What is the best position for a patient who needs endotracheal intubation?

Guy Jukes, Trainee ODP.

Guy’s and St Thomas’ NHS Trust, London; Terry Ferns, Lecturer Practitioner, University of Greenwich, Avery Hill Campus School of Health, London

The ability to secure a patient’s airway is crucial in the management of acutely life-threatening illnesses and injuries (Blanda, 2000). Endotracheal (ET) intubation can be hazardous, particularly as patients may have deteriorated rapidly or may have combined respiratory and cardiovascular failure (Shelly and Nightingale, 1999). In such a stressful and potentially life-threatening process, nurses need a clear understanding of their role.

Critical care nursing staff often face the dilemma of identifying which patients need to be intubated, and when (see below).

Once patient is identified

The priority is patient safety. A typical scenario might be to have three staff at the bedside:

- An experienced anaesthetist

- An experienced nurse

- A nurse new to critical care.

The old saying ‘failure to prepare means prepare to fail’ is particularly relevant. Nurses should ensure the patient is attached to adequate monitoring equipment - ECG, arterial line and saturation probe - and suction and oxygen should be checked and available. Some anaesthetists prefer high-vacuum suction to the normal suction generally available. The patient should have patent intravenous access. If the patient has a nasogastric tube the stomach contents should be aspirated.

Even the best equipment is of no use without a competent, professional team. The panel (right) lists what is necessary.

What size ET tube?

The Advanced Life Support Manual (ERC, 2001) suggests the usual size ET tube required for male ET intubation is 8-9cm and for women 7-8cm. The oral ET tube should be positioned at about 23cm at the incisors for men and 21cm for women (Jimenez, 2000). The tube should be positioned about 2cm above the carina, which can be observed on the post-intubation chest X-ray.

Prazeres (2002) says that, to ensure safety, the following essentials must be present before intubation, remembered by the mnemonic SALT:

-Suction: crucial to clear the airway and allow visualisation of the vocal chords

-Airway: the oral airway can make it easier to mask ventilate a patient and oxygen must always be available

-Laryngoscope: for inserting the tube

-Tube: an ET tube for intubation.

Preparing the patient

The nurse should tell the patient what is about to happen, and they should then be pre-oxygenated. Intubation should take no longer than 30 seconds and should be preceded by ventilation with a high concentration of oxygen, ideally at least 85%, for a minimum of 15 seconds (ERC, 2001).

In a controlled environment pre-oxygenation generally takes longer. The aim is to maximise the patient’s KPaO2 (partial pressure of oxygen) as the patient will be unable to maintain any respiratory effort. This is often the most frightening time for the patient. To ensure they stay calm they have a hand-held facial mask over the nose and mouth, medical/nursing staff standing behind them issuing instructions, and a change of position to facilitate the process.

The bed head should be removed and the patient’s position flat (Prazeres, 2002), with their face at the level of the xiphoid cartilage of the standing person performing the procedure. A small pad/pillow should be placed under the occiput. Extend the head at the atlanto-occipital joint, which aligns the oral, pharyngeal, and laryngeal axis so that the passage from the lips to the glottic opening is virtually a straight line and the patient adopts the classic ‘sniffing the morning air’ position (Prazeres, 2002; ERC, 2001).

Cricoid pressure

Before the procedure, the team should discuss applying cricoid pressure. This compresses the cricoid cartilage against the cervical vertebrae, preventing gastric reflux and aspiration. In my experience, this is the prerogative of the anaesthetist, but nurses should indicate when the patient last ate, and whether a nasogastric tube is in situ, when it was aspirated and what volume of gastric contents the patient has produced.

The cricoid cartilage lies just below the Adam’s apple and may be difficult to find. Once cricoid pressure is applied, it must not be removed without the consent of the person intubating, even if the ET tube appears to be inserted. The tube may be in the wrong place and removal of cricoid pressure may lead to vomiting. Do not apply cricoid pressure to a vomiting patient, as this can cause damage to the oesophagus (ERC, 2001). Do not remove cricoid pressure prematurely. Aspiration during intubation is disastrous for the patient. If you are right-handed it is easier to stand to the patient’s right and apply cricoid pressure with the right hand.

The process of intubation

As the procedure continues, the patient is given a combination of drugs. Holding the laryngoscope, the anaesthetist looks in the mouth for loose teeth, foreign bodies or dentures, and for key landmarks. The nurse should calmly describe the vital-signs status of the patient regularly as the anaesthetist will be focused on the airway, not the monitor. Be prepared to pass the ET tube and other equipment to the person intubating. Be alert all the time as complications are common (see below).

