, Amy Gospel2, Andrew Griffiths3 and Jeremy Henning4
Intensive Care Unit, James Cook University Hospital, Middlesbrough, UK
Tyne and Wear, UK
The York Hospital, Middlesbrough, UK
James Cook University Hospital, Middlesbrough, UK
At the end of this chapter you should:
Understand the importance of post-intubation care
Know the ABCDEF approach to pre-transfer checks
The quality of care delivered after intubation and during transfer to hospital may have as much influence on outcome as the intubation itself. Experience from intrahospital transfers suggests that unexpected problems or complications occur in around 65 % of transfers, with critical or life-threatening incidents occurring in nearly 9 % (Lovell et al. 2001; Papson et al. 2007). In the pre-hospital environment the incidence of complications can be expected to be higher, as the environment is often less controlled and the patient more unstable. Lovell et al. commented that many of the difficulties were preventable with adequate pre-transport communication and planning.
Intubating a patient increases the burden of patient monitoring and complicates the transfer. The patient can no longer protect their own airway, they are unable to ventilate themselves effectively or communicate the potential for deterioration or further injury. Additional equipment is required to adequately monitor their vital signs and ventilation. Vigilance is essential to avoid accidental extubation, disconnection, and decannulation. It is possible to minimise these risks by careful packaging and meticulous monitoring during the transfer to hospital. Minimum monitoring standards are essential for the safe transfer of intubated patients in the pre-hospital environment. Ventilators and monitors should include audible alarms which can be heard easily (through headsets if necessary), and visual alarms that can be seen clearly during transfer.
Long distance transfer of critically ill patients can be achieved without any major complications in the setting of a dedicated transfer team (Uusaro et al. 2002). It is reasonable to assume that a dedicated and well-trained pre-hospital team should also minimise, if not eliminate, the incidence of major complications on route to hospital. The transfer of intubated patients between hospitals is usually carried out by anaesthetists (Jameson and Lawler 2000), but a large number of pre-hospital intubations and subsequent transfers are not. For non-anaesthetists who are not used to transferring critically ill ventilated patients, there is a lot to remember. An ABCDEF approach (utilising a checklist) should make this easier. This system is also recommended for those who consider themselves experienced transfer doctors. The stress of managing a critically ill patient in a pre-hospital environment can easily result in incomplete preparation and an increased risk of adverse events.
Pre-transport planning and preparation in a structured manner is therefore the focus of this chapter. After intubation and before transfer a full check should be performed.
5.1 A (and C-Spine) BCDEF Approach
5.1.1 Airway (Box 5.1)
The airway only remains protected as long as the endotracheal tube (ETT) cuff remains inflated below the vocal cords. For this reason it must be secure. This can be achieved using either adhesive tape or a fabric tie. Both techniques have their limitations. Tape is unlikely to provide adequate security in the presence of rain, sweat, grease, blood, or facial hair. Fabric tube ties overcome these issues, however, if applied too tightly, can lead to venous congestion and increased intracranial pressure. For this reason, tape should be used preferentially for head-injured patients. This can be made even more secure by splitting the tape longitudinally (like trouser legs) and wrapping around the tube. Zinc oxide tape is preferred by many operators, as its gets more adhesive as it warms up. Alternatively others recommend more expensive proprietary fixation devices, which may hold the ETT more securely. The Thomas™ ETT holder allowed significantly less ETT displacement when compared to a tied tape in a manikin study (Murdoch and Holdgate 2007).
Flexion and extension of the head can lead to migration of the ETT. This is particularly relevant in children where smaller anatomy means that relatively small movements can result in either endobronchial intubation or extubation. Although in children, flexion appears to consistently cause downward displacement of the tube (distance relative to age) and extension causes upward movement, in adults the movement can be either way (up to 2 cm down or 3 cm out) (Weiss et al. 2006; Yap et al. 1994). In an adult the ETT cuff should be placed 2 cm below the cords to minimise the risk of problems occurring. Some ETTs are marked at the distal end to provide an indication of optimal positioning. The mark on the tube should usually be positioned just through the vocal cords.
In adults, the left main bronchus is narrower and branches off the trachea at more of an acute angle compared with the right; hence endobronchial intubation is invariably right-sided. The incidence of endobronchial intubation can be reduced by ensuring the presence of bilateral breath sounds and chest movement after securing the tube in position. Endobronchial intubation should be suspected in the presence of unexpectedly high airway pressures during ventilation. Bronchospasm may also be an indicator of endobronchial intubation or the potential for it (the bronchospasm may be due to carinal irritation). Withdrawing the ETT by 2 cm is usually adequate to improve the situation.
