When using an Abbocath , on cannulating the vein, remember to advance the sheath and needle a few mm to allow the tip of the plastic sheath (71 mm behind the tip of the beveled needle) to enter the vein. Holding the needle stationary, advance t he sheath over it into the vein. Arrange for a chest X-ray (CXR) to con \201 rm the position of the line. INTERNAL JUGULAR VEIN CANNULATION 793 Sternal head Sternal head Clavicular head Sternocleidomastoid muscle External jugular vein (a) Surface anatomy of external and internal jugular veins (b) Anterior approach: the chin is in the midline and the skin puncture is over the sternal head of the SCM muscle (c) Central approach: the chin is turned away and the skin puncture is between the two head s of the SCM muscle Fig. 18.3 Internal jugular vein cannulation. 794 CHAPTER 18 Practical procedures Subclavian vein cannulation The axillary vein becomes the subclavian vein (SCV) at the late ral border of the 1st rib and extends for 3 \200\2234 cm just deep to the clavicle. It is j oined by the ipsilateral IJV to become the brachiocephalic vein behind the ster- noclavicul ar joint (see Fig. 18.4 ). The subclavian artery and brachial plexus lie posteriorly, separ ated from the vein by the scalenus anterior muscle. The phrenic nerve and the internal mamm ary artery lie behind the medial portion of the SCV and, on the left, lies the thoracic duc t. \200 Select the point 1 cm below the junction of the medial third and middle third of the clavicle. If possible, place a bag of saline between the scapulae to extend th e spine. Clean the skin with iodine or chlorhexidine. \200 In \201 ltrate the skin and subcutaneo us tissue and periosteum of the inferior border of the clavicle with local anesthetic up to the hilt of the green (21G) nee dle, ensuring that it is not in a vein. Insert the introducer needle with a 10 mL syringe, guiding gently under the clavicle. It is safest to initially hit the clavicle, and \200\230walk \200\231 the needle under it until the inferior border is just cleared. In this way you keep the needle as super \201 cial t o the dome of the pleura as possible. Once it has just skimmed underneath the clavicle, adv ance it slowly towards the contralateral sternoclavicular joint, aspirating as you advance. Using this technique, the risk of pneumothorax is small, and success is high. Once the venous blood is obtained, rotate the bevel of the needle towards the heart. This encourages the guide wire to pass down the brachiocephalic vein rat her than up the IJV. The wire should pass easily into the vein. If there is dif \201 culty, try advancing durin g the inspiratory and expiratory phases of the respiratory cycle. Once the guide wire is in place, remove the introducer needle, and pass the dilator over th e wire. When removing the dilator, note the direction that it faces; it should be slightly curved downwards. If it is slightly curved upwards, then it is likely that the wire has pas sed up into the IJV. The wire may be manipulated into the brachiocephalic vein under \202 uoroscopic control but, if this is not available, it is safer to remove the wire and start again. After removing the dilator, pass the central venous catheter over the guide wire, remove the guide wire, and secure as above. A CXR is mandatory after subclavian line insertion, to exclude a pneumothorax and to con \201 rm satisfactory placement of the line, especially if \202 uoroscopy was not employed . SUBCLAVIAN VEIN CANNULATION 795 Scalenus anterior muscle Subclavian artery Clavicle Phrenic nerve Subclavian vein 1st rib 2nd rib 3rd rib Fig. 18.4 The subclavian vein and surrounding structures. 796 CHAPTER 18 Practical procedures Ultrasound-guided central venous catheterization (1) Traditional central venous catheteriza tion methods rely on anatomical landmarks to predict vein position. However, the relationsh ip between such landmarks and vein position varies signi \201 cantly in \200\230normal \200\231 individuals. Failure and complication rates using landmark methods are signi \201 cant, and therefore serious complications may occur. Recent advances in portable ultrasoun d equipment have now made it possible to insert central venous catheters under two-dimensio nal (2D) ultrasound guidance. Advantages of this technique include: identi \201 cation of the actual and relative vein position \200 identi \201 cation of anatomical variations \200 con \201 rmation of target vein patency. Guidelines from the National Institute for Clinical Excellence (September 2002) state: \200\230Two-dimensional imaging ultrasound guidance is recommended as the preferred method for insertion of centra l venous catheters into the internal-jugular vein (IJV) in adults and children in elective situations \200\231. However, training and equipment availability render such recommendatio ns effectively useless in the UK at