Practical procedures

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CHAPTER 15 PRACTICAL PROCEDURES

GENERAL INFORMATION

Critically ill patients require large numbers of practical procedures. The information in this chapter is intended only as a guide. The advice is generalized; you should always read the instructions provided with the equipment that you use, and follow your local hospital guidelines.

Universal infection control precautions

Contamination with blood or other body fluids imposes significant risk to staff from blood-borne infection, particularly hepatitis and HIV infection. Universal precautions should be adopted for all invasive procedures. These are intended to prevent the spread of infection, to protect you, your patients and colleagues. It is not always possible to know who has an infection; universal infection control precautions apply to everybody, all of the time:

Always follow guidelines and safety information that apply to your department. If you need further information, talk in the first place to a senior member of nursing staff. Where necessary, further advice can be obtained from specialists in microbiology, infection control, occupational health, COSHH (Control of Substances Hazardous to Health), health & safety, etc.

ARTERIAL CANNULATION

Arterial cannulation is one of the most commonly performed procedures in the ICU. There is, however, an associated risk of morbidity and the indication for arterial cannulation in the individual patient should be considered carefully.

Procedure

Decide which artery to cannulate. The radial artery of the non-dominant hand is usually preferred in the first instance. Alternatives include the ulnar, dorsalis pedis and posterior tibial arteries. It is pointless, however, to persist with attempts at peripheral arterial cannulation in patients who are hypotensive and ‘shut down’. The femoral and brachial arteries are useful during resuscitation of profoundly shocked patients. Ultrasound guidance is potentially useful at all sites to aid arterial cannulation, particularly in hypotensive patients and those whose landmarks are obscured by oedema or obesity.

USE OF PRESSURE TRANSDUCERS

A transducer converts one type of energy (e.g. arterial pressure) into another (e.g. electrical impulse). There are a number of different types of transducer available but the principle is similar for all:

In order for the arterial waveform and blood pressure recording to be accurate, the transducer must be used appropriately. Therefore:

CENTRAL VENOUS CANNULATION

Ultrasound guidance for vascular access

The use of ultrasound to guide central venous access procedures is recommended in all cases (NICE Guidance. Central venous catheters, ultrasound locating devices, Sept. 2002. www.nice.org.uk/guidance/TA49).

Ultrasound allows for:

Use of ultrasound clearly requires understanding of the ultrasound appearances of the anatomy at the various sites of interest. Arteries can be distinguished from veins by their round cross-section, non-compressibility and their pulsatility. Veins, by contrast, show respiratory fluctuation and are easily compressible. When using ultrasound for vascular access you should:

Traditional approaches to the central veins are described below.

Internal jugular vein

Right sided internal jugular vein cannulation is associated with a lower incidence of complications and higher incidence of correct line placement than other approaches. It is especially appropriate for patients with coagulopathy or those patients with lung disease in whom pneumothorax may be disastrous. It may be best avoided in those patients with carotid artery disease or those with raised intracranial pressure because of the risks of carotid puncture and of impaired cerebral venous drainage. Internal jugular cannulation is associated with a higher incidence of catheter infection than subclavian cannulation but both have a much lower infection rate than the femoral approach.

The internal jugular vein runs from the jugular foramen at the base of the skull (immediately behind the ear) to its termination behind the posterior border of the sternoclavicular joint, where it combines with the subclavian vein to become the brachiocephalic vein. Throughout its length it lies lateral, first to the internal and then common carotid arteries, within the carotid sheath, behind the sternomastoid muscle (Fig. 15.1A). Ultrasound demonstrates the close proximity of the vein to the carotid artery (Fig. 15.1B). Many approaches to the internal jugular vein have been described. A typical landmark approach is from the apex of the triangle formed by the two heads of the sternomastoid (Fig. 15.1).

Subclavian vein

Subclavian vein cannulation is associated with a higher incidence of complications, particularly pneumothorax, and a higher incidence of incorrect line placement than right internal jugular cannulation. It is, however, more comfortable for the patient long-term and is associated with a lower incidence of line infection than other sites of central venous cannulation.

