Dynamic Airflow Limitation after Topical Anaesthesia of the Upper Airway

Airway devices for awake tracheal intubation in adults: a systematic review and network meta-analysis

BACKGROUND

Awake tracheal intubation is commonly performed with flexible bronchoscopes, but the emerging role of alternative airway devices, such as videolaryngoscopes, direct laryngoscopes, and optical stylets, has been recognised.

METHODS

CENTRAL, CINAHL, EMBASE, MEDLINE, and Web of Science were searched for RCTs that compared flexible bronchoscopes, direct laryngoscopes, optical stylets and channelled or unchannelled videolaryngoscopes in adult patients having awake tracheal intubation were included. The co-primary outcomes were first-pass success rate and time to tracheal intubation. Continuous outcomes were extracted as mean and standard deviation, and dichotomous outcomes were converted to overall numbers of incidence. Frequentist network meta-analysis was conducted, and network plots and network league tables were produced.

RESULTS

Twelve RCTs were included, none of which evaluated direct laryngoscopes. The first-pass success rate was not different between flexible bronchoscopes, optical stylets, and channelled and unchannelled videolaryngoscopes, with the quality of evidence rated as moderate in view of imprecision. Optical stylets, followed by unchannelled videolaryngoscopes and then felxible bronchoscopes resulted in the shortest time to tracheal intubation, with the quality of evidence rated as high. No differences were shown between the airway devices with respect to the incidence of oesophageal intubation, change of airway technique, oxygen desaturation, airway bleeding, or the rate of hoarseness and sore throat.

CONCLUSIONS

Flexible bronchoscopes, optical stylets, and channelled and unchannelled videolaryngoscopes were clinically comparable airway devices in the setting of awake trachela intubation and the time to tracheal intubation was shortest with optical stylets and longest with flexible bronchoscopes.

Use of a trans-tracheal rapid insufflation of oxygen device in a "cannot intubate, cannot oxygenate" scenario in a parturient -a case report

Background

The trans-tracheal rapid insufflation of oxygen (TRIO) device is less commonly used and is an alternative to trans-tracheal jet ventilation for maintaining oxygenation in a "cannot intubate, cannot oxygenate" (CICO) scenario.

Case

We report the successful use of this device to maintain oxygenation after jet ventilator failure in a parturient who presented with the CICO scenario during the procedure for excision of laryngeal papilloma.

Conclusions

A stepwise approach to the airway plan and preparation for an event of failure is essential for good materno-fetal outcomes. The TRIO device may result in inadequate ventilation that can lead to hypercarbia and respiratory acidosis. Hence, it should only be used as a temporizing measure before a definitive airway can be secured.

Fibreoptic intubation in airway management: a review article

Since the first use of the flexible fibreoptic bronchoscope, a plethora of new airway equipment has become available. It is essential for clinicians to understand the role and limitations of the available equipment to make appropriate choices. The recent 4th National Audit Project conducted in the United Kingdom found that poor judgement with inappropriate choice of equipment was a contributory factor in airway morbidity and mortality. Given the many modern airway adjuncts that are available, we aimed to define the role of flexible fibreoptic intubation in decision-making and management of anticipated and unanticipated difficult airways. We also reviewed the recent literature regarding the role of flexible fibreoptic intubation in specific patient groups who may present with difficult intubation, and concluded that the flexible fibrescope maintains its important role in difficult airway management.

Clinical application of a novel endoscopic mask: a randomized controlled, multi-center trial in patients undergoing awake fiberoptic bronchoscopic intubation

BACKGROUND

Awake fiberoptic bronchoscopic tracheal intubation is usually regarded as an effective method in the management of predicted difficult airway. Hypoxia during awake nasal fiberoptic bronchoscopic intubation leads to discontinuation of the procedure, prolonged manipulation time and increased risk of severe complications. The main aim of the study was to test whether the novel endoscopic mask is helpful for hypoxia during the intubation.

METHODS

This was a randomized, controlled, multi-center study. 55 patients were recruited, but one patient was lost to follow-up. Finally, 54 patients (19 man and 35 women) were analyzed. After entering the operating room, nasal catheter oxygen-providing was given in the control group, and the treatment group received endoscopic mask oxygen-providing, with a flow rate of 3 L/min, lasting into the end of the intubation. Primary outcomes included mean arterial pressure, heart rate, minimum pulse oxygen saturation and incidence of pulse oxygen saturation ≤ 90%. Secondary outcomes included number of intubation attempts and time to intubation. All outcomes were finally measured.

RESULTS

Minimum pulse oxygen saturation during awake nasal fiberoptic bronchoscopic tracheal intubation was significantly higher in the endoscopic mask intubation group (91.7% ± 4.7%) than that the nasal catheter intubation group (87.6% ± 8.2%, P = 0.031. Furthermore, the incidence of pulse oxygen saturation ≤ 90% was significantly lower in the endoscopic mask intubation group (20.0%, 5/25) than that in the nasal catheter intubation group (51.7%, 15/29, P = 0.037). But mean arterial pressure of during intubation was significantly higher in the endoscopic mask group (100.0 ± 13.3 vs 90.3 ± 21.8, P = 0.049). In addition, there were no differences in the number of intubation attempts (P = 0.45) or time to intubation between the two groups (P = 0.38).