present. Equipment/personnel needed \200 Standard Seldinger-type kit or whatever is locally availa ble. \200 An assistant is essential. \200 Ultrasound equipment: screen: displays 2D ultrasound image of anatomical structures. \200 sheaths: dedicated, s terile sheaths of PVC or latex, long enough to cover the probe and connecting cable (a rubb er band secures the sheath to the probe). probe: transducer which emits and receives ultrasound information to be processed for displ ay; marked with an arrow or notch for orientation. power: battery or mains. \200 sterile gel: transmits ultrasound and provides good interfa ce between patient and probe. Preparation Perform a preliminary non-sterile scan to access each IJV for patency and size. Patient Sterile precautions should be taken with patient \200\231s head turned slightly awa y from the cannulation site. Head-down tilt (if tolerated) or leg ele- vation should be use d to increase the \201 lling and size of the IJV. Ensure adequate drapes to maintain a st erile \201 eld. Excessive head rotation or extension may decrease the diameter of the vein. ULTRASOUND-GUIDED CENTRAL VENOUS CATHETERIZATION (1) 797 Ultrasound equipment \200 Ensure that the display can be seen. \200 The sheath is opene d (operator) and gel squirted in (assistant). A generous amount of gel ensures good contact and air-free coupling between the probe tip a nd sheath. Too little may compromise image quality. The probe and connecting cable are lowered into the sheath (assistant), which is then unrol led along them (operator). A rubber band secures the sheath to the probe. \200 The sheath over the probe tip is smoo thed out (wrinkles will degrade image quality). Apply liberal amounts of gel to the sheathed probe tip for good ultrasound transmission and increased patient comfort during movement. 798 CHAPTER 18 Practical procedures Ultrasound-guided central venous catheterization (2) Scanning The most popular scanning ori entation for IJV central catheter placement is the transverse plane: \200 apply the probe tip gently to the neck lateral to the carotid pulse at the cricoid level or in the sternomastoid-clavicular triangle. keep the probe perpendicular at all times, with the tip \202 at against the skin. orientate the probe so that movement to the left ensures that the display looks to the left (and vise versa). Probes are usually marked to help orientation. By convention, the mark should be to the patient \200\231s right (transverse plane) or to t he head (longitudinal scan). The marked side appears on the screen as a bright dot. if the vessels are not immediately visible, keep the probe perpendicular and gently glide medially or laterally until they are found. When moving the probe, watch the screen \200\224 not your hands. After identi \201 cation of the internal jugular vein \200 Position the probe so that th e IJV is shown at the display \200\231s horizontal midpoint. Keep the probe immobile. \200 Direct the needle (bevel towards probe) caudally under the marked midpoint of the probe tip at approximately 60 to the skin. The needle bevel faces the probe to help direct the guide wire down the IJV later. Advance the needle towards the IJV. Needle passage causes a \200\230wavefront \200\231 of tissue compression. This is used to judge the progress of the needle and position. Absence of visible tissue reaction indicates incorrect needle placement. Just before vessel entry, \200\230tenting \200\231 of the vein is usually observed. One of the most dif \201 cult aspects to learn initially, is the steep needle angulation r equired, but this ensures that the needle enters the IJV in the ultrasound (US) beam and ta kes the shortest and most direct route through the tissues. Needle pressure may oppose the vein walls, resulting in vein trans \201 xion. Slow withdra wal of the needle with continuous aspiration can help result in lumen access. Pass the guide wire into the jugular vein in the usual fashion. Re-angling the needle from 60 to a shallower angle, e.g. 45 , may help guide-wire feeding. Scanning the vein in the longitudinal plane may demonstrate the catheter in the vessel but after securing and dr essing the central venous catheter (CVC), an X-ray should still be obtained to con \201 rm the CVC position, and exclude pneumothorax. The most common error in measurement of CVP, particularly in CVP lines that have been in pl ace for some time, is due to partial or complete line blockade. With the manometer connecte d, ensure that the line is ULTRASOUND-GUIDED CENTRAL VENOUS CATHETERIZATION (2) 799 free \202 owing; minor blockages can be removed by squeezing the rubber bung, with the pr oximal line being obliterated by acute angulation (i.e. bend the tube proximally). Measure the CVP at the mid-axillary line with the patient supine. CVP falls with upright or semi-up right recumbency, regardless of the reference point. If the CVP is high, lift the stand tha t holds the manometer so that the apparent CVP falls by 10 cm or so, and replace the CVP st and to ground level. If the saline or manometer reading rises to the same level, then the C VP reading is accurate. In other words, one ensures that the CVP manometer level both falls to and rises to the same level. 