Chapter 2. Use of equipment and procedures

The sterile field 19

Local anaesthetics 22

Venepuncture and cannulation 25

Blood cultures 27

Injections and infusions 29

Arterial blood gas sampling 31

Arterial line insertion 32

Urinary catheterization 34

Lumbar puncture 37

Pleural aspiration 38

Chest drain insertion and management 40

Nasogastric tube insertion 44

PEG tube re-insertion 45

Ascitic tap and drain insertion 46

Joint aspiration and injection 48

Central line insertion 50

Temporary cardiac pacing 54

Defibrillation and electrical cardioversion 58

Wound closure and dressings 61

Suturing 63

ECG recording 65

Oxygen delivery 66

Nebulizers 67

Peak flow and spirometry 68

PROCEDURAL COMPETENCE

Competence is a core principle of modern medical education, particularly in relation to clinical procedures. It represents an ability to perform what is required to an expected standard. It is not a measure of excellence and it relates to a specific moment in time, rather than a permanent state.

Competence is not a pre-determined ‘end result’ imparted by training in any discipline. It is a measure of, or comparison against, a specific standard and therefore, must be assessed to be acquired. For procedural competence to be achieved, an individual will need to demonstrate that prerequisite knowledge about the procedure (anatomy, pathophysiology, method, risks, complications, etc.) has been acquired; that they can perform the procedure correctly and safely; and that they apply appropriate professional attitudes to the patient and other staff. Competence is individual for both the procedure and the doctor. The number of procedures that any one doctor needs to complete to achieve it may differ from that required by their colleagues.

Competence in medical procedures is specific to the environment within which it is acquired. Skills laboratory-acquired ‘competence’ is not applicable to the clinical setting. It is simply a measure that the doctor performed the practice session satisfactorily, and is ready to progress to supervised learning in the clinical setting. Clinical competency ‘at the bedside’ must be separately learned and assessed. No doctor should attempt a clinical procedure on a patient, on the basis of skills laboratory-acquired learning, without supervision by somebody who is clinically competent in that procedure.

The process of acquiring competence in any one procedure will usually involve learning theory about it; observing and practising in a ‘patient safe’ skills laboratory; observing a ‘real’ procedure; supervision of attempts (by a clinician competent in the procedure); personal reflection, further learning or observation; supervised assessment and either ‘sign-off’ of achievement of competency, or recommendations regarding specific learning targets before the next assessment (see also ‘Assessment’, p. 431).

Although competency is ‘signed off’, it is important to note that this is in regard to performance on one particular day. It does not mean that the doctor involved is safe to do that procedure for ever. Sustaining competence requires regular practice. It may also require periods of further assessment to validate retention of skill.

Doctors must always ask themselves, ahead of any procedure, whether they are competent to undertake it, in that setting. Formal, supervised and validated clinical competency is what is required. Equally, if, despite being ‘signed-off’, the situation you are facing appears more difficult or risky than one you would usually feel equipped to handle, or some time has passed since you last were assessed or undertook that procedure, or you simply wish to have someone with you, ask for experienced help.

THE STERILE FIELD

Any invasive or surgical procedure must be performed within a sterile field; this minimizes the risk of infection to the patient. This area should include all parts of the patient that will be touched during the procedure, any part of the operator that might touch the procedure site or the sterile equipment being used, and the place used to store any sterile equipment during the procedure. The creation and maintenance of a sterile field is an essential component of aseptic technique.

Preparing the trolley

• wash your hands

• clean the trolley with an antiseptic wipe

• check you have several pairs of the correct size of gloves and the equipment you will need for the procedure

• open the outer cover of the dressing pack and drop the inner pack onto the trolley

• touching only the corners of the pack, pull it open

• open all the other outer packs of things you will need and drop the sterile contents onto the dressing pack

• lastly, open the outer packs of your gloves, gown and towel and drop the inner packs, without touching them, onto the trolley in that order (such that the towel lies at the top).

Handwashing and scrubbing

Before washing or scrubbing in readiness for a procedure, check that you are wearing any other items you require (e.g. hat, plastic or lead apron, mask, visor). (For guidance on surgical scrubbing, see ‘Theatre’, p. 393.) Simple handwashing should be conducted as follows:

• remove all jewellery and turn on the ‘elbow-taps’; if the taps are pushed too far back to reach with your elbows, touch the part where they join the sink, not the ‘wings’

• wet your hands, apply soap and rub together for at least 15 s, ensuring you observe the six washing stages: palm to palm; backs of the hands; between the fingers; fingertips; thumbs and wrists; nails (against the palm of the hand)

• rinse off all of the soap from your hands, ideally passing your hands and arms under the water while keeping your fingertips above the level of your elbows

• close the taps using your elbows

• dry your hands with a sterile paper towel (from the gown pack).

