Practical procedures and patient investigation

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8 Practical procedures and patient investigation

Aseptic technique

Transmission of infection is an ever-present problem, and the risk of spread should be minimized. As a minimum precaution, the skin should be cleansed with an antiseptic solution before all procedures, and sterile instruments used. For some procedures, such as central venous catheterization, bladder catheterization, insertion of chest drains and lumbar puncture, a full aseptic technique must be employed. The steps required are outlined in Table 8.1.

Table 8.1 Aseptic technique

Local anaesthesia

Local anaesthetic agents inhibit membrane depolarization and hence block the transmission of nerve impulses. They may be used topically, i.e. painted or sprayed on mucous membranes and wound surfaces, so that they are absorbed locally to produce analgesia. Areas suitable for topical analgesia include the urethra, eye, nose, throat and bronchial tree. Local anaesthesia may also be administered by local infiltration, and this is used widely for minor surgical procedures. Local anaesthetic drugs are potentially toxic and care must be taken to avoid inadvertent intravascular injection. The first sign of toxicity is often numbness or tingling of the tongue or around the mouth, followed by lightheadedness and tinnitus. At higher blood levels, there is loss of consciousness, convulsions and apnoea. Cardiovascular collapse eventually occurs as a result of myocardial depression, vasodilatation and hypoxia. In general, efficacy is related to correct placement and toxicity to total dose. Where there is doubt about placement or a wide area of infiltration is anticipated, it is safer to calculate the maximum recommended dose and dilute it to the desired volume with 0.9% saline.

Lidocaine is the most widely used local anaesthetic agent and is available in 0.5–2% solutions. The maximum recommended dose is 3 mg/kg. Lidocaine is a short-acting anaesthetic (lasting up to 2 hours), whereas bupivacaine is longer-acting (up to 8 hours). A mixture of the two can be administered.

Solutions of local anaesthetic mixed with a 1:200 000 concentration of adrenaline (epinephrine) are also available. Adrenaline acts as a vasoconstrictor. It minimizes bleeding and reduces redistribution of the anaesthetic agent, thereby increasing its efficacy and duration of action. Local anaesthetic agents with adrenaline should not be used in anatomical areas supplied by an end-artery, such as the digits, because of the risk of vasoconstriction, ischaemia and gangrene.

Suturing

The purpose of suturing is to approximate tissue in such a manner as to allow optimum primary healing to take place or to ligate bleeding vessels to arrest haemorrhage. Needles can be straight or curved. Straight needles are usually hand-held whereas curved needles are designed for use with a needle holder. The thread is ‘swaged’ inside the needle, which can be cutting or round-bodied. The latter push tissue aside and can be used to reduce the risk of needle-stick injuries e.g. for closing the linea alba in abdominal wound closure, or for bowel/vascular anastomosis. Cutting needles are more commonly used for skin closure.

Suture materials

Suturing the skin

Skin wounds are sutured under as near-sterile conditions as possible, using a strict aseptic technique. A few basic principles underlie good wound care:

Cutting needles are used to suture skin. Non-absorbable sutures are generally preferred, but require subsequent removal. Interrupted sutures have the advantage over a continuous suture in that the removal of one or two appropriately sited stitches may allow adequate drainage if the wound becomes infected. The sutures should be placed equidistant from one another, taking equal ‘bites’ on either side of the wound. A sufficient number should be inserted to maintain apposition without the skin edges gaping. The size of bite is determined by the amount of subcutaneous fat and by whether or not the fat has been separately sutured. For abdominal wounds, 5 mm bites are taken on either side of the wound, whereas on the face a 1–2 mm bite is preferred. The wound edge is picked up 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 and avoids the small pinpoint scars at the site of entry and exit of interrupted sutures, or the ugly cross-hatching that results if sutures are tied too tightly or left in too long. Table 8.2 gives the suggested times for removal of sutures. Cosmetic results as good as those achieved by subcuticular suturing can be obtained by removing sutures in half the times listed in Table 8.2 and by replacing them with adhesive strips (e.g. Steristrip). Skin stapling is commonly used for closure of wounds at any site, as it can be undertaken rapidly. The staples are supplied in disposable cartridges for single patient use and are easily removed.

Table 8.2 Times recommended for removal of sutures

4 days

7 days 7–10 days 7 days 10–14 days

Airway procedures

Maintaining the airway

The ability to maintain the airway is a basic skill that every doctor, nurse, paramedic and indeed member of the general public should have. Its simplicity belies its importance, but it is a life-saving skill, which must be learnt through practice.

In the unconscious patient, muscles that normally maintain a clear airway become lax. The tongue and soft tissue fall backwards, particularly in the supine patient, occluding the airway. Maintaining a clear airway allows the patient to breathe or allows the lungs to be ventilated.

Endotracheal intubation

Endotracheal intubation can be life-saving; it can maintain a patent airway, facilitate oxygenation and prevent aspiration. Every opportunity should be taken to acquire this skill in the elective situation in the anaesthetic room.

Procedure

The patient’s neck is flexed and the head extended at the atlanto-occipital joint. Retaining a pillow under the head but leaving a space free from beneath the shoulders will usually help to attain this position. Failure to position the patient correctly is one of the most common causes of difficulty in intubation.