800 CHAPTER 18 Practical procedures Pulmonary artery catheterization (1) Indications Pulmonary artery (PA) catheters (Swan \200 \223Ganz catheters) allow direct measurement of a number of haemodynamic parameters that ai d clinical decision making in critically ill patients (evaluate right and left ventricular function, guide treatment, and provide prognostic information). The catheter itself has no therapeutic bene \201 t and there have been a number of studies showing increased mortalit y (and morbidity) with their use. Consider inserting a PA catheter in any critically ill pa tient, after discus- sion with an experienced physician about whether the measurements will in \202 uence decisions on therapy (and not just to reassure yourself). Careful and frequ ent clinical assessment of the patient should always accompany measurements, and PA cathete rization should not delay treatment of the patient. General indications (not a comprehensive list) include: \200 management of complicated my ocardial infarction (MI). \200 assessment and management of shock. \200 assessment and management of respiratory distress (cardiogenic vs. non-cardiogenic pulmonary oedema). evaluation of the effects of treatment in unstable patients (e.g. inotropes, vasodilators, mechanical ventilation, etc.). \200 delivering therapy (e.g. thrombolysis for pulmonary e mbolism, prostacyclin for pulmonary hypertension, etc.). assessment of \202 uid requirements in critically ill patients. Equipment required \200 Full resuscitation facilities should be available and the patient \200\231s electrocardiogram (ECG) should be continuously monitored. Bag of heparinized saline for \202 ushing the catheter and transducer set for pressure mo nitoring. (Check that your assistant is experienced in setting up the transducer system BEF ORE you start.). 8F introducer kit (pre-packaged kits contain the introducer sheath and all the equipment required for central venous cannulation). \200 PA catheter: commonly a triple-lumen catheter, that allows simultanous measurement of right atrial (RA) pressure (proximal port) and PA pressure (dist al port) and incorporates a thermistor for measurement of cardiac output by thermodilution. Check your catheter before you start. Fluoroscopy is preferable, though not essential. General technique (see Fig. 18.5 ) \200 Do not attempt this without supervision if you ar e inexperienced. \200 Observe strict aseptic technique using sterile drapes, etc. \200 Insert the introducer sheath (at least 8F in size) into either the internal jugular or subc lavian vein in the standard way. Flush the sheath with saline and secure to the skin with s utures. Do not attach the plastic sterile expandable sheath to the introducer yet but keep it steri le for use later once the catheter is in position (the catheter is easier to manipulate wit hout the plastic covering). PULMONARY ARTERY CATHETERIZATION (1) 801 Flush all the lumens of the PA catheter and attach the distal lumen to the pressure transducer. Check the transducer is zeroed (conventionally to the mid -axillary point). Check the integrity of the balloon by in \202 ating it with the syringe provided (1 \200\2232 mL air), and then de \202 ate the balloon. (a) (b) (c) Fig. 18.5 Pulmonary artery catheterization. (a) The sheath and dilator are advanced into th e vein over the guide wire. A twisting motion makes insertion easier. (b) The guide wire an d dilator are then removed. The sheath has a haemostatic valve at the end preventing leakag e of blood. (c) The PA catheter is then inserted through the introducer sheath into the vei n. 802 CHAPTER 18 Practical procedures Pulmonary artery catheterization (2) Insertion technique \200 Flush all the lumens of the PA catheter and attach the distal lumen to the pressure transducer. Check the transducer is zeroed (conventionally to the mid -axillary point). Check the integrity of the balloon by in \202 ating it with the syringe provided and then de \202 ate the balloon. Pass the tip of the PA catheter through the plastic sheath, keeping the sheath compressed. The catheter is easier to manipulate without the sheath over it; once in position, extend t he sheath over the catheter to keep it sterile. With the balloon de \202 ated, advance the tip of the catheter to approx 10 \200\22315 cm from the right IJV or SCV, 15 \200\22320 cm from the left (the mark ings on the side of the catheter are at 10 cm intervals: 2 lines = 20 cm). Check that the p ressure tracing is typical of the right atrial pressure (Fig. 18.6 ). In \202 ate