V. Mitchell

Difficult Airway Society Guidelines for the management of tracheal extubation: Management of tracheal extubation

Tracheal extubation is a high‐risk phase of anaesthesia. The majority of problems that occur during extubation and emergence are of a minor nature, but a small and significant number may result in injury or death. The need for a strategy incorporating extubation is mentioned in several international airway management guidelines, but the subject is not discussed in detail, and the emphasis has been on extubation of the patient with a difficult airway. The Difficult Airway Society has developed guidelines for the safe management of tracheal extubation in adult peri‐operative practice. The guidelines discuss the problems arising during extubation and recovery and promote a strategic, stepwise approach to extubation. They emphasise the importance of planning and preparation, and include practical techniques for use in clinical practice and recommendations for post‐extubation care.

The use of cuffed tracheal tubes for paediatric tracheal intubation, a survey of specialist practice in the United Kingdom

Background and objective For more than 50 yr, uncuffed tracheal tubes have been the gold standard for intubation in children under the age of 8 yr. However, recently there has been interest in the use of cuffed tubes in paediatric practice. This survey aimed to benchmark UK practice with regard to tracheal intubation within specialist paediatric centres, exploring current cuffed tracheal tube use in children. Methods A questionnaire was e‐mailed to the paediatric intensive care unit and anaesthetic department clinical leads in all UK specialist paediatric hospitals with a paediatric intensive care unit (n = 30). Information was requested on the use of tracheal tubes across all paediatric age groups, as well as the reasons for non‐use and the incidence of complications attributed to cuffed tubes. Results A total of 20 paediatric intensive care unit and 15 anaesthetic questionnaires were returned, equating to a response rate of 67% and 50%, respectively. Only 5% of the paediatric intensive care unit and 7% of the anaesthetic respondents routinely use a cuffed tube in children under the age of 8 yr. The commonest reason cited in both groups for non‐cuff use was that there is minimal benefit to be gained over using an uncuffed tracheal tube. The most frequent specific indication for use of a cuffed tube was a reduced lung compliance (60% respondents both groups). In all, 45% of the paediatric intensive care unit respondents and 100% of the anaesthetists reported that they did not routinely monitor the intracuff pressure when using a cuffed tube. The incidence of observed complications attributed to the use of cuffed tubes was far higher amongst paediatric intensive care unit consultants (65% vs. 7% anaesthetists); however, the majority in both groups stated that such complications were no more common than when using an uncuffed tube (60% paediatric intensive care unit and 53% anaesthetists). Conclusion Cuffed tracheal tubes are rarely routinely used in children, particularly in the under 8 yr age group, in specialist paediatric centres in the UK. When used, it is predominantly for a specific indication, and the monitoring of intracuff pressure is not routine. Current expert consensus is that complications are equally as common when using a cuffed as an uncuffed tube.

A randomised comparison of the single use LMA Flexible™ with the reusable LMA Flexible™ in paediatric dental day‐case patients

In this study we compared the performance of the single use flexible laryngeal mask airway (LMA Flexible™) with the original reusable LMA Flexible™ in paediatric dento‐alveolar day‐case surgery. The aim of the study was to determine whether these two supraglottic airway devices were clinically equivalent when used for simple dental extractions in children under general anaesthesia. This randomised comparative trial in 100 healthy children used first attempt airway insertion success as its primary outcome measure. Secondary outcomes included the adequacy of ventilation, incidence of airway obstruction and the requirement for device manipulation and the incidence of adverse airway outcomes during recovery from anaesthesia. No difference was found between the devices in first attempt insertion success rate (94% with reusable LMA Flexible and 90% with single use LMA Flexible, p = 0.358), and ease of insertion was also similar (p = 0.5). Both devices performed equally well during surgery, with no significant differences in episodes of intra‐operative airway compromise (p = 0.387), and both the single use and reusable LMA Flexible displayed excellent recovery characteristics, with no occurrences of emergence airway obstruction. No blood was discovered within the inner LMA tube shaft in either device, implying that both protected against tracheobronchial soiling. We conclude therefore that the single use LMA Flexible is an acceptable alternative to the reusable LMA Flexible.

