Securing the airway, ventilation and procedural sedation

Published on 14/03/2015 by admin

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Chapter 2 Securing the airway, ventilation and procedural sedation

SECURING THE AIRWAY

(Paul Gaudry)

Assessment and stabilisation of the airway have priority over other aspects of resuscitation in patients with life-threatening illness or injury.

Factors confounding airway management

Shape of face. A poor seal between the face and mask impedes bag-valve-mask ventilation. Causes are a beard, edentia, emaciation, obesity, facial trauma and burns.

Difficult airway anatomy. Impedes direct laryngoscopy and endotracheal intubation. Evaluate the anatomy before both elective and emergency endotracheal intubation. Focus on protruding maxilla relative to mandible (macrognathia), high arched palate, poor dentition, large tongue (macroglossia), short neck, limited mouth opening (intercisor gap). Test for neck mobility if cervical spine injury is not an issue. A sternomental distance less than 12.5 cm in an adult is the best predictor of ‘difficult’ intubation. Remember the airway anatomy of children relative to adults. Anticipate ‘difficult’ intubation in certain congenital syndromes such as Down syndrome and Pierre Robin syndrome.

Upper airway obstruction. Initially the airway may only be threatened, but the pathological process may be progressive, as with burns and infection or movement of a foreign body. Priority must be given to securing the airway, as delay may itself precipitate complete obstruction. Intravenous sedation may also precipitate complete obstruction and should be avoided. If anaesthesia is required, inhalational induction may be preferred and relaxants avoided until bag-valve-mask ventilation is confirmed.

Cervical spine injury. Head and neck immobilisation must be maintained in the victim of blunt trauma until injury to the cervical spine is definitely excluded. If endotracheal intubation is indicated, it must be achieved without flexion, extension or distraction of the neck. Intubation should be performed while an assistant maintains in-line immobilisation, without traction, of the head and neck.

Full stomach. All seriously ill or injured patients requiring intubation must be presumed to have a full stomach. Apply cricoid pressure during intubation to prevent regurgitation and aspiration.

Limited haemodynamic reserves. A patient with any form of shock is subject to haemodynamic deterioration during intubation, from the drugs used to facilitate intubation or from hypoxaemia before or during intubation. Preintubation oxygenation volume resuscitation and sometimes inotrope support are needed. The drugs used, and especially the drug dosage, must be individualised.

Head injury. Autoregulation of cerebral blood flow is impaired in head injury. The therapeutic aim before, during and after intubation is to maximise the chance to maintain arterial blood pressure and minimise the rise in intracranial pressure.

Types of ventilation

Rapid sequence induction (RSI)

This is employed to induce unconsciousness and muscular paralysis to provide optimal intubating conditions, to avoid aspiration from a probable full stomach and to protect against reflex bradycardia and raised intracranial pressure due to manipulation of the airway. It is contraindicated if ‘difficult’ intubation is predicted and successful bag-valve-mask ventilation is considered unlikely. This will depend on the patient, the equipment and assistance available and the skill of the operator.