Non-absorbable sutures

Non-absorbable sutures may be classified into three groups:

Absorbable sutures

Absorbable sutures are generally made from synthetic materials. They cause relatively little tissue reaction, retain their tensile strength and are absorbed slowly. They can be multifilament, such as Dexon (polyglycolic acid) and Vicryl (polyglycolic plus polylactic acid), or monofilament, such as Maxon (polyglyconate) and PDS (polydioxonone). These synthetic sutures are commonly used for intra-abdominal 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.

Procedure

The simplest manoeuvre is to place the patient on their side with the neck extended in the so-called ‘recovery position’. This allows the tongue and soft tissues to fall clear of the larynx and provide a patent airway. The mouth and pharynx should be checked and cleared of debris, such as dentures, vomit or food.

When the patient has to be kept supine, the neck should be extended. The mouth is opened slightly and the mandible pulled firmly forward by pressure applied behind both angles of the jaw. The mandible is held in this position by closing the mouth and using the teeth as a splint. Forward pressure is maintained behind the angles of the jaw (jaw-thrust manoeuvre) or submentally (chin-lift manoeuvre), avoiding pressure on the soft tissues (Fig. 8.1). In some cases, particularly in edentulous patients, an oropharyngeal airway helps to maintain a patent airway.

Fig. 8.1 Maintaining the airway.

A The jaw-thrust manoeuvre. B The chin-lift manoeuvre.

Procedure

The airway is held patent with the patient supine, as described above. A mask is applied to the face and held in position using the thumb and index fingers of both hands. The little fingers of each hand are placed behind the angles of the jaw and used to lift the mandible forward. The ring and middle fingers are placed on the mandible to help maintain this position. The assistant squeezes the bag to ventilate the lungs. The adequacy of ventilation is assessed by observing appropriate chest movement.

With more experience, it is possible to maintain a patent airway and hold the mask on with one hand, and squeeze the bag with the other.

Procedure

For men a size 4 is suitable, and for women a size 3, with smaller sizes being available for children. The cuff should be deflated and lubricated with gel. The patient’s head is maintained in an extended position using the left hand, and the airway is held in the right hand and introduced into the mouth (Fig. 8.2). The airway is passed backwards over the tongue until resistance is felt. It should then be at the level of the larynx. The cuff is inflated and the airway should be seen to rise slightly out of the mouth. Position is confirmed by the ability to ventilate the lungs.

Fig. 8.2 Insertion of a laryngeal mask airway.

A Gentle insertion of airway with head in extended position. B Advancement of airway.

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.

Fig. 8.3 Oral endotracheal intubation.

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.

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.

Fig. 8.4 Surgical cricothyroidotomy.

A Palpation of thyroid cartilage. B Incision through cricothyroid membrane. C Insertion of tracheostomy tube.

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.

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.

Procedure

If a low lateral approach is to be used, reference should be made to the chest X-ray to ensure that the drain will not be inserted subdiaphragmatically. A strict aseptic technique must be used. The skin, intercostal muscles and pleura are infiltrated with local anaesthetic. If a rib is encountered by the needle, the tip is ‘walked’ up the rib to enter the pleura above the rib edge. The depth at which the pleural space is entered is determined by aspiration with the syringe. A 3 cm horizontal incision is now made in the skin. A tract is developed by blunt dissection through the subcutaneous tissues and the intercostal muscles are separated just superior to the top of the rib to avoid damage to the neurovascular bundle. The parietal pleura is punctured with the tip of a pair of artery forceps and a gloved finger is inserted into the pleural cavity (Fig. 8.5). This ensures the incision is correctly placed, prevents injury to other organs, and permits any adhesions or clots to be cleared. The trocar is removed from the thoracostomy tube, the proximal end is clamped, and the tube is advanced into the pleural space to the desired length. The tube is sutured to the skin with a heavy suture to prevent accidental dislodgement. A ‘Z’ suture is placed around the incision, wrapped tightly around the drainage tube and tied, thus securing the tube. A sterile dressing and an adhesive bandage are applied to form an airtight seal and prevent aspiration of air around the tube. The drainage tube is attached to an underwater drainage system and a chest X-ray is then obtained. Low-pressure suction may be applied to the drainage bottle to assist drainage or re-expansion of the lung.

