Endotracheal intubation

1. Endotracheal intubation Indications An artificial airway is necessary in the following circumstances : • Apnoea – The provision of mechanical ventilation, e.g. unconsciousness, severe respiratory muscle weakness, self-poisoning. • Respiratory failure – The provision of mechanical ventilation, e.g. ARDS, peumonia11 • Airway protection – Unconciousness, trauma, aspiration risk, poisoning • Airway obstruction – To maintain airway patency, e.g. trauma, laryngeal oedema, tumour, burns • Haemodynamic instability – To facilitate mechanical ventilation, e.g. shock, cardiac arrest.

2. Choice of endotracheal tube • Most adults require a standard high volume, low pressure cuffed endotracheal tube. • The averge sized adult will require a size 9.0mm id tube (size 8.0mm id for females) cut to length of 23cm (21cm for females). • Obviously, different size patients may require changes to these sizes and particular problems with the upper airway, e.g. trauma, oedema, may require a smaller tube. • In specific situations non-standard tubes may be used, e.g. jet ventilation, armoured tubes (where head mobility is expected or for patients who are to be positioned prone), double lumen tubes to isolate the right or left lung.

3. Route of intubation • The usual routes of intubation are oro-tracheal and naso-tracheal. • Oro-tracheal intubation in preferred. • The naso-tracheal route has the advantages of increased pateint comfort and the possibility of easier blind placement; it is also easier to secure the tube. • However, there are several disadvantages. • The tube is usually smaller, there is a risk of sinusitis and otitis media and the route is contrandicated in coagulopathy, CSF leak and nasal fractures.

4. Difficult intubation • If a difficult intubation is predicted is should not be attempted by an inexperienced operator. • Difficulty may be predicted in the patient with a small mouth, high arched palate, large upper incisors, hypognathia, large tongue, anterior larynx, short neck, immobile temporomandibular joints, immobile cervical joints or morbid obesity. • If a difficult intubation present unexpectedly the use of a stylet, a straight bladed laryngoscope or a fibreoptic laryngoscope may help. • It is important not to persist for too long; revert to bag and mask ventilation to ensure adequate oxygenation.

5. Complications of intubation Early complications • Trauma, e.g. haemorrhage, mediastinal perforation • Haemodynamic collapse, e.g. positive pressure ventilation, vasodilation, arrhythmias or rapid correction of hypercapnia. • Tube malposition, e.g. failed or endobronchial intubation. Later complications • Infection including maxillary sinusitis if nasally intubated • Cuff pressure trauma (maintain cuff pressure <25cmH2O) • Mouth /Lip trauma

6. Equipment required • Suction (Yankauer tip) • Oxyen, rebreathing bag and mask • Laryngoscope (two curved blades and straight blade) • Stylet / bougie • Endotracheal tubes (preferred size and smaller) • Magill forceps • Drugs (Induction agent, muscle relaxant, sedative, anticholinergic) • Syringe for cuff inflation • Tape to secure tube

7. Tracheostomy Indications • To provide an artificial airway where oro-or naso-tracheal intubation is to be avoided. • This may be to provide better patient comfort, to avoid mouth or nasal trauma or, in an emergency, where there is acute upper airway obstruction. • Converting an oro-or naso-tracheal tube to a tracheostomy should be considered early in cases of difficult intubation to avoid the risks of repeat intubation, or later in caes of prolonged intubation to avoid laryngela trauma.

8. The exact time that one should consider performing a tracheostomy in caes of prolonged intubation is not known although current practice is at about 10-16days. • High volume, low pressure cuffs on modern endoracheal tubes do not cause more tracheal damage than the equivalent cuffs of a tracheostomy tube, but avoiding the risks of laryngeal and vocal cord damage may provide some advantage for tracheostomy. • The reduced need for sedation is a definite advantage.

9. Percutaneous tracheostomy • A more rapid procedure with less tissue trauma and scarring than the standard open surgical technique. • Can be performed in the intensive care unit avoiding the need to transfer patients to theatre. • The technique involves infiltration of the subcutaneous tissues with lignocaine and adrenaline. • A1-1.5cm skin crease incision is made in the midline. Subcutaneous tissue is blunt dissected to the anterior tracheal wall. • The trachea is punctured with a 14G needle between the 1st and 2nd tracheal cartilages and a guide wire is inserted into the trachea. • The stoma is created either by progressive dilation to 36Fr (Ciaglia technique) or by use of single stage guided dilating tool (Schachner-Ovill technique). • In the former case the tracheostomy tube is introduced over an appropriate size dilator and in the latter through the open dilating tool.

