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# (p. 758) Practical procedures

Practical procedures
Chapter:
Practical procedures
DOI:
10.1093/med/9780199689903.003.0018
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date: 03 August 2020

Fig 18.1
nhs ‘clean your hands’ campaign poster.

Contains public sector information licensed under Open Government Licence v3.0. https://www.whatdotheyknow.com/request/21861/response/56086/attach/3/04072%20Hand%20Hygiene%205%201.1.pdf

Hungarian obstetrician Ignaz Semmelweis demonstrated the benefits of handwashing in the 1840s: he observed that maternal mortality was nearly three times as high on a doctor-run maternity ward compared to a midwife-run ward. The explanation remained elusive until Semmelweis’ friend Jakob Kolletschka died after receiving an accidental scalpel cut from a student during a post-mortem demonstration. Semmelweis recognized in Kolletschka’s death many of the features of the dying mothers. The explanation: the maternity ward doctors’ day started with post-mortem examinations, from which they would procede to perform vaginal examinations on the living without washing their hands. Noticing this, Semmelweis introduced the practice of washing hands with chloride of lime and cut death rates to that of the midwives’ patients. Despite the evidence he amassed, Semmelweis’s theory was rejected by his contemporaries, a rejection which undoubtedly contributed to his psychiatric distress, eventual commitment to an asylum, and ultimate death from the blows of his guards. It would take another 20 years and countless deaths before Lister published his landmark work on the use of carbolic acid in surgery.

Take a minute to wash your hands thoroughly before undertaking any procedure. This prerequisite will not only reduce infection risk for your patients, but give you a moment for mindfulness: focus on the hot water running over your hands, breathe deeply, and for a while forget about your list of jobs. Perhaps spare Dr Kolletschka a thought. You may find that the subsequent procedure goes more smoothly than anticipated.

## (p. 760) Placing iv cannulae

Much of what we do is not evidence based; however, in more recent years, particularly in intensive care units, the rise of hospital-acquired infections and multidrug-resistant organisms has prompted a review of standard practice and a series of evidence-based interventions put together as a ‘care bundle’ to reduce hospital-acquired infections. The technique for placing a cannula is best shown at the bedside by an expert, but following these simple rules will significantly reduce the risk of infection from the cannula.

### Preparation is key, remember the following before you start

1. 1 Equipment: Set up a tray with cleaning swabs, gauze, cannulae (swallow your pride and take at least three of different sizes, see table 18.1), dressings, 0.9% saline, 10mL syringe, needle-free adaptor (eg octopus with bionector), blood tubes if required, portable sharps bin → needlestick injuries do happen.

2. 2 Patient: Have them lying down, explain procedure, obtain verbal consent, place tourniquet around arm, rest the arm below the heart to aid venous filling.

3. 3 Site: Look for the best vein—it should be palpable; some of the best veins are not easily visible, some of the most visible collapse on insertion. Tapping gently helps. Never cannulate: av fistulae arms, limbs with lymphoedema. Avoid: Sites crossing a joint (if possible), the cephalic vein in a renal patient.

4. 4 Consider: emla® cream, cold spray, or 1% lidocaine for children or those with needle phobia. emla® takes 45min to work, but can save you hassle later.

Table 18.1 Intravenous cannulae sizes and uk colour conventions

Gauge

Colour

Diameter (mm)

Length (mm)

Flow rate (mL/min)

14g

orange/brown

2.0

45

250

16g

grey

1.7

42

170

18g

green

1.2

40

90

20g

pink

1.0

32

55

22g

blue

0.28

25

25

24g

yellow

0.07

19

24

Flow rate is given as maximum flow rate under gravity; faster rates may be achievable with rapid infusion devices.

According to Poiseuille’s law1 the flow rate (Q) of a fluid through a tubular structure is inversely proportional to viscosity (η‎) and length (l) and proportional to the pressure difference across it (PiPo) and the radius to the power of 4(r4). Hence:

$Display mathematics$

### Insertion care bundle

1. 1 Aseptic technique.

2. 2 Hand hygiene.

3. 3 Apron + non-sterile gloves.

4. 4 Skin preparation—2% chorhexidine in 70% isopropyl alcohol (allow to dry for 30 seconds). Do not repalpate vein after cleaning unless wearing sterile gloves.

5. 5 Dressing—sterile and transparent so that insertion site can be observed.

### After insertion

1. 1 Take blood with syringe or adaptor.

2. 2 Remove tourniquet.

3. 3 Attach needle-free device (if appropriate) and flush with 10mL 0.9% saline.

4. 4 Apply dressing.

5. 5 Let nursing staff know that cannula is in place and ready for use.

6. 6 Document insertion according to local policy.

7. 7 Write up appropriate fluids or parenteral medication.

