The ability to safely secure and manage a definitive airway on the cardiothoracic intensive care unit is an essential and challenging skill. Patients are frequently haemodynamically compromised with reduced cardiorespiratory reserve, resulting in poor tolerance of suboptimal ventilation.
Important airway competencies within cardiothoracic intensive care include endotracheal intubation and tracheostomy forming techniques, as well as a good working knowledge of how to rescue the airway should initial attempts fail.
Tracheal Intubation
The presence of a cuffed tube within the trachea represents a secure airway, providing protection from aspiration and facilitating positive pressure ventilation. Endotracheal tubes are made from polyvinyl chloride and are sized based on their internal diameter in millimetres. Since the internal diameter is inversely proportional to airflow resistance, it is appropriate to use the largest size that can be easily accommodated (usually 8–9 mm for males and 7–8 mm for females).
Many patients following cardiac surgery already have an endotracheal tube in place when admitted to the critical care unit. In these patients a period of haemodynamic stability may be required before preparations are made for discontinuation of sedation and extubation. It is important to document the endotracheal tube position, laryngoscopic grade and whether there were any difficulties with facemask ventilation and/or intubation following induction.
In contrast, the postoperative management of patients following thoracic surgery tends to focus on early extubation and the avoidance of positive pressure mechanical ventilation where possible. This is to avoid positive pressure stress on suture and staple sites, which may increase the risk of postoperative complications including persistent air leaks.
Patients who are breathing unsupported or receiving non-invasive ventilation may require intubation for a number of reasons (Table 8.1).
Table 8.1 Indications for tracheal intubation on the critical care unit
| Hypoxia |
| Hypercarbia |
| Reduced conscious level |
| Increased work of breathing |
| Cardiac arrest |
| Airway obstruction |
| To facilitate transfer |
Airway Assessment
When planning any intubation, it is important to perform an initial airway assessment to gauge whether there may be any potential difficulties with facemask ventilation or laryngoscopy. A key finding from the 4th National Audit Project on major airway events in the UK found that poor airway assessment contributed to poor airway outcomes. The degree of harm from airway incidents was also found to be highest in intensive care patients.
Recognised predictors of difficult intubation are listed in Table 8.2. An absence of these signs however does not guarantee straightforward airway management.
Performing Endotracheal Intubation
The intubating environment on the intensive care unit can be very different from that of the elective operating room. Critically ill patients have less physiological reserve and often require intubation urgently to address cardiorespiratory collapse. They may not be fasted and often experience delayed gastric emptying, so a rapid sequence induction with cricoid pressure is often performed.
Preparation
Prior to intubation, it is necessary to prepare the patient, drugs, equipment and intubating team. Roles should be applied to appropriately skilled personnel and a backup plan for a failed intubation should be in place. Essential equipment required for emergency intubation, along with rescue equipment in case of difficulty, should be immediately available in the intensive care unit and moved to the patient’s bedspace. A ‘difficult airway’ trolley containing basic and advanced equipment is an ideal way to organise this.
Patient
Critically ill patients requiring intubation should have standard monitoring (non-invasive blood pressure, electrocardiography, pulse oximetry) and working intravenous access as a minimum. Capnography to confirm correct tube position after intubation should be immediately available.
Head position should be gently manipulated (if it is safe to do so) into the ‘sniffing the morning air position’ which includes a mild amount of cervical flexion (a pillow is usually necessary behind the head to provide this) and mild atlanto-occipital extension in order to optimise direct laryngoscopic view. In obese patients extra pillows may be necessary behind the shoulders in order to allow atlanto-occipital extension.
Equipment
Basic airway equipment includes: a self-inflating bag, gum-elastic bougie, oropharyngeal airway, functioning laryngoscope (with a spare in case of failure) and at least two options of appropriately sized endotracheal tubes. A supraglottic airway device (laryngeal mask airway, LMA) should also be present in case of intubation difficulty, in order to assist with rescue oxygenation. A suitable device for emergency cricothyrotomy should also be available in case of failure to intubate or oxygenate.
