Dilemmas and Difficult Airways: more than just anatomy

Dilemmas and Difficult Airways: more than just anatomy

Introduction

The management of the difficult airway is now quite rightly entrenched in anaesthetic practice, and relies on a pragmatic and to some degree evidence based approach which has been formulated into guidance that will apply to most situations.(1)

Quite rightly, the guidelines concentrate on what is thought to be best practice when faced with technical or anatomical difficulty. However, airway difficulty can be caused by the circumstances in which the patient is presented, in which case the situational awareness displayed by the anaesthetist is the key skill to successful management.

This article outlines the successful urgent management of three cases of difficult airway where the difficulty was presented by circumstance, rather than technical or anatomical issues.

 

Case 1

The anaesthetic team were called to the emergency department to assist with a patient who had taken an overdose of a variety of neuroactive substances. The referral was based on the fact that the patient was “uncooperative” and needed “airway protection.”

On arrival, the team were presented with a male in his 40’s escorted by two large security guards. No medical or nursing staff was present at that time. He was disorientated and aggressive to the point where he refused to be monitored, and had displaced cannulae. He was face down on the emergency department (ED) trolley, with arms and legs entwined in the cot sides. When approached, his arms would flail wildly, with purpose. He would not however open his eyes or interact appropriately. Glasgow Coma Scale (GCS) was recorded as 7/15 by emergency department staff. The Anaesthetic team judged the GCS to be greater, but it was immediately clear that the patient was in a state of drug induced inebriation to the extent that the airway was not suitably protected, and was in a condition that a medical ward would not be able to cope with as he was neither orientated nor alert. The patient briefly tolerated a short period of monitoring with a pulse oximeter, which showed normal saturations. No other intervention was possible as the patient would violently repel any other intervention due to their semi -conscious state. Admission to critical care following anaesthesia and IPPV was required for the patient’s own safety.

The team set up for a rapid sequence induction, but were unable to secure any iv access, to pre oxygenate the patient or position them appropriately without risk of harm to themselves or the patient. Obvious signs of a head injury were excluded, and it was decided that administration of a sedative was required to provide optimum conditions. The choice was between nasal midazolam, rectal lorazepam or intramuscular (im) ketamine or benzodiazepine. It was decided that the im route would be unreliable, and ketamine unpredictable following the presumed effects the substances ingested. Rectal lorazepam was impractical. Therefore 20mg nasal midazolam was administered with the team fully standing by to intervene as required. After five minutes, the patient was less aggressive, and the team safely turned him onto his back, and pre oxygenated him whilst administering cricoid pressure. IV access was immediately obtained as standard AAGBI monitoring was placed. A rapid sequence induction with propofol and suxamethonium was commenced. A grade I intubation resulted, and anaesthesia was maintained with propofol infusion and atracurium. A chest X ray confirmed that there was no evidence of aspiration. A CT scan confirmed that there was no evidence of head injury. The patient was taken to critical care, where they were successfully extubated the next morning.

 

Case 2

The anaesthetic team were placed on standby by the emergency department staff who were expecting an 11 year old child with learning problems, whom the paramedics stated had “unreadably low saturations” due to a likely pneumonia. On arrival, the child was extremely frightened and aggressive, despite being accompanied by parents and carers, to the point where it was impossible to attach any monitors or to administer oxygen. They would not accept being positioned on a trolley. The child was however deeply cyanosed, and it was clear that without immediate intervention a cardiac arrest would soon result.

All anaesthetic equipment and drugs had been prepared already. Fortuitously, two anaesthetic consultants were present, and decided that the only course of action was to ask the carers to restrain the child whilst iv access, and immediate rapid sequence induction took place. The parents and carers consented that this was the only way forward, and with the agreement of all staff, the child was gently restrained, whilst the anaesthetic team secured venous access and immediately administered propofol, suxamethonium and fentanyl. As soon as possible, the child was placed in the appropriate position on the floor, cricoid and oxygen was administered, and intubation performed. Anaesthesia was maintained with a propofol infusion, and rocuronium. The child was then placed on a trolley, and further access and monitoring was put in place. The X ray showed an extensive pneumonia. There was no evidence of aspiration. The child was later transported to a tertiary specialist unit, and was successfully extubated a week later.

 

Case 3

A patient presented for electroconvulsive therapy. The past medical history was unremarkable except for proven malignant hyperpyrexia, necessitating the avoidance of suxamethonium, used to attenuate the intensity of the induced seizure.