When seeing your patient on the daily ward round (and to avoid being called to review or replace cannulae at 6pm) do a raid1 assessment: consider if the drip is:

• Required—can the patient manage with oral medication/fluids?

• Appropriate—should you consider a picc, central line, long-term line, etc?

• Infected—any signs of inflammation or infection? Remove if yes. Peripheral cannulae should be replaced every 72–96 hours.

• Dressed properly—many drips are replaced early because they have ‘fallen out’, or are kinked from poor dressings.

Tissued or infected cannulae need replacing, either with another peripheral cannula, or with a longer-term access device, such as a picc line.

### If you fail after three attempts

Shocked patients need fluid quickly: if you are having trouble putting in a drip, call your senior. The following advice assumes that the drip is not immediately life-saving. If it is, see box.

• Ask for help—from colleagues or seniors—do not be ashamed, everyone has to learn and even senior doctors have bad days; a fresh pair of eyes can be all it takes. As a house officer, one of us was asked to place a drip when a very shame-faced consultant had ‘had a go’ to prove he still could, and found out that he couldn’t!

• Help yourself—try putting the hand in warm water, using a small amount of gtn paste over the vein, or using ultrasound if available to help you identify the vein.

• If there is no one else to help, take a break and come back in half an hour. Veins come and go, and coming back with fresh eyes can make all the difference.

## (p. 762) Catheterizing bladders

Urinary tract infections are the second commonest health care-associated infection, and urinary catheters are frequently to blame. Think, does the patient really need a catheter? If so, use the smallest you can and take out as soon as possible.

### Size

(in French gauge): 12=small; 16=large; 20=very large (eg 3-way).

### Material

Coated latex catheters are soft and a good short-term option but unsuitable in true latex allergy. Silastic (silicone) catheters may be used long term, but cost more. Silver alloy coating reduces infections.

### Shape

Foley is typical (fig 18.2); coudé (elbow) catheters have an angled tip to ease around prostates but are more risky; 3-way catheters are used in clot or debris retention and have an extra lumen for irrigation fluid, attached to the irrigation set via an extra port on the distal end (fig 18.3). Get urology advice before starting irrigation. Condom catheters are often preferred by patients (less discomfort) even though they may leak and fall off.

Fig 18.2
A size14f latex Foley catheter with the balloon inflated via the topmost port of the outer end (green).

© Dr Tom Turmezei (not to scale).

Fig 18.3
The external end of a size 20F 3-way catheter. The lowest port is for the bladder irrigation fluid and the uppermost port (yellow) is for balloon inflation.

© Dr Tom Turmezei (not to scale).

### Catheter problems

• Infection: ~5% develop bacteraemia (most will have bacterial colonization, antibiotics may not be required unless systemically unwell—discuss with microbiology). A stat dose of, eg gentamicin 80mg is sometimes given pre-insertion despite a lack of evidence for benefit. Check your local policy.

• Bladder spasm: May be painful—try reducing the water in the balloon or an anticholinergic drug, eg oxybutynin.

### Per urethram

Aseptic technique required.

Indications

• Relieve urinary retention.

• Monitor urine output in critically ill patients.

• Collect uncontaminated urine for diagnosis.

It is contraindicated in urethral injury (eg pelvic fracture) and acute prostatitis.

• Explain the procedure, and obtain verbal consent. Prepare a catheterization trolley: gloves, catheter, lidocaine jelly, cleaning solution, drape, kidney dish, gauze swabs, drainage bag, 10mL water and syringe, specimen container.

• Lie the patient supine: women with knees flexed and hips abducted with heels together. Use a gloved hand to clean urethral meatus in a pubis-to-anus direction, holding the labia apart with the other hand. With uncircumcised men, retract the foreskin to clean the glans; use a gloved hand to hold the penis still. The hand used to hold the penis or labia should not touch the catheter. Place a sterile drape with a hole in the middle to help you maintain asepsis. Remember: left hand dirty, right hand clean.

• Put sterile lidocaine 1–2% gel on the catheter tip and ≤10mL into the urethra (≤5mL if ♀). In men, lift and gently stretch the penis upwards to eliminate any urethral folds that may lead to false passage formation.

• Use steady gentle pressure to advance the catheter, rotating slightly can help it slide in. Never force the catheter. Tilting the penis up towards the umbilicus while inserting may help negotiate the prostate. Insert to the hilt; wait until urine emerges before inflating the balloon. Remember to check the balloon’s capacity before inflation (written on the outer end). Collect a sterile specimen and attach a drainage bag. Pull the catheter back so that the balloon comes to rest at the bladder neck.

• If you are having trouble getting past the prostate, try: more lubrication, a gentle twisting motion; a larger catheter; or call the urologists, who may use a guidewire.

Remember to reposition the foreskin in uncircumcised men after the catheter is inserted to prevent oedema of the glans and paraphimos.