the balloon and advance the catheter gently. The \202 ow of blood will carry the balloon (and catheter) across the tricuspid valve, through the right ventricle and int o the pulmonary artery (see Fig. 18.5 ). \200 Watch the ECG tracing closely whilst the ca theter is advanced. The catheter commonly triggers runs of ventricular tachycardia (VT) when crossing the tricuspid valve and through the right ventricle (RV). The VT is usually self-limiting, but should no t be ignored. De \202 ate the balloon, pull back, and try again. If more than 15 cm of catheter is advanced into the RV without the tip entering the PA, thi s suggests the catheter is coiling in the RV. De \202 ate the balloon, withdraw the cathet er into the RA, rein \202 ate the balloon, and try again using clockwise torque while adva ncing in the ventricle, or \202 ushing the catheter with cold saline to stiffen the plast ic. If this fails repeatedly, try under \202 uoroscopic guidance. As the tip passes into a distal branch of the PA, the balloon will impact and not pass furt her \200\224 the wedge position \200\224 and the pressure tracing will change (see Fig. 1 8.6 ). De \202 ate the balloon and check that a typical PA tracing is obtained. If not, try \202 ushing the catheter lumen, and if that fails, withdraw the catheter until the tip is w ithin the PA and begin again. Rein \202 ate the balloon slowly. If the pulmonary capillary wedge pressure (PCWP) is seen before the balloon is fully in \202 ated, it suggests the tip has migrated further into t he artery. De \202 ate the balloon, withdraw the catheter 1 \200\2232 cm, and try again. If the pressure tracing \202 attens and then continues to rise, you have \200\230overwedged \200\231. De \202 ate the balloon, pull the catheter back 1 \200\2232 cm, and start again. When a stable position has been achieved, extend the plastic sheath over the catheter and s ecure it to the introducer sheath. Clean any blood from the skin insertion site with antise ptic, and secure a coil of the PA catheter to the patient \200\231s chest to avoid inadvert ent removal. \200 Obtain a CXR to check the position of the catheter. The tip of the cath eter should ideally be no more than 3 \200\2235 cm from the midline. PULMONARY ARTERY CATHETERIZATION (2) 803 Normal values of right heart pressures and \202 ows Right atrial pressure 0 \200\2238 mmHg Right ventricle systolic 15 \200\22330 mmHg 0 \200\2238 mmHg end diastolic Pulmonary artery systolic/diastolic 15 \200\22330/4 \200\22312 mmHg 9 \200\22316 mmHg mean PCWP 2 \200\22310 mmHg 2.8 \200\2234.2 L/min/m 2 Cardiac index 60 50 40 30 20 10 0 ) g H m m ( Right atrium Right ventricle Pulmonary artery Wedge position (PCWP) Fig. 18.6 Pressure tracings during pulmonary artery catheterization. 804 CHAPTER 18 Practical procedures Pulmonary artery catheterization (3) Tips and pitfalls \200 Never withdraw the catheter w ith the balloon in \202 ated. \200 Never advance the catheter with the balloon de \202 ated. \200 Never inject liquid into the balloon. \200 Never leave the catheter with the balloon in \202 ated, as pulmonary infarction may occur. The plastic of the catheter softens with time at body temperature and the tip of the cathet er may migrate further into the PA branch. If the pressure tracing with the balloon de \202 ated is \200\230partially wedged \200\231 (and \202 ushing the catheter does not im prove this), withdraw the catheter 1 \200\2232 cm and reposition. Sometimes it is impossible to obtain a wedged trace. In this situation, one has to use the PA diastolic pressure as a guide. In health there is 72 \200\2234 mmHg difference between P A diastolic pressure and PCWP. Any condition that causes pulmonary hypertension (e.g. sever e lung disease, acute respiratory distress syndrome (ARDS), longstanding valvular disease) will alter this relationship. Valvular lesions, ventricular septal defects (VSDs), prosthetic valves, and pacemakers : if these are present then seek advice from a cardiologist. The risk of subacute bacterial end ocarditis (SBE) may be suf \201 ciently great that the placement of a PA catheter may be m ore detrimental than bene \201 cial. Positive end-expiratory pressure (PEEP) : measurement and interpretation of PCWP in patient s on PEEP depends on the position of the catheter. Ensure the catheter is below the level o f the left atrium on a lateral CXR. Removing PEEP during measurement causes marked \202 u ctuations in haemodynamics and oxygenation and the pressures do not re \202 ect the state once back on the ventilator. Complications \200 Arrhythmias : watch the ECG tracing closely while the catheter is advanced. The catheter commonly triggers runs of VT when crossing the tricuspid valve and t hrough the RV. If this happens, de \202 ate the balloon, pull back, and try again. The VT is usually self-limiting, but should not be ignored. Pulmonary artery rupture (70.2 % in one series): damage may occur if the balloon is overin \202 ated in a small branch. Risk factors include mitral valve disea se (large v wave confused with poor wedging), pulmonary hypertension, multiple in \202 ati ons or hyperin \202 ations of the balloon. Haemoptysis is an early sign. It is safer to fo llow PA diastolic pressures if these correlate with the PCWP. Pulmonary infarction. \200 Knots : these usually occur at the time of initial placement i n patients where there has been dif \201 culty in traversing the RV. Signs include loss of pressure tracing, persistent ectopy, and resistance to catheter manipulation. If this is s uspected, stop manipulation and seek expert help. PULMONARY ARTERY CATHETERIZATION (3) 805 Infection : risks increase with the length of time the catheter is left in situ . The pressure transducer may occasionally be a source of infection. Remove the cathet er and introducer, and replace only if necessary. \200 Other complications : complication s associated with central line insertion, thrombosis and embolism, balloon rupture, intracardiac damage. 806 CHAPTER 18 Practical procedures Indications for temporary pacing 1. Following acute myocardial infarction \200 Asystole. \200 Symptomatic complete heart block (CHB) (any territory). \200 Symptomatic 2 o heart block (any territory). \200 Trifascicular block \200\224 alternating left and right bun dle branch block (LBBB and RBBB). \200 p heart block + RBBB + left anterior descending artery (LAD). \200 new RBBB and left posterior hemiblock. \200 LBBB and long PR interval. After anterior MI . asymptomatic CHB. \200 asymptomatic s (Mobitz II) block. Symptomatic sinus bradycardia unresponsive to atropine. \200 Recurrent VT for atrial or v entricular overdrive pacing. 2. Unrelated to myocardial infarction \200 Symptomatic sinus or junctional bradycardia th at is unresponsive to atropine (e.g. carotid sinus hypersensitivity). \200 Symptomatic s heart block or sinus a rrest. \200 Symptomatic complete heart block. \200 Torsades de pointes tachycardia. \200 Recurrent VT for atrial or ventricular overdrive pacing. \200 Bradycardia-dependent tachycardia. \200 Drug overdose (e.g. verapamil, B-blockers, digoxin). \200 Permanent pacemaker box change in a pacing-dependent patient. 3. Before general anesthesia \200 The same principles as for acute MI (see above). \200 Sinoatrial disease and s (Wenckebach) heart block only need prophylactic pacing if there are symptoms of syncope or pre-syncope. Complete heart block. Transvenous temporary pacing \200 The technique of temporary wire insertion is described on b Temporary ventricular pacing, p. 808. The most commonly used pacing mode and the mode of choice for life-threatening bradyarrhyth mias is ventricular demand pacing with a single bipolar wire positioned in the right ventri cle. In critically ill patients with impaired cardiac pump function and symptomatic bradycardia (especially with RV infarction), cardiac output may be increased by up to 20 % by maintaini ng atrioventricular (AV) synchrony. This requires two pacing leads, one atrial and one vent ricular, and a dual pacing box. Epicardial temporary pacing \200 Following cardiac surgery, patients may have epicardial wires (attached to the pericardial surface of the heart) left in for up to 1 week in case o f postoperative bradyarrhythmia. These are used in the same way as transvenous pacing wires , but the threshold may be higher. INDICATIONS FOR TEMPORARY PACING 807 Indications for temporary transvenous cardiac pacing Emergency/acute \200 Acute myocardial infarction: (class I: American College of Cardiolog y/ American Heart Association (ACC/AHA)). 3 Asystole. \200 Symptomatic bradycardia (sinus bradycardia with hypotension and type I sec ond-degree AV block with hypotension not responsive to atropine). Bilateral bundle branch block (alternating BBB or RBBB with alternating left anterior/left posterior hemiblock (LAHB/LPHB)). \200 New or indeterminat e age bifascicular block with \201 rst-degree AV block. Mobitz type II second-degree AV block. Bradycardia not associated with acute myocardial inf arction \200 Asystole. \200 Second or third-degree AV block with haemodynamic compromis e or syncope at rest. Ventricular tachyarrhythmias secondary to bradycardia. Elective \200 Support for procedur es that may promote bradycardia. \200 General anesthesia with: 2nd- or 3rd-degree AV block. \200 Intermittent AV block. \200 1st degree AV block with bifascicular block. \200 1st degree AV block and LBBB. Cardiac surgery. Aortic surgery. \200 Tricuspid surgery. \200 VSD closure. \200 Ostium primum repair. Rarely considered for coronary angioplasty (usually to right coronary artery) Overdrive suppression of tachyarrhythmias Reproduced with permission from Gammage MD (2000). Temporary cardiac pacing. Heart 83 : 715 \200\22320. Atrioventricular sequential pacing In critically ill patients with impaired cardiac pump fu nction and symp- tomatic bradycardia (especially with RV infarction), cardiac output may be increased by up to 20 % by maintaining AV synchrony. This requires two pacing leads, one a trial and one ventricular, and a dual pacing box (see b DC cardioversion: special situation s, p. 821). 