It is necessary to be able to tilt the patient’s bed in a head-down position in case of regurgitation during airway manipulation and to have working suction available. It is also prudent to ensure the ventilator to be used after intubation is fully operational and attached to a reliable oxygen source.
Occasionally it may be necessary to site a double-lumen endotracheal tube rather than a single-lumen tube, either to facilitate protection of one lung from soiling by secretions or blood from the other lung, or to enable differential ventilation of the lungs. Double-lumen tube placement requires additional experience and specific training.
Drugs
Rapid sequence induction involves the administration of a predetermined dose of intravenous induction agent followed immediately by a neuromuscular blocking drug to achieve rapid loss of consciousness and optimal intubating conditions with minimal patient apnoea time.
The haemodynamic side effects of the common induction agents at dosages used in anaesthetic practice are such that their administration in critically ill patients can cause catastrophic cardiovascular collapse. To reduce the amount of induction agent needed, operators often coadminister opioids and benzodiazepines. Despite coinduction, vasopressors are still frequently needed following induction and should be immediately available.
Suxamethonium has been the traditional neuromuscular blocking agent used to achieve paralysis due to its speed of onset and offset. Rocuronium is now an alternative option, since the recently developed sugammadex allows immediate block reversal in case of emergency.
Table 8.2 Predictors of difficult intubation
| Receding chin |
| Short neck |
| Thick neck |
| Limited neck extension/flexion |
| Long upper incisors |
| Prominent overbite |
| Inability to extend mandibular incisors anterior to the maxillary incisors |
| Less than 3 cm interincisor distance |
| High arched palate |
| Less than 3 finger breadth thyromental distance |
| Mallampati score greater than II |
| Non-compliant mandibular space |
The choice of drugs used should be tailored to the individual critical care patient based on an assessment of aspiration risk, physiological reserve and indication for intubation (Table 8.3).
Table 8.3 Commonly used intubating drugs
| Drug | Comments |
|---|---|
| Thiopentone | Fastest speed of onset |
| Cardiovascular suppression | |
| Potential harm from extravasation | |
| Propofol | Rapid speed of onset |
| Suppresses laryngeal reflexes | |
| Cardiovascular suppression | |
| Ketamine | Slower onset time |
| Cardiovascular stability | |
| Bronchodilation | |
| Etomidate | Rapid speed of onset |
| Cardiovascular stability | |
| Possible adrenal suppression | |
| Midazolam | Slower onset time |
| Prolonged duration of action | |
| Reduces anaesthetic dose requirements | |
| Opioids | Unreliable amnesic |
| Limits sympathetic response to intubation | |
| Reduces anaesthetic dose requirements | |
| Suxamethonium | Rapid onset and offset of paralysis |
| Hyperkalaemia | |
| Risk of malignant hyperthermia | |
| Rocuronium | Rapid onset of neuromuscular block |
| Rapid reversal with sugammadex |
Team
Clear roles matched to the skillset within the team need to be allocated prior to induction. The team leader is responsible for the overall running of the intubating process and ideally should not be performing any other tasks. The first intubator performs preoxygenation, laryngoscopy and intubation, with a second intubator on standby in case of failure. One team member is responsible for administering drugs and another should be competent at performing cricoid pressure.
Endotracheal Intubation: Sequence of Events
The salient sequence of events during an uncomplicated tracheal intubation on the intensive care unit is preoxygenation, cricoid pressure, anaesthetic induction, paralysis, laryngoscopy and confirmed endotracheal intubation.
Preoxygenation
Preoxygenation describes the process of replacing nitrogen with oxygen in the functional residual capacity (FRC) of the lungs to maximise oxygen stores. This allows for a longer apnoeic time to secure the airway before desaturation occurs, and should be performed where possible. Effective preoxygenation is performed by encouraging the patient to take tidal volume breaths of 100% oxygen through a tight fitting mask (to prevent entrainment of air) at flows above 10 l (to minimise rebreathing) for 3–5 minutes. Since FRC is lower in the supine position, adopting a head-up position can improve oxygen storage capacity. An expired oxygen concentration of 90% signifies effective preoxygenation. These ideal conditions for preoxygenation are not always possible, particularly in patients requiring intubation for respiratory failure who are deteriorating despite non-invasive respiratory support, or who are not able to cooperate with instructions. In these patients a careful attempt at preoxygenation can often be made, but care must be taken not to cause stomach inflation, which increases the risk of regurgitation and aspiration.