#### Documentation:

In the notes be sure to document the indication for catheterization, size of catheter, whether insertion was difficult or straightforward, any complications, residual volume and colour of urine. It is good practice to document that the foreskin has been replaced. Sign with your name, date, and designation.

### Suprapubic catheterization:

Sterile technique required Absolutely contraindicated unless there is a large bladder palpable or visible on ultrasound, because of the risk of bowel perforation. Be wary, particularly if there is a history of abdominal or pelvic surgery. Suprapubic catheter insertion is high risk and you should be trained before attempting it, speak to the urologists first.

Fig 18.4
A size 10f catheter for self-catheterization. They are usually smaller than indwelling catheters, eg 10f compared to 14f. Note that this catheter also has no balloon.

© Dr Tom Turmezei (not to scale).

## (p. 764) Draining ascites

For patients with refractory or recurrent ascites that is symptomatic, it is possible to drain the ascites using a long pig-tail catheter. Paracentesis in such patients even in the presence of spontaneous bacterial peritonitis may be safe. Learn at the bedside from an expert.

### Contraindications (these are relative, not absolute)

End-stage cirrhosis; coagulopathy; hyponatraemia (≲126mmol/L); sepsis. The main complication of the procedure is severe hypovolaemia secondary to reaccumulation of the ascites, so intravascular replenishment with a plasma expander is required. For smaller volumes, eg less than 5L, 500mL of 5% human albumin or Gelofusine® would be sufficient. For volumes over 5L, reasonable replacement would be 100mL 20% human albumin iv for each 1–3 litres of ascites drained (check your local policy). You may need to call the haematology lab to request this in advance.

### Procedure

Requires sterile technique.

• Ensure you have good iv access—eg 18g cannula in the antecubital fossa.

• Explain the procedure including the risks of infection, bleeding, hyponatraemia, renal impairment, and damage to surrounding structures (such as liver, spleen, and bowel), and obtain consent from the patient. Serious complications occur in less than 1 in 1000 patients. Ask the patient to empty their bladder.

• Examine the abdomen carefully, evaluating the ascites and checking for organomegaly. Mark where you are going to enter. If in doubt, ask the radiology department to ultrasound the abdomen and mark a spot for drainage. Approach from the left side unless previous local surgery/stoma prevents this—call a senior for support and advice if this is the case.

• Prepare a tray with 2% chlorhexidine solution, sterile drapes, 1% lidocaine, syringes, needles, sample bottles, and your drain. Clean the abdomen thoroughly and place sterile drapes, ensure you maintain sterile technique throughout. Infiltrate the local anaesthetic.

• Perform an ascitic tap (see p[link]) first so that you know you are in the correct place: remove 20mL fluid for mc&s.

• Away from the patient, carefully thread the catheter over the (large and long) needle using the guide so that the pig-tail has been straightened out. Remove the guide.

• With the left hand hold the needle ~2.5cm (1 inch) from the tip—this will stop it from advancing too far (and from performing an aortic biopsy). With the right hand, hold the other end.

• Gently insert the needle perpendicular to the skin at the site of the ascitic tap up to your hold with your left hand—ascites should now drain easily. If necessary, advance the needle and catheter a short distance until good flow is achieved.

• Advance the catheter over the needle with your left hand, keeping the needle in exactly the same place with your right hand. Do not re-advance the needle because it will go through the curled pig-tail and do not withdraw it because you won’t be able to thread in the catheter.

• When fully inserted, remove the needle, connect the catheter to a drainage bag (keep it below the level of the abdomen), and tape it down securely to the skin.

• The patient should stay in bed as the ascites drains.

• Document clearly in the notes the indication for the procedure, that consent was obtained, clotting and u&es checked pre-procedure, how much lidocaine was required, how much fluid was removed for investigations, and whether there were any complications to the procedure.

• Replenish intravascular volume with human albumin (see ‘Contraindications’ earlier in topic).

• Ask the nursing staff to remove the catheter after 6h or after a pre-determined volume has been drained (up to 20L can come off in 6h) and document this clearly in the medical notes. Drains are removed after 4–6h to prevent infection.

• Check u&es after the procedure and re-examine the patient.

Fig 18.6
Safe approach to entering the pleura by the intercostal route.

## (p. 766) Inserting a chest drain

### Indications

• Pneumothorax (p[link]): ventilated; tension; persistent/recurrent despite aspiration (eg <24h after 1st aspiration); large 2nd spontaneous pneumothorax if >50yrs old.

• Malignant pleural effusion, empyema, or complicated parapneumonic effusion.

• Pleural effusion compromising ventilation, eg in icu patients.

• Traumatic haemopneumothorax.

• Post-operatively: eg thoracotomy; oesophagectomy; cardiothoracic surgery.