808 CHAPTER 18 Practical procedures Temporary ventricular pacing \200 Cannulate a central vein : the wire is easiest to manip ulate via the right internal jugular (RIJ) approach but is more comfortable for the patient via the right subclavian (SC) vein. The left internal jugular (LIJ) approach is best avoid ed as there are many acute bends to negotiate and it is dif \201 cult to achieve a stable position. Avoid the left subclavicular area as this is the preferred area for permanent pac emaker insertion and should be kept \200\230virgin \200\231 if possible. The femoral vein may be used (incidence of deep vein thrombosis (DVT) and infection is high). \200 Insert a sheath (similar to that for PA catheterization) through which the pacing wire can be fed. Pacing wires are commonly 5F or 6F, and a sheath at least one s ize larger is necessary. Most commercially available pacing wires are pre-packed with an in troducer needle and plastic cannula similar to an Abbocath , which may be used to positi on the pacing wire. However, the cannula does not have a haemostatic seal. The plastic cann ula may be removed from the vein, leaving the bare wire entering the skin, once a stable po sition has been achieved. This reduces the risk of wire displacement but also makes reposit ioning of the wire more dif \201 cult should this be necessary, and infection risk is high er. \200 Pass the wire through the sterile plastic cover that accompanies the introducer sheath, and advance it into the upper right atrium (see Fig. 18.7 ) but do not unfurl the c over yet. The wire is much easier to manipulate with gloved hands without the hindrance of the plastic cover. Advance the wire with the tip pointing towards the right ventricle; it may cross the tricus pid valve easily. If it fails to cross, point the tip to the lateral wall of the atrium and form a loop. Rotate the wire and the loop should fall across the tricuspid valve into the ventricle. Advance and rotate the wire so that the tip points inferiorly as close to the tip of the right ventricle (laterally) as possible. If the wire does not rotate down to the apex easily, it may be because you are in the coron ary sinus rather than in the right ventricle. (The tip of the wire points to the left shoul der). Withdraw the wire and recross the tricuspid valve. Leave some slack in the wire; the \201 nal appearance should be like the outline of a sock, with the \200\230heel \200\231 in the right atrium, the \200\230arch \200\231 over the tricuspid, and the \200\230big toe \200\231 at the tip of the right vent ricle. \200 Connect the wire to the pacing box and check the threshold. Ventricular pacing thresholds should be <1.0 V but a threshold up to 1.5 V is acceptable if another stable position cannot be achieved. Check for positional stability. With the box pacing at a rate higher than the intrinsic hea rt rate, ask the patient to take some deep breaths, cough forcefully, and sniff. Watch for failure of capture and, if this occurs, reposition the wire. Set the output to 3 V and the box on \200\230demand \200\231. If the patient is in sinus r hythm and has an adequate blood pressure, set the box rate to just below the patient \200 \231s rate. If there is complete heart block or bradycardia, set the rate at 70 \200\22380/ min. Cover the wire with the plastic sheath and suture the sheath and wire securely to the skin. Loop the rest of the wire and \201 x to the patient \200\231s skin with adhesive dressin g. TEMPORARY VENTRICULAR PACING 809 When the patient returns to the ward, obtain a CXR to con \201 rm satisfactory positioning of the wire and to exclude a pneumothorax. Checklist for pacing wire insertion \200 Check the screening equipment and de \201 brill ator are working. \200 Check the type of pacing wire: atrial wires have a pre-formed \200\230J \200\231 that allows easy placement in the atrium or appendage and is very dif \201 cult to manipulate into a satisfactory position in the ventricle. Ventricular pacing w ires have a more open, gentle \200\230J \200\231. Check the pacing box (single vs. dual or sequential pacing box) and leads to attach to the wire(s). Familiarize yourself with the controls on the box: you may need to connect up in a hurry if the patient \200\231s intrinsic rhythm slows further. Remember to don the lead apron before wearing the sterile gown, mask and gloves. SVC Pulmonary artery RV Tricuspid valve IVC Fig. 18.7 Insertion of a ventricular pacing wire (see text for details) Reproduced with per mission from Ramrakha P, Moore K (2004). Oxford Handbook of Acute Medicine . 