Sterile and protective garments

Proper use prevents infective contamination of the patient and doctor and reduces damage to clothes.

Cleaning the skin

Equipment

For injections, cannulation or blood sampling, you will need an antiseptic wipe. For operations, you will need a special sponge-containing instrument, e.g. Rampley’s forceps. For procedures, you will need disposable forceps, gauze swabs and a bowl of cleaning solution. This can be an iodine-based preparation such as Betadine®, or a non-iodine preparation if the patient is allergic, e.g. 1% chlorhexidine. You should take care when using non-iodine preparations to ensure the whole area has been cleaned: it will be less easy to see patches that you have missed. Also note that you should not use alcohol-based preparations on the genitalia or mucous membranes.

For ward-based procedures, you might also want to consider placing a disposable absorbent pad under whatever part you are cleaning to protect the bed. Also, tape an open disposable bag onto the trolley handle or nearby, ready to collect your used swabs.

Method

For injections, cannulation or blood sampling

Ensure any obvious dirt is washed off with soap and water. Clean with an antiseptic wipe and allow to dry naturally.

For ward-based procedures

• ensuring sufficient patient privacy, expose the area to be cleaned

• if soiled, wash the area with soap and water; it is no longer thought advisable to shave any area – infection may develop in small cuts or abrasions

• wearing gloves, fold each swab into four and grip with the forceps

• dip the folded swab into the cleaning agent

• start at the centre of the area to be cleaned and, working in a circular motion outwards, clean towards the edge of the area that will be exposed during the procedure; clean about 5 cm beyond the area you intend to frame with drapes; never go back with the same swab towards the centre again

• without touching the swab or bag, drop your forceps into the bag

• take a fresh swab and forceps and repeat the process

• do this again a third time.

For theatre operations

This is much as per the above; however, you will usually have a specific instrument, e.g. Rampley’s forceps, to use and you will usually need to cover a larger area. Mark the edge of your ‘painting’ with one sponge dipped in cleaning agent. Then, with a second, ‘fill in’ the area, working from the incision site always outwards. Clean any creases/umbilicus last, or with a separate sponge only to that area.

Draping the field

The aim is to cover all of the area that you or your equipment might come into contact with during the procedure. No drape should touch the floor. A variety of drapes are available and your choice should depend on the area you need to work within during the procedure. Standard cloth or disposable paper drapes are deployed around the outside of the work area, working inwards with successive drapes until the edge of the cleaned area is covered entirely by 5 cm of drape. ‘Hernia’ towels have a central hole that can make it easier to mark off smaller work areas, and steridrapes have a central adhesive-edged hole that is applied to the skin immediately around the area of the procedure. ‘Incise’ drapes are applied in theatre across the whole operative field and some drapes are impregnated with antiseptic. Towel clips can be used (usually in theatre) to stop the drapes slipping.

Maintenance of the sterile field

It is important to consider the boundaries of the sterile field at all times during the procedure. This allows you minimize contamination and to deal appropriately with any contamination that does occur:

• place only sterile items within the sterile field

• do not allow the sterile parts of you to touch anything that is not sterile or allow any non-sterile part of you, e.g. lower gown or hat, to touch the field (in theatres it is not unusual for your hat to touch the sterile handle of the operating lamps; if it does, the handle will need to be changed)

• take particular care, when items are opened or dispensed onto the trolley or transferred to the patient, only to touch what is sterile and to keep it in the sterile field at all times (note that the edges of any pack holding a sterile item are not sterile)

• ensure other ‘non-sterile’ personnel do not reach across the sterile field or touch sterile items; likewise do not stretch over a non-sterile area

• avoid unnecessary procedure-related contamination, e.g. bleeding: if a sterile barrier (over operator or patient) has become wet, cut or torn, the area is no longer sterile

• immediately replace any contaminated items

• keep sterile items away from windows or doors.

LOCAL ANAESTHETICS

Local anaesthetic agents are complex drugs which have to be administered with care. You will need to use local anaesthetics when performing basic procedures, e.g. suturing, pleural aspiration. This section provides an introduction to local anaesthetic techniques and practice. It is not a substitute for practice in a skills laboratory environment or supervised clinical experience.

Pharmacology

Local anaesthetic (LA) drugs block conduction of nerve impulses at the level of the axonal membrane with effects on both sensory and motor neurones. Local anaesthetic techniques involve both the administration of the drug and the care of the patient to prevent possible adverse drug effects. Common local anaesthetics are shown in Table 2.1. Most clinically useful LA agents disrupt nerve impulses and act by blocking the cell membrane sodium channel.