Pleural effusions are best drained under us guidance using a Seldinger technique. This technique is also used for pneumathoraces (except in traumatic or post-operative situations) without us guidance; for this reason it is detailed here.

### Sterile procedure

• Identify the point for drainage. In effusions, this should be done with us, ideally under direct guidance or with a marked spot. For pneumothoraces, check the drainage point from cxr/ct/examination.

• Preparation: trolley with dressing pack; 2% chlorhexidine; needles; 10mL syringes; 1% lidocaine; scalpel; suture; Seldinger chest drain kit; underwater drainage bottle; connection tubes; sterile H2O; dressings. Incontinence pad under patient.

• Choose insertion site: 4–6th intercostal space, anterior- to mid-axillary line—the ‘safe triangle’ (see box ‘The “safe triangle” for insertion’ and fig 18.7). A more posterior approach, eg the 7th space posteriorly, may be required to drain a loculated effusion (under direct us visualization) and occasionally the 2nd intercostal space in the mid-clavicular line may be used for apical pneumothoraces—however, both approaches tend to be less comfortable.

• Maintain sterile technique—clean and place sterile drapes. Scrub for insertion.

• Prepare your underwater drain by filling the bottle to the marked line with sterile water. Ensure this is kept sterile until you need it.

• Infiltrate down to pleura with 10mL of 1% lidocaine and a 21g needle. Check that air/fluid can be aspirated from the proposed insertion site; if not, do not proceed.

• Attach the Seldinger needle to the syringe containing 1–2mL of sterile saline. The needle is bevelled and will direct the guidewire; in general advance bevel up for pneumothoraces, bevel down for effusions.

• Insert the needle gently, aspirating constantly. When fluid/air is obtained in the syringe, stop, note insertion depth from the markings on the Seldinger needle. Remove syringe, thread the guidewire through the needle. Remove the needle and clamp the guidewire to the sterile drapes to ensure it does not move. Using the markings on the Seldinger needle, move the rubber stops on the dilators to the depth noted earlier, to prevent the dilator slipping in further than intended.

• Make a nick in the skin where the wire enters, and slide the dilators over the wire sequentially from smallest to largest to enlarge the hole, keep gauze on hand. Slide the Seldinger drain over the wire into the pleural cavity. Remove the wire and attach a 3-way tap to the drain, then connect to the underwater drainage bottle.

• Suture the drain in place using a drain stitch—make a stitch in the skin close to the drain site, tie this fairly loosely with a double knot. Then tie the suture to the drain. It is usually best to be shown this before attempting it for yourself. Dress the drain, and ensure it is well taped down.

• Check that the drain is swinging (effusion) or bubbling (pneumothorax) and ensure the water bottle remains below the level of the patient at all times. If the drain needs to be lifted above the patient, clamp it briefly. You should never clamp chest drains inserted for pneumothoraces. Clamping for pleural effusions can control the rate of drainage and prevent expansion pulmonary oedema.

• Request a cxr to check the position of the drain.

### Removal

#### In pneumothorax:

Consider when drain is no longer bubbling and cxr shows re-inflation. Give analgesia beforehand, eg morphine. Smartly withdraw during expiration or Valsalva. There is no need to clamp the drain beforehand as reinsertion is unlikely.

#### In effusions:

Generally the drain can be removed when drainage is <200mL/24h, but for cirrhotic hydrothoraces the chest drain is treated similarly to the ascitic drain (see p[link]) with has supplementation and removal at 4–6 hours.

## (p. 768) Lumbar puncture (lp)

### Contraindications

• Bleeding diathesis.

• Cardiorespiratory compromise.

• Infection at site of needle insertion. Most importantly: icp (suspect if very severe headache, ↓level of consciousness with falling pulse, rising bp, vomiting, focal neurology, or papilloedema)—lp in these patients will cause coning, so unless it is a routine procedure, eg for known idiopathic intracranial hypertension, obtain a ct prior to lp. ct is not infallible, so be sure your indication for lp is strong.

### Method

Explain to the patient what sampling csf entails, why it is needed, that co-operation is vital, and that they can communicate with you at all stages.

• Place the patient on his or her left side, with the back on the edge of the bed, fully flexed (knees to chin). A pillow under the head and another between the knees may keep them more stable.

• Landmarks: plane of iliac crests through the level of l 3/4 (see fig 18.8). In adults, the spinal cord ends at the l 1/2 disc (fig 18.9). Mark l 3/4 intervertebral space (or one space below, l 4/5), eg by a gentle indentation of a needle cap on the overlying skin (better than a ballpoint pen mark, which might be erased by the sterilizing fluid).

• Use aseptic technique (hat, mask, gloves, gown) and 2% chlorhexidine in 70% alcohol to clean the skin, allow to dry and then place sterile drapes.