Fig. 8.5 Chest drain.

A Insertion. B In situ.

Procedure

The ‘Z’ suture is freed from the tube and can be used to close the wound. Where this is not possible, the suture should be totally removed and a new one inserted around the wound. Patients are asked to hold their breath in expiration and the tube is withdrawn, after which the skin is firmly closed with the previously inserted suture. A sterile dressing is firmly applied over the wound and a chest X-ray repeated to confirm that there is no pneumothorax.

Procedure

Where aspiration is to be undertaken for diagnostic purposes only, a 21-gauge needle and syringe are adequate. For therapeutic aspiration, a larger-bore needle, 50 ml syringe and three-way tap system should be used. The procedure is carried out using a strict aseptic technique.

The patient is positioned sitting up, resting the arms and elbows on a table. The position and size of the effusion should be outlined by percussion and chest X-ray. The lower border of the effusion is determined, particularly on the right to avoid puncturing the liver. In the case of small effusions, ultrasound guidance is helpful.

The skin, intercostal muscles and pleura are infiltrated with local anaesthetic in the seventh or eighth space, in line with the inferior angle of the scapula. The needle is advanced over the upper border of the rib to avoid damage to the neurovascular bundle. Continuous suction should be applied to the syringe and the needle advanced no further than is required to aspirate fluid freely, thereby avoiding damage to the underlying lung.

If the volume of fluid to be removed is greater than the volume of the syringe being used, a three-way tap greatly reduces the risk of air entry and allows the syringe to be emptied into a collection vessel (Fig. 8.6); this avoids having to disconnect the syringe each time it is filled. It is normally recommended that no more than 1–1.5 litres of fluid be removed at any one time. This reduces the risk of sudden mediastinal shift or the development of pulmonary oedema associated with rapid re-expansion of a collapsed lung. Coughing or pain on aspiration is an indication that visceral pleura is in close contact with the end of the cannula, which should be repositioned or withdrawn.

Fig. 8.6 Pleural aspiration.

At the end of the procedure, the needle is withdrawn and a sterile dressing applied. A chest X-ray is taken to assess the amount of residual fluid present and to exclude a pneumothorax.

Procedure

The nose is inspected for any deformity and the more patent nasal passage is chosen for insertion. The patient is placed in the sitting position and a local anaesthetic spray may be used to anaesthetize the nasal passage. The tube is well lubricated with gel and passed backwards along the floor of the nasal passage (Fig. 8.7). A slight resistance may be felt as the tube passes from the nasopharynx to the oropharynx, and the patient should be warned that a retching sensation may be experienced at this point.

Fig. 8.7 Nasogastric intubation.

Note the correct direction for inserting the tube.

The patient is now asked to swallow, and with each swallow the tube is advanced down the oesophagus. It is important not to push the tube rapidly and force its insertion in a patient who is retching; rather, slow and steady progress should be sought, with small advancements made during each act of swallowing. The oesophago-gastric junction is about 40 cm from the incisor teeth, and ideally, about 10–15 cm of the tube should be placed into the stomach. Most nasogastric tubes have markings to allow measurement of the length inserted. Correct placement of the tube is confirmed by free aspiration of gastric contents, and by auscultation in the epigastrium while 20 ml of air is insufflated. Once in place, the tube is fixed to the nose with adhesive tape.

In patients with head injuries, the nasal route is avoided because of the risk of introducing infection – or even the nasogastric tube itself – into the central nervous system through an open fracture of the skull base. The oral route is also considered in patients with serious coagulopathy, as passage of the tube through the nose may result in significant haemorrhage. Finally, blind passage of a tube in the early period following oesophagectomy should never be attempted, as this may disrupt the anastomosis.