**Table 2.1** Common local anaesthetics
Drug	Uses	Notes
Lidocaine	Local infiltration and regional	The most commonly used LA; onset in 5–10 min, duration 2–3 h with adrenaline; usually used in 1 or 2% solution max dose: without adrenaline 3–4 mg/kg (approx. 20 mL of 1% solution); with adrenaline 7 mg/kg (approx. 50 mL of 1% solution)
Bupivacaine	Nerve blocks or local infiltration	Long action (3–20 h, depending on area of application and concentration); must not be used for IV regional use
Prilocaine	Local and regional anaesthesia	High doses can cause methaemoglobinaemia; also available as topical cream mixed with lidocaine (Emla®), which is effective after about 1 h
Amethocaine	Topical preparation for venepuncture in children aged over 1 month	Not for use on inflamed, traumatized or highly vascular surfaces
Proxymetacaine	Topical ophthalmic anaesthesia

Speed of onset of action

The pKa of the drug or ‘dissociation constant’ is the pH at which a local analgesic drug is 50% ionized and 50% un-ionized. Lipoprotein cell membranes are penetrated by the un-ionized form only and local anaesthetics with a pKa closer to physiological pH tend to have a more rapid time of onset. The pH of the injected solution and the pH at the injection site also alter the balance of ionization and the onset of action. Smaller nerve fibres (pain and autonomic nerve fibres) are blocked earlier than larger ones, such as those for light touch and proprioception.

Duration of action

Systemic re-absorption from the tissue into the bloodstream is important, e.g. in highly vascular or inflamed sites. Also of relevance is the dosage and concentration of the drug, its lipid solubility and protein binding capacity.

Local anaesthetics are usually aminoamides, which are metabolized in the liver, or aminoesters, which are metabolized in the plasma by esterases. Aminoesters are more allergenic than aminoamides because of the metabolite, para-aminobenzoic acid (PABA). Sensitized patients may develop an allergic reaction unrelated to the anaesthetic itself.

Most LAs cause vasodilatation. The addition of a vasoconstrictor such as adrenaline (epinephrine) reduces local blood flow and prolongs its local effect by reducing drug absorption away from the site. Adrenaline must not be used along with local anaesthetics in digits or appendages as it can cause ischaemic necrosis. The total dose of adrenaline must not exceed 200 μg, or a concentration of 1 in 200 000 (5 μg/mL) if more than 50 mL is being used.

Using local anaesthetics

Preparation

Begin by obtaining informed consent. Position the patient for the procedure, prepare the sterile field, and select the appropriate equipment including LA, needles and syringes.

Once you, your field and the equipment are ready, check the drug name and expiry date on the vial of LA held by the assistant. Put a needle with a large bore (green or white) onto your syringe and draw up the drugs required from the vial. The vial is held upside down and you put your needle in at the tip and draw back on the syringe. If it is a fixed glass bottle with a bung rather than a glass tip that can be broken off, first fill your syringe with air, then insert the needle into the bung and inject some air into the bottle: that will allow the same amount of liquid to come back into your syringe without creating a vacuum.

Replace the needle with a small one for skin insertion and check you have any needles required for going deeper. Also check you have any other kit you need ready on the tray, e.g. for the pleural tap or suture.

Administration

Since LA drugs are used to avoid pain, it makes no sense to cause pain in giving the anaesthetic. Use as small a needle as possible, e.g. orange (24 gauge), and warm the vial of solution in your hand before drawing, as fluids closer to body temperature cause less pain when injected.

Consider your route

If you are preparing a track, e.g. for the insertion of a drain, you should be going in a straight line and looking for signs of fluid or air in your syringe. However, if you are trying to numb an area of skin, e.g. for suture, you should approach the area from a variety of angles making small repeated insertion, aspiration and injection moves around it. Nevertheless, try to numb the underlying tissue in several directions from one skin injection point rather than making several skin injections to cover the same area. Likewise if there is already a wound, inserting the needle from the cut edge of the skin, to allow injection of the adjacent subcutaneous tissue, will cause less pain than entering through the intact skin.

Hold the needle and plunger using your other hand as a ‘guard’; insert at a shallow angle (20–30°) and advance by no more than 1 cm at a time. As soon as you enter the skin, stop, use your ‘guard’ hand to brace against the skin and prevent movement forward, and aspirate with the hand holding the plunger. To avoid intravascular injection, look carefully for any sign of blood in the needle. If there is blood, do not inject but remove the needle (the blood in it will make it difficult for you to be sure you have not entered a vessel the next time), replace it and try again in a slightly different point or different direction.

If there is no blood, inject a small amount slowly (slower injections cause less pain), wait a few seconds then start to aspirate again as you advance another 0.5–1 cm. Again, if there is any blood in the needle remove your syringe and needle from the patient, and replace the needle before re-inserting it. Repeat this part of the process until you have covered the area to be numbed.