• Open the spinal pack. Assemble the manometer and 3-way tap. Have three plain sterile tubes and one fluoride tube (for glucose) ready.

• Using a 25g (orange) needle, raise a bleb of local anaesthetic, then use a 21g (green) needle to infiltrate deeper.

• Wait 1min, then insert spinal needle (22g, stilette in place) perpendicular to the body, through your mark, aiming slightly up towards the umbilicus. Feel resistance of spinal ligaments, and then the dura, then a ‘give’ as the needle enters the subarachnoid space. nb: keep the bevel of the needle facing up, parallel with dural fibres.

• Withdraw stilette. Check csf fills needle and attach manometer (3-way tap turned off towards you) to measure ‘opening’ pressure.

• Catch fluid in three sequentially numbered bottles (10 drops per tube).

• Reinsert stilette then remove needle and apply dressing. Document the procedure clearly in the notes including csf appearance and opening pressure.

• Send csf promptly for microscopy, culture, protein, lactate, and glucose (do plasma glucose too)—call the lab to let them know. If applicable, also send for: cytology, fungal studies, tb culture, virology (± herpes and other pcr), syphilis serology, oligoclonal bands (+serum sample for comparison) if multiple sclerosis suspected. Is there xanthochromia (p[link])?

• If you fail; ask for help—try with the patient sitting or with radiological guidance.

Fig 18.8
Defining the 3rd–4th lumbar vertebral interspace.

Adapted with permission from Vakil et al., Diagnosis and Management of Medical Emergencies, 1977 Oxford University Press.

Fig 18.9
Axial t2-weighted mri of the lumbar spine. The conus ends at the l1/l2 level with continuation of the cauda equina. Lumbar puncture below the l2 level will not damage the cauda equina as the nerve roots will part around an lp needle.

Image courtesy of Norwich Radiology Dept.

### csf composition

#### Normal values:

Lymphocytes <5/mm3; no polymorphs; protein <0.4g/L; glucose >2.2mmol/L (or ≥50% plasma level); pressure <200mm csf.

#### Bloody tap:

This is an artefact due to piercing a blood vessel, which is indicated (unreliably) by fewer red cells in successive bottles, and no yellowing of csf (xanthochromia). To estimate how many white cells (w) were in the csf before the blood was added, use the following:

$Display mathematics$

If the blood count is normal, the rule of thumb is to subtract from the total csf wcc (per μ‎L) one white cell for every 1000 rbcs. To estimate the true protein level, subtract 10mg/L for every 1000 rbcs/mm3 (be sure to do the count and protein estimation on the same bottle). nb: high protein levels in csf make it appear yellow.

#### Subarachnoid haemorrhage:

Xanthochromia (yellow supernatant on spun csf). Red cells in equal numbers in all bottles (unreliable). rbcs will excite an inflammatory response (eg csf wcc raised), most marked after 48h.

#### Raised protein:

Meningitis; ms; Guillain–Barré syndrome.

#### Very raised csf protein:

Spinal block; tb; or severe bacterial meningitis.

## (p. 770) Cardioversion/defibrillation

Do not wait for a crisis before familiarizing yourself with the defibrillator, as there are several types. All hospitals should include this information in your induction but check how the machine on your ward works.

### Indications

To restore sinus rhythm if vf/vt; af, flutter, or supraventricular tachycardias if other treatments (p[link]) have failed, or there is haemodynamic compromise (p[link] & p[link]). This may be done as an emergency, eg vf/vt, or electively, eg af.

### Aim

To completely depolarize the heart using a direct current.

### Procedure

For vf/pulseless vt follow the als algorithm on p[link] and call the arrest team!

• Unless critically unwell, conscious patients require a general anaesthetic or monitored heavy sedation.

• If elective cardioversion of af ensure adequate anticoagulation beforehand.

• Almost all defibrillators are now paddle-free and use ‘hands-free’ pads instead (less chance of skin arc than jelly). Place the pads on chest, one over apex (p[link]) and one below right clavicle. The positions are often given by a diagram on the reverse of the pad.

#### Cardioversion:

Synchronize the shock with the rhythm by pressing the ‘sync’ button on the machine. This ensures the shock does not initiate a ventricular arrhythmia. However, this only works for cardioversion; if the sync mode is engaged in vf, the defibrillator will not discharge.

• Monophasic defibrillators: (fig 18.10) Set the energy level at 360J for vf/vt (arrest situation); 200J for af; 50J for atrial flutter.

• Biphasic defibrillators: (fig 18.11) Impedance is less with a biphasic shock and 120–200J is used for shocks for vf/vt. They use less energy and are just as effective as monophasic defibs in cardio-version. 120–200J will cardiovert most arrhythmias.

• Automatic external defibrillators: (aeds) Can be used by anyone who can turn them on and apply the pads. Follow the instructions given by the aed.