Ultrasound-guided localisation of the trachea.

dropped down from 68 to 35 beats. min, managed with atropine 0.3 mg intravenously. Thereafter, the patient had an uneventful course. The patient was discharged with complete pain relief. Despite a plethora of available treatment modalities, PRGR remains the procedure of choice for the management of TGN because it is simple and safe with less morbidity [3]. However, in our case the temporal association between glycerol injection after placing the needle tip in the trigeminal cistern and the occurrence of cardiorespiratory arrest implies occurrence of a TCR. The afferent stimulus of TCR passes to the sensory nuclei of trigeminal nerve in the floor of fourth ventricle via the Gasserian ganglion [4]. Short internuncial nerve fibres in the reticular formation connect with the efferent pathway from the motor nucleus of the vagus nerve. Depressor fibres from the vagus nerve end in the myocardium. The efferent fibres are cardio-inhibitors leading to hypotension, bradycardia, asystole, and ventricular fibrillation through coronary vasospasm. Other efferent fibres induce apnoea and gastric hypermotility. TCR persists as long as the stimulus is present. Removing the triggering factor can cause cessation of the reflex, thereby returning the haemodynamic parameters back to normal [5]. Premedication with intramuscular atropine may not prevent occurrence of such reflexes [6]. However, intravenous atropine has proven beneficial in treating TCR [7], as in our case. The initial heart rate does not prevent the occurrence of TCR, and tachycardia is not protective [5]. There are various predisposing factors such as hypercapnia, hypoxia, light anaesthesia, a child with high resting vagal tone, opioids such as sufentanil and alfentanil, and pre-operative beta-blockade or calcium channel blockade. Though no such association existed in our case, we feel the possibility of TCR should always be considered during PRGR.

Re‐intubation over airway exchange catheters – mind the gap

Oximetry. Anaesthesia 2009; 64: 1045–8. 2 Funk L, Weiser T, Berry W, et al. Global operating room distribution and pulse oximetry supply: an estimation of essential infrastructural components for surgical care. Lancet 2010; In press. 3 Haynes AB, Weiser TG, Berry WR, et al. A surgical safety checklist to reduce morbidity and mortality in a global population. New England Journal of Medicine 2009; 360: 491–9. 4 Walker IA, Wilson IH. Anaesthesia in developing countries – a risk for patients. Lancet 2008; 371: 968–9. 5 Weiser TG, Regenbogen SE, Thompson KD, et al. An estimation of the global volume of surgery: a modelling strategy based on available data. Lancet 2008; 372: 139–44. 6 Ouro-Bang’na Maman AF, Tomta K, Ahouangbevi S, Chobli M. Deaths associated with anaesthesia in Togo, West Africa. Tropical Doctor 2005; 35: 220–2. 7 Heywood AJ, Wilson IH, Sinclair JR. Perioperative mortality in Zambia. Annals of the Royal College of Surgeons of England 1989; 71: 354–8. 8 Fenton PM, Whitty CJ, Reynolds F. Caesarean section in Malawi: prospective study of early maternal and perinatal mortality. British Medical Journal 2003; 327: 587.

Anaesthetic considerations for patients receiving photodynamic therapy in head and neck surgery

&NA; Photodynamic therapy is an innovative modality in the treatment of malignant and non‐malignant diseases. Owing to its widespread use, there will be an increase in the number of photosensitized patients presenting for both elective and emergency anaesthesia. As one of the few centres involved in providing this specialized treatment for maxillofacial conditions, we would like to highlight its main anaesthetic considerations.

Pre‐oxygenation before extubation

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ENTGas, tubes and flow

An understanding of the principles of fluid mechanics is essential when considering the physical concepts of gas flow in relation to the airway. Gases and liquids act as fluids. Their behaviour is governed by the gas laws, and is described in terms of pressure, volume and temperature. Flow is the amount of fluid moving per unit time and can be laminar or turbulent. Laminar flow is governed by Poiseuille’s law, is a function of the viscosity of a fluid, and has a linear relationship with pressure. Flow becomes turbulent once a fluid is above critical velocity. The onset of turbulent flow can be predicted using Reynolds’s number. The rate of turbulent flow is a function of the density of a fluid. Flow through an orifice is always turbulent and is inversely proportional to the square root of the density of the fluid. The Bernoulli effect describes the pressure drop when a fluid accelerates through a constriction and is used in Venturi devices, which have wide clinical applications. Although small-diameter tracheal tubes theoretically increase the resistance to airflow and the work of breathing, there is no evidence of respiratory compromise when tubes with an internal diameter of 6.0 mm or 6.5 mm are used in adult anaesthesia.