral nutrition will need venous access that can last for many months as opposed to a patient who simply requires a few days of intravenous fluid, where a peripheral cannula will suffice. You must also assess each individual patient and note any previous issues with access, any past episodes of upper limb DVT or surgery that may affect your approach and rule out or correct any underlying coagulopathy. Except for simple peripheral venous cannulation, most other types of vascular access are usually performed by the anaesthetic, vascular or radiologic teams, who have been specifically trained in USS placement of central lines under aseptic conditions.

Types of venous access

Peripherally inserted cannulas are indicated for short-term use (<4 days). They are generally placed in the upper limb and come in various sizes or gauges depending on the flow rate required. A blue cannula (22G) is the smallest and has a flow rate of 36 mL/min. The largest is orange (14G), which can accommodate flow rates of 240 mL/min and should be used in major haemorrhage patients. Avoid repeated unsuccessful attempts, and consider USS-aided insertion if venous cannulation has failed.

A midline is an 8- to 12-cm peripheral catheter that is traditionally inserted into the basilic vein, with the tip just below the axilla. It is commonly used where IV access is required for several weeks, such as long-term antibiotics in cases of osteomyelitis. Peripherally inserted central catheters (PICC) are similar to midlines in that they are placed in the basilic vein, but they are 50- to 60-cm long, with the tip sitting in the cavo-atrial junction. They can be used for 12 months or longer if well cared for. Central lines are usually inserted into the internal jugular or subclavian veins when short-term access is required (<10 days). They are commonly used in the critically ill patient in intensive care for haemodynamic monitoring and the administration of inotropes. They can have single or multiple lumens, depending on the indication for their use.

In patients who need long-term central access, such as the home parenteral nutrition or chemotherapy patient, a tunnelled line is often placed. A central line is placed into the internal jugular or subclavian veins but is tunnelled under the chest wall skin. These lines have a palpable cuff, which causes a foreign body reaction under the skin, preventing inadvertent displacement. Occasionally, a tunnelled central line is connected to a totally implanted port buried in the chest wall. This is placed under general anaesthesia and can be accessed by inserting a needle through the skin directly into the port.

Complications of venous access

Infection is the main risk with all types of venous access. Aseptic no-touch techniques when inserting and using the lines can help reduce this. Regular inspection of the insertion site is mandatory, and the line dressings should be changed regularly. Other complications include inadvertent arterial puncture, pneumothorax, haemothorax, stroke, air embolism, loss of guidewire and line fracture. These procedures should only be undertaken by individuals who are fully trained to do so and are able to recognise and treat these rare but life-threatening complications.

Venepuncture

Preparation

Alcohol wipe, tourniquet, needle/tube vacuum collection system, blood specimen collection bottles, gauze pad and tape are required.

Each arm is inspected to choose the easiest venepuncture site. The antecubital fossa is the most convenient and most frequently used site as the median cubital vein, median vein of the forearm and the cephalic vein are all easily accessible ( Fig. 10.4 ). Care must be taken to avoid the brachial artery. Sampling from smaller veins on the forearm or the back of the hand may appear attractive, but these veins collapse easily on aspiration and adequate samples are difficult to obtain. Blood should not be taken from the arm if there is broken/infected skin, intravenous fluids are running (as may interfere with blood results) or if there is another reason not to do so (e.g., lymphoedema, dialysis fistula, deformity).

Fig. 10.4, Venesection at the antecubital fossa.

The patient should be in a comfortable position with a pillow placed under the arm.

Procedure

Hands are washed and gloved. A tourniquet is placed above the chosen venepuncture site. The skin is cleaned with an alcohol swab and allowed to dry completely. The tube vacuum system is held between thumb and the first three fingers, and the needle is unsheathed. Using the nondominant hand, the skin is pulled down below the vein to stabilise it, and the patient is warned that the needle is about to be inserted. The needle is gently pushed through the skin over the vein at a shallow angle of less than 30 degrees until the vein is entered. The blood vacuum collection tubes are pushed onto the internal needle, and each sample tube filled in turn. The tourniquet and needle are removed in turn, and pressure is applied over the area with a clean gauze pad to reduce haematoma formation. The sharp is disposed of immediately into a sharps bin.

In patients with very difficult access, a small “butterfly” needle and syringe can often be used successfully to obtain blood samples. In emergency situations, venous blood can be obtained from the femoral vein, lying medial to the femoral artery in the groin.

Arterial blood sampling

Preparation

Arterial blood sampling is undertaken to measure arterial P o ₂ , P co ₂ , [H ⁺ ] and standard [HCO ₃ ⁻ ]. The radial artery is most often used, followed by the brachial or femoral arteries. The sample can be obtained either through a catheter in the artery or by using a needle and syringe. The syringe is preheparinised to avoid problems with analyser maintenance.

An alcohol swab, the needle and syringe, a dressing to cover the puncture site and ice to transport the specimen if not immediately analysed are all required. This can be an uncomfortable procedure, thus prior LA injection is recommended.

Procedure

Ensure that the patient is comfortable and consent is obtained. The radial artery is located by performing an Allen test, ensuring collateral circulation to the hand. Hand hygiene is performed and gloves donned. The course of the artery is defined by palpating the pulse between the index and middle fingers held 2 cm apart. The skin is cleansed, and a small bleb of LA is injected at the puncture site. The needle, with its bevel upwards, is pushed through the skin at an angle of about 60 degrees and advanced into the artery. A flashback should be obtained, and the syringe should fill spontaneously. The needle is withdrawn, and firm pressure is applied over the puncture site for 3 minutes to avoid haematoma formation. The needle is removed from the syringe and any air bubbles are expelled before capping the syringe. The syringe is gently inverted several times to ensure mixing of the heparin. The sample is sent immediately for analysis. Where delay is anticipated, it should be transported in ice.

Peripheral venous cannulation

Preparation

A cannula, an alcohol wipe, a gauze swab, a normal saline flush, a tourniquet and a cannula dressing are required.

Procedure

Both operator and patient should be positioned comfortably. Both arms are examined to choose the best site for cannulation. Hands are washed and gloved. The tourniquet is applied above the intended cannulation site. The area is cleansed with the alcohol swab. The cannula is inserted through the skin into the vein at a shallow angle. Once a flashback of blood is seen, the needle is advanced 2 mm further into the vein and the outer tube pushed forward, withdrawing the needle at the same time. The cap is applied to the end of the cannula. The position is checked with the flush. If the patient experiences pain, there is resistance to the flush or extravasation of fluid is seen around the cannula, then the cannula is not in the correct place. The cannula dressing is applied.

Venous cut-down

Venous cut-down for fluid replacement is rarely required except in seriously hypovolaemic patients, usually following trauma, and should only be regarded as a temporary measure for resuscitation. The most common site is the long saphenous vein at the ankle ( Fig. 10.5 ) or at the saphenofemoral junction in the groin, the basilic vein in the antecubital fossa or the cephalic vein at the wrist.

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