Fig 18.10
The dampened sine monophasic waveform.

Fig 18.11
Rectilinear biphasic waveform with truncated exponential decay. Most new external defibrillators use this waveform.

### Shocking

1. 1 Consider anticoagulation in af (see p[link]).

2. 2 Clearly state that you are charging the defibrillator.

3. 3 Make sure no one else is touching the patient, the bed, or anything is in turn touching these.

4. 4 Clearly state that you are about to shock the patient.

5. 5 Give the shock. If there is a change in rhythm before you shock and the shock is no longer required, turn the dial to ‘discharge’. Do not allow anyone to approach until the reading has dropped to 0J.

6. 6 After a shock: in resuscitation, resume cpr immediately and do not reassess rhythm until the end of the cycle (see p[link], fig A3); in cardioversion, watch ecg; consider need to repeat the shock. Up to three are usual for af/flutter.

7. 7 Get an up-to-date 12-lead ecg.

In children, use 4J/kg in vf/vt; see ohcs p[link].

## (p. 772) Emergency airway management

### Cricothyroidotomy

Thsi is an emergency procedure to overcome airway obstruction above the level of the larynx. It should only be done in absolute ‘can’t intubate, can’t ventilate’ situations, ie where ventilation is impossible with a bag and mask (± airway adjuncts) and where there is an immediate threat to life. If not, call anaesthetics or ent for immediate help.

### Indications

Upper airway obstruction when endotracheal intubation not possible, eg irretrievable foreign body; facial oedema (burns, angio-oedema); maxillofacial trauma; infection (epiglottitis).

### Procedure

Lie the patient supine with neck extended (eg pillow under shoulders) unless there is suspected cervical-spine instability. Run your index finger down the neck anteriorly in the midline to find the notch in the upper border of the thyroid cartilage (the Adam’s apple): just below this, between the thyroid and cricoid cartilages, is a depression—the cricothyroid membrane (see fig 18.14). If you cannot feel the depression and it is an emergency, you can access the trachea directly approximately halfway between the cricoid cartilage and the suprasternal notch.

Fig 18.14
The cricothyroid membrane.

Ideally use a purpose-designed kit (eg QuickTrach, MiniTrach), all hospitals will stock one version. If no kit is available then a cannula (needle cricothyroidotomy) can buy time, and in out-of-hospital situations a blade and empty biro case have saved lives. Needle and kit cricothyroidotomies are temporary measures pending formal tracheostomy.

1. 1 Needle cricothyroidotomy: Pierce the membrane perpendicular to the skin with large-bore cannula (14g) attached to syringe: withdrawal of air confirms position; lidocaine may or may not be required. Slide cannula over needle at 45° to the skin superiorly in the sagittal plane. Use a Y-connector (see fig 18.16) or improvise connection to O2 supply at 15L/min: use thumb on Y-connector to allow O2 in over 1s and CO2 out over 4s (‘transtracheal jet insufflation’). This is the preferred method in children <12yrs. This will only sustain life for 30–45min before CO2 builds up. However, if the patient has a completely obstructed airway then they will not be able to exhale through this, and it will lead to cardiovascular compromise and pneumothoraces.

2. 2 Cricothyroidotomy kit: Most contain a guarded blade, and a large (4–6mm) shaped cannula (cuffed or uncuffed depending on brand) over an introducer, plus a connector and binding tape. The patient will have to be ventilated via a bag, as the resistance is too high to breathe spontaneously. This will sustain for 30–45min.

3. 3 Surgical cricothyroidotomy: Smallest tube for prolonged ventilation is 6mm. Introduce high-volume, low-pressure cuff tracheostomy tube through a horizontal incision in membrane. Take care not to cut the thyroid or cricoid cartilages.

Fig 18.16
Methods of providing oxygen.

### Complications

Local haemorrhage ± aspiration; posterior perforation of trachea ± oesophagus; subglottic stenosis; laryngeal stenosis if membrane over-incised in childhood; tube blockage; subcutaneous tunnelling; vocal cord paralysis or hoarseness (the recurrent laryngeal nerve runs superiorly in the tracheo-oesophageal groove).

## (p. 774) Central venous cannulation

Central venous cannulae may be inserted to measure central venous pressure (cvp), to administer certain drugs (eg amiodarone, chemotherapy), or for intravenous access (fluid, parenteral nutrition). In an emergency, the procedure can be done using the landmark method (see p[link]), though nice recommends that all routine internal jugular catheters should be placed with us guidance. Even if the line is not placed under direct us visualization, a look to check vessel size, position in relation to artery, and patency (no thrombus or stenosis) is extremely useful. For contraindications, see table 18.2.