Cricoid
Cricoid pressure is a manoeuvre intended to reduce the risk of aspiration during induction. The circumferential cricoid cartilage is the most inferior laryngeal structure and can be pressed against the body of the fifth cervical vertebrae to compress the oesophageal lumen. The thumb and index finger are placed either side of the cartilage and a posterior force of 10 N is applied before induction, which is increased to 30 N following loss of consciousness. The assistant applying cricoid pressure needs to be experienced since incorrect technique can result in airway obstruction and a poor view on laryngoscopy.
Laryngoscopy
Laryngoscopy is most commonly performed with a curved Macintosh laryngoscope blade (sizes 3–5) to allow visualisation of the glottis and enable intubation under direct vision. The laryngoscope is held in the left hand and the blade is inserted into the oral cavity to the right side of the midline, which allows distraction of the tongue to the left. The tip is then slowly advanced over the base of the tongue and into the valecula, where an anterior vector force is applied to remove the tongue from the line of sight. The laryngeal view is graded according to the Cormack and Lehane classification (Table 8.4). Poor views can often be improved by external laryngeal manipulation (BURP; backwards, upwards and rightward pressure on the thyroid cartilage) or a reduction in cricoid pressure. With grade 3 and 4 views, the glottic aperture is not visualised and advanced airway equipment such as videolaryngoscopes and fibreoptic scopes may be required to aid intubation.
Table 8.4 Cormack and Lehane classification of laryngoscopy view
| Grade 1 | Full view of vocal cords/glottis |
| Grade 2 | Only posterior commissure/arytenoid cartilages visible |
| Grade 3 | Only epiglottis visible |
| Grade 4 | No glottic structure visible |
Confirming Correct Positioning
It is crucial to confirm that the endotracheal tube is in the trachea as opposed to the oesophagus following intubation. The most reliable test confirming correct positioning is six successive carbon dioxide traces on the capnograph with a value for end-tidal carbon dioxide (EtCO2) that corresponds to that expected for the patient. The absence of CO2 on the capnograph trace should prompt immediate suspicion of incorrect tube position, with direct laryngoscopy or fibreoptic bronchoscopy to resite the tube into the trachea. Failure to recognise oesophageal intubation will result in severe hypoxia within minutes followed by cardiac arrest and death. Clinical signs such as chest wall movement and breath sounds on auscultation, and misting within the tube, as well as appropriate compliance of the inflating bag are of value, but can all occur and give false reassurance with oesophageal intubation. Extra care is needed to confirm correct tube placement in patients in cardiac arrest undergoing CPR, or patients who are on venoarterial extracorporeal membrane oxygenation (VA ECMO) support since the value for EtCO2 on the capnograph trace will be lower than normal despite a correctly sited endotracheal tube (reduced pulmonary blood flow). If the value for EtCO2 is <2 kPa, extra steps should be taken to ensure that tube placement is correct.
The endotracheal tube should be sited to roughly 2 cm above the carina. Once capnography has confirmed placement within the patient’s airway, clinical examination can be used to avoid endobronchial intubation, but in difficult cases or where there is doubt, fibreoptic bronchoscopy can be used to ensure optimal placement above the carina. Too far in and flexion of the patient’s neck may cause contact with the carina causing irritation and bronchospasm or right main bronchial intubation. If the tube is not advanced far enough into the trachea, extension of the neck can lead to inadvertent extubation.
Difficult Intubation
A difficult intubation is defined as an inability to secure the airway with an endotracheal tube following three attempts, and occurs more commonly in critically ill patients. Repeated intubation attempts (more than three) can lead to airway oedema or bleeding, which will worsen visualisation with subsequent attempts. Expert help needs to be sought early, and the priority is to oxygenate via bag-mask ventilation aided by airway manoeuvres (jaw thrust, head tilt–chin lift) and adjuncts (oropharyngeal, nasopharyngeal airways), or ventilation via a supraglottic device. Management should follow local and national protocols (see Further Reading).