When the ETT is positioned satisfactorily, note the measurement at the teeth (usually 22–24 cm for an adult). This may then be used as a reference point if there are concerns that the tube has migrated during transfer. This information should be recorded and communicated on handover.
Prolonged ETT cuff inflation pressures of greater than 30 cm H2O can lead to tracheal mucosa ischaemia (Seegobin and van Hasselt 1984). This is unlikely to be an issue during transport following pre-hospital anaesthesia (PHA) within the UK due to relatively short transfer times. If longer journey times are expected, consideration should be given to monitoring and adjusting pressures with a simple hand-held device. This is more relevant when travelling by air, when actual cuff pressure remains the same but actual mucosal capillary pressure is lower (although the same relative to atmospheric pressure). Alternatively the air can be exchanged for saline, although it can be difficult to adjust cuff pressure using this.
Effective suction must always accompany the intubated patient. Both Yankauer (oropharyngeal) and endobronchial catheters should be available for airway toileting en route. More recent tubes have suction ports above the cuff to allow for regular suction of oropharyngeal secretions, which tend to pool above the cuff in the unconscious patient. In the intensive care setting, subglottic suction ETTs have been shown to decrease the incidence of ventilator associated pneumonia (Muscedere et al. 2011). If a patient is being transferred to a unit using these, it is preferable to use this type of tube for PHA to avoid unnecessary tube change at a later stage.
A heat moisture exchange filter (HMEF) should always be used between the patient and the ventilator circuit. This protects the ventilator equipment from contamination and allows some moisture and heat exchange between the inspired and expired gases. Cold dry inspired gases can increase heat loss and degrade the function of respiratory cilia.
Box 5.1: Post-intubation Airway Check
5.1.2 Cervical Spine (Box 5.2)
One in every nine trauma patients requiring intubation will have a cervical spine injury. Of these, one third will be unstable (Patterson 2004). Therefore it is not unreasonable to assume that every severely injured trauma patient may have an unstable neck injury and treat them as such.
A long spinal board and a semi-rigid collar are often used for extrication of casualties in Road Traffic Collisions (RTCs). The spinal board may then be used for onward transfer to hospital. Prolonged periods of immobilisation on a spinal board can lead to the development of pressure necrosis. This is more likely to occur in the hypotensive patient because of reduced tissue perfusion. The skin overlying bony prominences in contact with the spinal board is most at risk (scapulae, sacrum, and heels). The long spinal board is also not a good spinal splint as it allows a significant degree of lateral movement. Therefore it should be considered only as an extrication device. Increasingly a scoop stretcher is used for pre-hospital transfer of trauma patients. It confers advantages of requiring less rolling and movement of the patient, and offers more stability against lateral spinal movement. If transfer times are likely to be prolonged (e.g., >30 min), the patient should be “scooped” onto a vacuum mattress and the spinal board used purely for supporting the mattress during transfer between vehicles/trolleys. When a patient is transferred on a long spinal board or a scoop stretcher, it should be removed as soon as possible on arrival in the Emergency Department (i.e., on completion of the primary survey) (Vickery 2001).
Semi-rigid collars are also associated with significant morbidity. Inappropriate sizing can lead to raised intracranial pressure (ICP). It is important to ensure that no clothing is trapped under the collar as this may result in skin injury and inadequate stabilisation. It is essential that correct sizing and fitting takes place on scene. These collars often remain in situ for a considerable time prior to definitive management, and some hospital staff may have limited experience in their use. Secure head blocks (or fluid/sand bags with tape) are also required to ensure full cervical spine immobilisation.
Box 5.2: Post-intubation Cervical Spine Check
Collar sized and fitted correctly
Consider vacuum mattress
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5.1.3 Breathing (Box 5.3)
Manual ventilation cannot provide reliable and consistent minute ventilation (Cardman and Friedman 1997). It is also labour intensive and limits concurrent activity. Mechanical ventilators address both these issues. Even when mechanical ventilation is employed, optimal oxygenation and ventilation cannot be assured (Helm et al. 2003). End-tidal CO2 (ETCO2) must be used for any intubated ventilated patient, as it can be used to judge the adequacy of ventilation. The waveforms can also be useful for the recognition of trends in ventilation and diagnosing ventilatory problems (Fig. 5.1).
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