2nd edn. Oxfor d: Oxford University Press. 810 CHAPTER 18 Practical procedures Temporary atrial pacing \200 The technique of inserting an atrial temporary wire is simil ar to that of ventricular pacing. Advance the atrial wire until the \200\230J \200\231 is reformed in the right atrium. \200 Rotate the wire and withdraw slightly to position the tip in the right atrial appendage. Aim for a threshold of <1.5 V. If atrial wires are not available, a ventricular pacing wire may be manipulated into a similar position or passed into the coronary sinus for left atrial pacin g. ATRIOVENTRICULAR SEQUENTIAL PACING 811 Atrioventricular sequential pacing In critically ill patients with impaired cardiac pump fu nction and symp- tomatic bradycardia (especially with right ventricular infarction), cardia c output may be increased by up to 20 % by maintaining atrioventricular syn- chrony. This r equires two pacing leads, one atrial and one ventricular, and a dual pacing box. Patients most likely to bene \201 t from AV sequential pacing \200 Acute MI (especially RV infarction). \200 \200\230Stiff \200\231 left ventricle: aortic stenosis, hypertrophi c cardiomyopathy (HCM), hypertensive heart disease, amyloidosis. Low cardiac output states (cardiomyopathy). \200 Recurrent atrial arrhythmias. 812 CHAPTER 18 Practical procedures Temporary pacing: complications Ventricular ectopics or VT \200 Non-sustained VT is commo n as the wire crosses the tricuspid valve (especially in patients receiving an isoprenaline infusion) and does not require treatment. Try to avoid long runs of VT and, if necessary, withdraw the wire into the atrium and wait until the rhythm has settled. If ectopics persist after the wire is positioned, try adjusting the amount of slack in the wire in the region of the tricuspid valve (either more or less). Pacing the right ventricular out \202 ow tract (RVOT) can provoke runs of VT. Failure to pace and/or sense \200 It is dif \201 cult to get low pacing thresholds (<1.0 V) in patients with extensive MI (especially of the inferior wall) or cardiomyopathy, or w ho have received class I antiarrhythmic drugs. Accept a slightly higher value if the positi on is otherwise stable and satisfactory. If the position of the wire appears satisfactory and yet the pacing thresholds are high, th e wire may be in a left hepatic vein. Pull the wire back into the atrium and try again, loo king speci \201 cally for the ventricular ectopics as the wire crosses the tricuspid valve . The pacing threshold commonly doubles in the \201 rst few days due to endocardial oedema. If the pacemaker suddenly fails, the most common reason is usually wire displacement. Increase the pacing output of the box. \200 Check all the connections of the wire and the battery of the box. \200 Try moving the patient to the left lateral position until arran gements can be made to reposition the wire. Perforation \200 A pericardial rub may be present in the absence of perforation (especially post-MI). Presentation : pericardial chest pain, increasing breathlessness, falling blood pressure, e nlarged cardiac silhouette on CXR, signs of cardiac tamponade, left diaphragmatic pacing at low output. Management: if there are signs of cardiac tamponade arrange for urgent echocardiography (ECHO) and reposition the wire. monitor the patient carefully over the next few days, with repeat ECHOs to detect incipient cardiac tamponade. TEMPORARY PACING: COMPLICATIONS 813 Diaphragmatic pacing \200 High-output pacing (10 V), even with a satisfactory position of the ventricular lead may cause pacing of the left hemidiaphragm. At low voltages, this suggests perforation (see above). Right hemidiaphragm pacing may be seen with atrial pacing and stimulation of the right phrenic nerve. Reposition the wire if symptomatic (painful twitching, dyspnoea). Complications of temporary pacing \200 Complications associated with central line inserti on \200 Ventricular ectopics \200 Non-sustained VT \200 Perforation \200 Pericardit is \200 Diaphragmatic pacing \200 Infection \200 Pneumothorax \200 Cardiac tamponad e 814 CHAPTER 18 Practical procedures Pericardial aspiration (1) Equipment Establish peripheral venous access and check that full facilities for resusci- tation are available. Pre-prepared pericardiocentesis sets may be available. You will need: \200 trolley as for central line insertion, with iodine or chlo rhexidine for skin, dressing pack, sterile drapes, local anesthetic (lidocaine 2 % ), syrin ges (including a 50 mL), needles (25G and 22G), No. 11 blade, and silk sutures. pericardiocentesis needle (15 cm, 18G) or similar Wallace cannula. \200 J guide wire ( (c id:2) 80 cm, 0.035 diameter). \200 dilators (up to 7 Fr). \200 pigtail catheter ( (cid: 2) 60 cm with multiple sideholes, a large Seldinger-type CVP line can be used if no pigtail is