John J. Henderson

Difficult Airway Society guidelines for management of the unanticipated difficult intubation

Problems with tracheal intubation are infrequent but are the most common cause of anaesthetic death or brain damage. The clinical situation is not always managed well. The Difficult Airway Society (DAS) has developed guidelines for management of the unanticipated difficult tracheal intubation in the non‐obstetric adult patient without upper airway obstruction. These guidelines have been developed by consensus and are based on evidence and experience. We have produced flow‐charts for three scenarios: routine induction; rapid sequence induction; and failed intubation, increasing hypoxaemia and difficult ventilation in the paralysed, anaesthetised patient. The flow‐charts are simple, clear and definitive. They can be fully implemented only when the necessary equipment and training are available. The guidelines received overwhelming support from the membership of the DAS.

The Pentax‐AWS® rigid indirect video laryngoscope: clinical assessment of performance in 320 cases*

The Pentax‐AWS® airway scope system is a rigid indirect video laryngoscope with integrated tube guidance. Laryngoscopy and intubation are visualised using a built in LCD monitor which displays the view obtained by a CCD camera mounted in the tip of the laryngoscope. We describe its clinical performance in 320 patients. The Pentax‐AWS significantly improved the laryngeal view compared to the Macintosh laryngoscope. Forty‐six patients (14%) who were classified as Cormack Lehane glottic view grade 3 or 4 using the Macintosh laryngoscope were classified as grade 1 (45 cases) or 2a (1 case) using the Pentax‐AWS airway scope. Laryngeal views measured by percentage of glottic opening score were improved significantly using the Pentax‐AWS. Intubation using the Pentax‐AWS was successful in all cases, 96% at the first and 4% at the second attempt. The mean (SD) time required to place the tracheal tube was 20 (10) s. The Cormack Lehane grade obtained with the Macintosh blade did not affect the total time to correctly position the tube using the Pentax‐AWS. Intubation difficulty scale (score = 0 in 305 patients, score = 1 in 14 and score = 2 in one patient) indicates that tracheal intubation was performed easily in most cases. The Pentax‐AWS not only improves the laryngeal view, but its tube guide also facilitates rapid, easy and reliable tracheal intubation under vision. It can be useful in routine anesthesia care and may be advantageous in the situation of unanticipated difficult intubation.

Equipment and strategies for emergency tracheal access in the adult patient

The inability to maintain oxygenation by non‐invasive means is one of the most pressing emergencies in anaesthesia and emergency care. To prevent hypoxic brain damage and death in a ‘cannot intubate, cannot oxygenate’ situation, emergency percutaneous airway access must be performed immediately. Even though this emergency is rare, every anaesthetist should be capable of performing an emergency percutaneous airway as the situation may arise unexpectedly. Clear knowledge of the anatomy and the insertion technique, and repeated skill training are essential to ensure completion of this procedure rapidly and successfully. Various techniques have been described for emergency oxygenation and several commercial emergency cricothyroidotomy sets are available. There is, however, no consensus on the best technique or device. As each has its limitations, it is recommended that all anaesthetists are skilled in more than one technique of emergency percutaneous airway. Avoiding delay in initiating rescue techniques is at least as important as choice of device in determining outcome.

Airtraq for awake tracheal intubation.

tion to the fact that the majority of the fibreoptic intubations were performed by trainees. The authors state that this new technique achieved a mean intubation time of 6.3 min in patients with difficult laryngeal exposure, and compared this to a mean of 16.1 min in the study predominantly carried out by trainees. To prove the real benefit of this technique it would seem far more sensible to compare their new results with figures from their institute using the standard technique. This would eliminate the major confounder of comparing novice trainees with experienced fibreoptic intubators. Until this is done, the benefit of fibrecapnic intubation is not evidence-based.