If ventilation and oxygenation are satisfactory, a definitive airway is required by another technique. Allowing the patient to wake up (recommended in the elective setting) is unlikely to be an appropriate option in the critically ill patient.
Advanced airway options available to secure a definitive airway in the ‘can’t intubate, can ventilate’ scenario include the following.
1. Videolaryngoscopy There are a number of videolaryngoscopes available to aid intubation. All contain a distal light source and camera to allow indirect visualisation of the glottis on a screen. These devices obviate the need for a direct line of sight in order to intubate.
2. Asleep fibreoptic intubation
A fibrescope preloaded with an endotracheal tube can be passed either orally or nasally under direct vision into the trachea.
3. Intubation through the existing laryngeal mask airway
An Aintree catheter (hollow bougie) can be loaded on to a fibrescope and the whole unit passed through the lumen of the ventilating laryngeal mask airway and into the trachea under direct vision. Upon removal of the fibrescope, an endotracheal tube can then be passed over the Aintree catheter.
4. Intubating laryngeal mask airway
The intubating laryngeal mask airway is specifically designed to allow an endotracheal tube to blindly pass through its lumen into the trachea.
5. Tracheostomy
Tracheostomies are usually performed electively on intubated patients. However in the difficult intubation scenario in the critically ill, there may be a case for direct tracheostomy formation whilst ventilating with a laryngeal mask airway.
Failed Ventilation
Failure of ventilation is defined as the inability to maintain oxygen saturations above 90% (if initially above this value) whilst administering 100% oxygen using a facemask or laryngeal mask airway.
Failed ventilation with increasing hypoxaemia in the setting of a difficult intubation, the ‘can’t intubate, can’t oxygenate’ scenario, is a rare but life threatening emergency. The immediate priority is to achieve oxygenation and since the upper airway route has failed, an invasive approach via the cricothyroid membrane is recommended. The cricothyroid membrane lies inferior to the vocal cords, is relatively avascular and can normally be easily located below the thyroid cartilage and above the cricoid cartilage.
There are three types of cricothyroidotomy approach:
1. Small cannula devices (2–3 mm ID)
Kink resistant cannulae can be directed caudally into the trachea and their position confirmed by aspirating air freely. The resistance through these narrow devices is large, so a high pressure (2–4 bar) oxygen source is needed to oxygenate. Some degree of upper airway patency is required to allow passive exhalation. This limits their use beyond short-term rescue oxygenation.
2. Large-bore devices (>4 mm ID)
These devices are inserted using either the Seldinger or cannula-over-needle technique. The larger diameter accommodates a 15 mm standard breathing circuit, which allows the patient to be effectively low pressure ventilated.
3. Surgical cricothyroidotomy (>6 mm ID)
The surgical approach involves making a horizontal scalpel incision through the cricothyroid membrane. Caudal traction on the membrane can then be applied from a tracheal hook to allow intubation with a size 6 mm ID cuffed tracheal or tracheostomy tube.
Managing the Intubated Patient
Attention to the endotracheal tube needs to be maintained following intubation in order to prevent airway related morbidity. Continuous waveform capnography should be used for every intubated patient to ensure correct tube positioning and allow surveillance against tube migration. Endobronchial intubation should be monitored for using auscultation, and chest X-ray. Checking the cuff pressure regularly is important since excessive pressures can cause tracheal mucosal damage, whereas an inadequate pressure can lead to microaspirates and ineffective ventilation. Cuff pressures between 20 and 30 cmH2O are recommended.
To reduce the risk of inadvertent extubation, judicious use of sedation is required as well as care when moving patients.