CONCLUSIONS

The endoscopic mask was safely used in awake fiberoptic bronchoscopic tracheal intubation, with advantages of stable blood pressure and potential prevention of desaturation. Beginners for the intubation procedure and patients at high risk of hypoxia could benefit from the use of the endoscopic mask.

TRIAL REGISTRATION

Trial registration: www.chictr.org.cn . Registration No.: ChiCTR-TRC-13004086. Date of Registration: 8th, Sep, 2013.

Anaesthetic management of acute airway obstruction

The acutely obstructed airway is a medical emergency that can potentially result in serious morbidity and mortality. Apart from the latest advancements in anaesthetic techniques, equipment and drugs, publications relevant to our topic, including the United Kingdom's 4th National Audit Project on major airway complications in 2011 and the updated American Society of Anesthesiologists' difficult airway algorithm of 2013, have recently been published. The former contained many reports of adverse events associated with the management of acute airway obstruction. By analysing the data and concepts from these two publications, this review article provides an update on management techniques for the acutely obstructed airway. We discuss the principles and factors relevant to the decision-making process in formulating a logical management plan.

Optimizing oxygenation and intubation conditions during awake fibre-optic intubation using a high-flow nasal oxygen-delivery system

BACKGROUND

Awake fibre-optic intubation is a widely practised technique for anticipated difficult airway management. Despite the administration of supplemental oxygen during the procedure, patients are still at risk of hypoxia because of the effects of sedation, local anaesthesia, procedural complications, and the presence of co-morbidities. Traditionally used oxygen-delivery devices are low flow, and most do not have a sufficient reservoir or allow adequate fresh gas flow to meet the patient's peak inspiratory flow rate, nor provide an adequate fractional inspired oxygen concentration to prevent desaturation should complications arise.

METHODS

A prospective observational study was conducted using a high-flow humidified transnasal oxygen-delivery system during awake fibre-optic intubation in 50 patients with anticipated difficult airways.

RESULTS

There were no episodes of desaturation or hypercapnia using the high-flow system, and in all patients the oxygen saturation improved above baseline values, despite one instance of apnoea resulting from over-sedation. All patients reported a comfortable experience using the device.

CONCLUSIONS

The high-flow nasal oxygen-delivery system improves oxygenation saturation, decreases the risk of desaturation during the procedure, and potentially, optimizes conditions for awake fibre-optic intubation. The soft nasal cannulae uniquely allow continuous oxygenation and simultaneous passage of the fibrescope and tracheal tube. The safety of the procedure may be increased, because any obstruction, hypoventilation, or periods of apnoea that may arise may be tolerated for longer, allowing more time to achieve ventilation in an optimally oxygenated patient.

The incidence, success rate, and complications of awake tracheal intubation in 1,554 patients over 12 years: an historical cohort study

PURPOSE

Awake tracheal intubation is one recommended option to address select situations in the management of a patient with an anticipated difficult airway. A scarcity of data exists on how often awake intubation is performed or whether its use is changing over time, particularly with the increasingly widespread availability of video laryngoscopy. This retrospective database review was undertaken to determine the incidence, success, and complications of awake intubation and the incidence of other tracheal intubation techniques in the operating room over a 12-yr period (2002-2013) at our institution.

METHODS

The Anesthesia Information Management System in use at a Canadian tertiary care centre was searched for all awake intubations that occurred during the years 2002-2013. Records were also searched to identify airway methods other than direct laryngoscopy that may have been used after the induction of general anesthesia. Changes in both the incidence of awake intubation and in the use of video laryngoscopy over the 12 years were analyzed using linear regression modelling.

RESULTS

Of 146,252 cases performed under general anesthesia with endotracheal intubation, 1,554 intubations (1.06%) were performed awake. There was no significant change in the rate of awake intubation over the studied years (slope -1.4(-4) incidence·year(-1); 95% confidence interval [CI]: -3.0(-4) to 3.0(-5); P = 0.102). The relatively steady rate of awake intubation occurred despite a significant increase in the use of video laryngoscopy over the same time (slope 0.080 incidence·year(-1); 95% CI: 0.076 to 0.083; P < 0.001), particularly from 2009 onwards. Attempted awake intubation failed in 31 (2%) of the cases. Self-reported complications occurred in 15.7% of successful procedures. In addition, in a convenience sample of three years (2011-2013), the rate at which each of 49 attending staff performed awake intubation varied widely from 0-3.4 awake intubations per 100 cases of general anesthesia with endotracheal intubation.

CONCLUSIONS

At our tertiary care centre, we did not find a significant change in the use of awake tracheal intubation over the studied years 2002-2013 despite increasing availability and use of video laryngoscopy. It appears that awake tracheal intubation retains an important and consistent role in the management of the difficult airway.