The laryngoscope is held in the left hand; its blade is inserted into the right side of the patient’s mouth and passed backwards along the side of the tongue into the oropharynx. The blade is designed to push the tongue over to the left side of the mouth. Care is taken to avoid damage to the lips and teeth. The laryngoscope is pulled upwards and forwards, not used as a lever, to lift the tongue and jaw and reveal the epiglottis (Fig. 8.3). The blade is then advanced to the base of the epiglottis and the laryngoscope pulled further upwards and forwards to reveal the vocal cords.

For men, a 9 mm cuffed tube is usually appropriate, and for women an 8 mm tube is generally used. For children, a rough rule of thumb to gauge tube size is age divided by 4, + 4.5 mm. Normally, an uncuffed tube is used in children.

The endotracheal tube is passed through the vocal cords into the trachea and advanced until its cuff is about 1 cm through. Many endotracheal tubes have a mark to indicate this position. The laryngoscope blade is then withdrawn and the cuff inflated to provide an airtight seal in the trachea.

The most serious complication of endotracheal intubation is failure to recognize misplacement of the tube, particularly in the oesophagus or, to a lesser degree, in the right main bronchus. Misplacement is best avoided by direct visualization of passage of the tube between the vocal cords, inspection of the chest wall for equal movement of both sides of the chest, and auscultation for breath sounds bilaterally in the mid-axillary line. Absence of breath sounds or the presence of only quiet ones in the epigastrium is a further reassuring sign. If there is any doubt about the position of the tube, it should be removed and ventilation instituted by mask.

Surgical airway

Inability to intubate the trachea is an indication for creating a surgical airway. In the emergency situation, such as in patients with severe facial trauma or pharyngeal oedema secondary to burns, the insertion of a large-calibre plastic cannula through the cricothyroid membrane (needle cricothyroidotomy) below the level of the obstruction can be life-saving. Intermittent jet insufflation of oxygen at 15 litres/min (1 sec inspiration and 4 secs to allow expiration) can provide oxygenation for a limited period (30–45 minutes) until a more definitive procedure can be undertaken.

Surgical cricothyroidotomy is performed by making an incision that extends through the cricothyroid membrane and inserting a tracheostomy tube.

In children, care must be taken to avoid damage to the cricoid cartilage, which is the only circumferential support to the upper trachea. Surgical cricothyroidotomy is therefore not recommended for children under 12 years of age.

Procedure

It is important to check all equipment and connections before starting. With the patient in the supine position and the neck in a neutral position, the thyroid cartilage (Adam’s apple) and cricoid cartilage are palpated. The cricothyroid membrane lies between the lower border of the thyroid cartilage and the upper border of the cricoid cartilage. The skin is cleansed with antiseptic solution and local anaesthetic infiltrated into the skin, if the patient is conscious. The thyroid cartilage is stabilized with the left hand and a small transverse skin incision made over the cricothyroid membrane. The blade of the scalpel is inserted through the membrane and then rotated through 90° to open the airway. An artery clip or tracheal spreader may be inserted to enlarge the opening enough to admit a cuffed endotracheal or tracheostomy tube (Fig. 8.4). The central trocar of the tube is removed and the tube connected to a bag-valve or ventilator circuit. The cuff is then inflated and air entry to each side of the chest is checked. The tube is secured to prevent dislodgement.

Formal open tracheostomy may be performed as an emergency procedure, but is more commonly undertaken in critically ill patients requiring long-term ventilation. It is a procedure for an experienced clinician and involves making an inverted U-shaped opening through the second, third and fourth tracheal rings.

Changing a tracheostomy tube

It is common practice to change a tracheostomy tube every 7 days. Suction must be available.

Procedure

If a cuffed tube is to be inserted, the integrity of the cuff is checked and it is then fully deflated. Lubricant gel is applied to both the cuff and tube. The patient is placed semi-recumbent with the neck extended. If replacement is likely to be difficult, a suction catheter inserted into the old tracheostomy tube can be used as an introducer for the new tube.

The cuff of the old tube is deflated. Secretions often collect above the cuff and enter the trachea when it is deflated, causing the patient to cough; both patient and operator should be alert to this. Because the tube is curved, it should be removed with an ‘arc-like’ movement. The site is then cleansed and any secretions are removed. In the spontaneously breathing stable patient, there is no need for undue haste. The new tube is inserted with a similar movement to that employed for removal, and its cuff inflated.

Any signs of respiratory distress should raise suspicion of the possibility of misplacement or occlusion of the tube. The tube and trachea are immediately checked for patency by passing a suction catheter through the tube. If the catheter passes easily into the respiratory tract, usually signified by the patient coughing as the catheter touches the carina, other causes for respiratory distress should be sought.

When the tracheostomy is no longer needed, an airtight dressing is applied over the site after removing the tube. There is no need for formal surgical closure at this stage, as in most instances the wound will close and heal spontaneously. For the first few days, patients should be encouraged to press firmly on the dressing when they wish to cough, so as to avoid air leakage through the tracheostomy site.