Extubation
Tracheal extubation is the process of removing the endotracheal tube to allow the patient to protect and maintain their own airway. To increase the likelihood of a successful extubation on the intensive care unit, a number of criteria firstly need to be met:
1. Indication for intubation has been corrected,
2. Haemodynamic stability,
3. Adequate ability to cough and clear secretions,
4. Neurologically appropriate,
5. Adequate oxygenation without requiring high levels of PEEP/FiO2,
6. Fully rewarmed (i.e. after cardiac surgery),
7. Minimal chest drain output.
A spontaneous breathing trial can then be performed using a T-piece or low-level pressure support and low PEEP to determine the likelihood of extubation success.
A backup reintubation plan should always be part of the extubation strategy as it may be more difficult than the original intubation. Tracheal extubation in the presence of a known difficult airway can be performed over an airway exchange catheter, which may be tolerated for up to 72 hours.
To perform an extubation in an uncomplicated airway, the patient should be given 100% oxygen for at least 3 minutes and the nasogastric tube (if present) should be suctioned. Gentle positive pressure should be applied followed by cuff deflation and controlled tube removal. Patients may initially be extubated onto a facemask and Waters circuit with 100% oxygen in order to assess adequacy of spontaneous ventilation.
Tracheostomy
Tracheostomy refers to the creation of a stoma at the skin surface, which is in continuity with the trachea. This procedure is commonly performed on the cardiothoracic intensive care unit and involves the insertion of a tracheostomy tube usually between the second and third tracheal rings. Despite being one of the oldest airway interventions, controversy still exists regarding the optimal timing, insertion technique and type of tracheostomy tube to use.
Advantages
Tracheostomy tubes offer a number of practical and clinical advantages over oral endotracheal tubes when managing the critically ill.
1. The work of breathing is reduced since the dead-space and airflow resistance is less than for equivalent sized endotracheal tubes.
2. Suctioning the tracheobronchial tree in patients with a high secretion burden is easier.
3. Tracheostomy tubes are well tolerated, which often allows the sedation and associated adverse effects to be reduced.
4. Mouth hygiene is easier to maintain and phonation as well as swallowing is possible.
5. Complications associated with prolonged translaryngeal intubation such as vocal cord damage and laryngeal ulceration are avoided.
Indications
The most common indication for tracheostomy in the intensive care setting is to facilitate prolonged mechanical ventilation and weaning. Recent estimates suggest that approximately 5% of patients following cardiac surgery require mechanical ventilation for at least 7 days due to perioperative complications, often on a background of underlying respiratory disease.
Other indications for tracheostomy include failure of protective airway reflexes, management of excessive secretions and relief of upper airway obstruction.
Tracheostomy Tubes
Tracheostomy tubes are made from either polyvinyl chloride, silicone or metal, and are available in a variety of shapes and sizes. When sizing tracheostomy tubes, important dimensions to consider include the diameter (inner and outer), length (proximal and distal) and curvature.
The optimal tracheostomy tube size provides the maximum internal diameter to facilitate airflow, whilst confining the outer diameter to roughly three quarters of the tracheal lumen. This minimises resistance across the tube and also allows adequate airflow around the tube during weaning and attempted phonation.
Since the trachea is essentially straight, the tip of an inappropriately long and curved tracheostomy tube can traumatise the anterior tracheal wall, whilst shorter tubes can abut posteriorly. To avoid these problems, angled tracheostomy tubes have a straight portion designed to lie more anatomically within the trachea.
Tracheostomy tube length is also an important consideration since patients with large necks often need a longer proximal portion, whereas patients with tracheal pathology (tracheomalacia) may need extra distal length to bypass disease.
Two different sizing systems exist, which can cause confusion since one is based on the length (and taper) of the outer tube, whilst the other refers to the internal diameter. As a reference for the clinician and to avoid sizing errors, the diameters and distinguishing features of tracheostomy tubes are marked on the flange.
Cuffed and Uncuffed Tubes
In the intensive care setting, most patients will initially require a cuffed tracheostomy tube to facilitate positive pressure ventilation and protect against aspiration. To reduce the risk of tracheal mucosal ischaemia and subsequent stenosis, a high volume/low pressure cuff inflated to a pressure of no more than 20–25 cmH2O is recommended. Uncuffed tracheostomy tubes allow for airway clearance but do not protect from aspiration, so are usually reserved for patients with adequate bulbar function who are unable to clear secretions.