Procedure

Fine-bore nasogastric tubes have a wire stylet to facilitate passage. The tube is passed in the same way as a standard nasogastric tube. Again, it is important not to force the tube but to advance it slowly and steadily with each swallowing action made by the patient. The position of the tube is confirmed by X-ray, and only then is the stylet removed. Once removed, it must never be reintroduced while the tube remains in place, as there is a significant risk of perforating both the tube and the oesophagus. The tube tends to collapse if aspirated, so that aspiration cannot be used to check its position.

It is often advantageous to position the fine-bore feeding tube in the jejunum. This can be achieved using a radiological imaging technique or by the use of an enteral feeding tube with a mercury-filled tip that ‘self-propels’ into the jejunum.

Procedure

After the need for endotracheal intubation is assessed, the patient is placed on the left side in the recovery position, with a 15° head-down tilt of the trolley. A large-bore gastric tube is introduced into the mouth. A mouth gag is useful to prevent the patient from biting the tube. As the tube is passed into the oropharynx and upper oesophagus, the patient is likely to gag and even to vomit. The tube is advanced into the stomach and its correct position confirmed by the free flow of gastric contents. If there is doubt, auscultation of the epigastrium during injection of air down the tube will confirm correct placement. About 100–200 ml of warm water is passed down the tube into the stomach. The end of the tube is then lowered below the level of the stomach into a collecting bucket, and gastric contents are allowed to syphon out. The manoeuvre is repeated until the returned water becomes clear. It is important to avoid over-distension of the stomach. Activated charcoal can be instilled into the stomach to act as an absorbent, if this is appropriate. On completion of lavage, the tube is removed.

Procedure

The Sengstaken–Blakemore tube should be stored in a refrigerator, as this renders it less pliable and thus facilitates insertion. The oesophageal and gastric balloons are checked for leaks and then completely deflated using an aspiration syringe prior to insertion. The tube is inserted in the same way as a normal nasogastric tube. However, it is much more uncomfortable and local anaesthesia is recommended for nasal passage. A patient with bleeding varices is unlikely to cooperate fully and the tube may have to be passed with the patient on his or her side. If there is difficulty inserting the tube via the nasal route, the oral route may be used.

The tube is advanced approximately 60 cm and the gastric balloon inflated with 150–200 ml of air or water. The tube is then drawn back until this lower balloon impacts at the cardia. An assistant holds the tube in this position under slight tension, and the oesophageal balloon is inflated with air to a pressure of approximately 40 mmHg, checked by attaching a sphygmomanometer. The tube is secured in position with tape, but no additional traction is necessary.

The stomach is aspirated regularly through the main lumen of the tube to check for further bleeding. This lumen may also be used for the administration of medication, such as lactulose and neomycin. A fourth lumen allows aspiration of the upper oesophagus and pharynx and reduces the risk of bronchial aspiration. In patients who are stuporose or comatose, the airway should be protected by an endotracheal tube.

Procedure

The operator scrubs up and wears a gown and gloves. A site is chosen for insertion of the catheter. This can be either in the midline (one-third of the way from the umbilicus to the pubic symphysis), or in the right or left iliac fossa (at the junction of the outer and middle thirds of a line drawn from the umbilicus to the anterior superior iliac spine). The vicinity of scars should be avoided, as adhesions increase the risk of bowel perforation. Local anaesthetic is infiltrated through all layers of the abdominal wall. The depth at which the peritoneum is entered is determined by aspiration with the syringe.

A 3 mm stab incision is made in the skin with a scalpel. The trocar is introduced into the catheter and the shaft of the catheter is held firmly between left thumb and index finger some 4–5 cm higher than the estimated depth of the peritoneum. This prevents ‘overshoot’ as the right hand inserts the trocar and catheter through the abdominal wall into the peritoneum (Fig. 8.8).

Fig. 8.8 Insertion of a peritoneal dialysis catheter.

