Tracheostomy management Kate Regan MRCP FRCA Katharine Hunt FRCA

Transcription

1 Kate Regan MRCP FRCA Katharine Hunt FRCA The use of tracheostomy has increased over recent years. Traditionally, it was confined to the emergency management of upper airway obstruction; more recently, indications have extended to include prolonged mechanical ventilation, chronic respiratory insufficiency, failure of airway protective reflexes, management of excessive secretions, and obstructive sleep apnoea. 1 Percutaneous tracheostomy at the bedside in intensive care is increasingly popular. Compared with an open surgical procedure, there are similar rates of complications 2 and further studies are ongoing to determine the optimal timing of tracheostomy for patients on intensive care units ( The techniques of percutaneous tracheostomy insertion are becoming increasingly familiar to anaesthetists and have been the subject of a previous review in this journal. 3 The ongoing management of tracheostomies both in the ICU and the ward environment may be less familiar. A range of specialties may be involved in the management of such patients, including ENT and maxillofacial surgeons, speech and language therapists, physiotherapists, and critical care outreach nurses. Anaesthetists are often called to troubleshoot and give advice. This article describes the different types of tracheostomy tube that may be encountered and how to manage emergencies (e.g. blocked tracheostomy tube). It also considers more general aspects of the ward-based management of tracheostomy tubes. Tracheostomy tubes Tracheostomy tube size is described most commonly in terms of the internal diameter (ID) of the tube at its narrowest point which, together with the outer diameter (OD), is marked on the tube flange or cuff. A tube corresponding to the size of the patient s trachea should be selected; too small a tube will lead to increased airway resistance and an increased work of breathing during spontaneous respiration; 1 in addition, suctioning of secretions may be more difficult. Increased cuff pressures will also be required to create a seal in smaller tubes, which may increase the risk of tracheal mucosal injury. Too large a tube may be difficult to insert and lead to problems with insufficient leakage past the cuff when cuff deflation is attempted during weaning. The curvature and length of the tracheostomy tube should also be appreciated when selecting a tube for any given patient, as it will vary between different designs and manufacturers. While the trachea is essentially straight, some tube designs have a pronounced curvature that can lead to the tracheostomy tip becoming compressed against the anterior tracheal wall causing partial obstruction. A longer proximal length may be required in obese patients, while additional distal length maybe useful in patients with anatomical abnormalities of the tracheal wall, e.g. tracheomalacia. Single and double cannula tubes doi: /bjaceaccp/mkm049 Continuing Education in Anaesthesia, Critical Care & Pain Volume 8 Number & The Board of Management and Trustees of the British Journal of Anaesthesia [2008]. All rights reserved. For Permissions, please journals.permissions@oxfordjournals.org Traditionally, a single lumen tube is passed into the trachea (Fig. 1, left side). The tube is supplied with an obturator in the lumen which aids insertion and is removed before use. A tracheal cuff allows separation of the lungs from pharyngeal secretions, although it is recognized that some leakage of secretions past the cuff may still occur. Uncuffed tubes are available for patients requiring long-term tracheostomy who have reasonable bulbar function but are unable to clear their secretions. Double cannula tubes are supplied with an inner tube, which can be removed independently of the outer tube (Fig. 1, right side). In the event of tube obstruction, this inner tube can be removed and cleaned, thus reducing the incidence of potentially life-threatening complications. This means that this is often the tube of choice especially for ward-based weaning. However, it should be noted that the work of breathing through a double cannula tracheostomy is increased due to the reduction in ID of the tube. In addition, some designs need the inner tube to be in situ to allow connection to the 15 mm ventilator tubing. Double cannula tubes may be fenestrated or unfenestrated (Fig. 2). Key points Tracheostomy use has increased as techniques and equipment have improved. Tracheostomy tubes are increasingly encountered in the ward environment; a range of specialists may be involved in their management. A range of different sized and shaped tubes are available. They may be single or double cannula tubes. Double cannula tubes may be fenestrated or unfenestrated. Anaesthetists are often asked to advise about weaning and tube removal. They may also be called if a patient is in extremis to manage a blocked or dislodged tracheostomy. Patients may be able to speak and swallow food safely with a tracheostomy tube in situ. Kate Regan MRCP FRCA SpR in Anaesthesia and Intensive Care Medicine University College Hospital London UK Katharine Hunt FRCA Consultant Anaesthetist National Hospital for Neurology and Neurosurgery Queen Square London WC1 N 3BG UK Tel: þ Fax: þ katharine.hunt@uclh.nhs.uk/ khunt@doctors.org.uk (for correspondence) 31