The subclavian vein is a continuation of the axillary vein. It runs from the apex of the axilla behind the posterior border of the clavicle and across the first rib to join the internal jugular vein, forming the brachiocephalic vein behind the sternoclavicular joint. See Fig. 15.2.

Ultrasound can be used to guide cannulation of the subclavian vein using a more lateral approach. The axillary vein can be identified in the apex of the axilla at a depth of 3–4 cm in the average patient. Cannulation of the axillary vein is relatively straightforward under ultrasound control and minimizes the risk of pneumothorax owing to its position lateral to the pleura and chest wall. Longer catheters (20 cm left and 25 cm right) are required by this approach.

Procedure

COMMON PROBLEMS DURING CENTRAL VENOUS ACCESS

Complications

Complications of central venous cannulation depend in part on the route used but include those in Box 15.2.

Box 15.2 Complications of central venous cannulation

Early Late
Arrhythmias Infection
Vascular injury Thrombosis
Pneumothorax Embolization
Haemothorax Erosion/perforation of vessels
Thoracic duct injury (chylothorax) Cardiac tamponade
Cardiac tamponade AV fistula
Neural injury  
Embolization (including guide wire)  
AV fistula  

The management of pneumothorax depends upon the size of the pneumothorax and the patient’s condition, particularly whether they are ventilated or not. A small pneumothorax in an unventilated patient with good gas exchange may be observed, or aspirated using a small-bore cannula and syringe with three-way tap. Larger pneumothoraces, those that fail to resolve or those that cause any impairment of gas exchange and / or haemodynamics require a formal chest drain. Any significant haemothorax should be formally drained as soon as possible. Once blood has clotted in the chest, drainage is difficult. (See Chest drainage, p. 418.) Seek cardiothoracic / surgical opinion.

Bleeding around the puncture site can occasionally be a persistent problem. If this does not resolve with pressure, use a suture (5/0 nylon) to tie a purse string around the puncture site. This usually stops the bleeding.

Thrombus formation around central venous cannula is common and may lead to deep venous thrombosis and / or pulmonary embolus. Avoid insertion at sites where there is evidence of thrombus on ultrasound scanning. If thrombi are identified around an existing cannula, these should be removed and therapeutic anticoagulation commenced unless contraindicated.

CHANGING AND REMOVING CENTRAL VENOUS CATHETERS

Line colonization with bacteria and fungi is common and there is no evidence that changing lines on a regular basis (e.g. every 5–7 days) is of benefit. (See Catheter-related sepsis, p. 340.)

LARGE-BORE INTRODUCER SHEATHS / DIALYSIS CATHETERS

Procedure

See Central venous cannulation above.

All these devices are inserted using a Seldinger technique and a large stiff dilator is used to dilate the initial needle track sufficiently to allow the large-bore catheter to be passed easily into the vessel. These dilators do not pass around tight bends easily and can readily damage or perforate vessels. The left internal jugular vein is best avoided. Introducer sheaths can usually be sited safely at all other sites. Dialysis catheters may be best placed by the right internal jugular or femoral routes. The femoral route may be particularly appropriate in patients with chronic renal failure, to preserve the venous drainage of the arm for subsequent AV fistula formation.

PULMONARY ARTERY CATHETERIZATION

The place of pulmonary artery catheters has been questioned recently and their use has diminished. In general non-invasive cardiac output monitoring and the ready availability of bedside echocardiography have superseded them. (See Haemodynamic monitoring, p. 74.) They may be of value, however, in conditions where haemodynamic instability or shock is unresponsive to fluid and inotrope therapy guided by conventional CVP measurement, particularly where pulmonary hypertension/right heart failure are thought to contribute to the problem. As insertion of a PA catheter is not without hazard, you should always seek senior guidance. Traditional indications and contraindications are shown in Box 15.3.

Box 15.3 Indications and contraindications for pulmonary artery catheterization

Indications Relative contraindications
Shock Severe coagulopathy
Sepsis / SIRS Unstable ventricular rhythm
ARDS Heart block
Valvular heart disease* Temporary transvenous pacemaker (wire dislodgement)
Left ventricular failure Stenosis tricuspid or pulmonary valve
Cor pulmonale / pulmonary hypertension  
High-risk surgical patients  

* Relative indication.