Bear in mind that local anaesthetic injection into subcutaneous tissue causes it to swell and will make it more difficult to suture: use small amounts spread over an area rather than large volumes in one location. Now allow time for the anaesthetic to work before you proceed with your procedure.

Toxicity

Toxicity relates to the dose of drug given and its uptake from the tissues into the circulation. In addition, pre-existing medical conditions may influence sensitivity to drugs or their delivery. Likewise, accidental intravascular injection may deliver a toxic dose.

Overdose can result in symptoms indicative of CNS and cardiovascular toxicity, often starting with tingling in the lips, ringing in the ears, dizziness, tachycardia, anxiety and excitement, and later leading to sedation, disorientation, restlessness, twitching, convulsions, hypotension, bradycardia, coma and cardiorespiratory arrest.

To avoid toxicity, check the drug and the dose you are using is safe for this procedure and this patient. Always check an up-to-date source of information, e.g. the BNF website, for drug doses, cautions and interactions. Remember to avoid adrenaline for procedures on extremities, e.g. fingers, nose.

Calculate the dose carefully. Remember a 1% solution is 10 mg/mL. Have a trained nurse or another medical colleague check your calculations, drug, strength and use-by date before injecting any drug. Do not use topical anaesthetic creams for broken or inflamed skin as absorption is increased. Do not inject anaesthetic agents into inflamed areas. Before any local anaesthetic is given, especially when large volumes are given or in the case of regional blocks, also insert an indwelling venous cannula and ensure resuscitation equipment is in the vicinity. Observe caution in the presence of heart block, low cardiac output, hepatic insufficiency, porphyria, myasthenia gravis or epilepsy.

Management in suspected toxicity

• stop the procedure

• check the airway is protected and give oxygen

• call a senior colleague if you are concerned about the patient

• check your IV access is still in place

• connect to cardiac, blood pressure and pulse oximetry monitors

• give diazepam if convulsions develop

• give atropine for any bradycardia

• give fluids and raise the end of the bed if hypotensive.

Nerve blocks

Peripheral nerve blocks

A wide variety of nerves are suitable for blockade by local anaesthetic, e.g. median, ulnar, radial, intercostals, maxillary, infraorbital. These require knowledge of anatomy. Lidocaine 1–2% is usually used because of its speed of onset but solutions containing adrenaline should not be used in blocks affecting extremities, e.g. fingers, toes. The most commonly used block in A&E is probably the digital block.

Digital nerve block

• two common digital nerves run along both sides of each finger near the bone and next to the digital arteries, one on the dorsum and one on the palmar aspect; they run closer to the skin than the arteries on both sides

• using a small needle and 1–2% lidocaine, raise a small weal of anaesthetic on the dorsum of the finger just lateral to the bone

• pointing the needle medially, inject 1 mL between the bone and the skin on the dorsal aspect

• advance near the edge of the bone until you can feel the tip of the needle under (but not through) the skin of the palmar/plantar aspect

• aspirate and inject 1 mL in this new position

• withdraw and repeat the procedure on the other side of the joint

• finally, connect the two wheals on the dorsum with 1 mL of solution

• allow about 15 min for the anaesthetic to take effect.

Epidural and spinal blocks

During your initial training, you are unlikely to need to administer these. However, you will need to check with your patient if there are any reasons not to use such an approach when it is being considered. Contraindications include hypotension, abnormal clotting, increased intracranial pressure, fixed cardiac output states, e.g. heart block, aortic stenosis.

You also need to be aware of potential complications, including hypotension, paralysis, hypothermia, shivering, higher rates of obstetric intervention, urinary retention, nausea and itch (if opiates injected). Less common side-effects include nerve palsies, leg pain, spinal headache (if dura punctured), epidural haematoma or infection, drowsiness and respiratory depression – IV injection (convulsions or collapse) and intrathecal injection causing total spinal paralysis.

VENEPUNCTURE AND CANNULATION

Indications

Venepuncture is indicated where blood samples are required. Cannulation is required for the administration of IV fluids, drugs or blood products.

Contraindications

Never take blood from, or attempt to cannulate, a vein where there is paralysis or local sepsis. Do not insert cannulae where there is evidence of lymphoedema or in an arm leading to where axillary lymph node surgery has been performed, e.g. for breast cancer.

Complications

Extravasation

Extravasation or ‘tissuing’ occurs when the vein wall is breached and the contents of the infusion leak into the surrounding tissues. It is suggested by pain or swelling around the cannula, either during infusion or after injection of a saline flush.

Infection

Cannulae that remain in situ for over 72 h are more likely to become infected. Therefore, they should be checked regularly for signs such as pain, swelling and redness and removed after a maximum of 72 h. If infection is suspected, the cannula should be removed and a swab of the area sent to the laboratory. Antibiotic therapy is not required unless there are signs of systemic infection.