2 Fig. 1 Different types of tracheostomy tubes. On the left is a single lumen, adjustable phlange tracheostomy; on the right is a double cannula tracheostomy. Fig. 2 An unfenestrated (above) and fenestrated (below) inner tube. 32 Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

3 Fenestrated and unfenestrated tubes Fenestrated tubes have an opening in the posterior part of the outer tube. If the tube is cuffed, the fenestration lies above the cuff. Deflation of the cuff during spontaneous respiration (with the fenestrated inner tube in place) allows air to pass caudally through the tracheostomy lumen and fenestration, as well as around the tracheostomy tube, and up through the larynx. This encourages maximal airflow through the upper airways during speech and also allows assessment of the normal route of air passage during preparation for decannulation. If positive pressure ventilation is required, the unfenestrated inner tube should be inserted, to prevent air leak above the cuff. There are different designs of fenestrations; single and multiple fenestrated tubes are available. Other types Adjustable tracheostomy tubes have a movable flange such that the length of the tracheostomy tube from skin surface to trachea can be adjusted at the bedside (Fig. 1, left side). There is a locking mechanism on the flange to maintain the correct tube length. These tubes are used in patients with atypical anatomy, where there is a long depth from skin surface to trachea (e.g. obesity). At present, these tubes are only manufactured with a single lumen; hence, there is a greater risk of tube obstruction by secretions and they should always be used with humidified oxygen. It should also be noted that some of these tubes may be reinforced; therefore, because of the metal within the tube, it may not be safe for use with lasers or magnetic resonance imaging. Low profile tracheostomy tubes are available, and are often reserved for patients who have undergone tracheal or laryngeal surgery. Custom made tubes are available in silicone or silver, and may be useful when a tracheostomy is required for long-term or permanent use. The mini-tracheostomy tube is smaller (typically, 4 mm ID) and can be inserted through the cricothyroid membrane. It allows rapid access to the trachea and is designed to permit the entry of a size 10 suction catheter. As such, it may be inserted either to facilitate the suctioning of excessive secretions or as part of a weaning regimen. Since it is uncuffed, and its diameter does not permit mechanical ventilation, it should not be used in patients with inadequate airway reflexes or respiratory drive. Changing tracheostomy tubes Tracheostomy tubes may need to be changed periodically; there is little evidence to guide practice. After 10 days, the stoma has usually formed a defined tract, and changing the tracheostomy tube is usually straightforward. It is common practice to electively change single lumen tubes days after initial insertion, to prevent the development of granulation tissue around the tracheostomy tube and tube blockage from excessive secretions. Furthermore, many manufacturers recommend that a double cannula tube should not remain in situ for more than 30 days for similar reasons; many units change this type of tube monthly. Other indications for elective tube change include substituting for a different type of tube to facilitate weaning or speech and tube damage or obstruction. The insertion tract is often poorly defined until 7 10 days after formation; therefore, difficulties in changing tracheostomy tubes prior to this time should be anticipated. Failure to re-cannulate or the creation of a false tract is possible. Passing a bougie or airway exchange catheter through the existing tracheostomy tube before removing it may act as a guide into the trachea. A fibrescope can be used to visually confirm tube position and facilities should be readily available for oral tracheal intubation in the event of a problematic insertion. It should be noted that the oral route may not be an option if the patient has undergone extensive oral, cervical or laryngeal surgery, where there may be only a partial or no connection between the oral cavity and the trachea. The blocked tube The anaesthetist is often called to manage a blocked tracheostomy tube. While assessing the patient, oxygen should be delivered both via a facemask and the tracheostomy. If the patient is not in extremis, it may be preferable to transfer the patient to theatre, where improved monitoring, fibreoptic equipment and surgical expertise may be more readily available. It is important to establish whether there has been recent surgery to the upper airway (including laryngectomy), the previous grade of laryngoscopy (though it should be appreciated that this may have changed as a result of recent surgery or oedema), how long the tracheostomy has been in place, and how difficult its initial insertion was. If the patient is in extremis, the flowchart in Figure 3 is suggested as way of troubleshooting the possible causes for the obstruction. Weaning and decannulation Most patients are suitable for weaning as their condition improves. However, some patients require long-term tracheostomy tubes and arrangements need to be made for their management within the community. Before consideration for weaning, a multidisciplinary assessment should be made, including assessment of the patient s gag and swallowing reflexes, and dependency on suctioning and physiotherapy. Absolute requirements include a patent upper airway, spontaneous cough, and ability to swallow secretions. Assessment of swallow The blue dye test has previously been advocated as a method for assessing the patient s ability to swallow secretions. A teaspoon of water coloured with blue dye is given and respiratory sections from the tracheostomy are monitored over 24 h. The appearance of dye in the secretions implies inadequate swallowing reflexes. However, there is growing evidence that the blue dye test has a high rate of false positive results (i.e. clinical aspiration is not detected) and the sensitivity of this test may be as low as 38%. 4 It is therefore Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