Severe stenosis or mechanical valves absolute contraindication.

Procedure

COMMON PROBLEMS DURING PULMONARY ARTERY CATHETERIZATION

Complications

PA catheterization is not without risk and is certainly not a therapeutic manoeuvre in its own right! If patients are to benefit then regular collection and interpretation of haemodynamic and oxygen delivery variables, together with the appropriate therapeutic response, is required.

Potential complications of pulmonary artery catheterization are shown in Table 15.1.

TABLE 15.1 Complications of pulmonary artery catheterization

Complication Comment
Central venous puncture Any complications of central venous cannulation
Dysrhythmia Usually on passage through tricuspid valve and RV
Especially if hypoxia, acidosis, hypokalaemia: withdraw catheter and reposition
Complete heart block may occur
Pulmonary infarction Check catheter is in proximal PA on chest X-ray
Never leave balloon inflated
Display PA trace continuously
Pulmonary artery rupture Pulmonary haemorrhage and blood up the endotracheal tube
Avoid overinflation of the balloon
Watch trace and never inflate against resistance
Infection Risk includes endocardial damage and endocarditis
Careful aseptic technique and catheter care
Remove after 72 h or ASAP
Knotting Poor insertion technique
Do not insert more than 20 cm without a change in trace
Do not attempt to pull back. Call for help

MEASUREMENT OF CARDIAC OUTPUT BY THERMODILUTION

Pulmonary artery catheters incorporate a thermistor near the tip to allow thermodilution measurement of cardiac output. A volume of cold 5% dextrose solution (usually 10 mL) is injected through the central venous port of the PA catheter (in SVC or RA) and the temperature change in the PA is detected by the thermistor. The degree and the rate of temperature change is used to calculate cardiac output. (Some catheters incorporate a heated coil and fast reacting thermistor to allow continuous cardiac output measurement.)

Having measured the cardiac output and PA occlusion pressure a range of haemodynamic variables can be calculated. This is generally performed by the monitoring system. Normal values for these variables are given in Chapter 4. (See Optimizing haemodynamic status, p. 78.)

In addition by measuring blood gases on blood drawn simultaneously from the pulmonary artery catheter (mixed venous) and an arterial line, oxygen delivery and consumption variables may be calculated. (See Oxygen delivery and consumption, p. 68.)

PERICARDIAL ASPIRATION

DEFIBRILLATION AND DC CARDIOVERSION

Elective cardioversion is beyond the scope of this book. Life-threatening ‘shockable rhythm’ should be managed according to advanced life support protocols. (See pp. 9098.) For cardioversion in the emergency situation, i.e. the intensive care patient with haemodynamic compromise, the following approach is reasonable.

Procedure

If normal rhythm is not restored seek expert help. Consider:

INTUBATION OF THE TRACHEA

This is covered at greater length in standard anaesthesia texts; however, there are some aspects of tracheal intubation of particular relevance to patients in intensive care.

Indications

These fall broadly into three groups: relieving airway obstruction, protection of the airway from aspiration and facilitation of artificial ventilation of the lungs. Typical indications are given in Box 15.4.

Box 15.4 Indications for tracheal intubation

Airway obstruction Risks of aspiration Facilitation of IPPV
Tumours Obtunded consciousness level Anaesthesia and surgery
Head and neck trauma Bulbar palsy Cardiopulmonary resuscitation
Epiglottitis Impaired cough reflexes Respiratory failure
Surgery   Cardiac failure
Airway oedema   Multisystem organ failure
Major trauma including chest injury
Brain injury

Patients requiring intubation in ICU frequently have limited physiological reserve and are liable to haemodynamic collapse. Drugs used to facilitate intubation must therefore be used judiciously. In some cases patients may already have a markedly obtunded conscious level and small doses of benzodiazepines (e.g. diazepam 5–10 mg) may be all that is required. In other patients, low doses of i.v. anaesthetic agents may be appropriate (e.g. propofol 1–2 mg/kg or etomidate 0.1–0.2 mg/kg); however, these may be associated with cardiovascular collapse.