10. Complications • The main early complication is haemorrhage, either from trauma to the thyroid isthmus or aberrant superior thyroid vessels. • Although most early haemorrhage is easily controlled, coagulation disorder in critically ill patients may created additional problems. • Tracheal stenos is is related to creation of the tracheal stoma and subsequent low grade infection. • This is thought to be a greater problem with open surgical tracheostomies than percutaneous tracheostomies. • The presence of a foreign body in the trachea, bypassing the normal upper airway defence mechanisms, together with an open neck wound, presents an obvious infection risk. • Subglottic infection is more likely after trans-laryngeal intubation. • Tracheo-oesophageal fistula is a rare complication due to trauma or pressure necrosis of the posterior wall of the trachea.

11. Maintenance of a tracheostomy • Since the upper air passages have been bypassed artificial humidification is required. • Cough is less effective without a functioninglarynx so regular tracheal suction will be necessary. • Furthermore, the larynx provides a small amount of natural PEEP which is lost with a tracheostomy. • The risk of basal atelectasis can be overcome with CPAP or attention to respiratory exercises which promote deep breathing. • A safe fistula forms within 3 days allowing replacement of the tracheostomy tube.

12. Tracheostomy tubes Standard high volume, low pressure cuff Fenestrated with or without cuff • Useful where airway protection is not a primary concern. • May be closed during normal breathing while providing intermittent suction access. Fenestrated with inner tube • As above but with an inner tube to facilitate closure of the fenestration during intermittent mechanical ventilation.

13. Fenestrated with speaking valve • Inspiration allowed through the tracheostomy to reduce dead space and inspiratory resistance. • Expiration through the larynx, via the fenestration, allowing speech and the advantages of laryngeal PEEP. Adjustable flange • Accommodates extreme variations in skin to trachea depth while ensuring the cuff remains central in the trachea. Pitt speaking tube • A non fenestrated, cuffed tube for continuous mechanical ventilation and airway protection with a port to direct airflow above the cuff to the larynx. • When airflow is direct through the larynx some patients are able to vocalise. Sliver tube • An uncuffed tube which is used occasionally in ENT practice to maintain a tracheostomy fistula.

14. Defibrillation • Electrical conversion of a tachyarrhythmia to restore normal sinus rhythm. • This may be an emergency procedure (when the circulation is absent or severely comporomised), semi elective (when the circulation is compromised to a lasser degree), or elective (when synchronised cardioversion is performed to restore sinus rhythm for a non-compromisingsupra-ventricular tachycardia). • Synchronisation requires initial connection of ECG leads from the patient to the defibrillator so that the shock is delivered on the R wave to minimize the risk of ventricular fibrillation.

15. Indications • Compromised circulation, e.g. VF, VT • Restoration of sinus rhythm and more effective cardiac output • Lessens risk of cardiac thrombus formation Contraindications / cautions • Aware patient • Severe coagulopathy • Caution with recent thrombolysis • Digoxin levels in toxic range Complications • Surface burn • Pericardial tamponade • Electrocution of bystanders

16. Technique • The chances of maintaining sinus rhythm are increased in elective cardioversion if K+>4.5mmol/L and plasma Mg2+ levels are normal. • Prior to defibrillation, ensure self and onlookers are not in contact with patient or bed frame. • To reduce the risk of superficial burns, replace gel/gelled pads after every 3 shocks. • Consider resisting paddle position (e.g. antero-posterior) if defibrillation fails. • The risk of intractable VF following defibrillation in a patient receiving digoxin is small unless the plasma digoxin levels are in the toxic range or the patient is hypovolaemic.

17. Temporary internal pacing • When the heart’s intrinsic pacemaking ability fails, temporary internal pacing can be instituted. • Electrodes can be endocardial (inserted via a cental vein) or epicardial (placed on the external surface of the heart at thoracotomy). • The endocardial wire may be placed under fluoroscopic control or ‘blind’ using a balloon flotation catheter.