Single and Double Cannula Tubes
Tracheostomy tubes can be stand-alone single lumen devices or contain an accompanying inner cannula (double cannula tubes). Double cannula tubes are inherently safer since in the event of obstruction the inner cannula can be removed completely and independently from the outer lumen to manage the blockage. For this reason, and to facilitate cleaning, it is often the preferred choice of tube for patients discharged to a stepdown unit or ward. Many intensive care units now use double cannulas from the outset. It is however important to appreciate that the addition of an inner cannula reduces the functional internal diameter of the tracheostomy tube, which increases airflow resistance and the work of breathing. Furthermore, in some designs, attachment to the ventilator is only possible when the inner tube and its associated 15 mm connector is in place.
Fenestrated and Non-fenestrated Tubes
Fenestrated tracheostomy tubes have single or multiple openings located posteriorly and above the cuff. Following cuff deflation during spontaneous ventilation, the fenestrations encourage maximal airflow through the larynx to allow phonation and an assessment of native airway patency in preparation for decannulation. Fenestrated tracheostomy tubes are often used in conjunction with one-way speaking valves. These valves cap the tracheostomy tube and allow inspiration but close on expiration, which directs airflow through the larynx when the patient exhales. Non-fenestrated inner tubes should be used if positive pressure ventilation is required to avoid air leaks.
Insertion Technique
Tracheostomies can be performed as open surgical procedures, most commonly in the operating theatre or percutaneously at the bedside.
Both procedures carry low complication rates in experienced hands and individual unit practice is largely determined by resource and local preference.
The percutaneous approach is logistically easier and proponents suggest that peristomal bleeding and infection rates are lower. Surgical tracheostomies, however, are more appropriate in patients with difficult neck anatomy and in the emergency scenario.
Percutaneous Tracheostomy
Patients are in the supine position and often have a bolster placed between their shoulders to allow adequate neck extension and exposure. Preprocedural ultrasound scanning of the neck is now increasingly being used to assess the anterior neck landmarks. Sedation needs to be increased to anaesthetic levels and paralysis should be given. It is important to ventilate with 100% oxygen.
Capnography to confirm correct tube positioning is mandatory and bronchoscopy through the tracheal tube to guide tracheostomy placement is recommended. In order to accommodate the tracheostomy tube, the endotracheal tube needs to be withdrawn under bronchoscopic guidance so the tip lies at the level of the cricoid cartilage prior to needle puncture.
All percutaneous tracheostomy tube placements are based on the Seldinger technique, with initial needle aspiration and guidewire insertion midway between the cricoid cartilage and sternal notch. This usually correlates to the space between the second and third tracheal rings. Tract dilatation and tracheostomy railroading can be performed using single step or sequential dilators, balloon inflation, forceps dilatation, or by the retrograde translaryngeal approach.
Surgical Tracheostomy
This procedure is often performed in an operating room under general anaesthesia. A vertical incision below the cricoid cartilage is usually made and following blunt dissection down, the strap muscles and thyroid isthmus are retracted to expose the trachea for tracheostomy placement. Open-ended stay sutures can be sited either side of the tracheal stoma to facilitate postoperative tube reinsertion in case of displacement.
Timing
Controversy exists as to when the optimal time is to perform tracheostomy placement. The benefit of a tracheostomy over prolonged translaryngeal intubation needs to be balanced against the likelihood of the patient needing extended ventilation and the risks associated with the procedure.
The largest randomised controlled trial to date (Tracman) found no benefit in performing early tracheostomies within 4 days, and suggested delaying this procedure until day 10 of translaryngeal ventilation. The initial tracheostomy tube is usually cuffed, non-fenestrated and may be either single or double cannula in design. It is recommended that the first routine tube change should not be performed within 4 days after a surgical tracheostomy and 7–10 days after a percutaneous one to allow the stoma and tract to be established first. The decision to change the tracheostomy tube should be multidisciplinary, based on the weaning, swallowing and ventilatory needs of the patient. For the first tube change or if there are anticipated difficulties, the exchange is usually performed over a guide such as a gum-elastic bougie, exchange catheter or suction tubing. With well-established tracts a guide is not usually needed. During all tube exchanges, however, there needs to be the necessary equipment and personnel available to manage failure.