available). drainage bag and connectors. \200 facilities for \202 uoroscopy or echocardiographic sc reening. Technique (see Fig. 18.8 ) \200 Position the patient at 730 * . This allows the effusion to pool inferiorly within the pericardium. Sedate the patient lightly with midazolam (2.5 \200\2237.5 mg IV) and fentanyl 50 \200\2232 00 mcg IV) if necessary. Use with caution as this may drop the blood pressure (BP) in patie nts already compromised by the effusion. \200 Wearing a sterile gown and gloves, clean th e skin from mid-chest to mid-abdomen and put the sterile drapes on the patient. In \201 ltrate the skin and subcutaneous tissues with local anesthetic starting 1 \200\2231.5 cm below the xiphisternum and just to the left of the midline, aimin g for the left shoulder and staying as close to the inferior border of the rib cartilages a s possible. The pericardiocentesis needle is introduced into the angle between the xiphisternum and the left costal margin angled at 730 * . Advance slowly, aspirating gently, and then injecting more lidocaine every few millimeters, aiming for the left shoulder. As the parietal pericardium is pierced, you may feel a \200\230give \200\231 and \202 ui d will be aspirated. Remove the syringe and introduce the guide wire through the needle. Check the position of the guide wire by screening. It should loop within the cardiac silhou ette only and not advance into the superior vena cava (SVC) or PA. Remove the needle, leaving the wire in place. Enlarge the skin incision slightly using the blade, and dilate the track. Insert the pigtail over the wire into the pericardial space and remove the wire. Take specimens for microscopy, culture (and inoculate a sample into blood culture bottles), cytology, and haematocrit if blood stained (a full blood count (FBC) tube; ask the hematol ogists to run on the Coulter counter for rapid estimation of Hb). PERICARDIAL ASPIRATION (1) 815 Aspirate to dryness watching the patient carefully. Symptoms and haemodynamics (tachycardia) often start to improve with removal of as little as 100 mL of p ericardial \202 uid. If the \202 uid is heavily blood stained, withdraw \202 uid cautiously \200\224 if the pigtail is in the right ventricle, withdrawal of blood may cause cardiovascular collapse. Arrange for urgent Hb/haematocrit. Leave on free drainage and attached to the drainage bag. \200 Suture the pigtail to the s kin securely and cover with a sterile occlusive dressing. Fig. 18.8 Pericardial aspiration. Reproduced with permission from Ramrakha P, Moore K, and Sam M (2010). Oxford Handbook of Acute Medicine . 3rd ed. Oxford: Oxford University Press. Aftercare \200 Closely observe the patient for recurrent tamponade (obstruction of drain) and repeat ECHO. \200 Discontinue anticoagulants. \200 Remove the drain after 24 hours or when the drainage stops. \200 Consider the need for surgery (drainage, biopsy o r pericardial window) or speci \201 c therapy (chemotherapy if malignant effusion, antimic robials if bacterial, dialysis if renal failure, etc.). 816 CHAPTER 18 Practical procedures Pericardial aspiration (2) Tips and pitfalls \200 If the needle touches the heart \200 \231s epicardial surface , you may feel a \200\230ticking \200\231 sensation transmitted d own the needle: withdraw the needle a few millimeters, angulate the needle more super \201 cially, and try cautiously again, aspirating as you advance. If you do not enter the effusion , and the heart is not encountered: \200 withdraw the ne edle slightly and advance again, aiming slightly deeper, but still towards the left shoulder. if this fails, try again, aiming more medially (mid-clavicular point or even suprasternal notch). consider trying the apical approach (starting laterally at the cardiac apex and aiming for the right shoulder), if ECHO con \201 rms suf \201 cient \202 uid a t the cardiac apex. If available, intrathoracic ECG can be monitored by a lead attached to the needle as it is advanced. This is seldom clinically useful in our experience. Penetr ation of the myocardium results in ST elevation, suggesting the needle has been advanced to o far. Dif \201 culty in inserting the pigtail : this may be because of insuf \201 cient dilatation of the tract (use a larger dilator). holding the wire taught (by gentle traction) while pushing the catheter may help; take care not to pull the wire out of the pericardium. Haemorrhagic effusion vs. blood : compare the Hb of the pericardial \202 uid to the venous blood Hb \200 place some of th e \202 uid in a clean container; blood will clot, whereas haemorrhagic effusion will not, as the \200\230whipping \200\231 action of the heart tends to de \201 brinate it. con \201 rm the position of the needle by \201 rst withdrawing some \202 uid and then injecting 10 \200\22320 mL of contrast; using \202 uoroscopy; see if the contrast stays w ithin the cardiac sillhouette.