Pentax-AWS airway Scope as an alternative for awake flexible fiberoptic intubation of a morbidly obese patient in the semi-sitting position

For anesthesia induction in a morbidly obese patient with a full stomach, awake flexible fiberoptic bronchoscope (FOB) intubation in the semi-sitting position may be a suitable choice. A new rigid indirect videolaryngoscope, the Pentax-AWS system, has a unique feature of an adjustable built-in monitor and is designed to be used in patients in various positions. However, the efficacy of its use in such situations has not been investigated or reported. We used the Pentax-AWS system for the intubation of a morbidly obese patient (body mass index >50) who was at risk of regurgitation, anticipated difficult intubation, and supine hypotensive syndrome due to inferior vena cava compression by a huge ovarian cyst. The patient was placed in the sitting position during the intubation procedure. The patient’s trachea was intubated with the Pentax-AWS by an anesthesiologist positioned at the patient’s right and facing her. The Pentax-AWS offered easy intubation under good visualization of the glottic aperture as a consequence of its adjustable integrated monitor, in contrast to difficult intubation with other videolaryngoscopes which require an external monitor. This report illustrates that the Pentax-AWS is useful as an alternative for flexible fiberoptic intubation under these circumstances, as a consequence of its adjustable built-in monitor and integrated tube channel.

Ultrasound-guided cannula cricothyroidotomy.

1128 November 2012 W HEN difficulty with airway management is anticipated, standard guidelines recommend that the airway is secured in the awake patient.1 In the “cannot intubate, cannot ventilate” situation, surgical or cannula cricothyroidotomy is required.1 However, identification of the cricothyroid membrane by palpation is frequently inaccurate, even under elective conditions.2 Preoperative evaluation of the anterior neck with an ultrasound may be a viable technique of increasing the safety of cricothyroidotomy. An 82-yr-old man with a difficult intubation profile as a consequence of cervical spine disease was scheduled for percutaneous nephrolithotripsy in the prone position. Before awake fiberoptic intubation, his neck was scanned with an ultrasound linear probe to identify the cricothyroid membrane. Because he had a history of hypertension and ischemic heart disease, we decided to apply tracheal anesthesia before intubation. The distance from skin surface to the membrane was measured as 0.84 cm, and neither vessel nor abnormal structure was observed. Cannula cricothyroidotomy was then performed with a 22G intravenous catheter under ultrasonographic guidance in an out-of-plane configuration, because this is a more reliable technique of achieving exact midline puncture.3 The figure shows the anterior-posterior view of the larynx and sternocleidomastoid muscle (asterisk) as the cannula (arrow) enters the cricothyroid membrane (dashed line) from the 12 o’clock direction. As soon as loss-of-resistance sensation was detected, air was aspirated. Lidocaine was injected through the cannula, and then fiberoptic bronchoscope intubation was performed uneventfully. Preoperative examination of the larynx with sonography can accurately identify the cricothyroid membrane and may provide other anatomical information. Though the cricothyroid membrane puncture is less frequently used to achieve airway anesthesia, ultrasound guidance may improve safety whenever this technique is used, including prophylactic and emergency cannula cricothyroidotomy.

Comparison of the Pentax-AWS Airway Scope with the Macintosh laryngoscope for nasotracheal intubation: a randomized, prospective study

STUDY OBJECTIVE To evaluate the effectiveness of the Pentax-AWS Airway Scope (AWS) in comparison to the Macintosh laryngoscope during nasotracheal intubation. DESIGN Prospective randomized study. SETTING Operating room of a university-affiliated hospital. PATIENTS 90 ASA physical status 1 and 2 adults, aged 18 to 72 years, scheduled for orthodontia surgery requiring nasotracheal intubation. INTERVENTIONS Patients were randomly assigned to three groups to undergo tracheal intubation with a Macintosh laryngoscope (Group Mac; n = 30), AWS with its tip inserted into the vallecula for indirect elevation of the epiglottis (Group AWS-I; n = 30), or AWS with its tip positioned posterior to the epiglottis for direct elevation of the epiglottis (Group AWS-D; n = 30). MEASUREMENTS Percentage of glottic opening (POGO) score at the time of laryngeal exposure, time required for intubation, and intubation difficulty scale (IDS) were measured. The frequency of postoperative sore throat and hoarseness also were noted. MAIN RESULTS Patient demographics did not differ among the groups. In Groups AWS-I and AWS-D, IDS scores were reduced significantly, and the percentages of glottic opening were significantly improved, compared with the Macintosh group. Time to place the endotracheal tube was significantly shortest in Group AWS-I. In one case from each group, intubation within two attempts failed and a different approach was required. CONCLUSION The AWS offers better intubation conditions than the Macintosh laryngoscope during nasotracheal intubation. The AWS may be used to elevate the epiglottis both directly and indirectly for nasotracheal intubation.