Muscle relaxants will usually be required to facilitate intubation. Suxamethonium (1–2 mg/kg) is rapid in onset and relatively short-acting in most patients. It is the drug of choice for rapid sequence induction. It has a number of side-effects, however, which limit its use. Atracurium (0.5 mg/kg) is an alternative, but is slower in onset and has a longer duration of action.

Procedure

PERCUTANEOUS TRACHEOSTOMY

In recent years tracheostomy has become a common procedure on the ICU. Traditionally, tracheostomy was only performed after patients had been intubated for about 10–14 days because of fear of laryngeal and subglottic injury resulting from continued intubation. The advent of percutaneous techniques has allowed tracheostomy to be performed safely and easily at the bedside without the use of specialized surgical instruments, lighting or diathermy. As a result, many units now perform tracheostomy earlier.

Procedure

Explain to the patient (and relatives) what you are going to do. Get written or verbal consent. Check the patient’s coagulation status. Position the patient flat with the head and neck extended over a pillow. The majority of patients are already intubated and ventilated and are given either an intravenous or volatile anaesthetic. This is supplemented by infiltration of the surgical area with 10 mL of local anaesthetic plus adrenaline (epinephrine), which helps reduces skin edge bleeding.

A bronchoscope can be passed into the larynx during the procedure (through the endotracheal tube or laryngeal mask). This allows the anaesthetist to ensure that the endotracheal tube is withdrawn to a safe position and allows the operator to visualize the needle puncture of the trachea and the correct placement of guide wire, dilator and tracheostomy tube. A camera system and monitor make this much easier.

Operator

Tracheostomy may be safely performed through the cricothyroid membrane or in the subcricoid region. In the UK it is recommended that the tracheostomy stoma should be between the 2nd and 4th tracheal rings. At higher levels there may be an increased risk of laryngeal/tracheal stenosis, which may ultimately necessitate tracheal resection. (Resection may not be possible where the lesion is very high at the level of the first ring.) At lower levels there is an increased risk of haemorrhage from major vessels in the thoracic inlet and subsequent tube changes may be more difficult.

There are a number of different percutaneous tracheostomy kits available. Most require that the trachea is punctured by a needle and a guide wire passed through the needle into the lumen of the trachea. This is then used to guide a tracheal dilator, which creates the tracheostomy, allowing the insertion of a tracheostomy tube. The following notes are a guide only; the exact details of the method of insertion will depend upon the system used.

COMMON PROBLEMS DURING PERCUTANEOUS TRACHEOSTOMY

Complications

The potential complications of percutaneous tracheostomy are shown in Box 15.6.

Box 15.6 Complications of tracheostomy

Early Late
Bleeding (may lead to total airway obstruction) Tracheal stenosis
Pneumothorax Tracheo–oesophageal fistula
Tube misplacement or dislodgement Skin tethering / scarring
Air emphysema Late haemorrhage from innominate vessels
Mucus plugging / obstruction  
Stomal infection  

Air emphysema is common but, unless accompanied by a pneumothorax, is usually unimportant and will resolve over time. Pneumothorax is generally the result of attempting to ventilate the patient through a misplaced tube, resulting in air tracking down into the mediastinum and pleural cavities.

CRICOTHYROIDOTOMY/MINITRACHEOSTOMY

Cricothyroidotomy is a life-saving procedure used to provide emergency access to the airway (e.g. following obstruction of the upper airway) when measures such as bag and mask ventilation and tracheal intubation have failed. It involves the insertion of a small tube through the cricothyroid membrane, through which oxygen / ventilation can be provided until a definitive airway is obtained.

Minitracheostomy is a term used to describe the insertion of a similar small-bore non-cuffed tube through the cricothyroid membrane (4 mm internal diameter), principally to aid the clearance of secretions. The passage of suction catheters stimulates coughing and allows secretions to be aspirated. As a short-term measure these devices may help to prevent the need for naso-/orotracheal intubation and assisted ventilation. The small size of the tube limits its value and the use of minitracheostomy has declined in recent years.