The patient was under section at a neighbouring hospital which was not a designated ECT centre, and so had to be transported to the ECT suite, which, was in an isolated area of the receiving hospital. The multidisciplinary ECT team, which included an anaesthetist, discussed the logistics surrounding the procedure. Her physical health had been optimised, and the need for ECT was thought to be urgent. It was decided to use mivacurium to attenuate the seizure. The patient needed to be escorted by staff trained in physical restraint. The ECT suite was cleared, and the list timed to give extra time for the needs of the patient. The first anaesthetist assessed the airway and confirmed that her health was optimised. The patient was anaesthetised with propofol and mivacurium (0.1mg/kg). Following successful induction of a seizure, the airway was maintained with an LMA until spontaneous ventilation returned. Recovery occurred in the usual way, and a full course of ECT was administered over six weeks, aiding the patient’s recovery.

 

Discussion

These three cases are typical of the problems that can be presented to anaesthetists, where there is an urgent requirement to secure the airway, but the difficulty in doing so is logistical, rather than anatomical. In none of these cases were the anaesthetists “gung ho” or reckless; rather their decision to use in the one case pre intubation sedation to obtain control of an uncontrollable patient, and in the others therapeutic restraint to allow urgent, life preserving intervention (i.e. ventilation) to occur were taken after careful, considered-but rapid-thought regarding both the easiest and safest way to circumvent the difficulty in the patient’s best interests. In the first, the administration of a sedative in a non-usual manner was required, which resulted in rapid resolution of the difficulty. Nasal midazolam is proving to be a useful adjunct in the treatment of patients who can be uncooperative due to learning difficulty: it is reliable, and easy to administer, but has to be specially formulated and can be difficult to obtain(4,5). In the second, the requirement to intubate the patient as soon as possible in less than ideal circumstances was recognised as the safest way to proceed. In the third, planned restraint and the use of a longer acting muscle relaxant allowed the patient to receive potentially lifesaving therapeutic treatment.

These decisions were made on the background of proper facilities and equipment and staff being available, the presence of senior staff, and the recognition that the main reason airway control would be difficult was going to be the need to rapidly control the patient’s resistance to any intervention due to their underlying illness. The key role of the anaesthetists here was to prepare all essential staff and equipment as per usual, to recognise that unusual intervention was required, to ensure that the airway difficulty could be managed safely, and to be aware how they could correct the situation had the plan that was decided upon not been successful, or suffered complications.

We would not recommend these interventions as routine management. However, they are examples of when the situational awareness of the anaesthetist makes it clear that anaesthetic intervention is rapidly required, and that control of the situation can only be obtained in an unconventional manner. In both cases, the airway difficulty can be defined as how to achieve rapidly needed airway control, in cases where standard practice is impossible to apply in a reasonable time scale, and are examples where lateral, logical thinking can result in a safe, and successful, outcome.

 

Authors:

J Watts, BSc MB ChB FRCA FFICM, Consultant in Anaesthesia and Critical Care Medicine

K Beresford , MB ChB FRCA

K Butler, MBChB FRCA MRCS (A & E), Consultant in Anaesthesia

East Lancashire Teaching Hospitals NHS Trust, Blackburn

 

References

  1. Difficult Airway society Guidelines for management of unanticipated difficult intubation in adults 2015 https://www.das.uk.com/guidelines/das_intubation_guidelines accessed 4/12/17)
  2. Difficult Airway Society Paediatric Difficult Airway Guidelines https://www.das.uk.com/files/APA1-DiffMaskVent-FINAL.pdf accessed 4/12/17
  3. Frerk C Mitchell VS McGarry AFet al Difficult Airway society Guidelines for management of unanticipated difficult intubation in adults 2015 BJA: British Journal of Anaesthesia, Volume 115, Issue 6, 1 December 2015, Pages 827–848,)
  4. Watts J Safe sedation for all practitioners Radcliffe 2008
  5. Hartgraves PM Primosch RE An evaluation of oral and nasal midazolam for pediatric dental sedation. ASDC Journal of Dentistry for Children[01 May 1994, 61(3):175-181]
  6. Chiaretti A, Barone G, Rigante D, et al Intranasal lidocaine and midazolam for procedural sedation in children Archives of Disease in Childhood 2011;96:160-163.
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