Tracheostomy Management
A large proportion of adverse airway events on the intensive care unit involve tracheostomies and can be fatal. To minimise the risk of accidental decannulation or migration, the tracheostomy tube should be safely secured with sutures or an approved tracheostomy tube holder. Sedation should be used judiciously and care taken upon patient rolling and moving. In case of accidental tracheostomy dislodgement or removal, the safest approach is oral reintubation of the trachea to stabilise the situation.
Humidified air should be given in order to prevent the formation of excessively viscous secretions, which can obstruct the tube. Heat and moisture exchangers can be used for this purpose in patients who are either self-ventilating or needing ventilator support. To help manage especially thick secretions, heated water baths may be needed. Intermittent suctioning and physiotherapy at intervals dependent on patient secretion burden is also beneficial. The management of suspected dislodgement should follow guidance from the National Tracheostomy Safety Project (Figure 8.1 and Chapter 26 Airway Emergencies).
Figure 8.1 Emergency tracheostomy management.
Swallowing
Swallowing allows early establishment of oral feeding and contributes to the psychological well being of patients with tracheostomy tubes. However, these patients are at risk of aspiration since the tube and cuff can impede normal laryngeal movements during swallowing as well as cause oesophageal compression. Prior to allowing oral feeding, patients need to be able to tolerate cuff deflation and should have passed a bedside swallowing assessment by a speech therapist.
Weaning and Decannulation
There is no clear consensus on the optimal tracheostomy weaning protocol and different units vary in their practice. The overriding theme is to gradually reduce ventilatory support and encourage normal airflow patterns in the upper airways to such an extent that the patient can manage without the tracheostomy tube. This involves increasing periods of cuff deflation, changing to smaller diameter and fenestrated tubes, and using speaking valves or caps. A successful wean requires patient commitment and regular multidisciplinary input from nurses, physiotherapists, speech therapist, intensivists and surgeons.
Decannulation should occur as soon as the tracheostomy tube is no longer required and it is safe to do so. This occurs at the end of a successful wean, with multidisciplinary team agreement and when core criteria have been met (Table 8.5). It is advisable to decannulate during the morning when the patient is fasted and can be observed during the day with equipment and expertise to manage any complications to hand.
Table 8.5 Patient decannulation criteria
| Able to maintain and protect their own airway |
| Adequate respiratory function, free from ventilator support |
| Haemodynamically stable |
| Absence of fever or active infection |
| Consistently alert |
| Strong cough |
| Competent swallow |
| Clinically stable |
| No forthcoming procedures requiring anaesthesia (within 7–10 days) |
Summary
The establishment and maintenance of a patent airway with ventilation to the lungs is a critically important first step in the management of a patient on the cardiothoracic intensive care unit. Capnography is an essential adjunct for any patient receiving artificialventilatory support via an endotracheal tube or tracheostomy tube. Extra care must be taken not to miss tube dislodgement in the setting of reduced CO2 delivery to the lungs, i.e. in cardiac arrest, or in VA-ECMO support. Anticoagulation can increase the risk of bleeding into the airway following manipulation, and extra care is required in these patients.
Learning Points
Equipment for emergency intubation should be immediately available in the cardiothoracic critical care unit alongside equipment for management of the difficult airway.
Extra care is needed to avoid airway bleeding in patients receiving anticoagulation.
Oesophageal intubation may be difficult to diagnose in the presence of low pulmonary blood flow: use direct assessment via laryngoscopy or fibreoptic bronchoscopy in case of doubt.
Management of the difficult airway should follow local and national guidance.
Safe airway management requires multidisciplinary input.
Further Reading
MCQs
Please identify whether the below statements are true or false.