The catheter is then advanced further with the left hand while the trocar is withdrawn with the right. If any resistance is encountered, the catheter is withdrawn 2–3 cm, rotated 180° and then advanced again. The minimum final length of catheter within the peritoneal cavity must be 10 cm. If this position is not obtained, the side perforations of the catheter may lie within the abdominal wall and allow troublesome extravasation of ascitic fluid into the subcutaneous tissues. The catheter is secured to the skin and attached via a connection tube with a flow-control clamp to a sterile drainage bag (Fig. 8.9).

Fig. 8.9 Abdominal paracentesis catheter in situ.

A Catheter inserted in left iliac fossa. B Flange of catheter secured with sutures.

Drainage of large volumes of ascitic fluid must be accompanied by intravenous infusion of albumin in order to avoid precipitating a marked shift of fluid from the intravascular compartment into the peritoneal cavity. This prevents significant haemodynamic changes and reduces the risk of developing cardiovascular instability, renal impairment or hepatic encephalopathy.

Procedure

This procedure can be performed using a closed or open technique, the latter being favoured to minimize the risk of intra-abdominal injury. Under sterile conditions and following the instillation of local anaesthesia, a 5 cm vertical subumbilical incision is made and dissection continued through the subcutaneous tissue and linea alba. The peritoneum is opened and a cannula inserted into the peritoneal cavity and advanced into the pelvis. A syringe is connected to the dialysis catheter, and if frank blood is immediately aspirated, this is a positive DPL result. If gross blood is not obtained, 1 litre of warm sterile isotonic saline is infused and allowed to distribute evenly throughout the peritoneal cavity. The fluid is then retrieved by placing the infusion bag on the floor and allowing the effluent to drain from the abdomen by gravity. An unequivocal test will reveal gross evidence of blood, bile or faeces. If necessary, fluid can be sent to the laboratory for analysis. A positive result is obtained if the red cell count is > 100 × 10⁹, the white cell count is > 0.5 × 10⁹ or the amylase is > 175 U/ml.

Procedure

A venous tourniquet is applied to the upper arm and the patient is encouraged to clench the fist several times to increase venous filling. The position of the vein is identified and the skin cleansed. The needle is advanced through the skin and into the vein, with the needle bevel facing upwards. This manoeuvre is carried out in a ‘two-step’ fashion, first through the skin and then through the vein wall. Entry through the skin with a decisive action causes much less discomfort than a slow hesitant movement. The needle is advanced 2–3 mm into the vein and the position of the needle and syringe stabilized with one hand. The plunger of the syringe is slowly withdrawn with the other hand until the required amount of blood is obtained. The tourniquet is then released, the needle withdrawn and pressure immediately applied over the site of entry into the vein to prevent haematoma formation, which is painful for the patient and makes subsequent sampling more difficult.

The blood is placed into the appropriate sample tubes after removal of the needle from the syringe. With pre-vacuumed sample tubes, the needle should be left on the syringe in order to fill the tubes. Haemolysis invalidates some results – for example, potassium and phosphate levels – and is more likely to occur when smaller needles are used. It can be minimized by slow withdrawal of blood into the syringe.

Procedure

A venous tourniquet is applied, as before. The patient’s skin is thoroughly cleansed with an appropriate solution, using a sterile swab or cotton wool ball. Venepuncture is performed without the operator touching the skin around the site of entry of the needle. After withdrawal, the needle is removed from the syringe and a second sterile needle substituted. This is then used to introduce the appropriate aliquot of blood into both aerobic and anaerobic culture bottles. Exact volumes of blood required and the number of bottles filled will depend on local laboratory policies. All blood culture bottles should be sent immediately to the laboratory or, if this is not possible, placed in an incubator at 37°C until transport is available.

Procedure

A venous tourniquet is applied, the site of insertion chosen and the skin is cleansed. Venepuncture is made in the ‘two-step’ fashion described above and confirmed by a ‘flashback’ of blood into the cannula. The cannula is initially advanced 2–3 mm into the vein, and then the cannula sheath is advanced into the vein with one hand while the metal needle is partially withdrawn with the other.