4 Fig. 3 Suggested algorithm for tracheostomy patients with breathing difficulties. recommended that it is no longer used as the standard technique; it has been replaced by bedside clinical assessment by speech therapists, videofluroscopy, or fibre optic endoscopic evaluations of swallow. Weaning While there are many different suggested strategies for tracheostomy weaning, there is no consensus on the optimal approach. However, there is evidence that a systematic multi-disciplinary approach improves likelihood of success. 5 The aim of this approach is to develop goals for the individual patient, monitor ongoing progress and identify when further investigations may be required. Methods of weaning include increasing periods of cuff deflation, the use of fenestrated tubes and speaking valves and the downsizing or capping off of the tracheostomy tube prior to final removal. In our institution, progressive cuff deflation until the patient has tolerated this for a 24 h period, followed by capping off of the tracheostomy tube overnight is preferred. If the patient does not tolerate this, the cuff should be re-inflated and further investigations, including ENT referral to ensure patency of the upper airway, may be required. Humidification Tracheostomy bypasses the natural humidification of the upper airway and breathing dry gases can lead to damage of the respiratory cilia and epithelium. Secretions may dry out and lead to blockage of the tracheostomy lumen. For this reason, it is essential that all tracheostomy patients receive humidified, and preferably heated, gases if on supplemental oxygen. If breathing room air, a Swedish nose device incorporating a heat and moisture exchange filter can be employed. 6 Speech Communication difficulties are a significant problem in patients with a tracheostomy and various methods have been developed to facilitate speech. To attempt speech, patients need to be able to tolerate periods of cuff deflation without respiratory compromise and without the risk of gross aspiration. 34 Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number

5 In a spontaneously breathing patient, the simplest method of allowing speech is through cuff deflation, allowing air to pass around the tracheostomy and through the vocal cord apparatus. A fenestrated tube will allow maximal airflow, as described previously. If the tube is too big to allow sufficient air to pass, reducing the size of the tube may be considered. A one-way speaking valve can also be used with the tracheostomy tube to maximize speech. This allows air to be entrained through the tube during inspiration. The valve then closes during expiration such that exhaled air must pass through the natural airway and vocal cords to exit the lungs, thus aiding phonation. 6 A speaking valve may also be employed in some ventilator dependant patients. Studies have shown that speech for these patients acts as a psychosocial boost, allows patients to communicate, aids consent and may also help in reinstating smell and taste. Before employing this technique, the rate and work of breathing, as well as oxygen and ventilator dependency, must be assessed. In general, FI O2. 0.4, positive end expiratory pressure.5cm H 2 O and high levels of pressure support negate the use of speaking valves and cuff deflation in ventilator dependant patients. Feeding It is often stated that the presence of a tracheostomy tube prevents patients eating. The weight of the tube restricts laryngeal elevation during swallowing and the cuff may protrude into the oesophagus. However, the literature remains inconclusive and many centres now advocate trial feeding regimens with tracheostomy tubes in situ if the patient has low oxygen and respiratory support requirements and does not drool. References 1. Epstein SK. Anatomy and physiology of tracheostomy. Resp Care 2005; 3: Silvester W, Goldsmith D, Uchino S, Bellomo R, Knight S, Seevanayagam S, Brazzale D, McMahon M, Buckmaster J, Hart GK, Opdam H, Pierce RJ, Gutteridge GA. Percutaneous versus surgical tracheostomy: a randomised controlled study with long term follow up. Crit Care Med 2006; 8: Eggbert SM, Jerwood C, Percutaneous tracheostomy. CEACCP 2003; 3: Lewarski JS. Long term care of the patient with a tracheostomy. Resp Care 2005; 4: Hunt K, McGowan S. Tracheostomy management in the neurosciences: a systematic, multidisciplinary approach. Br J Neurosci Nurs 2005; 11: Hess DR. Facilitating speech in a patient with a tracheostomy. Resp Care 2005; 4: Please see multiple choice questions Continuing Education in Anaesthesia, Critical Care & Pain j Volume 8 Number