18. Indications • Third degree heart block • Mobitz Type II second – degree heart block when the circulation is compromised or an operation is planned • Overpacing (rarely) • Asystole (although external pacing is more useful initially) Complications • As for central venous catheter insertion • Arrhythmias • Infection (including endocarditis) • Myocardial perforation (rare) Contraindications/cautions • As for central venous catheter insertion

19. Troubleshooting Failure to pace may be due to : • No pacemaker output (no spikes seen) – check connections, battery • No capture (pacing spikes seen but no QRS complex following) – poor positioning/dislodgement of wire. • Temporarily increase output as this may regain capture. Reposition / replace wire.

20. General • Check threshold daily as it will rise slowly over 48-96h, probably due to fibrosis occurring around the electrodes. • Overpacing is occasionally indicated for a tachycardia not responding to antiarrhythmic therapy or cardioversion. For SVT, pacing is usually attempted with the wire sited in the right atrium. Pace at rate 20-30bpm above patient’s heart rate for 10-15sec then either decrease rate immediately to 80 bpm or slowly, by 20 bpm every 5-10sec. • If overpacing fails, underpacing may be attempted with the wire situated in either atrium (for SVT) or, usually, ventricle (for either SVT or VT). A paced rate of 80-100 bpm may produce a refractory period sufficient to suppress the intrinsic tachycardia. • Epicardial pacing performed during cardiac surgery requires sitting of either two epicardial electrodes or one epicardial and one skin electrode (usually a hypodermic needle). The pacing threshold of epicardial wires rises quickly and may become ineffective after 1-2 days.

21. Technique (for endocardial electrode placement) • If using fluoroscopy, move patient to X-ray suite or place lead shields around bed area. Place patient on screening table. Staff should wear lead aprons. • Use aseptic technique throughout. Insert 6Fr sheath in internal jugular or subclavian vein. Suture in position. • Connect pacing wire electrodes to pacing box (black = negative polarity = distal, red = positive polarity = proximal). Set pace maker to demand. Check box is working and battery charge adequate. Turn pacing rate to > 30 bpm above patient’s intrinsic rhythm. Set voltage 4V.

22. Insert pacing wire through sheath into central vein. If using balloon catheter, insert to 15-20cm depth then inflate ballon. Advance catheter, viewing ECG monitor for change in ECG morphology and capture of pacing rate. If using screening direct wire toward the apex of the right ventricle. Approximate insertion depth from a neck vein is 35-40 cm. • If pacing impulses not captured, (deflate balloon), withdraw wire to 15 cm insertion depth then repeat step 4. • Once pacing captured, decrease voltage by decrements to determine threshold at which pacing is no longer captured. Ideal position determined by a threshold <0.4V. If not achieved, re-position wire. • If possible, ask patient to cough to check that the wire does not dislodge. • Set voltage at 3X threshold and set desired heart rate on demand mode. Tape wire securely to patient prevent dislodgement.

23. External pacing • External pacing can be rapidly performed by placement of two electrodes on the fron and rear chest wall when asystole or third degree heart block has produced acute haemodynamic compromise. • It is often used as a bridge to temporary internal pacing. It can also be used as a prophylactic measure e.g. for Mobitz Type II second degree heart block. Indications • Asystole (in conjunction with cardiopulmonary resuscitation) • Third degree heart block • Prophylactic Complications • Discomfort

24. Technique • Connect pacing wire gelled electrodes to pacemaker. Place black (=negative polarity) electrode on the anterior chest wall to the left of the lower sternum and ed (= positive polarity) electrode to the corresponding position on the posterior hemithorax. • Connect ECG electrodes from ECG monitor to external pacemaker and another set of electrodes from pacemaker to patient. • Set pacemaker to demand. Turn pacing rate to >30 bpm above patient’s intrinsic rhythm. Set current to 70mA. • Start pacing. Increase current (by 5mA increments) until pacing rate captured on monitor. • If pacing rate not captured at current of 120-130mA, re-site electrodes and repeat steps 3-4. • Once pacing captured, set current at 5-10mA above threshold. General • In asystole, even though an electrical rhythm is produced by the external pacing, this does not guarantee an adequate output is being generated. • Although the patient may complain of discomfort, external chest wall pacing is better tolerated and more reliable than other forms or external pacing e.g. oesophageal.