Procedure

Preparation

Choose the appropriate needles or cannulae (see below). Where you are taking blood, ensure that you have the appropriate vials or Vacutainers®. In addition, you will need a tourniquet, gloves, cotton wool, a dressing, specimen labels and the relevant laboratory request forms. Take a sharps box to the bedside so that you can dispose of your equipment safely and immediately.

Choosing a vein

Before choosing a vein, inspect both hands and arms. Choose a vein that is palpable and refills when depressed. Avoid veins that have been used recently or feel hard and vessels overlying joints as these can be uncomfortable and are more likely to ‘tissue’.

In elderly patients and in those who have had chemotherapy, veins are often fragile and tissue easily; consider using a smaller cannula, a tourniquet that is not too tight and a reduced angle of insertion to reduce the risk of exiting the rear of the vessel; a ‘butterfly’ needle may also help (see below). Where patients are cold or peripherally shut down, veins are more difficult to access; consider encouraging vasodilatation by placing the limb in a basin of warm water.

Choosing needles or cannulae

There are many different sizes of needle and cannula. Green (18 gauge) is the standard needle size, but in elderly patients, children or those who have had chemotherapy, smaller gauges may be necessary. Larger cannulae (grey or white) are used in emergency situations when large volumes of fluids need to be infused. The tubing of ‘butterfly’ needles allows a much lower angle of vein entry than when a syringe is attached and can be useful where access is poor or veins are fragile.

Method

Phlebotomy

• check the identify of your patient

• in children, consider the application of a local anaesthetic cream, such as Emla®, 30 min beforehand

• wash hands and put on gloves

• choose a suitable vein and apply a tourniquet

• encourage venous filling: ask patient to clench and unclench their hand; allow arm to hang at patient’s side; tap vein lightly

• anchor vein with free hand applying manual traction of the skin 2–5 cm below the proposed insertion site

• with the bevel of the needle upwards, insert the needle into the vein and advance it a further 1–2 mm

• withdraw all necessary blood into the syringe(s) or allow the vacuum to withdraw blood into tube(s) from the vein; ensure that the bottles are filled in the correct order (see ‘Artefactual results’, p. 70)

• release the tourniquet

• remove the needle and do not re-sheath it; apply pressure with the cotton wool

• label all bottles and forms

• remember to phone the laboratories if you are sending urgent samples.

Cannulation

• identify and position your patient

• wash hands and put on gloves

• choose a suitable vein and apply tourniquet (see above)

• clean the skin over the cannulation site; this is good practice despite limited evidence that it reduces subsequent infection

• anchor vein (as above)

• insert the cannula into the vein at an angle of 25–30°; fragile veins may require a lower angle of insertion

• once you get a flash-back, lower the angle of the cannula to almost skin level

• advance the cannula a few millimetres into the vein, holding it at the wings or protection cap

• withdraw the needle slightly

• hold the flash-back chamber, immobilizing the needle, and advance the cannula forward off the needle into the vein in a single smooth movement

• release the tourniquet

• apply pressure over the vein distal to the cannula tip and remove the needle

• blood samples may be taken at this point if required: be aware that haemolysis is more likely when using small cannulae

• close the cannula with a Luer-Lok injection cap/interlink

• dispose of sharps appropriately

• secure the cannula in position with appropriate dressing

• flush the cannula with saline and check for any signs of extravasation (seep. 26).

BLOOD CULTURES

In any patient with suspected bacteraemia or fungaemia, samples for blood culture should be taken, in addition to appropriate site-specific samples. This allows the prescription of targeted antibiotic therapy and modification of risk factors to prevent future infection. Correct sampling technique is essential as contamination with skin commensals leads to false positive results and may result in unnecessary antibiotic treatment. It involves inoculation into two separate culture bottles, one aerobic and the other anaerobic.

Indications

Features suggestive of possible septicaemia:

• core temperature out of the normal range

• significant focal signs of infection

• abnormal heart rate, blood pressure or respiratory rate

• chills or rigors

• raised or unusually low WBC

• new or worsening confusion: may be the only sign in the elderly or very young.

Contraindications

There are no specific contraindications to taking a sample for blood culture.

Complications

Complications are those related to venepuncture; see p. 26).

Procedure

Timing and number of samples

The collection of multiple sets of blood cultures, ideally from different sites, increases diagnostic sensitivity and is required in cases of suspected endocarditis or pyrexia of unknown origin. However, there is no evidence that sampling during spikes of fever significantly improves sensitivity.

Sampling sites

Blood cultures should be collected from fresh puncture sites rather than existing cannulae or central venous lines. Avoid femoral punctures, since there is a high risk of skin contamination. If multiple cultures are required, sample from at least two different sites, at least 30 min apart, e.g. right antecubital fossa then left antecubital fossa before returning to the right antecubital fossa. If a line infection is suspected, cultures should be sent from both the line and a peripheral site; sampling should be performed from the peripheral site first to minimize contamination risk.