Once the cannula sheath is fully inserted into the vein, the tourniquet is released and gentle pressure applied over the vein at the tip of the cannula. The metal needle is then fully withdrawn from the cannula and the giving set, previously primed with normal saline, is connected. The cannula and distal 10–15 cm of the giving set are securely fixed to the skin with adhesive tape.

Cannulation sites should be inspected regularly for signs of swelling, erythema or tenderness, which may indicate extravasation, thrombophlebitis or infection. If any of these is present or the patient complains of pain at the site, the infusion must be stopped and the cannula resited. Extravasation may cause tissue necrosis. Thrombophlebitis occurs more readily when small veins are used, or when the pH of the infusate differs significantly from blood pH. The chances of infection increase the longer a cannula is left in situ, and infusion sites must be changed regularly.

Bolus injections through an intravenous cannula should not be made without first ensuring that the cannula is patent and that there is no extravasation.

Procedure

Venous cutdown is performed with an aseptic technique. A transverse incision is made in the skin over the vein, which is then identified by blunt dissection. At the ankle, the site of cutdown is 2–3 cm anterior to the medial malleolus. The vein should be cleared for a distance of 1–2 cm. The distal end of the vein is ligated with an absorbable ligature. A second absorbable ligature is placed under the proximal end of the exposed vein and is elevated to prevent backflow of blood. A transverse incision is then made in the vein. A large-bore cannula is passed through the skin 2 cm below the skin incision and guided into the vein. The cannula is advanced beyond the proximal ligature, which is then tied securely.

The intravenous infusion is then commenced to ensure it flows freely, and the wound is closed with non-absorbable sutures. The cannula is sutured to the skin to prevent accidental displacement and a sterile dressing is applied.

Internal jugular vein cannulation

A high approach at the level of the thyroid cartilage carries the least risk. The right internal jugular vein is preferred, as this provides a straighter route into the superior vena cava and avoids the risk of damaging the thoracic duct on the left. In general, the Seldinger technique is used; several commercial kits are available containing the necessary equipment.

Procedure

The patient is placed in a supine position, with at least 15° head-down tilt to distend the neck veins and reduce the risk of air embolism. The patient’s head is turned to the left, unless there is potential for a cervical spine injury following trauma. A wide area on the right side of the neck is cleansed and draped.

The carotid artery is identified at the level of the thyroid cartilage, using the index and middle fingers of the left hand. The internal jugular vein lies just lateral and parallel to it. A bleb of local anaesthetic can be infiltrated into the skin at the proposed puncture site.

Using ultrasound guidance an 18-gauge needle on a 10 ml syringe held in the right hand, the needle is advanced through the skin just lateral to the carotid pulsation, at an angle of 60° to the skin and in the line of the vein (Fig. 8.12). Free aspiration of blood confirms the position of the vein. This manoeuvre is repeated to place a larger (16-gauge) needle in the vein. The flexible ‘J’ end of the guidewire is now passed through this needle into the vein, and the needle removed over it. This leaves the guidewire in the internal jugular vein. A dilator is now passed over the wire into the vein and then withdrawn. The catheter is advanced over the wire and then the wire is removed, leaving the catheter in situ. In most adults, no more than 15 cm of catheter need be advanced into the vein to ensure correct placement. Blood is then aspirated from the catheter to confirm its position in the major vein. Heparinized saline (5 ml) is injected and the catheter is sutured to the skin to fix it in position. A chest X-ray is taken to check the position of the catheter and to exclude the presence of a pneumothorax, which is a recognized complication.

Fig. 8.12 Cannulation of the internal jugular vein.

Note the triangle between the sternal and clavicular heads of the sternocleidomastoid muscle.

Subclavian vein cannulation

Subclavian vein cannulation carries a significant risk of causing a pneumothorax or puncturing the subclavian artery and should only be attempted by an experienced operator.