Table 18.2 Contraindications to central venous cannulation

Absolute

Relative

Infection at insertion site

Coagulopathy

Ipsilateral carotid endarterectomy

Newly inserted cardiac pacemaker leads

Thrombus within the vein

Venous stenosis

Ipsilateral abnormal anatomy

### Sites of insertion

These include the internal jugular vein (see p[link] and p[link]), subclavian vein, and the femoral vein. The choice depends largely on operator experience, but evidence suggests that the femoral approach is associated with a higher rate of line infection and thrombosis. Overall, the internal jugular approach (with ultrasound guidance) is most commonly used and risks fewer complications than the subclavian. If possible, get written consent (p[link]). Check clotting and platelets. The technique for internal jugular (routine) and femoral (emergency) are given here.

### Complications

(~20%.) Insertion is not without hazard, so decide whether the patient requires a line first, and then ask for help if you are inexperienced.

Bleeding; arterial puncture/cannulation; av fistula formation; air embolism; pneumothorax; haemothorax; chylothorax (lymph); phrenic nerve palsy (the right phrenic nerve passes over the brachiocephalic artery, posterior to the subclavian vein—hiccups may be a sign of injury); phlebitis; thrombus formation on tip or in vein (if high risk for thromboembolism, eg malignancy, consider anticoagulation, eg lmwh); bacterial colonization; cellulitis; sepsis (can be reduced by adherence to a strict aseptic technique; if taking blood cultures in a febrile patient with a central venous line, remember to take samples from the central line and from a peripheral vein).

### Peripherally inserted central cannulas (picc lines)

These are a good alternative to central lines, as they can stay in situ for up to 6 months, and provide access for blood sampling, fluids, antibiotics (allowing home iv therapy). They are placed using a Seldinger technique, puncturing the brachial or basilic vein then threading the line into the subclavian or superior vena cava. Because of the insertion site there is a much lower risk of pneumo- or haemothorax, but they are tricky to insert in an emergency.

### Removing central lines

Should be done carefully with aseptic technique. Position the patient slightly head down, remove dressings, clean and drape the area, remove sutures. Ask the patient to inhale and hold their breath, then breathe out smoothly while you are pulling the line out. This helps to prevent air emboli. Ask the patient to rehearse this sequence with you to ensure they have understood their role. Apply pressure for 5 minutes (longer if coagulopathic).

## (p. 775) Internal jugular catheterization

### Internal jugular

Should be the approach of choice in a non-emergency situation. Ideally the right side as it offers a direct route to the heart and there is less chance of misplacement of the line compared to the left. The subclavian approach is trickier and best taught by an expert. Use us guidance if at all possible, ideally to insert the line under direct vision, but at least to define the anatomy. If possible, have the patient attached to a cardiac monitor in case of arrhythmias.

• Position the patient slightly head down to avoid air embolism and fill the veins to improve your chances of success. This can compromise cardiac function and precipitate acute lvf so check if your patient has a cardiac history. Minimize the time the patient is head down; if they are unable to lie flat, consider a femoral approach. Turn their head slightly to the left.

• This should be a sterile procedure so use full aseptic technique (hat, mask, gloves, gown) and clean with 2% chlorhexidine in 70% isopropyl alcohol before draping. Ensure your equipment is prepared, flush the catheter lumens with saline.

• If us is unavailable, the landmark procedure can be used to identify insertion point—approximately at the junction of the two heads of sternocleidomastoid at about the level of the thyroid cartilage (fig 18.17). Feel gently for the carotid pulse, then infiltrate with 1% lidocaine just lateral to this. The vein is usually superficial (fig 18.18).

• Insert the introducer needle with a 5mL syringe attached, advance gently at a 45° angle, aiming for the ipsilateral nipple and aspirating continuously. If you are using us, watch the needle tip enter the vein, if the landmark approach keep your fingers on the carotid pulse.

• As soon as blood is aspirated, lay down the us probe and hold the introducer needle in position, remove the syringe and thread the guidewire through the needle. It should pass easily, if there is resistance try lowering the angle of the needle and gently advancing the wire. If the wire will not pass do not remove it alone, the tip can shear off and embolize; remove the needle with the wire, apply pressure and attempt a second puncture.

• If the wire threads easily, insert to 30cm (see markings on the wire), remove the needle keeping hold of the wire at all times. Make a nick in the skin with a scalpel at the insertion point, and gently thread the dilator over the wire. You do not need to insert the dilator far, only as far as the vein (you often feel a loss of resistance as the dilator enters the vein, so insert gently: a pneumothorax can result from enthusiastic dilating).

• Remove the dilator, keeping hold of the wire, thread the flushed catheter over the wire, then remove the wire. The line should sit at about 13cm on the right side (17cm on the left). Check you can aspirate blood from each lumen, then flush them.