Preparation

Explain the procedure to the patient, and obtain verbal consent. You will need cleaning solution, e.g. 2% chlorhexidine or 70% isopropyl alcohol-impregnated swabs, 2 pairs of examination gloves and a tourniquet. You will also need 3 green needles and a 10 or 20 mL syringe (10 mL is the minimum volume suitable for culture) or a Vacutainer blood culture set.

Method

• put the tourniquet on and identify the target vein

• wash your hands and put on a set of gloves

• clean the skin over the target vein (see p. 21); allow to dry

• remove the plastic caps covering the bottles

• clean the surface of the rubber seals with a fresh cleaning swab; allow them to dry.

Sampling

• remove and discard the first set of gloves, wash your hands again and put on a fresh pair

• being careful not to touch the overlying skin, advance the needle into the target vein

• if a Vacutainer system is being used, load each culture bottle into the Vacutainer shield, onto the covered proximal end of the Vacutainer needle

• if a needle and syringe is being used, withdraw at least 10 mL of blood (ideally 20 mL) into the syringe and inoculate each culture bottle (anaerobic first) with 5–10 mL of blood; there is no need to change the needle between sampling and inoculation

• do not remove the barcode strips on the culture bottles

• record the procedure in the patient’s notes, including the date and time

• complete an electronic or paper microbiology request, including patient details, date, time, site sampled and any antibiotic therapy

• arrange for the samples to taken immediately to the microbiology lab; if this is not possible they should be stored in an incubator set at body temperature until analysis.

INJECTIONS AND INFUSIONS

Indications

A variety of drug delivery options are available and their use is dependent on the drug, the reason for delivery, the presence or absence of IV access and the condition of the patient.

Intravenous

There is a rapid onset of action and the entire dose is bioavailable since it does not require absorption and also bypasses first-pass metabolism. A lower dose can often be administered IV rather than orally. Drugs may be administered as a bolus, an infusion or continuously. The route is commonly used for antibiotics, unfractionated heparin, cytotoxic agents and vasoactive drugs.

Intramuscular

Like IV administration, IM drugs avoid first-pass metabolism but absorption using this route is variable and depends on the muscle and blood supply to it. Intramuscular injections are commonly used for administration of analgesics, antiemetics and antibiotics where parenteral administration is required but where there is no intravenous access or where staff are unable to give medication intravenously, e.g. psychiatry or surgical wards. The volume of an IM drug dose should not exceed 5 mL.

Subcutaneous or intradermal

The subcutaneous route is used to deliver 0.5–2 mL of drug. Absorption is slower than for IM injections, but similarly dependent on local blood flow. It is commonly used for insulin therapy or LMWH administration and also for the administration of local anaesthesia.

Intradermal injection (<0.1 mL) is rarely used in hospital medical practice, but indications include vaccination, e.g. BCG, or allergen testing.

Contraindications

Intramuscular (IM), subcutaneous (SC) and intradermal (ID) routes should be used with caution in patients with bleeding diathesis or on warfarin. Care should be also taken only to administer drugs via these routes where tissue deposition of the drug will not cause necrosis.

Complications

In general, complications may result from infection, needle-stick injury and those that relate to the drug injected or the diluent. With doses intended for IM, SC and ID injection, care must be taken not to inject the drug IV. Complications that result from IV injections include extravasation, with resultant tissue necrosis and air-embolus.

Procedure

In all cases, you are responsible for injecting the correct drug into the correct patient and it is good practice to draw up the medication yourself. Always check that the route of administration is appropriate for the drug and dose. Where the drug is being given as an infusion, check that the rate is permissible.

In all cases, explain the procedure to the patient, gain verbal consent and following the injection, ensure that you document that the medication has been given on the cardex.

Preparation

Drawing up medication

• check the name of the medication, the dose and the expiry date

• use a large white needle to draw up drugs (it is quicker)

• dry powder medication: clean the rubber stopper on the top of the medication vial with an alcohol-impregnated wipe and allow it to dry; inject a small amount of (previously checked) diluent into the vial (1.5–2 mL); mix thoroughly by agitating the vial until all the powder has dissolved

• liquid medication: open the ampoule of medication; glass vials have a dot at the point where your thumb should be; take care not to touch the top of the ampoule with your fingers

• carefully insert the needle into the top of the vial/ampoule, taking care not to let the needle scrape the bottom

• invert the ampoule and draw up the liquid into the syringe: if the vial has a rubber bung, you may need to inject some air into the vial to allow fluid to be removed

• once the drug has been drawn up, hold the syringe upright to encourage any air to rise to the top; gentle tap the barrel of the syringe; expel the air until droplets of fluid are seen at the top of the needle

• remove the needle and dispose of it in the sharps bin

• for IM, SC, ID injections, fit a fresh new narrow-gauge needle.