Procedure

The Seldinger technique is generally used to insert a subclavian catheter. The patient should be placed in a supine position, with head-down tilt of at least 15°. A small pad is placed between the shoulder blades to allow the shoulders to drop backwards. Local anaesthetic is infiltrated into the skin and subcutaneous tissue. Under aseptic conditions, a large-calibre needle attached to a 10 ml syringe is introduced 1 cm below the junction of the middle and medial thirds of the clavicle. The needle is directed medially, slightly cephalad and posteriorly behind the clavicle towards the tip of a finger placed in the suprasternal notch (Fig. 8.13). Applying suction, the needle is advanced until blood is withdrawn into the syringe. The syringe is then disconnected, a flexible guidewire inserted through the needle and the needle removed. The catheter is subsequently passed over the guidewire and the latter is withdrawn. The catheter is flushed with heparinized saline and fixed in position. A chest X-ray is taken to check the position and exclude a pneumothorax. An occlusive dressing covers the skin entry point.

Fig. 8.13 Cannulation of the subclavian vein.

Peripheral venous catheterization

In theory, this is the safest approach, as it avoids the risk of pneumothorax. Haemorrhage from accidental arterial puncture or as a result of a coagulopathy can be controlled by pressure. Thrombosis and thrombophlebitis are, however, more frequent compared to the internal jugular or subclavian route.

Summary Box 8.1 Central venous cannulation

• Air embolism is always a risk, even in the head-down position

• When using a guidewire, always hold it at some point along its length while it remains in the patient

• Blood should be easily aspirated from the catheter, if it is correctly positioned

• A chest X-ray should always be taken to confirm the absence of a pneumothorax and correct positioning. A rough guide to position is that the tip of the catheter should lie at the level of the carina on X-ray

• Cannulae inserted for intravenous nutrition are tunnelled in the subcutaneous tissue to emerge on the chest wall at a distance from the site of entry into the vein (Fig. 8.14). This minimizes the risk of sepsis spreading down the tract into the vein.

Fig. 8.14 Skin tunnel for central venous catheter.

Procedure

If the syringe is not preheparinized, up to 0.5 ml of 1000 U/ml heparin is drawn into the syringe. The plunger is then fully withdrawn, following which the air and excess heparin are expelled from the syringe. The residual heparin will be sufficient to anticoagulate the sample. A 23-gauge needle is suitable for arterial puncture.

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 the needle, with its bevel upwards, introduced through the skin at an angle of about 60°. The needle is then advanced into the artery. Correct positioning is confirmed by blood pulsating into the syringe under pressure; 1–1.5 ml is normally sufficient.

The needle is withdrawn and firm pressure applied over the puncture site for 3 minutes to avoid haematoma formation. The needle is removed from the syringe and any air bubbles 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.

Procedure

The patient should be monitored throughout this procedure, with particular reference to the vital signs, CVP and electrocardiogram (ECG). An aseptic technique is used and the skin in the subxiphoid region is infiltrated with local anaesthetic. The skin is punctured 1–2 cm inferior to the left xiphochondral junction, using a wide-bore plastic-sheathed needle (at least 15 cm in length) with a syringe attached. The needle is angled at 45° and aimed towards the tip of the left scapula (Fig. 8.15). The syringe is aspirated as the needle is advanced, until it easily fills with blood. ECG changes suggest the needle has been advanced too far. Positive pericardiocentesis must be followed by surgical exploration.

Fig. 8.15 Needle pericardiocentesis.

Procedure in the male

The shaft of the penis is held with a sterile swab, the foreskin if present is retracted and the urethral orifice cleansed with a non-alcoholic, non-iodine-containing solution. The shaft of the penis is held erect with a sterile swab in the left hand and traction applied to elongate the urethra. Lidocaine gel is instilled into the urethra slowly and carefully, with light but steady pressure. It is important to leave the local anaesthetic agent for a sufficient length of time before proceeding with catheterization, as difficulty in male catheterization is often caused by poor analgesia.