Tips for intubation with the Pentax‐AWS® Rigid Indirect Laryngoscope in morbidly obese patients

Angioedema is a potentially life-threatening condition, which may occur following the administration of tramadol. The reported incidence is 1 in 1000 to 1 in 10 000. I recently encountered this rare complication in a patient who had previously developed angioedema in response to ACE-inhibitor therapy. The elderly patient was admitted for investigation of atypical chest pain and had a number of comorbid conditions including IDDM, COPD, ischaemic heart disease, congestive heart failure and end-stage kidney disease. Tramadol was the only new agent commenced in the preceding 48 h. The patient woke early in the morning with a massively swollen tongue. There was no indication that this had been traumatic. His tongue was protruding from the oral cavity and he was drooling profusely. There was no stridor or stertorous breathing and he had a relatively comfortable breathing pattern. Haemoglobin saturation on pulse oximetry was 98%. Auscultation revealed no bronchospasm and there was no flushing or pruritus. Haemodynamic parameters were within normal limits. Surprisingly he did not appear alarmed. It became apparent that he had suffered four similar episodes and had been advised to avoid ACE-inhibitors. He was treated with nebulised adrenaline, hydrocortisone, chlorphenamine, ranitidine and oral doses of dexamethasone. As his airway was not critically compromised instructions were given to closely observe him and inform the anaesthetist of any change in his condition. Frequent assessments were made throughout the day and the swelling resolved within 12 h. An internet search conducted on the ward highlighted a number of reports of angioedema following the administration of tramadol. The Swedish Medical Products Agency reported 11 cases. The authors alluded to the fact that a known reaction to ACE-inhibitors may be associated with a predisposition to tramadol-induced angioedema [1]. Another report questioned the safety of tramadol as an alternative to NSAID following NSAID-induced urticaria [2]. Of 28 patients with NSAID-induced urticaria, five developed urticaria in response to tramadol. This included one case of life-threatening laryngeal oedema. The British National Formulary mentions urticaria and rashes as adverse reactions to tramadol, but not angioedema per se [3].

Cardiovascular responses to tracheal intubation with the Airway Scope (Pentax-AWS).

The recommended laryngoscopy technique with the AWS involves using the blade tip to elevate the epiglottis directly. This procedure is very similar to that used with the Bullard laryngoscope (BuLS; Gyrus ACMI, Southborough, MA, USA). Araki et al. [2] demonstrated that there were no signifi cant differences in cardiovascular responses after intubation between the BuLS and the McL in 30 patients without airway problems. The Airtraq laryngoscope (ATQ; Prodol, Vizcaya, Spain) is another device similar to the AWS, but the view of the glottis can be optimized either by lifting the epiglottis directly, as with the AWS or BuLS, or indirectly by tensioning the hyoepiglottic ligament after the blade tip is positioned in the vallecula. Maharaj et al. [3] demonstrated that increases in HR were less when intubation was achieved with the ATQ than with the McL. Both the AWS and the ATQ provide a view of the glottis from behind the dorsum of the tongue, and therefore both devices probably require less lifting force than that required during direct laryngoscopy. It is unlikely that the technique of epiglottis elevation could cause this different result, (i.e., ATQ, but AWS attenuates cardiovascular responses), because the McL blade tip is alCardiovascular responses to tracheal intubation with the Airway Scope (Pentax-AWS)

Use of a new curved forceps for McGrath MAC TM video laryngoscope to remove a foreign body causing airway obstruction

view was achieved. Tracheal intubation was performed under vision, using the image displayed on the built-in monitor of the McGrath MACTM. Some chicken meat particles were suctioned through the tracheal tube, and ventilation was performed effectively. The SpO2 rapidly returned to 99%. The patient recovered consciousness after 1 h and became rousable on vocal stimulus. The tracheal tube was removed and he recovered uneventfully within a day.