• Suture the catheter in place (many have little ‘wings’ for suturing) and dress. Request a cxr to confirm position and exclude pneumothorax. The tip of the catheter should sit vertically in the svc.

Fig 18.17
Position of internal jugular and subclavian veins (red) compared to the clavicle (yellow).

Fig 18.18
Vessels seen on ultrasound. The compressible vein is above the artery.

### Femoral vein

In an emergency situation where ultrasound is not easily accessible, if the patient is unable to lie flat, or where speed is of the essence, the femoral approach is often the safest, as there is no risk of pneumothorax or haemothorax and a much reduced risk of arrhythmia. The technique is similar to internal jugular, except the insertion point is just medial to the femoral artery at the groin crease.

### Subclavian vein

Should be taught by an expert and should ideally be carried out under us guidance. Some physicians prefer this approach, but even in experienced hands there is a ↑risk of complications compared to us-guided internal jugular lines.

## (p. 776) Inserting a temporary cardiac pacemaker

Often it is wiser to liaise with a specialist pacing centre to arrange prompt, definitive pacing than to try temporary transvenous pacing, which often has complications (see later in topic) and therefore may delay a definitive procedure.

### Possible indications in the acute phase of myocardial infarction

• Complete av block:

• With inferior mi (right coronary artery occlusion) pacing may only be needed if symptomatic; spontaneous recovery may occur.

• With anterior mi (representing massive septal infarction).

• Second-degree block:

• Wenckebach (p[link]; implies decremental av node conduction; may respond to atropine in an inferior mi; pace if anterior mi).

• Mobitz type 2 block is usually associated with distal fascicular disease and carries high risk of complete heart block, so pace in both types of mi.

• First-degree block: Observe carefully: 40% develop higher degrees of block.

• Bundle branch block: Pace prophylactically if evidence of trifascicular disease (p[link]) or non-adjacent bifascicular disease.

• Sino-atrial disease + serious symptoms: Pace unless responds to atropine.

### Other indications where temporary pacing may be needed

• Pre-op: if surgery is required in patients with type 2 or complete heart block (whether or not mi has occurred); do 24h ecg; liaise with the anaesthetist.

• Drug poisoning, eg with β‎-blockers, digoxin, or verapamil.

• Symptomatic bradycardia, uncontrolled by atropine or isoprenaline.

• Suppression of drug-resistant vt and svt (overdrive pacing; do on icu).

• Asystolic cardiac arrest with p-wave activity (ventricular standstill).

• During or after cardiac surgery—eg around the av node or bundle of His.

### Technique for temporary transvenous pacing

Learn from an expert.

• Preparation: Monitor ecg; have a defibrillator to hand, ensure the patient has peripheral access; check that a radiographer with screening equipment is present. If you are screening, wear a protective lead apron.

• Insertion: Using an aseptic technique, place the introducer into the (ideally right) internal jugular vein (p[link]) or subclavian. If this is difficult, access to the right atrium can be achieved via the femoral vein. Pass the pacing wire through the introducer into the right atrium, ideally under radiological screening. It will either pass easily through the tricuspid valve or loop within the atrium. If the latter occurs, it is usually possible to flip the wire across the valve with a combined twisting and withdrawing movement (fig 18.19). Advance the wire slightly. At this stage the wire may try to exit the ventricle through the pulmonary outflow tract. A further withdrawing and rotation of the wire will aim the tip at the apex of the right ventricle. Advance slightly again to place the wire in contact with the endocardium. Remove any slack to ↓risk of subsequent displacement.

• Checking the threshold: Connect the wire to the pacing box and set the ‘demand’ rate slightly higher than the patient’s own heart rate and the output to 3V. A paced rhythm should be seen. Find the pacing threshold by slowly reducing the voltage until the pacemaker fails to stimulate the tissue (pacing spikes are no longer followed by paced beats). The threshold should be less than 1V, but a slightly higher value may be acceptable if it is stable—eg after a large infarction.

• Setting the pacemaker: Set the output to 3V or over 3 times the threshold value (whichever is higher) in ‘demand’ mode. Set the rate as required. Suture the wire to the skin, and fix with a sterile dressing.

• Check the position of the wire (and exclude pneumothorax) with a cxr.

• Recurrent checks of the pacing threshold are required over the next few days. The formation of endocardial oedema can raise the threshold by a factor of 2–3.

Fig 18.19
Siting a temporary cardiac pacemaker.

### Complications

Pneumothorax; sepsis; cardiac perforation; pacing failure: from loss of capture, loss of electrical continuity in pacing circuit, or electrode displacement.

## Notes:

We thank our Specialist Reader, Dr Andrew Johnston, for his contribution to this chapter.

1 Poiseuille’s law is a neat piece of physiology and worth remembering—it is applicable in some form to almost every system in the body. Note that it is a 4th-power law: a small change in the radius makes a huge difference to flow.