Both cricothyroidotomy and minitracheostomy kits are commercially available. The technique for the insertion of each is essentially the same.

Procedure

Explain to the patient what you are going to do. Get written or verbal consent if appropriate. Check the patient’s coagulation status. Position the patient comfortably with the head and neck extended over a pillow. Then:

FIBREOPTIC BRONCHOSCOPY

Flexible fibreoptic bronchoscopy is a useful diagnostic and therapeutic tool in the ICU. In this situation it is usually performed on patients who have access to their airway via an endotracheal tube or tracheostomy.

Procedure

Before commencing the procedure, check that the size of the patient’s endotracheal tube is adequate to allow bronchoscopy. Tubes smaller than 8 mm internal diameter may be significantly occluded by the bronchoscope, making ventilation and oxygenation of the patient difficult. There are smaller diameter fibreoptic scopes available specifically to aid fibreoptic intubation that may be useful in this situation.

BRONCHOALVEOLAR LAVAGE

Bronchoalveolar lavage (BAL) is a technique for obtaining microbiology specimens from low in the respiratory tree, avoiding contamination of samples with upper respiratory tract flora. It may be performed during bronchoscopy or using specially designed BAL catheters.

INSERTION OF CHEST DRAIN

The emergency treatment of life-threatening tension pneumothorax is large-bore needle decompression. The diagnosis is made on clinical grounds without chest X-ray. (Hyper-resonance, reduced breath sounds, deviated trachea, haemodynamic compromise.) A 14-gauge cannula is inserted into the pleural cavity immediately above the second rib in the midclavicular line to allow air under tension in the pleural space to escape. This should always be followed by placement of a formal chest drain.

Procedure

COMMON PROBLEMS DURING INSERTION OF CHEST DRAINS

PASSING A NASOGASTRIC TUBE

Most patients in the ICU who require ventilation require a nasogastric tube, initially at least, to ensure gastric drainage and early enteral feeding (Box 15.9).

Box 15.9 Indications and contraindications for nasogastric tube

Indications Contraindications
To deflate the stomach after bag mask ventilation Base of skull fracture (use orogastric tube)
To aspirate gastric contents which might otherwise reflux and soil the airway Recent gastric or oesophageal surgery (discuss with surgeon)
To provide a route for enteral feeding and drugs Oesophageal varices (relative contraindication)
  Severe coagulopathy (consider oral route to avoid nose bleed)

PASSING A SENGSTAKEN–BLAKEMORE TUBE

A number of tubes have been designed to apply pressure to oesophageal varices in order to compress the vessels and reduce bleeding while the patient is resuscitated and definitive treatment carried out. The Sengstaken–Blakemore tube has three lumens. Two are used to inflate balloons, one in the stomach and the other in the oesophagus, while the third is used to aspirate gastric contents.

Procedure

TURNING A PATIENT PRONE

Patients may be turned prone when oxygenation is critical despite ventilation and high inspired oxygen concentrations. (See ALI, p. 154.) Turning large adult patients prone can be hazardous both for the staff and the patient. Where possible, hoists or other aids to handling patients should be used. The nursing staff will advise on the best approach. In general terms, whatever approach to physically turning the patient is adopted, there must be adequate numbers of staff available to ensure patient safety, and security of airway, vascular cannulae and drains, etc.

TRANSPORT OF CRITICALLY ILL PATIENTS

Critically ill patients in intensive care often require transport either within the hospital (for example for investigations or surgery), or between hospitals (for example, for specialist care). You are therefore likely to be involved in transporting a patient at some stage, even if only within your own hospital.

The standards of care during transport, whether intrahospital or interhospital, should be the same as that provided within the ICU. Before moving the patient, it is important that the patient is fully resuscitated and stable. If there is any doubt regarding the adequacy of resuscitation, this should be addressed before transfer. The general principles are as follows:

During the transfer you should be accompanied by an intensive care nurse or an operating department assistant. The transfer should be fully documented, including a record of pulse, blood pressure, ventilation and other vital signs. In the case of inter-hospital transfer, notify the receiving hospital of your departure and expected arrival times in advance to enable suitable preparation to be made.