Making up infusions

Infusions require a drug, in powder or liquid form, to be added to a diluent which is then infused at a predetermined rate. Common diluents include 0.9% sodium chloride (normal saline) and 5% dextrose; note that some medications must be used in conjunction with a specific diluent.

• select a bag of the appropriate diluent and volume, e.g. 50, 100, 250 or 500 mL; open it and check the expiry date

• draw up the drug (as above)

• clean the bung on the end of the diluent bag with an alcohol-impregnated wipe and allow it to dry

• hold the diluent bag with the bung at the bottom and insert the needle on the syringe with the drug into it; be careful that you do not pierce the outer skin of the bag

• once the drug has been injected into the bag of diluent, agitate the bag to allow mixing

• write a label which will include patient’s name and details, drug name and dose, name and volume of diluent, time of addition and expiry, as well as your signature and that of a witness

• appropriately dispose of any sharps (including vials).

Method

For all injections:

• wash your hands and put on a pair of gloves

• check that the patient is not allergic to the medication and obtain their consent to the injection

• ensuring patient privacy, clean the injection area with an alcohol wipe.

Intravenous injections

In addition to the drug, you will also need 10 mL 0.9% sodium chloride as a flush. Do not use the injection ports attached to giving sets. If a central line is being used, use aseptic technique (see ‘Sterile field’, p. 19) to clean the injection port before and after injection.

• inject 1–2 mL of flush to ensure cannula patency

• inject the drug at the prescribed rate through the injection port

• inject the remaining flush; if multiple doses of different drugs are being given, a flush should be given between each drug to prevent mixing in the cannula.

Intramuscular injections

Common sites include the outer aspect of the upper arm, outer aspect of the middle third of the thigh and the upper outer quadrant of the buttock:

• stretch the skin with your non-dominant hand

• hold the needle like a dart and warn the patient; insert the needle quickly and smoothly at 90° to the skin, leaving about 1 cm of the needle showing (this will be dependent on the size of the patient)

• with the ulnar border of your hand against the skin, stabilize the syringe

• aspirate to ensure you are not in a vessel; if there is no blood, inject slowly

• once the drug has been injected, withdraw the needle quickly and gently and apply pressure to the area until bleeding stops.

Subcutaneous injection

Common sites for injection include the upper outer aspect of the arms, the anterior aspect of the thighs and the anterior abdominal region:

• pinch the skin using your non-dominant hand

• insert the needle into the subcutaneous tissue; angle of 45° for normal hypodermic needles or 80–90° for ultra-fine needles, e.g. pre-filled insulin syringes

• aspirate to confirm you have not entered a vessel; inject the drug and, on completion, pause briefly to reduce backtracking

• remove the needle and use a tissue to wipe away any blood; do not massage the site.

Intradermal injection

Usually performed on the volar aspect of the forearm or outer aspect of the upper arm:

• pinch the skin using your non-dominant hand

• insert the needle at 10–15°

• inject the drug (usually <0.1 mL), which will raise a small weal

• remove the needle, as above; do not massage the site.

ARTERIAL BLOOD GAS SAMPLING

Indications

Arterial blood gas (ABG) sampling is commonly required in acutely ill patients who may be hypoxic or acidotic. It is also required in the assessment of chronic respiratory disease and necessary for the prescription of long-term oxygen therapy.

Contraindications

Contraindications include those that pertain to venepuncture, in particular localized infection. It is also contraindicated where the pulse is not palpable or in patients with no collateral flow (as indicated by a negative Allen’s test, see below).

Complications

Complications include localized bruising, bleeding and, more rarely, infection. There is a small risk of ischaemia, secondary to damage to the artery following puncture (see below).

Procedure

Preparation

Explain the procedure to the patient and gain verbal consent. You will need an ABG syringe, cleaning agent and swab, cotton wool ball, sticking plaster, a pair of gloves, a specimen label and a biochemistry form. This should be filled out including a note of the concentration of inspired oxygen and ventilator settings (IPAP and EPAP), if appropriate.

Collateral blood supply

ABGs are most commonly taken from the radial artery, although they may be obtained from the brachial or femoral artery. If a radial artery puncture is being performed, assess collateral blood supply using Allen’s test and document the result in the notes.

Allen’s test

This assesses the integrity of the collateral ulnar circulation to the hand, and should be performed prior to performing a radial artery puncture or cannulation.

• ask the patient to elevate their hand and make a fist for 20 s

• occlude both the radial and ulnar arteries

• ask the patient to open their hand – it should blanche white

• release compression over the ulnar artery.