1. Difficult intubation management in the cardiothoracic critical care unit should involve:
2. Regarding tracheostomy:
The tube with deflated cuff should be a tight fit in the trachea so that no air can escape around it
3. Endotracheal intubation:
Should always have waveform capnography available continuously to aid with assessment of tube position
4. Cardiothoracic patients may experience airway complications due to:
Introduction
The pleural space is a thin, fluid filled space between the visceral and parietal pleura. In a healthy 70 kg individual, this space contains a few millilitres of serous pleural fluid, the function of which is to allow the pleurae to slide easily over the lungs during ventilation. The presence of air or fluid (pus, blood, chyle or excessive pleural fluid) impedes the normal function of the lungs, and depending on the symptoms and signs affecting the patient, will require chest drainage.
Usually, the pressure in the pleural space is less than atmospheric. This negative pressure helps maintain partial lung expansion and the magnitude of negativity changes during the respiratory cycle. In inspiration the pressure is approximately −8 cmH2O and in expiration this falls to −4 cmH20. A breach of the pleural cavity leads to development of a positive pressure in this space either equal to or more than atmospheric pressure, leading to a pneumothorax.
History
The earliest known reference to chest drainage dates back to the fifth century Hippocratic texts. Here conservative management of empyemas is described using plants and herbs, and open drainage for persistent infections is well documented including the surgical technique for doing this. Hippocrates gave detailed descriptions of using a scalpel to cut between the ribs, evacuating pus and leaving a hollow tube in for 2 weeks.
Since this, other physicians have described the technique including the leading French physician surgeon Guy de Chauliac in 1395. The first description of a closed chest drainage system was by Hewett in 1876.
Indications
The indications for chest drain insertion are to remove fluid, air or both from the pleural space. Table 9.1 shows the common indications for chest drainage.
Table 9.1 Common indications for chest drainage
| Traumatic haemothorax |
| Large spontaneous or traumatic pneumothorax |
| Benign or malignant pleural effusion |
| Chylothorax |
| Following cardiac or thoracic surgery |
Figure 9.1a shows a chest radiograph of a patient with a large pneumothorax following cardiac surgery, and Figure 9.1b shows the same patient post chest drain insertion. Figure 9.2a shows a chest radiograph of a patient with a left pleural effusion and Figure 9.2b shows the same patient post drain insertion.
Figure 9.1 (a) Radiograph of a patient with a large right pneumothorax (black arrows). (b) The same patient with a right sided chest drain in situ (white arrow) and reinflation of the right lung.
Figure 9.2 (a) Chest radiograph of a patient with a large right pleural effusion (black arrows) and (b) resolution of the effusion with the insertion of a right sided chest drain (black arrows).
Technique
The emergency insertion of a large bore chest drain for the relief of a tension pneumothorax is well described in the Advanced Trauma Life Support guidelines and there are many published step-by-step descriptions of the procedure.
The British Thoracic Society guidelines for the insertion of chest drains were originally developed in 2003 and subsequently updated in 2010. These guidelines were in effect aimed at training and guiding physicians to safely perform this procedure. Figure 9.3 shows the BTS guidelines as an algorithm.
Anatomical Landmarks
The BTS describes the triangle of safety within which chest drains should be placed (Figure 9.4). This triangle is the area bounded by the anterior border of latissimus dorsi and the lateral edge of pectoralis major with the base formed by a line superior to the horizontal line of the nipple.
The advantages of this position are to minimise potential damage to underlying nerve and vascular structures such as the long thoracic nerve and the lateral thoracic artery. Additionally, placement in this area may prevent excessive breast or muscle tissue dissection, reducing the risk of scarring. The presence of a loculated effusion may require a more posterior drain placement but this should be undertaken under the supervision of a specialist or under image guidance. Posteriorly placed drains are more likely to cause discomfort.
Related posts:
Section 1 – Diagnosis
Section 3 – Therapeutic Intervention
Section 4 – Advanced Organ Support
Section 6 – Perioperative Care: The Patient Post Cardiac Surgery
Section 7 – Disease Management in the Cardiothoracic Intensive Care Unit: Incidence; Aetiology; Diagnosis; Prognosis; Treatment
Section 5 – Acute Disorders
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