The urinary catheter is introduced into the urethra with a ‘no-touch’ technique and advanced fully to ensure the balloon on the catheter is within the bladder (Fig. 8.16). Correct placement is confirmed by the passage of urine down the catheter. If this does not occur, suprapubic pressure may help. Alternatively, a bladder syringe can be attached to the catheter and aspiration used. With the passage of urine, the balloon on the catheter is inflated with the recommended volume of sterile water (generally, 10–30 ml). The catheter is gently withdrawn until the balloon engages the bladder neck, and it is then connected to the drainage tubing. It is very important that the foreskin, where present, should be replaced over the glans to prevent paraphimosis.

Fig. 8.16 Male catheterization.

Procedure in the female

A 16–18 Fr catheter is suitable for this procedure. The labia minora are separated with the thumb and fingers of the left hand to expose the urethral meatus on the anterior vaginal wall. The pudenda are now swabbed with antiseptic solution. Two swabs are used, each being swept once across the pudenda from anterior to posterior and then discarded.

In general, the catheter need only be inserted for half its length before the passage of urine confirms correct placement. The balloon is inflated and the catheter withdrawn until the balloon impacts in the bladder neck.

Procedure

The position of the bladder is determined by percussion. Where available, ultrasound guidance is helpful. Generally, the point of insertion lies two finger-breadths above the pubic symphysis in the midline.

The area is cleansed and draped. Local anaesthetic is then infiltrated through all layers of the anterior abdominal wall, using an 18-gauge needle. The depth and position of the bladder can be gauged by the free aspiration of urine through this needle. The needle is withdrawn and a stab incision made in the skin. The trocar and catheter are advanced through the incision, into the bladder (Fig. 8.17). Entry into the bladder is confirmed by the loss of resistance, at which point the catheter is advanced as the trocar is withdrawn. Free passage of urine confirms correct placement. The catheter must be advanced far enough into the bladder so that the balloon, when inflated, is well within the bladder. The balloon is then filled with 10 ml of water and a sterile dressing is applied.

Fig. 8.17 Suprapubic catheterization.

Procedure

Lumbar puncture is carried out using a strict aseptic technique. Patients are placed on one side (usually the left), with their back at the edge of the bed or trolley. They are then asked to curl up as much as possible, to flex the lumbar spine and open up the interspinous spaces (see Fig. 5.4).

The skin is thoroughly cleansed and drapes are applied. The space between the spinous processes of the third and fourth lumbar vertebrae is identified by the point at which a vertical line dropped from the highest point of the iliac crest crosses the spine. Local anaesthetic is infiltrated into the skin and subcutaneous tissues to a depth of about 2 cm. A small stab incision is made in the midline, midway between the two spinous processes.

For most purposes, a 22-gauge spinal needle is adequate. The needle is inserted through the stab incision and advanced in the midline in a slightly headward direction. Entry into the subarachnoid space is felt with a distinct loss of resistance, and will occur in most adults at a depth of 4–6 cm from the skin.

The stylet is withdrawn from the needle and the position confirmed by the free flow of CSF. If the subarachnoid space is not entered or bone is encountered, the position of the needle in the midline should be checked. This is best done by observing (from the side) the angle of the needle in relation to the patient’s back. If the needle is in the midline, it should be withdrawn and reinserted in a slightly more headward direction. If the patient experiences pain, a nerve has been touched. The needle should be immediately withdrawn and repositioned.

Once the procedure is complete, the needle is withdrawn and a sterile dressing applied. The patient is usually advised to remain supine for at least 12 hours to minimize the risk of developing a ‘spinal’ headache. Persistent headache may be a result of continued CSF leakage through the puncture in the dura. In these circumstances, an anaesthetist should be asked to advise on an epidural ‘blood patch’. With modern needles, the risk of CSF leakage is lessened and the advice to remain supine for 12–24 hours may be unnecessary.