If redness/flushing of hand (thenar eminence first) occurs in under 10 s, the ulnar circulation is said to be satisfactory. If the hand fails to flush/return to normal colour, the ulnar circulation may be compromised and a radial artery puncture should not be performed.

Method

• wash hands and put on gloves

• check the expiry date of the syringe, remove syringe guard, fit needle and remove sheath. Note: some ABG syringes are pre-filled with heparin, which should be expelled before the puncture

• place a folded pillow underneath the outstretched wrist such that the arm is supported and the hand can be bent back over the edge; if the patient is drowsy or has difficulty lying still, ask for help to hold the arm

• clean the site with a Medi-Swab™ and allow to dry

• palpate the pulse, placing the index and middle fingers of your non-dominant hand parallel to the vessel; move laterally across the wrist until you are confident of the vessel’s maximal impulse; move the fingers back until the fingernails are in line with the vessel and use them as a guide for the insertion point

• insert needle at 45–90°, until blood enters the syringe; in most cases, arterial pressure will be great enough to fill the syringe without additional suction

• draw at least 1 mL of arterial blood

• withdraw the needle and ask your assistant to apply firm pressure with the cotton wool ball directly to the site for at least 5 min and then apply a sticking plaster (if not allergic); where a brachial artery is used, the arm should not be bent at the elbow, but kept straight, raised and pressed

• do not re-sheath the needle: detach it and dispose in the sharps bin

• apply the clear/blue filter to the syringe, hold it upright and expel air; roll gently to mix, label, phone the lab and send the sample

• for interpretation of results, see ‘Arterial blood gases’, p. 71.

ARTERIAL LINE INSERTION

Indications

Arterial lines allow invasive and continuous monitoring of systolic, diastolic and mean blood pressure (MBP) via a transducer connection. This information is helpful in the management of patients with shock and is particularly useful in tailoring inotropic support to optimize tissue perfusion.

Arterial lines can also be used continuously to monitor or obtain repeated samples for arterial blood gas analysis, e.g. ventilated patients and those with respiratory failure. Patients who require arterial lines should be cared for in an environment where both they and the arterial line can be safely and adequately monitored, e.g. HDU/ITU.

Contraindications

Contraindications to arterial line insertion are the same as for arterial blood sampling (see ‘Arterial blood sampling’, p. 32). Deranged clotting or a bleeding diathesis will increase the risk of localized bleeding or haematoma.

Complications

Patients are at risk of haematoma, bleeding, infection and damage to the artery.

Procedure

Preparation

Explain the procedure and obtain consent. You will need the following equipment and you should assemble the line, transducer and pressure bag and check that the monitor is working before approaching the patient:

• sterile dressing pack, sterile gloves and gown, protective eyewear

• cleaning solution, e.g. iodine solution or other if the patient has an allergy

• suture pack/equipment

• an arterial line, see below

• transducer cable, pressure bag and appropriate fluids, e.g. 500/1000 mL bag of saline

• local anaesthetic (lidocaine 1–2%)

• 5 mL syringe, 23 or 25 gauge needle

• 2/0 or 3/0 silk suture

• sharps bin, disposal bag.

Arterial lines

There are several different types of arterial line, but they essentially fall into two groups:

• line over wire: the artery is located with a needle, down which a wire is inserted; after removal of the seeker needle, the arterial line is inserted over the guidewire

• line over needle: the arterial line is inserted over a needle, much like a cannula is inserted into a vein; do not use a venous cannula.

Method

• position the patient’s hand: dorsiflex at 45–60° and tape in place if necessary; it may be helpful to place a 500 mL bag of fluid under the wrist to optimize position

• wash hands and put on gloves, gown and protective eyewear if required

• clean the site with the cleaning agent

• apply the sterile drape

• check the expiry date of the local anaesthetic and draw up 1–2 mL

• locate the radial artery with your non-dominant hand (see ‘Method’, p. 32)

• raise a skin bleb of local anaesthetic overlying the radial artery using as small a volume as possible; lidocaine must not be injected into a vessel, so you must always aspirate before injecting (see ‘Local anaesthetics’, p. 22)

• check the area is numb before proceeding

• insert the arterial cannula with your dominant hand at 40–45°; the technique you use will depend on the arterial line you have, see above

• the pulsation of arterial blood will confirm the correct location of the a-line, at which point you can cap the cannula or close the switch (if present)

• secure the a-line with a silk suture on either side (see ‘Suturing’, p. 63)

• attach the monitoring line

• calibrate the monitor to zero; if you cannot see an arterial waveform on the monitor, check the arterial line, the transducer, the monitor connections and ensure that the scale on the monitor is appropriate

• dispose of all equipment, including sharps, as per local infection control policy

• record the procedure in the notes with reference to site of insertion, drugs used with doses, initial blood pressure and any complications.