High prevalence of exercise-induced laryngeal obstruction in athletes

INTRODUCTION

Unexplained respiratory symptoms reported by athletes are often incorrectly considered secondary to exercise-induced asthma. We hypothesized that this may be related to exercise-induced laryngeal obstruction (EILO). This study evaluates the prevalence of EILO in an unselected cohort of athletes.

METHODS

We retrospectively reviewed the prevalence of EILO in a cohort of athletes (n = 91) referred consecutively during a 2-yr period for asthma workup including continuous laryngoscopy during exercise (CLE) testing. We compared clinical characteristics and bronchial hyperreactivity between athletes with and without EILO.

RESULTS

Of 88 athletes who completed a full workup, 31 (35.2%) had EILO and 38 (43.2%) had a positive bronchoprovocation or bronchodilator reversibility test. The presence of inspiratory symptoms did not differentiate athletes with and without EILO. Sixty-one percent of athletes with EILO and negative bronchoprovocation and bronchodilator reversibility tests used regular asthma medication at referral.

CONCLUSIONS

In athletes with unexplained respiratory symptoms, EILO is an important differential diagnosis not discerned from other etiologies by clinical features. These findings have important implications for the assessment and management of athletes presenting with persistent respiratory symptoms despite asthma therapy.

Tracheal intubation with a flexible intubation scope versus other intubation techniques for obese patients requiring general anaesthesia

BACKGROUND

The prevalence of obesity (body mass index (BMI) > 30 kg/m(2)) is increasing in both developed and developing countries, leading to a rise in the numbers of obese patients requiring general anaesthesia. Obese patients are at increased risk of anaesthetic complications, and tracheal intubation can be more difficult. Flexible intubation scopes (FISs) are recommended as an alternative method of intubation in these patients. Intubation with an FIS is considered an advanced method, requiring training and experience; therefore it may be underused in clinical practice. Patient outcomes following intubation with these scopes compared with other devices have not been systematically reviewed.

OBJECTIVES

We wished to compare the safety and effectiveness of a flexible intubation scope (FIS) used for tracheal intubation in obese patients (BMI > 30 kg/m(2)) with other methods of intubation, including conventional direct laryngoscopy, non-standard laryngoscopy and the use of intubating supraglottic airway devices. We aimed to compare the frequency of complications, as well as process indicators, such as time taken for intubation and the proportion of first attempts that were successful, between groups using the different methods of intubation.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and two trial registers on 18 January 2013, and performed reference checking and citation searching and contacted study authors to identify additional studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) of participants aged 16 years and older with a BMI > 30 kg/m(2) that had compared the use of an FIS for tracheal intubation with any one of three comparison groups: direct laryngoscopy; non-standard laryngoscopy (including indirect laryngoscopy using a videolaryngoscope (VLS) or a rigid or semi-rigid stylet); or intubation of supraglottic airway devices (SADs).

DATA COLLECTION AND ANALYSIS

We used standard methodological approaches expected by The Cochrane Collaboration, including independent review of titles, data extraction and risk of bias assessment by two investigators.

MAIN RESULTS

Three eligible studies were identified, all comparing the use of an FIS with a VLS. All studies were small, with only 131 participants in total across all trials. It was impossible for the intubators to be unaware of the device used, so all studies were at high risk of performance and detection bias for outcomes related to intubation. Because of substantial differences in design between the studies, we did not combine their results in meta-analyses. The results for all outcomes were inconclusive, with no differences noted between FIS and VLS. Two studies with experienced intubators reported first attempt success rates greater than 70% in both groups and less than 5% of participants requiring a change of intubation device. No evidence was found of any difference in difficulty or time taken between FIS and VLS intubation. No serious complications or airway trauma was reported, so we were unable to address these outcomes. Bleeding was uncommon, occurring in less than 5% of participants, and we found no evidence that it was more likely in the FIS group. One small study with a novice intubator reported no successful intubations using an FIS and compared with the use of an intubating SAD and stylet, as well as with a VLS. With only five participants in each group, no conclusions can be drawn from these additional comparisons.

AUTHORS' CONCLUSIONS

The evidence base is sparse, and the existing literature does not address the clinical questions of patient safety posed by this review. We are therefore unable to draw any conclusions on safety or effectiveness. More primary research is needed to investigate optimal intubation techniques in obese patients, and new studies should be powered to detect differences in complications and in success rates rather than process measures such as speed, which are of limited clinical importance.

Anesthesia for the patient with tracheal stenosis

Tracheal stenosis may occur secondary to trauma, tumors, infection, inflammatory diseases, or iatrogenic causes. Understanding these lesions requires a basic understanding of the physics of airflow. All of these patients must be carefully evaluated and require a series of tests, including pulmonary function tests and radiographic studies. Treatment of tracheal lesions is a multidisciplinary issue and requires the close participation of interventional pulmonologists, anesthesiologists, and surgeons.