Once the tube is inserted, the cuff should be inflated and checked for pressure with a manometer. The patient’s chest should be observed for equal expansion and auscultation performed at the mid-axillary line (ERC, 2001). Be suspicious if only one side of the chest expands, as this may indicate that the tube has been pushed in too far. This is more likely to occur into the right main bronchus, due to its anatomical position.

The tube should be secured, the patient attached to an appropriate ventilator and a check X-ray ordered. A high concentration of oxygen should continue and arterial blood gases should be taken. Appropriate humidification is required, as the tube bypasses the upper airway - responsible for warming, moistening and filtering inhaled air. Finally, the patient should be cared for on a one-to-one basis and closely monitored.

Drugs used during intubation

In a cardiac arrest situation pharmacological intervention may not be considered necessary. However, in critical care, safe intubation of a deteriorating patient requires drugs to facilitate passage of the ET tube.The choice is up to the anaesthetist (and beyond this Factfile’s scope). Nurses should be aware of the Nursing and Midwifery Council Guidelines on the Administration of Medicines (2002). Drugs can be divided into sedatives and drugs producing neuromuscular blockade (depolarising and non-depolarising muscle relaxants):

- Neuromuscular blocking agents (depolarising muscle relaxants). The most common is suxamethonium. It imitates acetylcholine and is taken up by post-synaptic receptors producing a lengthened period of depolarisation. Paralysis results for three to four minutes, depending on dosage

- Non-depolarising muscle relaxants. These agents antagonise the action of acetylcholine at the neuromuscular junction (Blanchard, 2002). Common drugs include atracurium, pancuronium and vecuronium

- Sedatives: a wide variety of sedatives are available for intubation. Administration is dangerous and guidelines (UKAMERC, 2002) have recently became available. Once again, minimal effects on the cardiovascular system are required, which influences drug choice.

REASONS FOR INTUBATING

- Airway protection due to, for example, obstruction, facial trauma or if patient is unconscious

- To treat profound hypoxaemia and respiratory failure and to initiate positive pressure ventilation, for example, for patients with pneumonia or cardiogenic shock

- To facilitate tracheal suction and the removal of secretions

- To maintain respiratory function during surgery/anaesthetics

- To facilitate patient rest

Source: Shelly and Nightingale, 1999

EQUIPMENT NEEDED

- Laryngoscopes, generally with a curved (Macintosh) blade and a straight (Millar) blade. Check light regularly and before use. Have spare blades, lights and batteries to hand

- Self-refilling bag valve combination (for example an Ambu-bag)

- A selection of endotracheal tubes - inflate the tube before inserting it to ensure there are no leaks

- Oral airways

- Gloves

- A rigid oral suctioning catheter

- Lubrication, Magill forceps, introducer

- 10ml syringe, artery forceps, tape

- Catheter mount

- Cuff pressure manometer

- Stethoscope

- Checked and working ventilator

- Resuscitation equipment immediately available in case of complications

Source: ERC, 2001

POST-INTUBATION COMPLICATIONS

- Trauma to lips, teeth, vocal chords

- Transient cardiac arrhythmia related to vagal or sympathetic nerve traffic

- Hypertension, tachycardia or raised intracranial pressure

- Aspiration

- Oesophageal intubation

- Infection

- Reduced cough reflex

- Tracheal ulceration

- Tracheal stenosis

- Hypersalivation

- Laryngeal oedema

- Bronchospasm

- Reduced ability to communicate

- Biting on tube

- Discomfort

- Tube kinked or damaged on insertion, resulting in perforation and leaks

Source: ERC, 2001

Blanchard, A.R. (2002) Sedation and analgesia in intensive care. Medications attenuate stress response in critical illness. Postgraduate Medicine 111: 2, 59-74.

Blanda, M. (2000)The difficult airway: tools and techniques for acute management. Journal of Critical Illness 15: 7, 358-373.

European Resuscitation Council. (2001) Advanced Life Support Manual (4th edn). Antwerp: University of Antwerp/European Resuscitation Council.

Jimenez, R. (2000) How to Decrease the Incidence of Mainstream Intubation. Northbrook, Ill: American College of Chest Physicians.

Nursing and Midwifery Council. (2002) Guidelines for the Safe Administration of Medicines. London: NMC.

Prazeres, G. de A. (2002) Orotracheal Intubation. Available at: www. medstudents.com.br/proced/ proced5/intubat.htm

Shelly, M.P., Nightingale, P. (1999) Respiratory support: ABC of intensive care. British Medical Journal 318: 1674-1677.

UK Academy of Medical Royal Colleges and Their Faculties. (2002) Implementing and Ensuring Safe Sedation Practice for Healthcare Procedures in Adults (Report of an Intercollegiate Working Party chaired by Royal College of Anaesthetists). London: UKAMRCF.